Viper

https://pkg.go.dev/github.com/spf13/viper
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Viper is a complete configuration solution for Go applications that supports multiple file formats...
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### Viper Configuration Priority Example

Source: https://pkg.go.dev/github.com/spf13/viper

Example demonstrating how Viper merges configuration sources based on priority.

```text
Defaults : {
	"secret": "",
	"user": "default",
	"endpoint": "https://localhost"
}
Config : {
	"user": "root"
	"secret": "defaultsecret"
}
Env : {
	"secret": "somesecretkey"
}
```

```text
{
	"secret": "somesecretkey",
	"user": "root",
	"endpoint": "https://localhost"
}
```

--------------------------------

### Install Viper

Source: https://pkg.go.dev/github.com/spf13/viper

Use the go get command to add the Viper package to your Go module dependencies.

```bash
go get github.com/spf13/viper
```

--------------------------------

### WatchConfig

Source: https://pkg.go.dev/github.com/spf13/viper

Starts watching the configuration file for changes.

```go
func (v *Viper) WatchConfig()
```

--------------------------------

### Watch configuration file for changes

Source: https://pkg.go.dev/github.com/spf13/viper

Starts a background process to watch the configuration file for modifications.

```go
func WatchConfig()
```

--------------------------------

### Watch remote configuration

Source: https://pkg.go.dev/github.com/spf13/viper

Starts watching a remote configuration source.

```go
func WatchRemoteConfig() error
```

--------------------------------

### Get Configuration Value

Source: https://pkg.go.dev/github.com/spf13/viper

Retrieves a value by key, checking override, flag, env, config file, and defaults in order.

```go
func Get(key string) any
```

--------------------------------

### WatchRemoteConfigOnChannel

Source: https://pkg.go.dev/github.com/spf13/viper

Starts watching the remote configuration on a channel.

```go
func (v *Viper) WatchRemoteConfigOnChannel() error
```

--------------------------------

### Get Config File Path

Source: https://pkg.go.dev/github.com/spf13/viper

Returns the path of the configuration file currently in use.

```go
func ConfigFileUsed() string
```

--------------------------------

### WatchConfig

Source: https://pkg.go.dev/github.com/spf13/viper

Starts watching a configuration file for changes.

```APIDOC
## func WatchConfig()

### Description
WatchConfig starts watching a config file for changes.
```

--------------------------------

### WatchRemoteConfig

Source: https://pkg.go.dev/github.com/spf13/viper

Starts watching the remote configuration for changes.

```go
func (v *Viper) WatchRemoteConfig() error
```

--------------------------------

### Get Environment Prefix

Source: https://pkg.go.dev/github.com/spf13/viper

Retrieves the current environment variable prefix.

```go
func GetEnvPrefix() string
```

--------------------------------

### func (*Viper) Get

Source: https://pkg.go.dev/github.com/spf13/viper

Retrieves a value from the configuration by key.

```APIDOC
## func (*Viper) Get

### Description
Retrieves the value associated with the given key.

### Signature
`func (v *Viper) Get(key string) any`
```

--------------------------------

### Get

Source: https://pkg.go.dev/github.com/spf13/viper

Retrieves a value for a given key.

```APIDOC
## func Get(key string) any

### Description
Retrieves any value given the key. The key is case-insensitive. Viper checks in the following order: override, flag, env, config file, key/value store, default.
```

--------------------------------

### Get Duration Value

Source: https://pkg.go.dev/github.com/spf13/viper

Retrieves a configuration value as a time.Duration.

```go
func GetDuration(key string) time.Duration
```

--------------------------------

### Get Boolean Value

Source: https://pkg.go.dev/github.com/spf13/viper

Retrieves a configuration value as a boolean.

```go
func GetBool(key string) bool
```

--------------------------------

### Get Absolute File Path

Source: https://pkg.go.dev/github.com/spf13/viper/internal/testutil

Resolves a relative path to an absolute path using filepath.Abs. Requires a testing.T instance for context.

```go
func AbsFilePath(t *testing.T, path string) string
```

--------------------------------

### Bind Environment Variables

Source: https://pkg.go.dev/github.com/spf13/viper

Demonstrates setting an environment prefix and binding a configuration key to an environment variable.

```go
SetEnvPrefix("spf") // will be uppercased automatically
BindEnv("id")

os.Setenv("SPF_ID", "13") // typically done outside of the app

id := Get("id") // 13
```

--------------------------------

### Read Configuration Files

Source: https://pkg.go.dev/github.com/spf13/viper

Configure search paths and file names to load configuration data. Ensure at least one path is added before reading.

```go
viper.SetConfigName("config") // name of config file (without extension)
viper.SetConfigType("yaml") // REQUIRED if the config file does not have the extension in the name
viper.AddConfigPath("/etc/appname/")   // path to look for the config file in
viper.AddConfigPath("$HOME/.appname")  // call multiple times to add many search paths
viper.AddConfigPath(".")               // optionally look for config in the working directory
err := viper.ReadInConfig() // Find and read the config file
if err != nil { // Handle errors reading the config file
	panic(fmt.Errorf("fatal error config file: %w", err))
}
```

--------------------------------

### Set Filesystem and Options

Source: https://pkg.go.dev/github.com/spf13/viper

Configures the filesystem or global options for the Viper instance.

```go
func SetFs(fs afero.Fs)
```

```go
func SetOptions(opts ...Option)
```

--------------------------------

### Configure File Paths and Types

Source: https://pkg.go.dev/github.com/spf13/viper

Defines the configuration file path, name, type, and permissions.

```go
func SetConfigFile(in string)
```

```go
func SetConfigName(in string)
```

```go
func SetConfigPermissions(perm os.FileMode)
```

```go
func SetConfigType(in string)
```

--------------------------------

### Write Configuration Files

Source: https://pkg.go.dev/github.com/spf13/viper

Save current configuration state to disk using various write methods.

```go
viper.WriteConfig() // writes current config to predefined path set by 'viper.AddConfigPath()' and 'viper.SetConfigName'
viper.SafeWriteConfig()
viper.WriteConfigAs("/path/to/my/.config")
viper.SafeWriteConfigAs("/path/to/my/.config") // will error since it has already been written
viper.SafeWriteConfigAs("/path/to/my/.other_config")
```

--------------------------------

### Register and Use Aliases

Source: https://pkg.go.dev/github.com/spf13/viper

Map multiple keys to the same configuration value.

```go
viper.RegisterAlias("loud", "Verbose")

viper.Set("verbose", true) // same result as next line
viper.Set("loud", true)   // same result as prior line

viper.GetBool("loud") // true
viper.GetBool("verbose") // true
```

--------------------------------

### Running Development Commands

Source: https://pkg.go.dev/github.com/spf13/viper

Commands for testing, linting, and formatting the project.

```makefile
make test
```

```makefile
make lint # pass -j option to run them in parallel
```

```makefile
make fmt
```

--------------------------------

### Read Configuration

Source: https://pkg.go.dev/github.com/spf13/viper

Methods to load configuration from files or remote sources.

```go
func ReadConfig(in io.Reader) error
```

```go
func ReadInConfig() error
```

```go
func ReadRemoteConfig() error
```

--------------------------------

### Retrieve All Settings

Source: https://pkg.go.dev/github.com/spf13/viper

Merges all configuration settings into a single map.

```go
func AllSettings() map[string]any
```

--------------------------------

### Handle Missing Configuration Files

Source: https://pkg.go.dev/github.com/spf13/viper

Check for specific errors when a configuration file is not found.

```go
if err := viper.ReadInConfig(); err != nil {
	if _, ok := err.(viper.ConfigFileNotFoundError); ok {
		// Config file not found; ignore error if desired
	} else {
		// Config file was found but another error was produced
	}
}

// Config file found and successfully parsed
```

--------------------------------

### Configure Environment Variables

Source: https://pkg.go.dev/github.com/spf13/viper

Sets prefixes and replacers for environment variable lookups.

```go
func SetEnvKeyReplacer(r *strings.Replacer)
```

```go
func SetEnvPrefix(in string)
```

--------------------------------

### Initialize DefaultCodecRegistry

Source: https://pkg.go.dev/github.com/spf13/viper

Creates a new instance of DefaultCodecRegistry.

```go
func NewCodecRegistry() *DefaultCodecRegistry
```

--------------------------------

### Configure Remote Key/Value Stores

Source: https://pkg.go.dev/github.com/spf13/viper

Connect to remote providers by specifying the provider type, endpoint, and path. Set the configuration type explicitly as remote streams lack file extensions.

```go
viper.AddRemoteProvider("etcd", "http://127.0.0.1:4001","/config/hugo.json")
viper.SetConfigType("json") // because there is no file extension in a stream of bytes, supported extensions are "json", "toml", "yaml", "yml", "properties", "props", "prop", "env", "dotenv"
err := viper.ReadRemoteConfig()
```

```go
viper.AddRemoteProvider("etcd3", "http://127.0.0.1:4001","/config/hugo.json")
viper.SetConfigType("json") // because there is no file extension in a stream of bytes, supported extensions are "json", "toml", "yaml", "yml", "properties", "props", "prop", "env", "dotenv"
err := viper.ReadRemoteConfig()
```

```json
{
    "port": 8080,
    "hostname": "myhostname.com"
}
```

```go
viper.AddRemoteProvider("consul", "localhost:8500", "MY_CONSUL_KEY")
viper.SetConfigType("json") // Need to explicitly set this to json
err := viper.ReadRemoteConfig()

fmt.Println(viper.Get("port")) // 8080
fmt.Println(viper.Get("hostname")) // myhostname.com
```

```go
viper.AddRemoteProvider("firestore", "google-cloud-project-id", "collection/document")
viper.SetConfigType("json") // Config's format: "json", "toml", "yaml", "yml"
err := viper.ReadRemoteConfig()
```

```go
viper.AddRemoteProvider("nats", "nats://127.0.0.1:4222", "myapp.config")
viper.SetConfigType("json")
err := viper.ReadRemoteConfig()
```

--------------------------------

### New

Source: https://pkg.go.dev/github.com/spf13/viper

Creates a new, independent Viper instance.

```APIDOC
## New()

### Description
Creates and returns a new Viper instance, allowing for multiple isolated configuration sets within an application.
```

--------------------------------

### Utility Functions

Source: https://pkg.go.dev/github.com/spf13/viper

Miscellaneous utilities for aliasing keys and resetting configuration state.

```go
func RegisterAlias(alias, key string)
```

```go
func Reset()
```

--------------------------------

### WriteConfigTo

Source: https://pkg.go.dev/github.com/spf13/viper

Writes the current configuration to an io.Writer.

```go
func (v *Viper) WriteConfigTo(w io.Writer) error
```

--------------------------------

### Define Supported Extensions

Source: https://pkg.go.dev/github.com/spf13/viper

List of file extensions supported by Viper for configuration files.

```go
var SupportedExts = []string{"json", "toml", "yaml", "yml", "properties", "props", "prop", "hcl", "tfvars", "dotenv", "env", "ini"}
```

--------------------------------

### Handle Configuration Changes

Source: https://pkg.go.dev/github.com/spf13/viper

Registers a callback function to execute when the configuration file changes.

```go
func OnConfigChange(run func(in fsnotify.Event))
```

--------------------------------

### Add Configuration Path

Source: https://pkg.go.dev/github.com/spf13/viper

Adds a directory path to the search list for configuration files.

```go
func AddConfigPath(in string)
```

--------------------------------

### Debug Configuration to Writer

Source: https://pkg.go.dev/github.com/spf13/viper

Prints configuration registries to a specified io.Writer.

```go
func DebugTo(w io.Writer)
```

--------------------------------

### func New

Source: https://pkg.go.dev/github.com/spf13/viper

Creates and returns a new initialized Viper instance.

```APIDOC
## func New

### Description
New returns an initialized Viper instance.

### Signature
`func New() *Viper`
```

--------------------------------

### Managing Multiple Viper Instances

Source: https://pkg.go.dev/github.com/spf13/viper

Initialize separate Viper instances to maintain independent configuration sets.

```go
x := viper.New()
y := viper.New()

x.SetDefault("ContentDir", "content")
y.SetDefault("ContentDir", "foobar")

//...
```

--------------------------------

### Write configuration to an io.Writer

Source: https://pkg.go.dev/github.com/spf13/viper

Writes the current configuration to the provided io.Writer.

```go
func WriteConfigTo(w io.Writer) error
```

--------------------------------

### SetConfigFile

Source: https://pkg.go.dev/github.com/spf13/viper

Explicitly sets the configuration file path.

```go
func (v *Viper) SetConfigFile(in string)
```

--------------------------------

### Write Configuration Safely

Source: https://pkg.go.dev/github.com/spf13/viper

Writes the current configuration to a file only if it does not already exist.

```go
func SafeWriteConfig() error
```

```go
func SafeWriteConfigAs(filename string) error
```

--------------------------------

### Viper Configuration Methods

Source: https://pkg.go.dev/github.com/spf13/viper

A collection of methods for managing configuration settings, file paths, and unmarshaling data.

```APIDOC
## func (*Viper) Set(key string, value any)
Sets the value for the key in the viper instance.

## func (*Viper) SetDefault(key string, value any)
Sets the default value for a given key.

## func (*Viper) SetConfigFile(in string)
Explicitly defines the path, name and extension of the config file.

## func (*Viper) SetConfigName(in string)
Sets the name of the config file without the extension.

## func (*Viper) SetConfigType(in string)
Sets the type of the configuration (e.g., "yaml", "json").

## func (*Viper) Unmarshal(rawVal any, opts ...DecoderConfigOption) error
Unmarshals the config into a struct.

## func (*Viper) WatchConfig()
Starts watching a configuration file for changes.
```

--------------------------------

### Write current configuration to file

Source: https://pkg.go.dev/github.com/spf13/viper

Persists the current configuration state to the associated file.

```go
func WriteConfig() error
```

--------------------------------

### SetConfigName

Source: https://pkg.go.dev/github.com/spf13/viper

Sets the name of the configuration file (without extension).

```go
func (v *Viper) SetConfigName(in string)
```

--------------------------------

### Watch Configuration Changes

Source: https://pkg.go.dev/github.com/spf13/viper

Enable live reloading of configuration files. Ensure all config paths are added before calling WatchConfig.

```go
viper.OnConfigChange(func(e fsnotify.Event) {
	fmt.Println("Config file changed:", e.Name)
})
viper.WatchConfig()
```

--------------------------------

### Debug Configuration

Source: https://pkg.go.dev/github.com/spf13/viper

Prints all configuration registries to standard output for debugging.

```go
func Debug()
```

--------------------------------

### Sub

Source: https://pkg.go.dev/github.com/spf13/viper

Returns a new Viper instance representing a sub-tree of the configuration.

```go
func (v *Viper) Sub(key string) *Viper
```

--------------------------------

### Bind Environment Variables

Source: https://pkg.go.dev/github.com/spf13/viper

Binds environment variables with panic handling on error.

```go
func MustBindEnv(input ...string)
```

--------------------------------

### WriteConfig

Source: https://pkg.go.dev/github.com/spf13/viper

Writes the current configuration to the file.

```go
func (v *Viper) WriteConfig() error
```

--------------------------------

### Set Configuration Overrides

Source: https://pkg.go.dev/github.com/spf13/viper

Manually set configuration values programmatically.

```go
viper.Set("Verbose", true)
viper.Set("LogFile", LogFile)
viper.Set("host.port", 5899)   // set subset
```

--------------------------------

### Check Configuration State

Source: https://pkg.go.dev/github.com/spf13/viper

Functions to verify if keys exist or are set within the configuration.

```go
func InConfig(key string) bool
```

```go
func IsSet(key string) bool
```

--------------------------------

### Set

Source: https://pkg.go.dev/github.com/spf13/viper

Sets the value for a specific key.

```go
func (v *Viper) Set(key string, value any)
```

--------------------------------

### Read Configuration from io.Reader

Source: https://pkg.go.dev/github.com/spf13/viper

Feed configuration data directly from a buffer or custom source.

```go
viper.SetConfigType("yaml") // or viper.SetConfigType("YAML")

// any approach to require this configuration into your program.
var yamlExample = []byte(`
Hacker: true
name: steve
hobbies:
- skateboarding
- snowboarding
- go
clothing:
  jacket: leather
  trousers: denim
age: 35
eyes : brown
beard: true
`)

viper.ReadConfig(bytes.NewBuffer(yamlExample))

viper.Get("name") // this would be "steve"
```

--------------------------------

### Bind Environment Variable

Source: https://pkg.go.dev/github.com/spf13/viper

Binds a specific configuration key to one or more environment variables.

```go
func BindEnv(input ...string) error
```

--------------------------------

### Marshalling Settings to YAML String

Source: https://pkg.go.dev/github.com/spf13/viper

Convert all current Viper settings into a string format using an external marshaller.

```go
import (
	yaml "go.yaml.in/yaml/v3"
	// ...
)

func yamlStringSettings() string {
	c := viper.AllSettings()
	bs, err := yaml.Marshal(c)
	if err != nil {
		log.Fatalf("unable to marshal config to YAML: %v", err)
	}
	return string(bs)
}
```

--------------------------------

### Configure Empty Environment Variables

Source: https://pkg.go.dev/github.com/spf13/viper

Sets whether empty environment variables should be treated as valid values.

```go
func AllowEmptyEnv(allowEmptyEnv bool)
```

--------------------------------

### Define Finder interface

Source: https://pkg.go.dev/github.com/spf13/viper

Interface for locating files and directories within an afero filesystem.

```go
type Finder interface {
	Find(fsys afero.Fs) ([]string, error)
}
```

--------------------------------

### Set Default Configuration Values

Source: https://pkg.go.dev/github.com/spf13/viper

Define fallback values for configuration keys that are used if no other source provides a value.

```go
viper.SetDefault("ContentDir", "content")
viper.SetDefault("LayoutDir", "layouts")
viper.SetDefault("Taxonomies", map[string]string{"tag": "tags", "category": "categories"})
```

--------------------------------

### Write configuration to a specific file

Source: https://pkg.go.dev/github.com/spf13/viper

Writes the current configuration to the specified filename.

```go
func WriteConfigAs(filename string) error
```

--------------------------------

### SetConfigPermissions

Source: https://pkg.go.dev/github.com/spf13/viper

Sets the file permissions for the configuration file.

```go
func (v *Viper) SetConfigPermissions(perm os.FileMode)
```

--------------------------------

### ConfigFileAlreadyExistsError type and error method

Source: https://pkg.go.dev/github.com/spf13/viper

Represents a failure when attempting to write a new configuration file that already exists.

```go
type ConfigFileAlreadyExistsError string
```

```go
func (faee ConfigFileAlreadyExistsError) Error() string
```

--------------------------------

### SetOptions

Source: https://pkg.go.dev/github.com/spf13/viper

Sets options on the global Viper instance.

```APIDOC
## func SetOptions(opts ...Option)

### Description
Sets the options on the global Viper instance. Be careful when using this function: subsequent calls may override options you set.

### Parameters
- **opts** (...Option) - Required - Variadic list of options.
```

--------------------------------

### ConfigFileNotFoundError type and error method

Source: https://pkg.go.dev/github.com/spf13/viper

Represents a failure to locate a configuration file.

```go
type ConfigFileNotFoundError struct {
	// contains filtered or unexported fields
}
```

```go
func (fnfe ConfigFileNotFoundError) Error() string
```

--------------------------------

### Configure Secure Remote Provider

Source: https://pkg.go.dev/github.com/spf13/viper

Use AddSecureRemoteProvider to connect to encrypted remote configuration stores.

```go
viper.AddSecureRemoteProvider("etcd","http://127.0.0.1:4001","/config/hugo.json","/etc/secrets/mykeyring.gpg")
viper.SetConfigType("json") // because there is no file extension in a stream of bytes,  supported extensions are "json", "toml", "yaml", "yml", "properties", "props", "prop", "env", "dotenv"
err := viper.ReadRemoteConfig()
```

--------------------------------

### WriteConfigTo

Source: https://pkg.go.dev/github.com/spf13/viper

Writes the current configuration to an io.Writer.

```APIDOC
## func WriteConfigTo(w io.Writer) error

### Description
WriteConfigTo writes current configuration to an io.Writer.
```

--------------------------------

### Extracting a configuration sub-tree

Source: https://pkg.go.dev/github.com/spf13/viper

Use viper.Sub() to create a new Viper instance representing a subset of the configuration. Always check if the returned instance is nil.

```yaml
cache:
  cache1:
    max-items: 100
    item-size: 64
  cache2:
    max-items: 200
    item-size: 80
```

```go
cache1Config := viper.Sub("cache.cache1")
if cache1Config == nil { // Sub returns nil if the key cannot be found
	panic("cache configuration not found")
}

cache1 := NewCache(cache1Config)
```

```go
func NewCache(v *Viper) *Cache {
	return &Cache{
		MaxItems: v.GetInt("max-items"),
		ItemSize: v.GetInt("item-size"),
	}
}
```

--------------------------------

### Add Secure Remote Provider

Source: https://pkg.go.dev/github.com/spf13/viper

Registers a secure remote configuration source using an OpenPGP secret keyring.

```go
func AddSecureRemoteProvider(provider, endpoint, path, secretkeyring string) error
```

--------------------------------

### Configuration Management Methods

Source: https://pkg.go.dev/github.com/spf13/viper

Methods for reading, merging, and managing configuration state.

```APIDOC
## func ReadInConfig() error

### Description
Discovers and loads the configuration file from disk and key/value stores, searching in defined paths.

### Returns
- (error) - Returns an error if the configuration cannot be read.
```

```APIDOC
## func MergeConfig(in io.Reader) error

### Description
Merges a new configuration provided via an io.Reader with an existing configuration.

### Parameters
- **in** (io.Reader) - Required - The reader containing the new configuration data.

### Returns
- (error) - Returns an error if the merge fails.
```

--------------------------------

### Bind PFlag Set

Source: https://pkg.go.dev/github.com/spf13/viper

Binds a full pflag set to the configuration.

```go
func BindPFlags(flags *pflag.FlagSet) error
```

--------------------------------

### Configuration Error Types

Source: https://pkg.go.dev/github.com/spf13/viper

Error types for unsupported file formats or remote providers.

```go
type UnsupportedConfigError string
```

```go
func (str UnsupportedConfigError) Error() string
```

```go
type UnsupportedRemoteProviderError string
```

```go
func (str UnsupportedRemoteProviderError) Error() string
```

--------------------------------

### SetFs

Source: https://pkg.go.dev/github.com/spf13/viper

Sets the filesystem to use for file operations.

```go
func (v *Viper) SetFs(fs afero.Fs)
```

--------------------------------

### Set Configuration Values

Source: https://pkg.go.dev/github.com/spf13/viper

Sets values in the override register or defines default values for keys.

```go
func Set(key string, value any)
```

```go
func SetDefault(key string, value any)
```

--------------------------------

### Add Remote Provider

Source: https://pkg.go.dev/github.com/spf13/viper

Registers a remote configuration source. Providers are searched in the order they are added.

```go
func AddRemoteProvider(provider, endpoint, path string) error
```

--------------------------------

### SetConfigType

Source: https://pkg.go.dev/github.com/spf13/viper

Sets the configuration file type (e.g., yaml, json).

```go
func (v *Viper) SetConfigType(in string)
```

--------------------------------

### SetEnvPrefix

Source: https://pkg.go.dev/github.com/spf13/viper

Sets a prefix for environment variables.

```go
func (v *Viper) SetEnvPrefix(in string)
```

--------------------------------

### Manage remote configuration with crypt

Source: https://pkg.go.dev/github.com/spf13/viper

Use the crypt tool to set and retrieve configuration values from a remote key/value store.

```bash
$ go get github.com/sagikazarmark/crypt/bin/crypt
$ crypt set -plaintext /config/hugo.json /Users/hugo/settings/config.json
```

```bash
$ crypt get -plaintext /config/hugo.json
```

--------------------------------

### SetFs

Source: https://pkg.go.dev/github.com/spf13/viper

Sets the filesystem to use for reading configuration.

```APIDOC
## func SetFs(fs afero.Fs)

### Description
Sets the filesystem to use to read configuration.

### Parameters
- **fs** (afero.Fs) - Required - The filesystem interface.
```

--------------------------------

### Handling key path collisions

Source: https://pkg.go.dev/github.com/spf13/viper

If a key exists that matches the full delimited path, its value takes precedence.

```json
{
    "datastore.metric.host": "0.0.0.0",
    "host": {
        "address": "localhost",
        "port": 5799
    },
    "datastore": {
        "metric": {
            "host": "127.0.0.1",
            "port": 3099
        },
        "warehouse": {
            "host": "198.0.0.1",
            "port": 2112
        }
    }
}
```

```go
GetString("datastore.metric.host") // returns "0.0.0.0"
```

--------------------------------

### RegisterAlias

Source: https://pkg.go.dev/github.com/spf13/viper

Registers an alias for a configuration key.

```go
func (v *Viper) RegisterAlias(alias, key string)
```

--------------------------------

### Register custom codec

Source: https://pkg.go.dev/github.com/spf13/viper

Registers a custom codec for a given format string.

```go
func (r *DefaultCodecRegistry) RegisterCodec(format string, codec Codec) error
```

--------------------------------

### SetConfigFile

Source: https://pkg.go.dev/github.com/spf13/viper

Explicitly defines the path, name, and extension of the configuration file.

```APIDOC
## func SetConfigFile(in string)

### Description
Explicitly defines the path, name and extension of the config file. Viper will use this and not check any of the config paths.

### Parameters
- **in** (string) - Required - The full path to the configuration file.
```

--------------------------------

### Enable Automatic Environment Variable Loading

Source: https://pkg.go.dev/github.com/spf13/viper

Instructs Viper to automatically check for environment variables matching existing configuration keys.

```go
func AutomaticEnv()
```

--------------------------------

### Implement Decoder method

Source: https://pkg.go.dev/github.com/spf13/viper

Retrieves a decoder for the specified format, which is case-insensitive.

```go
func (r *DefaultCodecRegistry) Decoder(format string) (Decoder, error)
```

--------------------------------

### Configuration Retrieval Methods

Source: https://pkg.go.dev/github.com/spf13/viper

Methods for retrieving configuration values by key in various data types.

```APIDOC
## func GetString(key string) string

### Description
Returns the value associated with the key as a string.

### Parameters
- **key** (string) - Required - The configuration key to retrieve.

### Returns
- (string) - The value associated with the key.
```

```APIDOC
## func GetInt(key string) int

### Description
Returns the value associated with the key as an integer.

### Parameters
- **key** (string) - Required - The configuration key to retrieve.

### Returns
- (int) - The value associated with the key.
```

--------------------------------

### Viper Registry Structure

Source: https://pkg.go.dev/github.com/spf13/viper

The main Viper configuration registry struct.

```go
type Viper struct {
	// contains filtered or unexported fields
}
```

--------------------------------

### AddConfigPath

Source: https://pkg.go.dev/github.com/spf13/viper

Adds a directory path for Viper to search for configuration files.

```APIDOC
## func AddConfigPath(in string)

### Description
Adds a path for Viper to search for the config file in. Can be called multiple times to define multiple search paths.
```

--------------------------------

### SafeWriteConfig

Source: https://pkg.go.dev/github.com/spf13/viper

Writes configuration to a file without overwriting existing files.

```go
func (v *Viper) SafeWriteConfig() error
```

--------------------------------

### func (*Viper) ReadInConfig

Source: https://pkg.go.dev/github.com/spf13/viper

Reads the configuration file into the Viper instance.

```APIDOC
## func (*Viper) ReadInConfig

### Description
Reads the configuration file from the configured paths.

### Signature
`func (v *Viper) ReadInConfig() error`
```

--------------------------------

### Merge Configuration

Source: https://pkg.go.dev/github.com/spf13/viper

Functions to merge new configuration data into the existing state.

```go
func MergeConfig(in io.Reader) error
```

```go
func MergeConfigMap(cfg map[string]any) error
```

```go
func MergeInConfig() error
```

--------------------------------

### Implement Encoder method

Source: https://pkg.go.dev/github.com/spf13/viper

Retrieves an encoder for the specified format, which is case-insensitive.

```go
func (r *DefaultCodecRegistry) Encoder(format string) (Encoder, error)
```

--------------------------------

### Retrieve All Keys

Source: https://pkg.go.dev/github.com/spf13/viper

Returns all keys currently holding a value, including nested keys with delimiters.

```go
func AllKeys() []string
```

--------------------------------

### Integrate standard library flags with Pflags

Source: https://pkg.go.dev/github.com/spf13/viper

Use AddGoFlagSet to include standard library flags in a Pflag set before binding to Viper.

```go
package main

import (
	"flag"
	"github.com/spf13/pflag"
)

func main() {

	// using standard library "flag" package
	flag.Int("flagname", 1234, "help message for flagname")

	pflag.CommandLine.AddGoFlagSet(flag.CommandLine)
	pflag.Parse()
	viper.BindPFlags(pflag.CommandLine)

	i := viper.GetInt("flagname") // retrieve value from viper

	// ...
}
```

--------------------------------

### Bind Flag Value Set

Source: https://pkg.go.dev/github.com/spf13/viper

Binds an entire set of flags to the configuration using long names as keys.

```go
func BindFlagValues(flags FlagValueSet) error
```

--------------------------------

### Unmarshal

Source: https://pkg.go.dev/github.com/spf13/viper

Unmarshals the configuration into a struct.

```go
func (v *Viper) Unmarshal(rawVal any, opts ...DecoderConfigOption) error
```

--------------------------------

### Retrieve Configuration Values

Source: https://pkg.go.dev/github.com/spf13/viper

Methods to retrieve configuration values cast to specific types.

```go
func GetFloat64(key string) float64
```

```go
func GetInt(key string) int
```

```go
func GetInt32(key string) int32
```

```go
func GetInt64(key string) int64
```

```go
func GetIntSlice(key string) []int
```

```go
func GetSizeInBytes(key string) uint
```

```go
func GetString(key string) string
```

```go
func GetStringMap(key string) map[string]any
```

```go
func GetStringMapString(key string) map[string]string
```

```go
func GetStringMapStringSlice(key string) map[string][]string
```

```go
func GetStringSlice(key string) []string
```

```go
func GetTime(key string) time.Time
```

```go
func GetUint(key string) uint
```

```go
func GetUint8(key string) uint8
```

```go
func GetUint16(key string) uint16
```

```go
func GetUint32(key string) uint32
```

```go
func GetUint64(key string) uint64
```

--------------------------------

### Viper Configuration Options

Source: https://pkg.go.dev/github.com/spf13/viper

Functions used to configure Viper behavior via functional options.

```go
func EnvKeyReplacer(r StringReplacer) Option
```

```go
func ExperimentalBindStruct() Option
```

```go
func ExperimentalFinder() Option
```

```go
func KeyDelimiter(d string) Option
```

```go
func WithCodecRegistry(r CodecRegistry) Option
```

```go
func WithDecodeHook(h mapstructure.DecodeHookFunc) Option
```

```go
func WithDecoderRegistry(r DecoderRegistry) Option
```

```go
func WithEncoderRegistry(r EncoderRegistry) Option
```

```go
func WithFinder(f Finder) Option
```

```go
func WithLogger(l *slog.Logger) Option
```

--------------------------------

### Remote Provider Interface

Source: https://pkg.go.dev/github.com/spf13/viper

Interface for defining remote key/value store connections.

```go
type RemoteProvider interface {
	Provider() string
	Endpoint() string
	Path() string
	SecretKeyring() string
}
```

--------------------------------

### Bind Flag Value

Source: https://pkg.go.dev/github.com/spf13/viper

Binds a configuration key to a custom FlagValue implementation.

```go
func BindFlagValue(key string, flag FlagValue) error
```

--------------------------------

### AddRemoteProvider

Source: https://pkg.go.dev/github.com/spf13/viper

Adds a remote configuration source to the search list.

```APIDOC
## func AddRemoteProvider(provider, endpoint, path string) error

### Description
Adds a remote configuration source. Remote Providers are searched in the order they are added. Supported providers include "etcd", "etcd3", "consul", "firestore", or "nats".
```

--------------------------------

### ConfigMarshalError type and error method

Source: https://pkg.go.dev/github.com/spf13/viper

Represents a failure during configuration marshaling.

```go
type ConfigMarshalError struct {
	// contains filtered or unexported fields
}
```

```go
func (e ConfigMarshalError) Error() string
```

--------------------------------

### Define Option Interface

Source: https://pkg.go.dev/github.com/spf13/viper

Interface for configuring Viper using the functional options pattern.

```go
type Option interface {
	// contains filtered or unexported methods
}
```

--------------------------------

### WriteConfigAs

Source: https://pkg.go.dev/github.com/spf13/viper

Writes the current configuration to a specific file.

```go
func (v *Viper) WriteConfigAs(filename string) error
```

--------------------------------

### Retrieve Configuration Values

Source: https://pkg.go.dev/github.com/spf13/viper

Access configuration values using type-specific getter methods. These methods return zero values if the key is missing or fails to parse.

```go
viper.GetString("logfile") // case-insensitive Setting & Getting
if viper.GetBool("verbose") {
	fmt.Println("verbose enabled")
}
```

--------------------------------

### Combine multiple finders

Source: https://pkg.go.dev/github.com/spf13/viper

Utility function to aggregate multiple Finder implementations into a single Finder.

```go
func Finders(finders ...Finder) Finder
```

--------------------------------

### Supported Remote Providers

Source: https://pkg.go.dev/github.com/spf13/viper

List of remote configuration providers supported by Viper.

```go
var SupportedRemoteProviders = []string{"etcd", "etcd3", "consul", "firestore", "nats"}
```

--------------------------------

### WriteConfig

Source: https://pkg.go.dev/github.com/spf13/viper

Writes the current configuration to a file.

```APIDOC
## func WriteConfig() error

### Description
WriteConfig writes the current configuration to a file.
```

--------------------------------

### SetConfigName

Source: https://pkg.go.dev/github.com/spf13/viper

Sets the name for the configuration file without the extension.

```APIDOC
## func SetConfigName(in string)

### Description
Sets name for the config file. Does not include extension.

### Parameters
- **in** (string) - Required - The name of the configuration file.
```

--------------------------------

### SetEnvPrefix

Source: https://pkg.go.dev/github.com/spf13/viper

Defines a prefix for environment variables.

```APIDOC
## func SetEnvPrefix(in string)

### Description
Defines a prefix that ENVIRONMENT variables will use.

### Parameters
- **in** (string) - Required - The prefix string.
```

--------------------------------

### SetDefault

Source: https://pkg.go.dev/github.com/spf13/viper

Sets a default value for a key.

```go
func (v *Viper) SetDefault(key string, value any)
```

--------------------------------

### Unmarshal configuration into a struct

Source: https://pkg.go.dev/github.com/spf13/viper

Unmarshals configuration data into a struct. Ensure struct tags are properly set.

```go
func Unmarshal(rawVal any, opts ...DecoderConfigOption) error
```

--------------------------------

### Watch Remote Configuration Changes

Source: https://pkg.go.dev/github.com/spf13/viper

Monitor remote configuration for updates using a goroutine and WatchRemoteConfig.

```go
// alternatively, you can create a new viper instance.
var runtime_viper = viper.New()

runtime_viper.AddRemoteProvider("etcd", "http://127.0.0.1:4001", "/config/hugo.yml")
runtime_viper.SetConfigType("yaml") // because there is no file extension in a stream of bytes, supported extensions are "json", "toml", "yaml", "yml", "properties", "props", "prop", "env", "dotenv"

// read from remote config the first time.
err := runtime_viper.ReadRemoteConfig()

// unmarshal config
runtime_viper.Unmarshal(&runtime_conf)

// open a goroutine to watch remote changes forever
go func(){
	for {
		time.Sleep(time.Second * 5) // delay after each request

		// currently, only tested with etcd support
		err := runtime_viper.WatchRemoteConfig()
		if err != nil {
			log.Errorf("unable to read remote config: %v", err)
			continue
		}

		// unmarshal new config into our runtime config struct. you can also use channel
		// to implement a signal to notify the system of the changes
		runtime_viper.Unmarshal(&runtime_conf)
	}
}()
```

--------------------------------

### Define DecoderRegistry interface

Source: https://pkg.go.dev/github.com/spf13/viper

Defines the interface for retrieving a decoder based on a specific format string.

```go
type DecoderRegistry interface {
	Decoder(format string) (Decoder, error)
}
```

--------------------------------

### Define RemoteConfig Variable

Source: https://pkg.go.dev/github.com/spf13/viper

Represents the remote configuration factory. Requires the remote package to be utilized.

```go
var RemoteConfig remoteConfigFactory
```

--------------------------------

### Unmarshal

Source: https://pkg.go.dev/github.com/spf13/viper

Unmarshals all configuration settings into a provided struct or map.

```APIDOC
## Unmarshal(rawVal any) : error

### Description
Unmarshals the entire configuration into the provided struct or map.

### Parameters
- **rawVal** (any) - Required - The destination struct or map to populate with configuration values.
```

--------------------------------

### ConfigParseError type and methods

Source: https://pkg.go.dev/github.com/spf13/viper

Represents a failure to parse a configuration file.

```go
type ConfigParseError struct {
	// contains filtered or unexported fields
}
```

```go
func (pe ConfigParseError) Error() string
```

```go
func (pe ConfigParseError) Unwrap() error
```

--------------------------------

### Remote Response Structure

Source: https://pkg.go.dev/github.com/spf13/viper

Container for data returned from a remote configuration provider.

```go
type RemoteResponse struct {
	Value []byte
	Error error
}
```

--------------------------------

### func Finders

Source: https://pkg.go.dev/github.com/spf13/viper

Combines multiple Finder implementations into a single Finder.

```APIDOC
## func Finders

### Description
Combines multiple finders into one.

### Signature
func Finders(finders ...Finder) Finder
```

--------------------------------

### Accessing array indices in configuration

Source: https://pkg.go.dev/github.com/spf13/viper

Access specific elements in an array by including the index number in the path.

```json
{
    "host": {
        "address": "localhost",
        "ports": [
            5799,
            6029
        ]
    },
    "datastore": {
        "metric": {
            "host": "127.0.0.1",
            "port": 3099
        },
        "warehouse": {
            "host": "198.0.0.1",
            "port": 2112
        }
    }
}
```

```go
GetInt("host.ports.1") // returns 6029
```

--------------------------------

### Define Codec struct

Source: https://pkg.go.dev/github.com/spf13/viper/internal/encoding/yaml

Represents the YAML codec implementation.

```go
type Codec struct{}
```

--------------------------------

### ReadRemoteConfig

Source: https://pkg.go.dev/github.com/spf13/viper

Reads configuration from a remote source.

```go
func (v *Viper) ReadRemoteConfig() error
```

--------------------------------

### SafeWriteConfig

Source: https://pkg.go.dev/github.com/spf13/viper

Writes the current configuration to a file only if the file does not already exist.

```APIDOC
## func SafeWriteConfig()

### Description
Writes current configuration to file only if the file does not exist.

### Signature
`func SafeWriteConfig() error`
```

--------------------------------

### SetConfigPermissions

Source: https://pkg.go.dev/github.com/spf13/viper

Sets the file permissions for the configuration file.

```APIDOC
## func SetConfigPermissions(perm os.FileMode)

### Description
Sets the permissions for the config file.

### Parameters
- **perm** (os.FileMode) - Required - The file mode permissions.
```

--------------------------------

### Unmarshal configuration with strict field checking

Source: https://pkg.go.dev/github.com/spf13/viper

Unmarshals configuration into a struct, returning an error if a field does not exist in the destination.

```go
func UnmarshalExact(rawVal any, opts ...DecoderConfigOption) error
```

--------------------------------

### Define DefaultCodecRegistry struct

Source: https://pkg.go.dev/github.com/spf13/viper

A concrete implementation of CodecRegistry that supports custom codec registration.

```go
type DefaultCodecRegistry struct {
	// contains filtered or unexported fields
}
```

--------------------------------

### Remote Configuration Error Handling

Source: https://pkg.go.dev/github.com/spf13/viper

Error type and method for handling failures when fetching remote configuration.

```go
type RemoteConfigError string
```

```go
func (rce RemoteConfigError) Error() string
```

--------------------------------

### Set

Source: https://pkg.go.dev/github.com/spf13/viper

Sets a value for a key in the override register.

```APIDOC
## func Set(key string, value any)

### Description
Sets the value for the key in the override register. This is case-insensitive and takes precedence over other configuration sources.

### Parameters
- **key** (string) - Required - The configuration key.
- **value** (any) - Required - The value to assign to the key.
```

--------------------------------

### Unmarshal

Source: https://pkg.go.dev/github.com/spf13/viper

Unmarshals the configuration into a struct.

```APIDOC
## func Unmarshal(rawVal any, opts ...DecoderConfigOption) error

### Description
Unmarshal unmarshals the config into a Struct. Make sure that the tags on the fields of the structure are properly set.

### Parameters
- **rawVal** (any) - The destination struct to unmarshal into.
- **opts** (...DecoderConfigOption) - Optional configuration options for the decoder.
```

--------------------------------

### Unmarshaling Configuration into Structs

Source: https://pkg.go.dev/github.com/spf13/viper

Use Unmarshal to map configuration values into a Go struct. Ensure the struct fields match the configuration keys or use mapstructure tags.

```go
type config struct {
	Port int
	Name string
	PathMap string `mapstructure:"path_map"`
}

var C config

err := viper.Unmarshal(&C)
if err != nil {
	t.Fatalf("unable to decode into struct, %v", err)
}
```

--------------------------------

### func NewCodecRegistry()

Source: https://pkg.go.dev/github.com/spf13/viper

Creates a new instance of DefaultCodecRegistry, which is used to manage custom codecs.

```APIDOC
## func NewCodecRegistry()

### Description
Returns a new CodecRegistry, ready to accept custom Codecs.

### Signature
func NewCodecRegistry() *DefaultCodecRegistry
```

--------------------------------

### UnmarshalExact

Source: https://pkg.go.dev/github.com/spf13/viper

Unmarshals the configuration into a struct, returning an error if keys do not match.

```go
func (v *Viper) UnmarshalExact(rawVal any, opts ...DecoderConfigOption) error
```

--------------------------------

### Define Finder constant

Source: https://pkg.go.dev/github.com/spf13/viper/internal/features

Sets the default boolean value for the finder mechanism.

```go
const Finder = false
```

--------------------------------

### BindPFlag

Source: https://pkg.go.dev/github.com/spf13/viper

Binds a specific configuration key to a pflag.

```APIDOC
## func BindPFlag(key string, flag *pflag.Flag) error

### Description
Binds a specific key to a pflag (as used by cobra).
```

--------------------------------

### SetEnvKeyReplacer

Source: https://pkg.go.dev/github.com/spf13/viper

Sets a replacer to map environment variable keys.

```go
func (v *Viper) SetEnvKeyReplacer(r *strings.Replacer)
```

--------------------------------

### Bind PFlag

Source: https://pkg.go.dev/github.com/spf13/viper

Binds a specific key to a pflag instance, commonly used with Cobra.

```go
func BindPFlag(key string, flag *pflag.Flag) error
```

```go
serverCmd.Flags().Int("port", 1138, "Port to run Application server on")
Viper.BindPFlag("port", serverCmd.Flags().Lookup("port"))
```

--------------------------------

### Implement the FlagValue interface

Source: https://pkg.go.dev/github.com/spf13/viper

Define a custom struct implementing FlagValue to bind non-Pflag systems to Viper.

```go
type myFlag struct {}
func (f myFlag) HasChanged() bool { return false }
func (f myFlag) Name() string { return "my-flag-name" }
func (f myFlag) ValueString() string { return "my-flag-value" }
func (f myFlag) ValueType() string { return "string" }
```

```go
viper.BindFlagValue("my-flag-name", myFlag{})
```

--------------------------------

### SafeWriteConfigAs

Source: https://pkg.go.dev/github.com/spf13/viper

Writes configuration to a specific filename without overwriting existing files.

```go
func (v *Viper) SafeWriteConfigAs(filename string) error
```

--------------------------------

### SetDefault

Source: https://pkg.go.dev/github.com/spf13/viper

Sets a default value for a key.

```APIDOC
## func SetDefault(key string, value any)

### Description
Sets the default value for this key. Default only used when no value is provided by the user via flag, config or ENV.

### Parameters
- **key** (string) - Required - The configuration key.
- **value** (any) - Required - The default value.
```

--------------------------------

### WriteConfigAs

Source: https://pkg.go.dev/github.com/spf13/viper

Writes the current configuration to a specific filename.

```APIDOC
## func WriteConfigAs(filename string) error

### Description
WriteConfigAs writes current configuration to a given filename.
```

--------------------------------

### UnmarshalKey

Source: https://pkg.go.dev/github.com/spf13/viper

Unmarshals a single configuration key into a struct.

```APIDOC
## func UnmarshalKey(key string, rawVal any, opts ...DecoderConfigOption) error

### Description
UnmarshalKey takes a single key and unmarshals it into a Struct.
```

--------------------------------

### Define FlagValue Interface

Source: https://pkg.go.dev/github.com/spf13/viper

Implement this interface to bind custom flags to the Viper configuration system.

```go
type FlagValue interface {
	HasChanged() bool
	Name() string
	ValueString() string
	ValueType() string
}
```

--------------------------------

### Codec interface definition

Source: https://pkg.go.dev/github.com/spf13/viper

Combines Encoder and Decoder interfaces.

```go
type Codec interface {
	Encoder
	Decoder
}
```

--------------------------------

### Implement the FlagValueSet interface

Source: https://pkg.go.dev/github.com/spf13/viper

Define a custom struct implementing FlagValueSet to bind a collection of custom flags to Viper.

```go
type myFlagSet struct {
	flags []myFlag
}

func (f myFlagSet) VisitAll(fn func(FlagValue)) {
	for _, flag := range flags {
		fn(flag)
	}
}
```

```go
fSet := myFlagSet{
	flags: []myFlag{myFlag{}, myFlag{}},
}
viper.BindFlagValues("my-flags", fSet)
```

--------------------------------

### Define EncoderRegistry interface

Source: https://pkg.go.dev/github.com/spf13/viper

Interface for retrieving an encoder for a specific format.

```go
type EncoderRegistry interface {
	Encoder(format string) (Encoder, error)
}
```

--------------------------------

### SafeWriteConfigAs

Source: https://pkg.go.dev/github.com/spf13/viper

Writes the current configuration to a specified filename if it does not exist.

```APIDOC
## func SafeWriteConfigAs(filename string)

### Description
Writes current configuration to a given filename if it does not exist.

### Parameters
- **filename** (string) - Required - The path and name of the file to write.
```

--------------------------------

### Accessing nested keys with dot notation

Source: https://pkg.go.dev/github.com/spf13/viper

Use dot-delimited paths to retrieve values from nested JSON structures.

```json
{
    "host": {
        "address": "localhost",
        "port": 5799
    },
    "datastore": {
        "metric": {
            "host": "127.0.0.1",
            "port": 3099
        },
        "warehouse": {
            "host": "198.0.0.1",
            "port": 2112
        }
    }
}
```

```go
GetString("datastore.metric.host") // (returns "127.0.0.1")
```

--------------------------------

### UnmarshalExact

Source: https://pkg.go.dev/github.com/spf13/viper

Unmarshals the configuration into a struct, erroring if a field is nonexistent.

```APIDOC
## func UnmarshalExact(rawVal any, opts ...DecoderConfigOption) error

### Description
UnmarshalExact unmarshals the config into a Struct, erroring if a field is nonexistent in the destination struct.
```

--------------------------------

### Unmarshaling with Custom Key Delimiters

Source: https://pkg.go.dev/github.com/spf13/viper

Change the default dot delimiter when configuration keys contain dots themselves.

```go
v := viper.NewWithOptions(viper.KeyDelimiter("::"))

v.SetDefault("chart::values", map[string]any{
	"ingress": map[string]any{
		"annotations": map[string]any{
			"traefik.frontend.rule.type":                 "PathPrefix",
			"traefik.ingress.kubernetes.io/ssl-redirect": "true",
		},
	},
})

type config struct {
	Chart struct{
		Values map[string]any
	}
}

var C config

v.Unmarshal(&C)
```

--------------------------------

### Configure Type Inference

Source: https://pkg.go.dev/github.com/spf13/viper

Enables or disables type inference based on default values.

```go
func SetTypeByDefaultValue(enable bool)
```

```go
[]string {"a", "b", "c"}
```

```go
"a b c"
```

--------------------------------

### Codec.Encode

Source: https://pkg.go.dev/github.com/spf13/viper/internal/encoding/toml

Encodes a map into TOML format as a byte slice.

```APIDOC
## func (Codec) Encode

### Description
Encodes a map into TOML format as a byte slice.

### Signature
`func (Codec) Encode(v map[string]any) ([]byte, error)`

### Parameters
- **v** (map[string]any) - The map to encode into TOML.

### Returns
- **[]byte** - The encoded TOML byte slice.
- **error** - Returns an error if encoding fails, otherwise nil.
```

--------------------------------

### Define FlagValueSet Interface

Source: https://pkg.go.dev/github.com/spf13/viper

Implement this interface to bind a collection of flags to Viper.

```go
type FlagValueSet interface {
	VisitAll(fn func(FlagValue))
}
```

--------------------------------

### StringReplacer Interface

Source: https://pkg.go.dev/github.com/spf13/viper

Interface for applying string transformations, often used for environment variable mapping.

```go
type StringReplacer interface {
	// Replace returns a copy of s with all replacements performed.
	Replace(s string) string
}
```

--------------------------------

### SetConfigType

Source: https://pkg.go.dev/github.com/spf13/viper

Sets the type of the configuration (e.g., json, yaml).

```APIDOC
## func SetConfigType(in string)

### Description
Sets the type of the configuration returned by the remote source, e.g. "json".

### Parameters
- **in** (string) - Required - The configuration format type.
```

--------------------------------

### SetEnvKeyReplacer

Source: https://pkg.go.dev/github.com/spf13/viper

Sets a string replacer for environment variable keys.

```APIDOC
## func SetEnvKeyReplacer(r *strings.Replacer)

### Description
Sets the strings.Replacer on the viper object. Useful for mapping an environmental variable to a key that does not match it.

### Parameters
- **r** (*strings.Replacer) - Required - The replacer instance.
```

--------------------------------

### Unmarshal a specific configuration key

Source: https://pkg.go.dev/github.com/spf13/viper

Unmarshals a single configuration key into a struct.

```go
func UnmarshalKey(key string, rawVal any, opts ...DecoderConfigOption) error
```

--------------------------------

### CodecRegistry interface definition

Source: https://pkg.go.dev/github.com/spf13/viper

Combines EncoderRegistry and DecoderRegistry interfaces.

```go
type CodecRegistry interface {
	EncoderRegistry
	DecoderRegistry
}
```

--------------------------------

### DecoderConfigOption type and DecodeHook function

Source: https://pkg.go.dev/github.com/spf13/viper

Configures mapstructure.DecoderConfig options, including custom decode hooks.

```go
type DecoderConfigOption func(*mapstructure.DecoderConfig)
```

```go
func DecodeHook(hook mapstructure.DecodeHookFunc) DecoderConfigOption
```

```go
 mapstructure.ComposeDecodeHookFunc(
		mapstructure.StringToTimeDurationHookFunc(),
		mapstructure.StringToSliceHookFunc(","),
	)
```

--------------------------------

### func (*DefaultCodecRegistry) RegisterCodec

Source: https://pkg.go.dev/github.com/spf13/viper

Registers a custom codec for a specific format.

```APIDOC
## func (*DefaultCodecRegistry) RegisterCodec

### Description
Registers a custom Codec for a given format. The format string is case-insensitive.

### Signature
func (r *DefaultCodecRegistry) RegisterCodec(format string, codec Codec) error
```
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