### Setup Environment

Source: https://github.com/cloudfoundry/buildpackapplifecycle/blob/main/_autodocs/00_START_HERE.md

Use this function to set up the application launch environment.

```go
CalcEnv()
```

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

### Builder Configuration Example

Source: https://github.com/cloudfoundry/buildpackapplifecycle/blob/main/_autodocs/INDEX.md

Example of how to configure the builder using command-line flags. Specifies build directory, buildpack order, and output droplet path.

```bash
./builder -buildDir=/app -buildpackOrder=ruby_buildpack -outputDroplet=/out/drop.tgz
```

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

### Platform Options Parsing Examples

Source: https://github.com/cloudfoundry/buildpackapplifecycle/blob/main/_autodocs/api-reference/platform-options.md

Demonstrates parsing valid, empty, and invalid JSON strings for platform options using the Get function.

```go
// Scenario 1: Valid options with Credhub URI
jsonOpts := `{"credhub-uri":"https://credhub.example.com:8844"}`
opts, err := platformoptions.Get(jsonOpts)
if err != nil {
	log.Fatal(err)
}
if opts != nil {
	fmt.Printf("Credhub URI: %s\n", opts.CredhubURI)
	// Output: Credhub URI: https://credhub.example.com:8844
}

// Scenario 2: Empty options
opts, err := platformoptions.Get("")
if err != nil {
	log.Fatal(err)
}
if opts == nil {
	fmt.Println("No platform options provided")
}

// Scenario 3: Invalid JSON
opts, err := platformoptions.Get("{invalid json}")
if err != nil {
	fmt.Printf("Parse error: %v\n", err)
	// err is the JSON unmarshaling error
}
```

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

### Builder Integration Example

Source: https://github.com/cloudfoundry/buildpackapplifecycle/blob/main/_autodocs/api-reference/platform-options.md

Shows how to get and use platform options in the builder to configure Credhub integration.

```go
// In builder/main.go
if platformOptions, err := platformoptions.Get(os.Getenv("VCAP_PLATFORM_OPTIONS")); err != nil {
	fmt.Fprintf(os.Stderr, "Invalid platform options: %v", err)
	os.Exit(3)
} else if platformOptions != nil && platformOptions.CredhubURI != "" {
	attempts := config.CredhubConnectAttempts()
	delay := config.CredhubRetryDelay()
	err = credhub.New(&osshim.OsShim{}, attempts, delay).InterdhubURI()
	if err != nil {
		fmt.Fprintf(os.Stderr, "Unable to interpolate credhub refs: %v", err)
		os.Exit(4)
	}
}
```

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

### Complete Builder Example with Environment

Source: https://github.com/cloudfoundry/buildpackapplifecycle/blob/main/_autodocs/configuration.md

This example demonstrates the full builder command with various flags and the necessary environment variables for Credhub and VCAP services.

```bash
./builder \
	-buildDir=/var/vcap/app \
	-buildpacksDir=/var/vcap/buildpacks \
	-buildpacksDownloadDir=/var/vcap/buildpackdownloads \
	-buildArtifactsCacheDir=/var/vcap/cache \
	-outputDroplet=/var/vcap/result/droplet.tgz \
	-outputMetadata=/var/vcap/result/result.json \
	-outputBuildArtifactsCache=/var/vcap/result/cache.tgz \
	-buildpackOrder=ruby_buildpack,nodejs_buildpack \
	-skipDetect=false \
	-skipCertVerify=false \
	-credhubConnectAttempts=3 \
	-credhubRetryDelay=1s
```

```bash
export VCAP_PLATFORM_OPTIONS='{"credhub-uri":"https://credhub.example.com:8844"}'
export VCAP_SERVICES='{"postgresql":[{"credentials":{"uri":"postgresql://..."}}]}'
export CF_INSTANCE_CERT=/var/vcap/instance_certs/cert
export CF_INSTANCE_KEY=/var/vcap/instance_certs/key
export CF_SYSTEM_CERT_PATH=/var/vcap/certs
```

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

### Launcher Integration Example

Source: https://github.com/cloudfoundry/buildpackapplifecycle/blob/main/_autodocs/api-reference/platform-options.md

Illustrates how to obtain and utilize platform options in the launcher for Credhub service reference interpolation.

```go
// In env/env.go
if platformOptions, err := platformoptions.Get(os.Getenv("VCAP_PLATFORM_OPTIONS")); err != nil {
	return fmt.Errorf("Invalid platform options: %v", err)
} else if platformOptions != nil && platformOptions.CredhubURI != "" {
	err := credhub.New(&osshim.OsShim{}, attempts, delay).InterpolateServiceRefs(
		platformOptions.CredhubURI,
	)
	if err != nil {
		return fmt.Errorf("Unable to interpolate credhub refs: %v", err)
	}
}
```

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

### Setup Build Environment

Source: https://github.com/cloudfoundry/buildpackapplifecycle/blob/main/_autodocs/api-reference/buildpack-runner.md

Initializes the filesystem structure required for the build process. This includes creating necessary directories, downloading remote buildpacks, and cleaning the cache directory.

```APIDOC
## Setup Build Environment

### Description
Initializes the filesystem structure needed for the build. Creates all necessary directories, downloads remote buildpacks, and cleans the cache directory.

### Signature
```go
func (runner *Runner) Setup() error
```

### Returns
- **error** - Error if directory creation, download, or cache cleanup fails
```

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

### Launcher Workflow Entry Points

Source: https://github.com/cloudfoundry/buildpackapplifecycle/blob/main/_autodocs/README.md

Demonstrates the entry points for the launcher workflow, focusing on environment calculation and process execution. This involves calculating the environment and then executing the start command.

```Go
package main

import (
	"code.cloudfoundry.org/buildpackapplifecycle/env"
	"syscall"
)

func main() {
	// ... parse arguments, load staging info ...

	calculatedEnv := env.CalcEnv(stagingInfo, credhubFlags)
	// ... set up environment variables ...

	execErr := syscall.Exec(appPath, args, os.Environ())
	if execErr != nil {
		// handle error
	}
}
```

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

### Get Output Metadata Path

Source: https://github.com/cloudfoundry/buildpackapplifecycle/blob/main/_autodocs/api-reference/lifecycle-builder-config.md

Returns the absolute path where build metadata JSON will be written.

```go
config.OutputMetadata()
```

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

### Launcher Command-Line Arguments

Source: https://github.com/cloudfoundry/buildpackapplifecycle/blob/main/_autodocs/configuration.md

Use this command to launch an application. It requires the application directory and start command, with optional Credhub flags.

```bash
launcher <app-directory> <start-command> [credhub-flags...]
```

```bash
/tmp/lifecycle/launcher /home/vcap/app "bundle exec rails server" \
	-credhubConnectAttempts=3 \
	-credhubRetryDelay=1s
```

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

### Write Start Commands

Source: https://github.com/cloudfoundry/buildpackapplifecycle/blob/main/_autodocs/api-reference/buildpack-runner.md

Writes result JSON and staging info YAML files. Use this to generate output files containing process definitions and buildpack metadata after a build.

```go
resultPath, stagingInfoPath, err := runner.WriteStartCommands(
	"/tmp/buildpacks/ruby_buildpack",
	"ruby_buildpack",
	"Ruby 2.7.2",
	launchData,
)
```

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

### Get Application Build Directory Path

Source: https://github.com/cloudfoundry/buildpackapplifecycle/blob/main/_autodocs/api-reference/lifecycle-builder-config.md

Returns the absolute path to the directory where application bits are staged for building.

```go
func (s LifecycleBuilderConfig) BuildDir() string {
	return s.workingDir
}
```

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

### Get Function Signature

Source: https://github.com/cloudfoundry/buildpackapplifecycle/blob/main/_autodocs/api-reference/platform-options.md

Defines the signature for the Get function, which parses VCAP_PLATFORM_OPTIONS.

```go
func Get(jsonPlatformOptions string) (*PlatformOptions, error)
```

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

### Execute Full Buildpack Lifecycle

Source: https://github.com/cloudfoundry/buildpackapplifecycle/blob/main/_autodocs/api-reference/buildpack-runner.md

Runs the complete build pipeline, including setup, detection, supply, compilation, release, and packaging. Returns the path to the staging info YAML file upon success or an error if any phase fails.

```go
runner := buildpackrunner.New(&config)
deferrunner.CleanUp()

stagingInfoPath, err := runner.Run()
if err != nil {
	fmt.Fprintf(os.Stderr, "Build failed: %v", err)
	os.Exit(buildpackapplifecycle.ExitCodeFromError(err))
}

fmt.Printf("Build succeeded. Staging info at: %s\n", stagingInfoPath)
```

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

### Set Up Application Environment

Source: https://github.com/cloudfoundry/buildpackapplifecycle/blob/main/_autodocs/README.md

Parses CredHub flags and calculates the environment for application execution. This is typically used at the start of the application lifecycle.

```go
credhubFlags := credhub_flags.NewCredhubFlags("launcher")
if err := credhubFlags.Parse(os.Args[3:]); err != nil {
	log.Fatal(err)
}

err := env.CalcEnv(
	&osshim.OsShim{},
	"/home/vcap/app",
	credhubFlags.ConnectAttempts(),
	credhubFlags.RetryDelay(),
)
if err != nil {
	log.Fatal(err)
}

// Environment is now set up for application execution
```

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

### CredHub Integration Example in Builder and Launcher

Source: https://github.com/cloudfoundry/buildpackapplifecycle/blob/main/_autodocs/api-reference/credhub.md

Demonstrates typical usage of CredHub flags and client initialization within both the builder and launcher components of a Cloud Foundry application lifecycle.

```go
// In builder
if platformOptions, err := platformoptions.Get(os.Getenv("VCAP_PLATFORM_OPTIONS")); err != nil {
	fmt.Fprintf(os.Stderr, "Invalid platform options: %v", err)
	os.Exit(3)
} else if platformOptions != nil && platformOptions.CredhubURI != "" {
	attempts := config.CredhubConnectAttempts()
	delay := config.CredhubRetryDelay()
	err = credhub.New(&osshim.OsShim{}, attempts, delay).InterpolateServiceRefs(platformOptions.CredhubURI)
	if err != nil {
		fmt.Fprintf(os.Stderr, "Unable to interpolate credhub refs: %v", err)
		os.Exit(4)
	}
}

// In launcher
credhubFlags := credhub_flags.NewCredhubFlags("launcher")
if err := credhubFlags.Parse(os.Args[3:]); err != nil {
	fmt.Fprintf(os.Stderr, "Could not parse credhub flags: %s", err)
	os.Exit(1)
}

attempts := credhubFlags.ConnectAttempts()
delay := credhubFlags.RetryDelay()

if err := env.CalcEnv(&osshim.OsShim{}, dir, attempts, delay); err != nil {
	fmt.Fprint(os.Stderr, err.Error())
	os.Exit(3)
}
```

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

### VCAP_APPLICATION JSON Mutation Example

Source: https://github.com/cloudfoundry/buildpackapplifecycle/blob/main/_autodocs/api-reference/environment.md

Illustrates the transformation of the VCAP_APPLICATION JSON object, showing how runtime information like host, instance_id, port, and instance_index is added.

```json
{
	"name": "my-app",
	"version": "1.0.0",
	"limits": {"mem": 512, "disk": 1024},
	"uris": ["my-app.example.com"]
}
```

```json
{
	"name": "my-app",
	"version": "1.0.0",
	"limits": {"mem": 512, "disk": 1024},
	"uris": ["my-app.example.com"],
	"host": "0.0.0.0",
	"instance_id": "abcd1234-5678-90ef-ghij-klmno1234567",
	"port": 8080,
	"instance_index": 0
}
```

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

### Get Buildpack Order

Source: https://github.com/cloudfoundry/buildpackapplifecycle/blob/main/_autodocs/api-reference/lifecycle-builder-config.md

Retrieves the ordered list of buildpacks to attempt during the build process, as configured by the buildpackOrder flag.

```go
order := config.BuildpackOrder()
// Might return: ["ruby_buildpack", "nodejs_buildpack"]
```

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

### GoLikeLightning Build Phases

Source: https://github.com/cloudfoundry/buildpackapplifecycle/blob/main/_autodocs/api-reference/buildpack-runner.md

Executes the core build phases: detection, supply, finalize/compile, release, and start command resolution. It writes result JSON even on failure to capture buildpack metadata.

```APIDOC
## GoLikeLightning Build Phases

### Description
Executes the main build phases: detection (if needed), supply, finalize/compile, release, and start command resolution.

### Signature
```go
func (runner *Runner) GoLikeLightning() (string, string, error)
```

### Returns
- **string** - Path to result JSON
- **string** - Path to staging info YAML
- **error** - Error if build fails

### Note
This method writes result JSON even on failure to capture buildpack metadata.
```

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

### Run Build Pipeline

Source: https://github.com/cloudfoundry/buildpackapplifecycle/blob/main/_autodocs/api-reference/buildpack-runner.md

Executes the complete build pipeline, including setup, detection, supply, finalize/compile, release, and packaging. Returns the path to the staging info YAML file upon success.

```APIDOC
## Run Build Pipeline

### Description
Executes the complete build pipeline: setup, detection/selection, supply, finalize/compile, release, and packaging.

### Signature
```go
func (runner *Runner) Run() (string, error)
```

### Returns
- **string** - Path to the staging info YAML file
- **error** - Error if any phase fails

### Example
```go
runner := buildpackrunner.New(&config)
defers runner.CleanUp()

stagingInfoPath, err := runner.Run()
if err != nil {
	fmt.Fprintf(os.Stderr, "Build failed: %v", err)
	os.Exit(buildpackapplifecycle.ExitCodeFromError(err))
}

fmt.Printf("Build succeeded. Staging info at: %s\n", stagingInfoPath)
```
```

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

### Get Output Droplet Path

Source: https://github.com/cloudfoundry/buildpackapplifecycle/blob/main/_autodocs/api-reference/lifecycle-builder-config.md

Returns the absolute path where the final compressed droplet will be written.

```go
config.OutputDroplet()
```

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

### Get Buildpack Path (MD5 Legacy)

Source: https://github.com/cloudfoundry/buildpackapplifecycle/blob/main/_autodocs/api-reference/lifecycle-builder-config.md

Calculates the legacy path for a buildpack using MD5 hashing. This is primarily for compatibility with older cached buildpacks.

```go
func (s LifecycleBuilderConfig) LegacyBuildpackPath(buildpackName string) string {
	return s.buildpackPath(buildpackName, md5.New())
}
```

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

### Get Configured Flags as Arguments

Source: https://github.com/cloudfoundry/buildpackapplifecycle/blob/main/_autodocs/api-reference/lifecycle-builder-config.md

Returns all configured flags as a slice of command-line argument strings. This can be used to inspect or pass flags to external processes.

```go
args := config.Args()
// Might return: ["-buildDir=/tmp/app", "-outputDroplet=/tmp/droplet", ...]
```

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

### VCAP_PLATFORM_OPTIONS Environment Variable Example

Source: https://github.com/cloudfoundry/buildpackapplifecycle/blob/main/_autodocs/api-reference/platform-options.md

Shows the bash command to export the VCAP_PLATFORM_OPTIONS environment variable with a JSON-encoded Credhub URI.

```bash
export VCAP_PLATFORM_OPTIONS='{"credhub-uri":"https://credhub.internal:8844"}'
```

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

### Get Buildpacks Download Directory Path

Source: https://github.com/cloudfoundry/buildpackapplifecycle/blob/main/_autodocs/api-reference/lifecycle-builder-config.md

Returns the absolute path to the directory where downloaded remote buildpacks are stored.

```go
config.BuildpacksDownloadDir()
```

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

### Get Output Build Artifacts Cache Path

Source: https://github.com/cloudfoundry/buildpackapplifecycle/blob/main/_autodocs/api-reference/lifecycle-builder-config.md

Returns the absolute path where the compressed build artifacts cache will be written.

```go
config.OutputBuildArtifactsCache()
```

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

### ExitCodeFromError Function Example

Source: https://github.com/cloudfoundry/buildpackapplifecycle/blob/main/_autodocs/errors.md

This Go code demonstrates how to use the `ExitCodeFromError` function to map an error returned from the buildpack runner to its corresponding exit code, and then exit the process with that code.

```go
config := buildpackapplifecycle.NewLifecycleBuilderConfig([]string{}, false, false)
config.Parse(os.Args[1:])

runner := buildpackrunner.New(&config)
deferrunner.CleanUp()

_, err := runner.Run()
if err != nil {
	exitCode := buildpackapplifecycle.ExitCodeFromError(err)
	fmt.Fprintf(os.Stderr, "Build failed: %v\n", err)
	os.Exit(exitCode)
}
```

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

### Get Entrypoint Prefix from DeaStagingInfo

Source: https://github.com/cloudfoundry/buildpackapplifecycle/blob/main/_autodocs/api-reference/launch-data.md

Retrieve the entrypoint prefix from the `BuildpackConfig` within a `DeaStagingInfo` object. Returns an empty string if no configuration is set. This is useful for legacy DEA compatibility.

```go
info := buildpackrunner.DeaStagingInfo{
	DetectedBuildpack: "ruby_buildpack",
	StartCommand: "bundle exec rails server",
	Config: &buildpackapplifecycle.BuildpackConfig{
		EntrypointPrefix: "/bin/sh -c",
	},
}

prefix := info.GetEntrypointPrefix()  // Returns: "/bin/sh -c"
```

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

### Get Buildpack Path (XXHash)

Source: https://github.com/cloudfoundry/buildpackapplifecycle/blob/main/_autodocs/api-reference/lifecycle-builder-config.md

Calculates the absolute path for a buildpack, using XXHash for consistent naming. Handles both local and remote buildpack references.

```go
// For local buildpack
path1 := config.BuildpackPath("ruby_buildpack")
// Returns: /tmp/buildpacks/3f8d2a5c4b1e9f76

// For remote buildpack (URL)
path2 := config.BuildpackPath("https://github.com/cloudfoundry/ruby-buildpack/releases/download/v1.8.0/ruby-buildpack-v1.8.0.zip")
// Returns: /tmp/buildpackdownloads/a1b2c3d4e5f6g7h8
```

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

### Get Supply Buildpacks

Source: https://github.com/cloudfoundry/buildpackapplifecycle/blob/main/_autodocs/api-reference/lifecycle-builder-config.md

Retrieves all buildpacks except the last one, which are used to run their supply scripts for dependency provision. Returns an empty list if skipDetect is false or only one buildpack is configured.

```go
// If buildpackOrder is ["ruby_buildpack", "nodejs_buildpack"]
supply := config.SupplyBuildpacks()
// Returns: ["ruby_buildpack"]
```

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

### Get Platform Options

Source: https://github.com/cloudfoundry/buildpackapplifecycle/blob/main/_autodocs/api-reference/platform-options.md

Parses the VCAP_PLATFORM_OPTIONS JSON string and returns a PlatformOptions struct. Handles valid JSON, empty input, and invalid JSON scenarios.

```APIDOC
## Get Platform Options

### Description
Parses the VCAP_PLATFORM_OPTIONS JSON string and returns a PlatformOptions struct. This function is used to retrieve and interpret platform-specific configuration settings.

### Method
Go Function Call

### Signature
```go
func Get(jsonPlatformOptions string) (*PlatformOptions, error)
```

### Parameters
#### Path Parameters
None

#### Query Parameters
None

#### Request Body
None

### Parameters
- **jsonPlatformOptions** (string) - Required - JSON-encoded platform options string (typically from VCAP_PLATFORM_OPTIONS environment variable)

### Returns
- **`*PlatformOptions`** — Parsed options, nil if input is empty.
- **`error`** — JSON parsing error if input is invalid.

### Behavior
- If input is empty string: Returns (nil, nil)
- If input is valid JSON: Parses and returns (*PlatformOptions, nil)
- If input is invalid JSON: Returns (nil, error)

### Example
```go
// Scenario 1: Valid options with Credhub URI
jsonOpts := `{"credhub-uri":"https://credhub.example.com:8844"}`
opts, err := platformoptions.Get(jsonOpts)
if err != nil {
	log.Fatal(err)
}
if opts != nil {
	fmt.Printf("Credhub URI: %s\n", opts.CredhubURI)
	// Output: Credhub URI: https://credhub.example.com:8844
}

// Scenario 2: Empty options
opts, err := platformoptions.Get("")
if err != nil {
	log.Fatal(err)
}
if opts == nil {
	fmt.Println("No platform options provided")
}

// Scenario 3: Invalid JSON
opts, err := platformoptions.Get("{invalid json}")
if err != nil {
	fmt.Printf("Parse error: %v\n", err)
	// err is the JSON unmarshaling error
}
```
```

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

### Run Buildpack Lifecycle

Source: https://github.com/cloudfoundry/buildpackapplifecycle/blob/main/_autodocs/README.md

This Go code demonstrates how to initialize and run the buildpack lifecycle builder. It includes configuration parsing, validation, and error handling using exit codes. Ensure necessary imports are present.

```go
config := buildpackapplifecycle.NewLifecycleBuilderConfig(
	[]string{"ruby_buildpack"},
	false,  // perform detection
	false,  // verify SSL certs
)

if err := config.Parse(os.Args[1:]); err != nil {
	log.Fatal(err)
}

if err := config.Validate(); err != nil {
	log.Fatal(err)
}

runner := buildpackrunner.New(&config)
deffer runner.CleanUp()

stagingInfo, err := runner.Run()
if err != nil {
	exitCode := buildpackapplifecycle.ExitCodeFromError(err)
	os.Exit(exitCode)
}

fmt.Printf("Build complete. Staging info at: %s\n", stagingInfo)
```

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

### Get Contents Directory

Source: https://github.com/cloudfoundry/buildpackapplifecycle/blob/main/_autodocs/api-reference/buildpack-runner.md

Returns the absolute path to the temporary contents directory that holds the droplet structure.

```APIDOC
## Get Contents Directory

### Description
Returns the path to the temporary contents directory containing the droplet structure.

### Signature
```go
func (runner *Runner) GetContentsDir() string
```

### Returns
- **string** - Absolute path to contents directory
```

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

### Get Dependencies Directory

Source: https://github.com/cloudfoundry/buildpackapplifecycle/blob/main/_autodocs/api-reference/buildpack-runner.md

Returns the absolute path to the dependencies directory where buildpacks place their supplied dependencies.

```APIDOC
## Get Dependencies Directory

### Description
Returns the path to the dependencies directory where buildpacks place their supplied dependencies.

### Signature
```go
func (runner *Runner) GetDepsDir() string
```

### Returns
- **string** - Absolute path to deps directory
```

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

### Get Credhub Retry Delay from Flags

Source: https://github.com/cloudfoundry/buildpackapplifecycle/blob/main/_autodocs/EXPORTS.md

Retrieves the retry delay duration from a CredhubFlags struct. Returns a time.Duration.

```go
func (chf CredhubFlags) RetryDelay() time.Duration {
	// ... implementation details ...
}
```

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

### Get Credhub Connect Attempts from Flags

Source: https://github.com/cloudfoundry/buildpackapplifecycle/blob/main/_autodocs/EXPORTS.md

Retrieves the number of connection attempts from a CredhubFlags struct. Returns an integer.

```go
func (chf CredhubFlags) ConnectAttempts() int {
	// ... implementation details ...
}
```

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

### WriteStartCommands

Source: https://github.com/cloudfoundry/buildpackapplifecycle/blob/main/_autodocs/api-reference/buildpack-runner.md

Writes the result JSON and staging info YAML files with process definitions and buildpack metadata. It requires the buildpack directory, name, detect output, and complete launch data.

```APIDOC
## WriteStartCommands

### Description
Writes the result JSON and staging info YAML files with process definitions and buildpack metadata.

### Method
*Implicitly a method call on a Runner object*

### Parameters
#### Path Parameters
* None

#### Query Parameters
* None

#### Request Body
* None

### Parameters
- **detectedBuildpackDir** (string) - Required - Path to the final buildpack
- **detectedBuildpack** (string) - Required - Name of the final buildpack
- **detectOutput** (string) - Required - Output from buildpack detect phase (if not skipping detect)
- **procMap** (resources.LaunchData) - Required - Complete launch data with all processes

### Response
#### Success Response
- **string** - Path to result JSON
- **string** - Path to staging info YAML
- **error** - Error if write fails

### Request Example
```go
resultPath, stagingInfoPath, err := runner.WriteStartCommands(
	"/tmp/buildpacks/ruby_buildpack",
	"ruby_buildpack",
	"Ruby 2.7.2",
	launchData,
)
```
```

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

### Create New ZipDownloader

Source: https://github.com/cloudfoundry/buildpackapplifecycle/blob/main/_autodocs/api-reference/buildpack-support.md

Initializes a new ZipDownloader. Use `skipSSLVerification` set to true to bypass SSL certificate verification, which is not recommended for production environments.

```go
// Verify SSL certificates (recommended for production)
downloader := buildpackrunner.NewZipDownloader(false)

// Skip SSL verification (for testing with self-signed certs)
unsafeDownloader := buildpackrunner.NewZipDownloader(true)
```

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

### Buildpack Directory Structure

Source: https://github.com/cloudfoundry/buildpackapplifecycle/blob/main/_autodocs/api-reference/buildpack-support.md

Illustrates the expected layout of a buildpack directory, including required and optional scripts within the '/bin' directory.

```text
buildpack/
├── bin/
│   ├── detect        (required)
│   ├── supply        (optional, for multi-buildpack support)
│   ├── finalize      (optional, replaces compile)
│   └── compile       (required if no finalize)
│   └── release       (required)
└── [other files]

```

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

### Get Buildpacks Directory Path

Source: https://github.com/cloudfoundry/buildpackapplifecycle/blob/main/_autodocs/api-reference/lifecycle-builder-config.md

Returns the absolute path to the local buildpacks directory where local buildpacks are stored.

```go
config.BuildpacksDir()
```

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

### Initialize BuildpackRunner

Source: https://github.com/cloudfoundry/buildpackapplifecycle/blob/main/_autodocs/api-reference/buildpack-runner.md

Creates a new BuildpackRunner instance with the provided configuration. It's recommended to defer the CleanUp method to ensure temporary directories are removed after the build.

```go
config := buildpackapplifecycle.NewLifecycleBuilderConfig([]string{}, false, false)
config.Parse(os.Args[1:])

runner := buildpackrunner.New(&config)
deferrunner.CleanUp()

resultPath, err := runner.Run()
if err != nil {
	log.Fatal(err)
}
```

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

### Process Buildpack Launch Data

Source: https://github.com/cloudfoundry/buildpackapplifecycle/blob/main/_autodocs/README.md

This Go code shows how to process launch data from buildpacks. It merges data from supply buildpacks and the final buildpack, then converts it into a staging result. Error handling is included.

```go
runner := buildpackrunner.New(&config)

// Merge launch.yml from supply buildpacks
launchData, err := runner.ProcessYML(config.SupplyBuildpacks())
if err != nil {
	log.Fatal(err)
}

// Process final buildpack and Procfile
launchData, err = runner.ProcessFinalBuildpack(
	detectedBuildpack,
	detectedBuildpackDir,
	launchData,
)
if err != nil {
	log.Fatal(err)
}

// Convert to staging result
result := resources.ConvertToResult(launchData)
```

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

### Get Builder Executable Path

Source: https://github.com/cloudfoundry/buildpackapplifecycle/blob/main/_autodocs/api-reference/lifecycle-builder-config.md

Retrieves the absolute path to the builder executable. This is useful for invoking the builder directly.

```go
func (s LifecycleBuilderConfig) Path() string {
	return s.ExecutablePath
}
```

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

### Get Credhub Connect Attempts

Source: https://github.com/cloudfoundry/buildpackapplifecycle/blob/main/_autodocs/api-reference/credhub.md

Retrieves the configured number of Credhub connection attempts from the flags. The default value is 3.

```go
func (chf CredhubFlags) ConnectAttempts() int
```

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

### Configure Buildpack Order

Source: https://github.com/cloudfoundry/buildpackapplifecycle/blob/main/_autodocs/configuration.md

Specifies the ordered list of buildpacks to try, separated by commas. This flag is required but auto-populated.

```bash
./builder -buildpackOrder=ruby_buildpack
```

```bash
./builder -buildpackOrder=ruby_buildpack,nodejs_buildpack,java_buildpack
```

```bash
./builder -buildpackOrder=https://github.com/cloudfoundry/ruby-buildpack/releases/download/v1.8.0/ruby-buildpack-v1.8.0.zip
```

```bash
./builder -buildpackOrder=ruby_buildpack,https://github.com/org/custom-buildpack.zip#v2.0.0
```

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

### Configure Builder with Command-Line Flags

Source: https://github.com/cloudfoundry/buildpackapplifecycle/blob/main/_autodocs/README.md

Use these flags to configure the builder's behavior, including input/output paths, buildpack order, and detection settings. Ensure paths are correctly specified.

```bash
./builder \
	-buildDir=/path/to/app \
	-buildpackOrder=buildpack1,buildpack2 \
	-outputDroplet=/path/to/droplet.tgz \
	-outputMetadata=/path/to/result.json \
	-skipDetect=false \
	-credhubConnectAttempts=3 \
	-credhubRetryDelay=1s
```

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

### Get Build Artifacts Cache Directory Path

Source: https://github.com/cloudfoundry/buildpackapplifecycle/blob/main/_autodocs/api-reference/lifecycle-builder-config.md

Returns the absolute path to the directory where previous build artifacts cache is extracted.

```go
config.BuildArtifactsCacheDir()
```

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

### Builder Workflow Entry Points

Source: https://github.com/cloudfoundry/buildpackapplifecycle/blob/main/_autodocs/README.md

Illustrates the entry points for the builder workflow in the buildpackapplifecycle package. This involves creating a new runner instance and executing the build process.

```Go
package main

import (
	"code.cloudfoundry.org/buildpackapplifecycle/buildpackrunner"
)

func main() {
	// ... setup config ...

	runner := buildpackrunner.New(config)
	runner.Run()
}
```

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

### Get Credhub Retry Delay

Source: https://github.com/cloudfoundry/buildpackapplifecycle/blob/main/_autodocs/api-reference/credhub.md

Retrieves the configured delay duration between Credhub connection retry attempts. The default value is 1 second.

```go
func (chf CredhubFlags) RetryDelay() time.Duration
```

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

### Process Struct Definition (resources package)

Source: https://github.com/cloudfoundry/buildpackapplifecycle/blob/main/_autodocs/types.md

An extended process definition from launch.yml, including platform-specific metadata like sidecars and memory limits.

```go
type Process struct {
	Type      string `yaml:"type" json:"type"
	Command   string `yaml:"command" json:"command"
	Platforms struct {
		Cloudfoundry struct {
			SidecarFor []string `yaml:"sidecar_for" json:"sidecar_for"
		} `yaml:"cloudfoundry" json:"cloudfoundry"
	} `yaml:"platforms" json:"platforms"
	Limits struct {
		Memory int `yaml:"memory" json:"memory"
	} `yaml:"limits" json:"limits"
}

```

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

### Get Zero-Padded Deps Index

Source: https://github.com/cloudfoundry/buildpackapplifecycle/blob/main/_autodocs/api-reference/lifecycle-builder-config.md

Returns a zero-padded string index for use in the deps directory structure. The padding width is calculated to accommodate all buildpacks.

```go
// If there are 10 buildpacks total
idx := config.DepsIndex(0)  // Returns: "00"
idx := config.DepsIndex(9)  // Returns: "09"
```

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

### ProcessYML Configuration

Source: https://github.com/cloudfoundry/buildpackapplifecycle/blob/main/_autodocs/api-reference/buildpack-runner.md

Reads and merges launch.yml files from multiple buildpacks based on the provided list of selected buildpacks.

```APIDOC
## ProcessYML Configuration

### Description
Reads and merges launch.yml files from multiple buildpacks.

### Signature
```go
func (runner *Runner) ProcessYML(selectedBuildpacks []string) (resources.LaunchData, error)
```

### Parameters
#### Path Parameters
- **selectedBuildpacks** ([]string) - Required - Buildpack names to process

### Returns
- **resources.LaunchData** - Merged launch data
- **error** - Error if parsing fails
```

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

### Execute Build

Source: https://github.com/cloudfoundry/buildpackapplifecycle/blob/main/_autodocs/00_START_HERE.md

Use this function to execute the build process with a runner.

```go
Run()
```

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

### Set Build Directory

Source: https://github.com/cloudfoundry/buildpackapplifecycle/blob/main/_autodocs/configuration.md

Specifies the directory containing the raw application source code to be built. This is a required flag.

```bash
./builder -buildDir=/path/to/app -buildpackOrder=ruby_buildpack
```

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

### MergeLaunchYML Data

Source: https://github.com/cloudfoundry/buildpackapplifecycle/blob/main/_autodocs/api-reference/buildpack-runner.md

Reads and merges a single buildpack's launch.yml file with existing process data, identified by its buildpack index.

```APIDOC
## MergeLaunchYML Data

### Description
Reads and merges a single buildpack's launch.yml with existing process data.

### Signature
```go
func (runner *Runner) MergeLaunchYML(buildpackIndex int, procMap resources.LaunchData) (resources.LaunchData, error)
```

### Parameters
#### Path Parameters
- **buildpackIndex** (int) - Required - Zero-based index of the buildpack
- **procMap** (resources.LaunchData) - Required - Existing launch data to merge into

### Returns
- **resources.LaunchData** - Updated launch data
- **error** - Error if read/parse fails
```

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

### Interpolate Credhub References

Source: https://github.com/cloudfoundry/buildpackapplifecycle/blob/main/_autodocs/README.md

Illustrates the usage of the InterpolateServiceRefs function from the credhub package to interpolate Credhub references within a configuration. This is typically done during the launcher environment setup.

```Go
import "code.cloudfoundry.org/buildpackapplifecycle/credhub"

// ...

err := credhub.InterpolateServiceRefs(config)
if err != nil {
	// handle error
}

```

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

### Create New Databaseuri Instance

Source: https://github.com/cloudfoundry/buildpackapplifecycle/blob/main/_autodocs/api-reference/database-uri.md

Instantiates a new Databaseuri object. This object is stateless and used to call its methods.

```go
dbUri := databaseuri.New()
```

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

### Path

Source: https://github.com/cloudfoundry/buildpackapplifecycle/blob/main/_autodocs/api-reference/lifecycle-builder-config.md

Returns the absolute path to the builder executable.

```APIDOC
## Path

### Description
Returns the absolute path to the builder executable.

### Signature
```go
func (s LifecycleBuilderConfig) Path() string
```

### Returns
- **string** - Path to the lifecycle builder executable
```

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

### Calculate Environment Variables

Source: https://github.com/cloudfoundry/buildpackapplifecycle/blob/main/_autodocs/EXPORTS.md

Calculates environment variables for the application. Requires an OS interface, directory, number of attempts, and delay duration.

```go
func CalcEnv(os osshim.Os, dir string, attempts int, delay time.Duration) error {
	// ... implementation details ...
}
```

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

### Create New StagingResult

Source: https://github.com/cloudfoundry/buildpackapplifecycle/blob/main/_autodocs/api-reference/models.md

Initializes a new StagingResult with specified process types and lifecycle metadata. Use this when creating a staging result from scratch.

```go
procTypes := buildpackapplifecycle.ProcessTypes{
	"web": "bundle exec rails server -p $PORT",
}
metadata := buildpackapplifecycle.LifecycleMetadata{
	DetectedBuildpack: "ruby_buildpack",
	BuildpackKey:      "ruby",
}
result := buildpackapplifecycle.NewStagingResult(procTypes, metadata)
```

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

### Handle Empty or Missing Credentials

Source: https://github.com/cloudfoundry/buildpackapplifecycle/blob/main/_autodocs/api-reference/database-uri.md

This snippet demonstrates how the Credentials method returns an empty list when VCAP_SERVICES is empty or credentials are not found. No error is returned in this scenario.

```Go
creds, err := dbUri.Credentials([]byte("{}"))
if err != nil {
	log.Fatal(err)
}
// creds == []string{} (empty slice)
```

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

### BuildpackConfig Struct

Source: https://github.com/cloudfoundry/buildpackapplifecycle/blob/main/_autodocs/api-reference/models.md

Defines configuration options for a buildpack, including an optional entrypoint prefix.

```go
type BuildpackConfig struct {
	EntrypointPrefix string `json:"entrypoint_prefix,omitempty" yaml:"entrypoint_prefix,omitempty"`
}
```

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

### Prepare Application Environment

Source: https://github.com/cloudfoundry/buildpackapplifecycle/blob/main/_autodocs/api-reference/environment.md

Use CalcEnv to set up standard Cloud Foundry environment variables like HOME, TMPDIR, DEPS_DIR, VCAP_APPLICATION, and DATABASE_URL. It also handles Credhub reference interpolation and cleans up VCAP_PLATFORM_OPTIONS. Requires an OS interface, application directory, and optional Credhub connection parameters.

```go
dir := "/var/vcap/app"
credhubFlags := credhub_flags.NewCredhubFlags("launcher")
if err := credhubFlags.Parse(os.Args[3:]); err != nil {
	fmt.Fprintf(os.Stderr, "Could not parse credhub flags: %s", err)
	os.Exit(1)
}

attempts := credhubFlags.ConnectAttempts()
delay := credhubFlags.RetryDelay()

if err := env.CalcEnv(&osshim.OsShim{}, dir, attempts, delay); err != nil {
	fmt.Fprint(os.Stderr, err.Error())
	os.Exit(3)
}

// Environment is now ready for application startup
// Available environment variables:
// HOME=/var/vcap/app
// TMPDIR=/var/vcap/tmp
// DEPS_DIR=/var/vcap/deps
// VCAP_APPLICATION={"host":"0.0.0.0","instance_id":"...","port":8080,...}
// VCAP_SERVICES={interpolated credentials}
// DATABASE_URL=postgresql://user:pass@host/db (if applicable)
```

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

### Configure Multi-Buildpack Order

Source: https://github.com/cloudfoundry/buildpackapplifecycle/blob/main/_autodocs/README.md

Specify the order of buildpacks for multi-buildpack support. The last buildpack in the list performs the finalize/compile and release steps.

```bash
-buildpackOrder=buildpack1,buildpack2,buildpack3
```

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

### Args

Source: https://github.com/cloudfoundry/buildpackapplifecycle/blob/main/_autodocs/api-reference/lifecycle-builder-config.md

Returns all configured flags as command-line arguments in the format "-flag=value".

```APIDOC
## Args

### Description
Returns all configured flags as command-line arguments.

### Signature
```go
func (s LifecycleBuilderConfig) Args() []string
```

### Returns
- **[]string** - Slice of argument strings in "-flag=value" format

### Example
```go
args := config.Args()
// Might return: ["-buildDir=/tmp/app", "-outputDroplet=/tmp/droplet", ...]
```
```

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

### Set DATABASE_URL Environment Variable

Source: https://github.com/cloudfoundry/buildpackapplifecycle/blob/main/_autodocs/api-reference/database-uri.md

Integrates database URI resolution into an application's startup logic. It checks for VCAP_SERVICES, extracts credentials, normalizes the URI, and sets the DATABASE_URL environment variable if a supported database is found.

```go
// Extract and set DATABASE_URL if available
if os.Getenv("VCAP_SERVICES") != "" {
	dbUri := databaseuri.New()
	if creds, err := dbUri.Credentials([]byte(os.Getenv("VCAP_SERVICES"))); err == nil {
		databaseUrl := dbUri.Uri(creds)
		if databaseUrl != "" {
			err = os.Setenv("DATABASE_URL", databaseUrl)
			if err != nil {
				fmt.Fprintf(os.Stderr, "Unable to set DATABASE_URL: %v", err)
				os.Exit(5)
			}
		}
	}
}
```

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

### Process Struct

Source: https://github.com/cloudfoundry/buildpackapplifecycle/blob/main/_autodocs/api-reference/models.md

Represents a single process with its type and command.

```go
type Process struct {
	Type    string `yaml:"type" json:"type"`
	Command string `yaml:"command" json:"command"`
}
```

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

### NewZipDownloader Constructor

Source: https://github.com/cloudfoundry/buildpackapplifecycle/blob/main/_autodocs/api-reference/buildpack-support.md

Creates a new ZipDownloader instance, which is used for downloading and extracting ZIP-based buildpacks. SSL verification can be optionally skipped.

```APIDOC
## NewZipDownloader Constructor

### Description
Creates a new ZipDownloader with optional SSL verification bypass.

### Signature
```go
func NewZipDownloader(skipSSLVerification bool) *ZipDownloader
```

### Parameters
#### Path Parameters
- **skipSSLVerification** (bool) - Required - If true, skips SSL certificate verification

### Returns
- **&#42;ZipDownloader** - Initialized downloader

### Example:
```go
// Verify SSL certificates (recommended for production)
downloader := buildpackrunner.NewZipDownloader(false)

// Skip SSL verification (for testing with self-signed certs)
unsafeDownloader := buildpackrunner.NewZipDownloader(true)
```
```

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

### Process Type Definition

Source: https://github.com/cloudfoundry/buildpackapplifecycle/blob/main/_autodocs/api-reference/launch-data.md

Defines a single process with its type, command, platform-specific configurations, and resource limits.

```go
type Process struct {
	Type      string `yaml:"type" json:"type"`
	Command   string `yaml:"command" json:"command"`
	Platforms struct {
		Cloudfoundry struct {
			SidecarFor []string `yaml:"sidecar_for" json:"sidecar_for"`
		} `yaml:"cloudfoundry" json:"cloudfoundry"`
	} `yaml:"platforms" json:"platforms"`
	Limits struct {
		Memory int `yaml:"memory" json:"memory"`
	} `yaml:"limits" json:"limits"`
}
```

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

### Download and Extract ZIP Buildpack

Source: https://github.com/cloudfoundry/buildpackapplifecycle/blob/main/_autodocs/api-reference/buildpack-support.md

Downloads a ZIP file from a given URL and extracts its contents to a specified destination directory. It handles temporary file creation, download progress, and extraction, returning the downloaded file size and any errors encountered. The download process has a 10-minute timeout.

```go
downloader := buildpackrunner.NewZipDownloader(false)

u, _ := url.Parse("https://github.com/cloudfoundry/python-buildpack/releases/download/v1.7.0/python-buildpack-v1.7.0.zip")

size, err := downloader.DownloadAndExtract(u, "/tmp/buildpacks/python_buildpack")
if err != nil {
	fmt.Printf("Download failed: %v\n", err)
	os.Exit(1)
}

fmt.Printf("Downloaded and extracted %d bytes\n", size)
```

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

### WriteStagingInfoYML

Source: https://github.com/cloudfoundry/buildpackapplifecycle/blob/main/_autodocs/api-reference/buildpack-runner.md

Writes a YAML file with staging information for DEA compatibility. It takes build result data and a list of buildpack metadata.

```APIDOC
## WriteStagingInfoYML

### Description
Writes a YAML file with staging information for DEA compatibility (legacy format).

### Method
*Implicitly a method call on a Runner object*

### Parameters
#### Path Parameters
* None

#### Query Parameters
* None

#### Request Body
* None

### Parameters
- **resultData** (buildpackapplifecycle.StagingResult) - Required - Build result data
- **buildpacks** ([]buildpackapplifecycle.BuildpackMetadata) - Required - List of buildpack metadata

### Response
#### Success Response
- **string** - Path to staging info file
- **error** - Error if write fails
```

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

### Create Builder Config

Source: https://github.com/cloudfoundry/buildpackapplifecycle/blob/main/_autodocs/00_START_HERE.md

Use this function to create a new configuration for the lifecycle builder.

```go
NewLifecycleBuilderConfig()
```

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

### BuildpackMetadata Struct

Source: https://github.com/cloudfoundry/buildpackapplifecycle/blob/main/_autodocs/api-reference/models.md

Contains detailed information about a specific buildpack, such as its key, name, version, and configuration.

```go
type BuildpackMetadata struct {
	Key            string           `json:"key" yaml:"key"`
	Name           string           `json:"name" yaml:"name"`
	Version        string           `json:"version,omitempty" yaml:"version,omitempty"`
	Config         *BuildpackConfig `json:"config,omitempty" yaml:"config,omitempty"`
	OutputMetadata map[string]any   `json:"output_metadata,omitempty" yaml:"output_metadata,omitempty"`
}
```

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

### hasSupply (Unix)

Source: https://github.com/cloudfoundry/buildpackapplifecycle/blob/main/_autodocs/api-reference/buildpack-support.md

Checks whether a buildpack has a `/bin/supply` script. This is used for multi-buildpack support.

```APIDOC
## hasSupply (Unix)

### Description
Checks whether a buildpack has a `/bin/supply` script. This is used for multi-buildpack support.

### Signature
```go
func hasSupply(buildpackPath string) (bool, error)
```

### Parameters
#### Path Parameters
- **buildpackPath** (string) - Required - Path to buildpack directory

### Returns
- **bool** — true if /bin/supply exists
- **error** — Error if check fails
```

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

### BuildDir

Source: https://github.com/cloudfoundry/buildpackapplifecycle/blob/main/_autodocs/api-reference/lifecycle-builder-config.md

Returns the absolute path to the application build directory where raw app bits are located.

```APIDOC
## BuildDir

### Description
Returns the absolute path to the application build directory.

### Signature
```go
func (s LifecycleBuilderConfig) BuildDir() string
```

### Returns
- **string** - Path where raw app bits are located
```

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

### Create New Container Path

Source: https://github.com/cloudfoundry/buildpackapplifecycle/blob/main/_autodocs/EXPORTS.md

Creates a new container path object. Accepts a string argument, likely a path identifier.

```go
func New(_ string) *cpath {
	// ... implementation details ...
}
```

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

### Create Builder Configuration

Source: https://github.com/cloudfoundry/buildpackapplifecycle/blob/main/_autodocs/README.md

Shows how to create a new instance of LifecycleBuilderConfig, which is used for configuring the builder process. This function is part of the main buildpackapplifecycle package.

```Go
import "code.cloudfoundry.org/buildpackapplifecycle"

// ...

config := buildpackapplifecycle.NewLifecycleBuilderConfig()
// ... configure config ...

```

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

### Convert LaunchData to StagingResult

Source: https://github.com/cloudfoundry/buildpackapplifecycle/blob/main/_autodocs/api-reference/launch-data.md

Use this function to convert `LaunchData` into a `buildpackapplifecycle.StagingResult`. It separates regular processes from sidecars and populates both the process list and process type map. Processes without `sidecar_for` are added to `ProcessList` and `ProcessTypes`, while those with `sidecar_for` are converted to `Sidecar` entries.

```go
launchData := resources.LaunchData{
	Processes: []resources.Process{
		{
			Type:    "web",
			Command: "npm start",
		},
		{
			Type:    "logging-agent",
			Command: "node logging-agent.js",
			Platforms: struct {
				Cloudfoundry struct {
					SidecarFor []string `yaml:"sidecar_for"`
				}
			}{
				Cloudfoundry: struct {
					SidecarFor []string `yaml:"sidecar_for"`
				}{
					SidecarFor: []string{"web"},
				},
			},
			Limits: struct {
				Memory int `yaml:"memory"`
			}{
				Memory: 256,
			},
		},
	},
}

result := resources.ConvertToResult(launchData)
// result.ProcessTypes == map[string]string{"web": "npm start"}
// result.ProcessList == []Process{web process}
// result.Sidecars == []Sidecar{logging-agent sidecar for web}
```

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

### DeaStagingInfo.GetEntrypointPrefix

Source: https://github.com/cloudfoundry/buildpackapplifecycle/blob/main/_autodocs/api-reference/launch-data.md

Returns the entrypoint prefix from the buildpack config, or an empty string if no config is set.

```APIDOC
## DeaStagingInfo.GetEntrypointPrefix

### Description
Returns the entrypoint prefix from the buildpack config, or an empty string if no config is set.

### Signature
```go
func (stagingInfo DeaStagingInfo) GetEntrypointPrefix() string
```

### Parameters
N/A

### Returns
- **string** — Entrypoint prefix or empty string

### Example
```go
info := buildpackrunner.DeaStagingInfo{
	DetectedBuildpack: "ruby_buildpack",
	StartCommand: "bundle exec rails server",
	Config: &buildpackapplifecycle.BuildpackConfig{
		EntrypointPrefix: "/bin/sh -c",
	},
}

prefix := info.GetEntrypointPrefix()  // Returns: "/bin/sh -c"
```
```

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

### Set Output Metadata Path

Source: https://github.com/cloudfoundry/buildpackapplifecycle/blob/main/_autodocs/configuration.md

Specifies the file path where the build result metadata JSON will be written. This is a required flag.

```bash
./builder -outputMetadata=/output/result.json
```

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

### Configure Network Certificate Verification

Source: https://github.com/cloudfoundry/buildpackapplifecycle/blob/main/_autodocs/configuration.md

Use the -skipCertVerify flag to control SSL certificate verification for remote buildpack downloads. Skipping verification is not recommended for production due to security risks.

```bash
# Verify certificates (recommended for production)
./builder -skipCertVerify=false
```

```bash
# Skip verification (use only for testing)
./builder -skipCertVerify=true
```

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

### Parse Platform Options

Source: https://github.com/cloudfoundry/buildpackapplifecycle/blob/main/_autodocs/api-reference/environment.md

This snippet shows how to parse the VCAP_PLATFORM_OPTIONS environment variable to retrieve platform configuration, such as the Credhub URI, using the platformoptions module.

```go
platformOptions, err := platformoptions.Get(os.Getenv("VCAP_PLATFORM_OPTIONS"))
```

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

### LifecycleBuilderConfig Methods

Source: https://github.com/cloudfoundry/buildpackapplifecycle/blob/main/_autodocs/EXPORTS.md

Provides access to various configuration details and paths within the LifecycleBuilderConfig.

```APIDOC
## Methods for LifecycleBuilderConfig

### Path()
Returns the builder executable path.

### Args()
Returns the command-line arguments for the builder.

### Validate()
Performs validation on the builder configuration and returns an error if invalid.

### BuildDir()
Returns the path to the application source directory.

### BuildpackPath(buildpackName string)
Returns the storage path for a specific buildpack.

### LegacyBuildpackPath(buildpackName string)
Returns the legacy MD5 path for a specific buildpack.

### BuildpackOrder()
Returns the ordered list of buildpacks.

### SupplyBuildpacks()
Returns the list of buildpacks used for supplying dependencies (non-final).

### DepsIndex(i int)
Returns the zero-padded index for dependencies.

### BuildpacksDir()
Returns the path to the local buildpacks directory.

### BuildpacksDownloadDir()
Returns the path for downloading remote buildpacks.

### BuildArtifactsCacheDir()
Returns the path to the build artifacts cache directory.

### OutputDroplet()
Returns the output path for the droplet.

### OutputMetadata()
Returns the output path for the metadata.

### OutputBuildArtifactsCache()
Returns the output path for the build artifacts cache.

### SkipCertVerify()
Returns a boolean indicating if SSL certificate verification is skipped.

### SkipDetect()
Returns a boolean indicating if the detect phase is skipped.

### CredhubConnectAttempts()
Returns the number of connection attempts for CredHub.

### CredhubRetryDelay()
Returns the retry delay duration for CredHub connections.
```

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

### NewLifecycleBuilderConfig Constructor

Source: https://github.com/cloudfoundry/buildpackapplifecycle/blob/main/_autodocs/api-reference/lifecycle-builder-config.md

Creates a new builder configuration with default values. Use this to initialize the builder configuration and register flags.

```go
config := buildpackapplifecycle.NewLifecycleBuilderConfig(
	[]string{"ruby_buildpack", "nodejs_buildpack"},
	false,  // perform detect
	false,  // verify SSL certs
)

// Parse command-line arguments
if err := config.Parse(os.Args[1:]); err != nil {
	log.Fatal(err)
}

if err := config.Validate(); err != nil {
	log.Fatal(err)
}
```

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

### PlatformOptions Struct Definition

Source: https://github.com/cloudfoundry/buildpackapplifecycle/blob/main/_autodocs/types.md

Holds platform-level configuration passed via the VCAP_PLATFORM_OPTIONS environment variable.

```go
type PlatformOptions struct {
	CredhubURI string `json:"credhub-uri"
}

```

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

### Check for /bin/supply Script (Unix)

Source: https://github.com/cloudfoundry/buildpackapplifecycle/blob/main/_autodocs/api-reference/buildpack-support.md

Verifies if a buildpack directory contains a '/bin/supply' script. This is used for multi-buildpack support.

```go
func hasSupply(buildpackPath string) (bool, error)
```

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

### Create Runner

Source: https://github.com/cloudfoundry/buildpackapplifecycle/blob/main/_autodocs/00_START_HERE.md

Use this function to create a new runner instance for buildpack execution.

```go
New()
```

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

### BuildpackOrder

Source: https://github.com/cloudfoundry/buildpackapplifecycle/blob/main/_autodocs/api-reference/lifecycle-builder-config.md

Returns the ordered list of buildpacks to try, as configured in the buildpackOrder flag. This method provides the sequence in which buildpacks are evaluated during the build process.

```APIDOC
## BuildpackOrder

### Description
Returns the ordered list of buildpacks to try, as configured in the buildpackOrder flag.

### Signature
```go
func (s LifecycleBuilderConfig) BuildpackOrder() []string
```

### Returns
`[]string` — Buildpack names/URLs in order of preference

### Example
```go
order := config.BuildpackOrder()
// Might return: ["ruby_buildpack", "nodejs_buildpack"]
```
```