Witness

https://pkg.go.dev/github.com/transparency-dev/witness
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Witness is a transparency log guardian that prevents split-view attacks by verifying logs evolve...
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### Example Usage: Omniwitness Load Test Setup

Source: https://pkg.go.dev/github.com/transparency-dev/witness/cmd/loadtest

This example demonstrates the full workflow: generating log keys and configuration, starting the omniwitness with the generated config, and then running the load test against it. The omniwitness is left running in the background after its setup.

```bash
# Generate log keys and configuration
go run ./cmd/loadtest/ --log_count=50 > /tmp/logs.yaml

# Run the omniwitness with the generated config. This leaves the process running in the background!
go run ./cmd/omniwitness \
  -v=1 \
  --alsologtostderr \
  --private_key=PRIVATE+KEY+HammerMe+4447e4a4+AZjU0/B7AorRLJHVqRaWaWExHbRQKWgUDb8Bf9NEpee7 \
  --additional_logs=/tmp/logs.yaml \
  --poll_interval=0 \
  --db_file=/tmp/hammerwit.db &

# Run the load test against the witness
go run ./cmd/loadtest/ \
  --target=http://localhost:8080 \
  --log_count=50 \
  --timeout=5s
```

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

### Run Omniwitness in Bastion Mode

Source: https://pkg.go.dev/github.com/transparency-dev/witness/cmd/omniwitness

Example command to run omniwitness with bastion support. Ensure to set `--bastion_addr` to the bastion host's address and `--bastion_key_path` to the private key file. Set `--poll_interval` to 0 for bastion-only mode.

```bash
# Example flags for running omniwitness with bastion support:
omniwitness --bastion_addr=localhost:8080 --bastion_key_path=./my_bastion_private_key.pem --poll_interval=0

```

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

### Start OmniGCP Witness Service

Source: https://pkg.go.dev/github.com/transparency-dev/witness/cmd/omniwitness_gcp

Run the OmniGCP witness binary on a GCP VM. Ensure the SPANNER and SECRET environment variables are set to the resource names of your Spanner database and Secret Manager secret, respectively.

```bash
export SPANNER="projects/..." # This is the spanner resource name of the existing database.
export SECRET="projects/..." # This is the secret manager secret name.
go run ./cmd/omniwitness_gcp/ --signer_private_key_secret_name=${SECRET} --spanner=${SPANNER}
```

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

### Example Witnessed Checkpoint

Source: https://pkg.go.dev/github.com/transparency-dev/witness

An example of a witnessed checkpoint showing signatures from the log and multiple witnesses. This format is used to verify the append-only nature of logs.

```text
developers.google.com/android/binary_transparency/0
611
2GZ1zmS5VkfUZmn2ZyR4KZXwHLD+xnwBIWzql/cD50w=

— pixel_transparency_log csh42zBFAiAd3Y1FwqNTt5RglY0uG7heC6Yu1gEbXXPYmZ7LdOILMAIhAIt68PnR/3TADAaC7hvrSHbpziV7TmpIwOUydLmcjyTQ
— ArmoredWitness-small-breeze nRq5UQAAAABnoqrsRIofXn68vTohcAm2KG4ACGyRPNePUk02BSWD0WKV5ElejTk5Z+Tm3GmJ5j/etA+fkL9XuaQsnTyZbr437sF4AQ==
— ArmoredWitness-autumn-wood qZb5XQAAAABnoqrl57G9CblEl3lwwuqzbaJvVMqNiZCbYZseYT1YZHYmls3CmT1wxZ1fNgM4RxHuUxjAwcI2ghTx6R5aCg+L0DGPBA==
```

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

### Get Metric Factory - Witness Monitoring

Source: https://pkg.go.dev/github.com/transparency-dev/witness/monitoring

Returns the singleton MetricFactory for the application. Avoid calling this during static initialization. Recommended to use with sync.Once.

```go
func GetMetricFactory() MetricFactory

```

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

### Run OmniWitness Standalone with Flags

Source: https://pkg.go.dev/github.com/transparency-dev/witness/cmd/omniwitness

Run the OmniWitness binary directly without Docker, configuring it via command-line flags. This setup allows for basic operation where witnessed checkpoints are accessible via HTTP endpoints.

```bash
go run github.com/transparency-dev/witness/cmd/omniwitness@main --alsologtostderr --v=1 \
  --private_key_path ./path/to/private_key_in_vkey_format \
  --db_file ~/witness.db


```

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

### FetchProofFn Type - witness/feeder

Source: https://pkg.go.dev/github.com/transparency-dev/witness/internal/feeder

FetchProofFn is the signature of a function that fetches a consistency proof. It takes a context, a starting checkpoint number, and an ending checkpoint, returning the proof data and any error encountered.

```go
type FetchProofFn func(ctx context.Context, from uint64, to log.Checkpoint) ([][]byte, error)
```

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

### OmniWitness Docker Compose Environment Variables

Source: https://pkg.go.dev/github.com/transparency-dev/witness/cmd/omniwitness

Environment variables for the Docker Compose setup of the OmniWitness. Ensure the private key path is correctly set.

```env
WITNESS_PRIVATE_KEY_PATH=./path/to/private_key_in_vkey_format

WITNESS_VERSION=latest


```

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

### SumDBClient.FullLeavesAtOffset

Source: https://pkg.go.dev/github.com/transparency-dev/witness/internal/client

Fetches a chunk of leaves (2^height) starting from a specified offset.

```APIDOC
## FullLeavesAtOffset

### Description
FullLeavesAtOffset gets the Nth chunk of 2**height leaves.

### Signature
func (c *SumDBClient) FullLeavesAtOffset(offset int) ([][]byte, error)
```

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

### Get Checkpoint

Source: https://pkg.go.dev/github.com/transparency-dev/witness/internal/witness

Retrieves a checkpoint for a specified log, ensuring it is consistent with other checkpoints for the same log signed by this witness.

```APIDOC
## GetCheckpoint

### Description
Gets a checkpoint for a given log, which is consistent with all other checkpoints for the same log signed by this witness. Returns a nil checkpoint if no checkpoint is stored for the given logID.

### Signature
```go
func (w *Witness) GetCheckpoint(ctx context.Context, origin string) ([]byte, error)
```

### Parameters
- **ctx** (context.Context) - The context for the operation.
- **origin** (string) - The identifier of the log for which to retrieve the checkpoint.
```

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

### Main

Source: https://pkg.go.dev/github.com/transparency-dev/witness/omniwitness

Main runs the omniwitness, with the witness listening using the listener, and all outbound HTTP calls using the client provided.

```APIDOC
## Main

### Description
Runs the omniwitness service.

### Signature
```go
func Main(ctx context.Context, operatorConfig OperatorConfig, p Persistence, httpListener net.Listener, httpClient *http.Client) error
```
```

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

### New Witness Function

Source: https://pkg.go.dev/github.com/transparency-dev/witness/internal/witness

Creates and initializes a new Witness instance. It takes context and options as parameters.

```go
func New(ctx context.Context, wo Opts) (*Witness, error)
```

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

### Proof Marshal Method

Source: https://pkg.go.dev/github.com/transparency-dev/witness/internal/witness

Marshals the Proof into its common format string representation.

```go
func (p Proof) Marshal() string
```

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

### Config struct for bastion connection

Source: https://pkg.go.dev/github.com/transparency-dev/witness/internal/bastion

Configuration for connecting to the bastion service. Includes address, prefix, private key, and a verifier.

```go
type Config struct {
	Addr            string
	Prefix          string
	BastionKey      ed25519.PrivateKey
	WitnessVerifier note.Verifier
}
```

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

### NewSumDB Client Constructor

Source: https://pkg.go.dev/github.com/transparency-dev/witness/internal/client

Creates a new SumDBClient instance. It requires the desired tree height, a verifier, the SumDB URL, and an HTTP client.

```go
func NewSumDB(height int, verifier note.Verifier, url string, c *http.Client) *SumDBClient
```

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

### NewWitness Constructor

Source: https://pkg.go.dev/github.com/transparency-dev/witness/client/http

Creates a new Witness client. It requires a URL to the witness and an http.Client to use for requests.

```go
func NewWitness(url *url.URL, c *http.Client) Witness
```

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

### Main Function Signature

Source: https://pkg.go.dev/github.com/transparency-dev/witness/omniwitness

The Main function is the entry point for running the omniwitness service. It accepts context, operator configuration, persistence, an HTTP listener, and an HTTP client.

```go
func Main(ctx context.Context, operatorConfig OperatorConfig, p Persistence, httpListener net.Listener, httpClient *http.Client) error
```

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

### Run Load Test Against Witness

Source: https://pkg.go.dev/github.com/transparency-dev/witness/cmd/loadtest

Execute the loadtest tool pointing at a running witness instance. Ensure the witness is configured to trust the keys generated by the loadtest tool.

```go
go run ./cmd/loadtest/ --target=http://localhost:8080 --log_count=50
```

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

### PublicFetchOpts Structure

Source: https://pkg.go.dev/github.com/transparency-dev/witness/omniwitness

PublicFetchOpts holds options for fetching public witness network configuration.

```APIDOC
## PublicFetchOpts Structure

### Description
The `PublicFetchOpts` struct contains options used when fetching public witness network configuration files.

### Fields

- **Client** (*http.Client)
  - The HTTP client to use. If unset, `http.DefaultClient` is used.
- **URL** (string)
  - The URL of the configuration file to fetch.
```

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

### New Static Log Configuration

Source: https://pkg.go.dev/github.com/transparency-dev/witness/omniwitness

Creates a new LogConfig from provided YAML data. Use this to initialize log configurations programmatically.

```go
func NewStaticLogConfig(yamlCfg []byte) (*staticLogConfig, error)
```

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

### Generate Logs Configuration with Loadtest

Source: https://pkg.go.dev/github.com/transparency-dev/witness/cmd/loadtest

Run the loadtest tool without a target to generate cryptographic keys for simulated logs and output the required YAML configuration. Redirect this output to a file for later use in witness configuration.

```go
go run ./cmd/loadtest/ --log_count=50 > /tmp/logs.yaml
```

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

### RunFeedOpts Struct Definition

Source: https://pkg.go.dev/github.com/transparency-dev/witness/omniwitness

Configuration options for running feeders. Includes settings for maximum QPS, HTTP client, log matching, feeder configurations, and target witnesses.

```go
type RunFeedOpts struct {
	// MaxWitnessQPS is the maximum number of requests to make per second to any given witness.
	// If unset, a default of 1 QPS will be assumed.
	MaxWitnessQPS float64
	// HTTPClient is the HTTPClient to use, if nil uses http.DefaultClient.
	HTTPClient *http.Client
	// MatchLogs is an optional regex to select a submet of logs to feed.
	MatchLogs string
	// FeederConfigs provides access to feeder configs. Required.
	FeederConfigs func(context.Context) iter.Seq2[FeederConfig, error]
	// Witnesses is the set of witnesses to feed to. Required.
	Witnesses []Witness
}
```

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

### NewSumDB

Source: https://pkg.go.dev/github.com/transparency-dev/witness/internal/client

Creates a new SumDB client instance. It requires an initial height, a verifier for security, the SumDB URL, and an optional HTTP client.

```APIDOC
## NewSumDB

### Description
Creates a new client that fetches tiles of the given height.

### Signature
func NewSumDB(height int, verifier note.Verifier, url string, c *http.Client) *SumDBClient
```

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

### Witness Opts Struct

Source: https://pkg.go.dev/github.com/transparency-dev/witness/internal/witness

Defines the configuration options for creating a new witness instance. It includes persistence, signers, and a verifier function.

```go
type Opts struct {
	Persistence    persistence.LogStatePersistence
	Signers        []note.Signer
	VerifierForLog func(ctx context.Context, origin string) (note.Verifier, bool, error)
}
```

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

### FetchPublicConfig Function

Source: https://pkg.go.dev/github.com/transparency-dev/witness/omniwitness

Fetches public log configurations from a remote source. Use this to dynamically load log details.

```go
func FetchPublicConfig(ctx context.Context, opts PublicFetchOpts) ([]Log, error)
```

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

### Register bastion connection

Source: https://pkg.go.dev/github.com/transparency-dev/witness/internal/bastion

Connects to the bastion to receive checkpoints. Retries on broken connections and returns when the context is done.

```go
func Register(ctx context.Context, c Config, witnessHandler http.Handler) error
```

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

### PublicFetchOpts Struct Definition

Source: https://pkg.go.dev/github.com/transparency-dev/witness/omniwitness

Holds options for fetching public witness network configurations. Allows specifying an HTTP client and the URL of the config file.

```go
type PublicFetchOpts struct {
	// Client is the HTTP client to be used, if unset uses http.DefaultClient.
	Client *http.Client
	// URL is the URL of the config file.
	URL string
}
```

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

### MetricFactory Interface - Witness Monitoring

Source: https://pkg.go.dev/github.com/transparency-dev/witness/monitoring

Defines the interface for creating different types of metrics. Use this to abstract metric creation.

```go
type MetricFactory interface {
	NewCounter(name, help string, labelNames ...string) Counter
}

```

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

### Witness Update Method

Source: https://pkg.go.dev/github.com/transparency-dev/witness/client/http

Attempts to advance the witness state. It takes the current size, new checkpoint data, and a proof. Returns the HTTP status code, response body, or an error.

```go
func (w Witness) Update(ctx context.Context, oldSize uint64, newCP []byte, proof [][]byte) ([]byte, uint64, error)
```

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

### Proof Unmarshal Method

Source: https://pkg.go.dev/github.com/transparency-dev/witness/internal/witness

Unmarshals common proof format data into the Proof struct. Returns an error if parsing fails.

```go
func (p *Proof) Unmarshal(data []byte) error
```

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

### New Witness Creation

Source: https://pkg.go.dev/github.com/transparency-dev/witness/internal/witness

Creates a new witness instance. Initially, the witness will not follow any logs.

```APIDOC
## New

### Description
Creates a new witness, which initially has no logs to follow.

### Signature
```go
func New(ctx context.Context, wo Opts) (*Witness, error)
```

### Parameters
- **ctx** (context.Context) - The context for the operation.
- **wo** (Opts) - The options to configure the witness.
```

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

### ConfigYAML Structure

Source: https://pkg.go.dev/github.com/transparency-dev/witness/omniwitness

Represents the YAML configuration structure for logs, containing a list of LogYAML.

```go
type ConfigYAML struct {
	Logs []LogYAML `yaml:"Logs"`
}
```

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

### RunFeedOpts Structure

Source: https://pkg.go.dev/github.com/transparency-dev/witness/omniwitness

RunFeedOpts configures the options for running feeders.

```APIDOC
## RunFeedOpts Structure

### Description
The `RunFeedOpts` struct defines the configuration parameters for running feeders, including rate limits, HTTP client settings, log matching, and the set of witnesses to feed.

### Fields

- **MaxWitnessQPS** (float64)
  - The maximum number of requests per second to any given witness. Defaults to 1 QPS if unset.
- **HTTPClient** (*http.Client)
  - The HTTP client to use. If nil, `http.DefaultClient` is used.
- **MatchLogs** (string)
  - An optional regular expression to filter which logs to feed.
- **FeederConfigs** (func(context.Context) iter.Seq2[FeederConfig, error])
  - Required function to access feeder configurations.
- **Witnesses** ([]Witness)
  - Required slice of `Witness` structs representing the targets to feed.
```

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

### ParsePublicWitnessConfig Function

Source: https://pkg.go.dev/github.com/transparency-dev/witness/omniwitness

Parses the public witness configuration from an io.Reader. Implements the parser for the public witness config format.

```go
func ParsePublicWitnessConfig(r io.Reader) ([]Log, error)
```

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

### SumDBClient LatestCheckpoint Method

Source: https://pkg.go.dev/github.com/transparency-dev/witness/internal/client

Fetches the most recent checkpoint from the SumDB log.

```go
func (c *SumDBClient) LatestCheckpoint() (*Checkpoint, error)
```

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

### Interactively Feed Checkpoints to Witness

Source: https://pkg.go.dev/github.com/transparency-dev/witness/cmd/omniwitness

Use the `feedwitness` command to send checkpoints to your omniwitness instance for testing. Adjust the `--witness_url` if your witness is not running on `http://localhost:8080`.

```bash
# Change the --witness_url value to point to your witness instance if necessary
go run github.com/transparency-dev/witness/cmd/feedwitness@main --alsologtostderr --witness_url=http://localhost:8080

```

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

### SumDBClient TileData Method

Source: https://pkg.go.dev/github.com/transparency-dev/witness/internal/client

Fetches raw tile data from the SumDB log at a specific level and offset. Supports fetching partial tiles.

```go
func (c *SumDBClient) TileData(level, offset, partial int) ([]byte, error)
```

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

### InertCounter Implementation - Witness Monitoring

Source: https://pkg.go.dev/github.com/transparency-dev/witness/monitoring

An internal-only implementation of the Counter interface, useful for testing or scenarios where metrics are not actively collected.

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

```

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

### Source Struct - witness/feeder

Source: https://pkg.go.dev/github.com/transparency-dev/witness/internal/feeder

Source holds parameters for calling the Feed function. It includes functions to fetch checkpoints and proofs, a verifier for log signatures, and the expected origin of the log.

```go
type Source struct {
	// FetchCheckpoint should return a recent checkpoint from the source log.
	FetchCheckpoint func(ctx context.Context) ([]byte, error)

	// FetchProof should return a consistency proof from the source log.
	//
	// Note that if the witness knows the log but has no previous checkpoint stored, this
	// function will be called with a default `from` value - this allows compact-range
	// type proofs to be supported.  Implementations for non-compact-range type proofs
	// should return an empty proof and no error.
	FetchProof FetchProofFn

	// LogSigVerifier a verifier for log checkpoint signatures.
	LogSigVerifier note.Verifier
	// LogOrigin is the expected first line of checkpoints from the source log.
	LogOrigin string
}
```

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

### FetchPublicConfig

Source: https://pkg.go.dev/github.com/transparency-dev/witness/omniwitness

FetchPublicConfig fetches the public configuration for logs.

```APIDOC
## FetchPublicConfig

### Description
Fetches the public configuration for logs.

### Signature
```go
func FetchPublicConfig(ctx context.Context, opts PublicFetchOpts) ([]Log, error)
```
```

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

### Default Witness Configuration

Source: https://pkg.go.dev/github.com/transparency-dev/witness/omniwitness

This variable holds the default configuration for the witness, embedded as YAML.

```go
var (
	// DefaultConfigLogs is the config for the witness used in the omniwitness.
	// Its schema is LogConfig
	//go:embed logs.yaml
	DefaultConfigLogs []byte
)
```

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

### NewFeedSource

Source: https://pkg.go.dev/github.com/transparency-dev/witness/internal/feeder/tiles

Creates and returns a new feeder.Source instance configured for a tlog-tiles log. This function is used to initialize the feeder with the necessary parameters.

```APIDOC
## func NewFeedSource

### Description
NewFeedSource returns a populated feeder.NewFeedSource configured for a tlog-tiles log.

### Signature
```go
func NewFeedSource(origin string, verifier note.Verifier, logURL string, c *http.Client) (feeder.Source, error)
```

### Parameters
* **origin** (string) - The origin of the log.
* **verifier** (note.Verifier) - The verifier to use for validating notes.
* **logURL** (string) - The URL of the tlog-tiles log.
* **c** (*http.Client) - An HTTP client to use for communication.

### Returns
* **feeder.Source** - A new feeder source instance.
* **error** - An error if the source could not be created.
```

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

### Feeder NewSourceFunc Method

Source: https://pkg.go.dev/github.com/transparency-dev/witness/omniwitness

Returns a function that creates a new Source for the feeder. This is used internally for creating data sources.

```go
func (f Feeder) NewSourceFunc() func(origin string, v note.Verifier, url string, c *http.Client) (feeder.Source, error)
```

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

### Obtain Bastion Backend ID Hash

Source: https://pkg.go.dev/github.com/transparency-dev/witness/cmd/omniwitness

This command derives the bastion backend ID hash from a private key file. This hash is required by the bastion host operator for provisioning. The omniwitness also prints this ID upon startup.

```bash
$ openssl pkey -in ./my_bastion_private_key.pem -pubout -outform der | tail -c32 | sha256sum
02b2442688cd1728f5c25c8425d69a915daddcfa4eb28a809a6b144b0ba889f3  -

```

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

### Witness Update Method

Source: https://pkg.go.dev/github.com/transparency-dev/witness/internal/witness

Updates the latest checkpoint for a log if the new checkpoint is consistent with the current one. It returns the new checkpoint's signature and size, or an error indicating the reason for rejection.

```go
func (w *Witness) Update(ctx context.Context, oldSize uint64, nextRaw []byte, cProof [][]byte) ([]byte, uint64, error)
```

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

### Generate GCP Witness Keys

Source: https://pkg.go.dev/github.com/transparency-dev/witness/cmd/omniwitness_gcp

Use this command to generate a new Ed25519 signing and verification key pair and store them directly in Secret Manager. Ensure WITNESS_SHORT_NAME and WITNESS_ORIGIN environment variables are set.

```bash
export WITNESS_SHORT_NAME=example-witness
export WITNESS_ORIGIN="<something including ${WITNESS_SHORT_NAME}"
go run github.com/transparency-dev/witness/cmd/generate_keys_gcp@HEAD \
   --origin="${WITNESS_ORIGIN}" \
   --resource_suffix="${WITNESS_SHORT_NAME}"
```

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

### Proof Type Definition

Source: https://pkg.go.dev/github.com/transparency-dev/witness/internal/witness

Represents a common format proof as a slice of byte slices. The interpretation of the bytes is ecosystem-dependent.

```go
type Proof [][]byte
```

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

### NewFeedSource

Source: https://pkg.go.dev/github.com/transparency-dev/witness/internal/feeder/sumdb

NewFeedSource returns a populated NewFeedSource configured for a sumdb log.

```APIDOC
## func NewFeedSource

### Description
NewFeedSource returns a populated NewFeedSource configured for a sumdb log.

### Signature
```go
func NewFeedSource(origin string, verifier note.Verifier, logURL string, c *http.Client) (feeder.Source, error)
```

### Parameters
* **origin** (string) - The origin for the SumDB log.
* **verifier** (note.Verifier) - The verifier to use for validating log entries.
* **logURL** (string) - The URL of the SumDB log.
* **c** (*http.Client) - The HTTP client to use for communication.

### Returns
* **feeder.Source** - A new SumDB feeder source.
* **error** - An error if the source could not be created.
```

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

### Set Metric Factory - Witness Monitoring

Source: https://pkg.go.dev/github.com/transparency-dev/witness/monitoring

Sets a singleton MetricFactory instance. This must be called before initializing counters. Only the first call has an effect.

```go
func SetMetricFactory(imf MetricFactory)

```

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

### Proof Unmarshal

Source: https://pkg.go.dev/github.com/transparency-dev/witness/internal/witness

Parses common proof format data and populates the Proof struct.

```APIDOC
## Unmarshal

### Description
Unmarshal parses common proof format data and stores the result in the Proof struct.

### Signature
```go
func (p *Proof) Unmarshal(data []byte) error
```

### Parameters
- **data** ([]byte) - The byte slice containing the proof data.
```

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

### LogConfig Interface Definition

Source: https://pkg.go.dev/github.com/transparency-dev/witness/omniwitness

Defines the contract for accessing and managing log configurations. Use this interface to interact with log data in a standardized way.

```go
type LogConfig interface {
	// Logs returns an iterator of all known logs.
	Logs(ctx context.Context) iter.Seq2[Log, error]
	// Log returns the configuration info of the log with the specified log ID, if it exists.
	Log(ctx context.Context, id string) (Log, bool, error)
	// AddLogs should attempt to merge the provided logs into the current config.
	// The merge must be additive only with respect to the logs.
	AddLogs(ctx context.Context, cfg []Log) error
}
```

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

### Proof Marshal

Source: https://pkg.go.dev/github.com/transparency-dev/witness/internal/witness

Converts a Proof struct into its common format string representation.

```APIDOC
## Marshal

### Description
Marshal returns the common format representation of this proof.

### Signature
```go
func (p Proof) Marshal() string
```
```

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

### Feeder.String

Source: https://pkg.go.dev/github.com/transparency-dev/witness/omniwitness

String returns the string representation of the Feeder.

```APIDOC
## Feeder.String

### Description
Returns the string representation of the Feeder.

### Signature
```go
func (f Feeder) String() string
```
```

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

### HTTPAddCheckpoint Constant

Source: https://pkg.go.dev/github.com/transparency-dev/witness/api

Defines the URL path for adding a new checkpoint. This endpoint requires a request compliant with https://c2sp.org/tlog-witness.

```go
const (
	// HTTPAddCheckpoint is the path of the URL to update to a new checkpoint.
	// This endpoint expects a https://c2sp.org/tlog-witness compliant request.
	HTTPAddCheckpoint = "/add-checkpoint"
)
```

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

### Feeder UnmarshalYAML Method

Source: https://pkg.go.dev/github.com/transparency-dev/witness/omniwitness

Populates the Feeder from YAML data using the provided unmarshal function. Handles deserialization from YAML.

```go
func (f *Feeder) UnmarshalYAML(unmarshal func(any) error) (err error)
```

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

### NewFeedSource

Source: https://pkg.go.dev/github.com/transparency-dev/witness/internal/feeder/pixelbt

NewFeedSource returns a FeedSource configured for PixelBT logs.

```APIDOC
## func NewFeedSource

### Description
NewFeedSource returns a FeedSource configured for PixelBT logs.

### Signature
```go
func NewFeedSource(origin string, verifier note.Verifier, logURL string, c *http.Client) (feeder.Source, error)
```

### Parameters
#### Path Parameters
- **origin** (string) - Description not available.
- **verifier** (note.Verifier) - Description not available.
- **logURL** (string) - Description not available.
- **c** (*http.Client) - Description not available.

### Returns
- **feeder.Source** - Description not available.
- **error** - Description not available.
```

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

### HTTPFetcher GetData Method

Source: https://pkg.go.dev/github.com/transparency-dev/witness/internal/client

Implements the GetData method for HTTPFetcher to retrieve data.

```go
func (f *HTTPFetcher) GetData(path string) ([]byte, error)
```

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

### Create Rekor v1 Feed Source

Source: https://pkg.go.dev/github.com/transparency-dev/witness/internal/feeder/rekor_v1

Use NewFeedSource to create a populated FeedSource struct configured for Rekor v1 logs. It requires the origin, a verifier, the log URL, and an HTTP client.

```go
func NewFeedSource(origin string, verifier note.Verifier, logURL string, c *http.Client) (feeder.Source, error)
```

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

### HTTPFetcher.GetData

Source: https://pkg.go.dev/github.com/transparency-dev/witness/internal/client

Fetches data from a given path over HTTP(S).

```APIDOC
## GetData

### Description
GetData gets the data.

### Signature
func (f *HTTPFetcher) GetData(path string) ([]byte, error)
```

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

### FeederConfig Structure

Source: https://pkg.go.dev/github.com/transparency-dev/witness/omniwitness

Combines a Log configuration with a Feeder type. Used to configure individual log feeders.

```go
type FeederConfig struct {
	Log    Log
	Feeder Feeder
}
```

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

### Fetcher Interface Definition

Source: https://pkg.go.dev/github.com/transparency-dev/witness/internal/client

Defines the Fetcher interface for retrieving data at a given path. This allows for different implementations, including test mocks.

```go
type Fetcher interface {
	// GetData gets the data at the given path, or returns an error.
	GetData(path string) ([]byte, error)
}
```

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

### Register Function

Source: https://pkg.go.dev/github.com/transparency-dev/witness/internal/bastion

The Register function connects to the bastion to receive checkpoints to be witnessed. It handles retries if the connection breaks and returns only when the provided context is done.

```APIDOC
## func Register

### Description
Register connects to the bastion to receive checkpoints to be witnessed. If the connection to the bastion is broken for any reason, it will be retried. This function returns only once the provided context is done.

### Signature
```go
func Register(ctx context.Context, c Config, witnessHandler http.Handler) error
```

### Parameters
#### Path Parameters
This function does not have path parameters.

#### Query Parameters
This function does not have query parameters.

#### Request Body
This function does not have a request body.

### Parameters
- **ctx** (context.Context) - The context for the operation.
- **c** (Config) - The configuration for connecting to the bastion.
- **witnessHandler** (http.Handler) - The handler to process witnessed checkpoints.

### Returns
- **error** - An error if the registration fails, otherwise nil.
```

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

### Counter Interface - Witness Monitoring

Source: https://pkg.go.dev/github.com/transparency-dev/witness/monitoring

Defines a metric for numeric values that increase. Use this for counting events or occurrences.

```go
type Counter interface {
	Inc(labelVals ...string)
}

```

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

### Generate Ed25519 Private Key for Bastion

Source: https://pkg.go.dev/github.com/transparency-dev/witness/cmd/omniwitness

Use this command to generate a new ed25519 private key in PKCS8 PEM format for bastion authentication. It is recommended to use a separate key for bastion operations.

```bash
openssl genpkey -algorith ed25519 -out ./my_bastion_private_key.pem

```

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

### Create New Prometheus Counter

Source: https://pkg.go.dev/github.com/transparency-dev/witness/monitoring/prometheus

The NewCounter method creates a new Counter object, backed by Prometheus. It requires the metric name, a help string, and optionally, label names.

```go
func (pmf MetricFactory) NewCounter(name, help string, labelNames ...string) monitoring.Counter
```

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

### NewPersistence

Source: https://pkg.go.dev/github.com/transparency-dev/witness/internal/persistence/sql

Initializes and returns a new persistence object that utilizes the provided SQL database connection for storing log states.

```APIDOC
## func NewPersistence

### Description
NewPersistence returns a persistence object that is backed by the SQL database.

### Signature
```go
func NewPersistence(db *sql.DB) *sqlLogPersistence
```

### Parameters
#### Path Parameters
This function does not have path parameters.

#### Query Parameters
This function does not have query parameters.

#### Request Body
This function does not have a request body.

### Request Example
```go
// Assuming db is an initialized *sql.DB connection
persistence := sql.NewPersistence(db)
```

### Response
#### Success Response
- **persistence** (*sqlLogPersistence) - A new persistence object configured to use the provided SQL database.
```

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

### SumDBClient ParseCheckpointNote Method

Source: https://pkg.go.dev/github.com/transparency-dev/witness/internal/client

Parses raw checkpoint data into a Checkpoint struct. Use this to process previously obtained checkpoint notes.

```go
func (c *SumDBClient) ParseCheckpointNote(checkpoint []byte) (*Checkpoint, error)
```

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

### Feeder.UnmarshalYAML

Source: https://pkg.go.dev/github.com/transparency-dev/witness/omniwitness

UnmarshalYAML populates the log from yaml using the unmarshal func provided.

```APIDOC
## Feeder.UnmarshalYAML

### Description
Populates the Feeder from YAML data.

### Signature
```go
func (f *Feeder) UnmarshalYAML(unmarshal func(any) error) (err error)
```
```

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

### Run Feeders Function

Source: https://pkg.go.dev/github.com/transparency-dev/witness/omniwitness

Continuously feeds checkpoints from logs to witnesses. This function is long-running and returns when the context is done.

```go
func RunFeeders(ctx context.Context, opts RunFeedOpts) error
```

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

### Log Structure Definition

Source: https://pkg.go.dev/github.com/transparency-dev/witness/omniwitness

Defines the structure for a verifiable log, including its public key, verifier, origin, expected requests per day, contact information, and URL.

```go
type Log struct {
	// VKey is the serialised note-compliant vkey for the log.
	VKey string
	// Verifier is a signature verifier for log checkpoints.
	Verifier note.Verifier
	// Origin is the expected first line of checkpoints from the log.
	Origin string
	// QPD is the expected number of witness requests per day from the log.
	QPD float64
	// Contact is an arbitrary string with contact information for the log operator.
	Contact string
	// URL is the URL of the root of the log.
	URL string
}
```

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

### NewPersistence Function

Source: https://pkg.go.dev/github.com/transparency-dev/witness/internal/persistence/sql

Creates a new persistence object backed by a SQL database. Requires an initialized *sql.DB connection.

```go
func NewPersistence(db *sql.DB) *sqlLogPersistence
```

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

### LogConfig Interface

Source: https://pkg.go.dev/github.com/transparency-dev/witness/omniwitness

The LogConfig interface defines methods for retrieving and managing log configurations within the OmniWitness system.

```APIDOC
## LogConfig Interface

### Description
The `LogConfig` interface provides methods to interact with log configurations. It allows fetching all logs, retrieving a specific log by its ID, and adding new logs to the configuration.

### Methods

- **Logs(ctx context.Context) iter.Seq2[Log, error]**
  - Returns an iterator for all known logs.

- **Log(ctx context.Context, id string) (Log, bool, error)**
  - Retrieves the configuration information for a log with the specified ID. Returns the log, a boolean indicating if it was found, and an error if any occurred.

- **AddLogs(ctx context.Context, cfg []Log) error**
  - Attempts to merge the provided logs into the current configuration. The merge is strictly additive for logs.
```

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

### OperatorConfig Struct Definition

Source: https://pkg.go.dev/github.com/transparency-dev/witness/omniwitness

Defines the configuration for an operator, including witness keys, verifiers, network addresses, rate limits, and distribution settings. This struct allows for minimal operator-specific configuration.

```go
type OperatorConfig struct {
	WitnessKeys []note.Signer
	// This must verify one of the sigs from the previous checkpoint. If the same
	// signing keys are always used for this witness, then this will be a verifier
	// for one of the signers above.
	WitnessVerifier note.Verifier

	// BastionAddr is the host:port of the bastion host to connect to, if any.
	BastionAddr string
	// BastionKey is the key used to authenticate the witness to the bastion host, if
	// a BastionAddr is configured.
	BastionKey ed25519.PrivateKey

	// RateLimit is the maximum number of update requests to serve per second.
	RateLimit float64

	// RestDistributorBaseURL is optional, and if provided gives the base URL
	// to a distributor that takes witnessed checkpoints via a PUT request.
	// TODO(mhutchinson): This should be baked into the code when there is a public distributor.
	RestDistributorBaseURL string

	FeedInterval       time.Duration
	DistributeInterval time.Duration
	// DistributeRateLimit is the maximum number of calls per second to the configured distributor.
	DistributeRateLimit float64

	ServeMux *http.ServeMux

	// Logs provides the witness with the log configuration.
	// If unset, uses the embedded default config.
	Logs LogConfig

	// Feeders provides the witness with the config for self-feeding from logs.
	Feeders func(context.Context) iter.Seq2[FeederConfig, error]

	// WitnessNetworkConfigURLs is optional, and may be set to one or more URLs pointing to resources
	// in the public witness network config format.
	// These resources will be periodically retrieved and incorporated into the LogConfig provided above.
	WitnessNetworkConfigURLs []string

	// WitnessNetworkConfigInterval is the time between attempts to fetch and merge configs from the
	// URLs provided above.
	WitnessNetworkConfigInterval time.Duration
}
```

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

### NewFeedSource

Source: https://pkg.go.dev/github.com/transparency-dev/witness/internal/feeder/serverless

NewFeedSource returns a populated FeedSource configured for a serverless log.

```APIDOC
## func NewFeedSource

### Description
NewFeedSource returns a populated FeedSource configured for a serverless log.

### Signature
```go
func NewFeedSource(origin string, verifier note.Verifier, logURL string, c *http.Client) (feeder.Source, error)
```

### Parameters
* **origin** (string) - The origin of the log.
* **verifier** (note.Verifier) - The verifier to use for validating log entries.
* **logURL** (string) - The URL of the serverless log.
* **c** (*http.Client) - An HTTP client to use for fetching log data.

### Returns
* **feeder.Source** - A new FeedSource instance.
* **error** - An error if the FeedSource could not be created.
```

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

### New Inert Counter - Witness Monitoring

Source: https://pkg.go.dev/github.com/transparency-dev/witness/monitoring

Creates a new inert Counter. This is part of the InertMetricFactory implementation and returns a Counter that does not record metrics.

```go
func (imf InertMetricFactory) NewCounter(name, help string, labelNames ...string) Counter

```

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

### SumDBClient FullLeavesAtOffset Method

Source: https://pkg.go.dev/github.com/transparency-dev/witness/internal/client

Retrieves a chunk of leaves from the SumDB log at a specified offset.

```go
func (c *SumDBClient) FullLeavesAtOffset(offset int) ([][]byte, error)
```

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

### Feeder.MarshalYAML

Source: https://pkg.go.dev/github.com/transparency-dev/witness/omniwitness

MarshalYAML serializes the feeder to its string representation.

```APIDOC
## Feeder.MarshalYAML

### Description
Serializes the Feeder enum to its YAML string representation.

### Signature
```go
func (f Feeder) MarshalYAML() (any, error)
```
```

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

### Feeder.NewSourceFunc

Source: https://pkg.go.dev/github.com/transparency-dev/witness/omniwitness

NewSourceFunc returns a function that creates a new Source for the feeder.

```APIDOC
## Feeder.NewSourceFunc

### Description
Returns a function to create a new Source for the feeder.

### Signature
```go
func (f Feeder) NewSourceFunc() func(origin string, v note.Verifier, url string, c *http.Client) (feeder.Source, error)
```
```

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

### SumDBClient PartialLeavesAtOffset Method

Source: https://pkg.go.dev/github.com/transparency-dev/witness/internal/client

Retrieves the final tile containing incomplete leaves from the SumDB log.

```go
func (c *SumDBClient) PartialLeavesAtOffset(offset, count int) ([][]byte, error)
```

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

### OperatorConfig Structure

Source: https://pkg.go.dev/github.com/transparency-dev/witness/omniwitness

OperatorConfig allows for minimal operator-specific configuration of the OmniWitness.

```APIDOC
## OperatorConfig Structure

### Description
The `OperatorConfig` struct allows for operator-specific configuration of the OmniWitness. It includes settings for witness keys, verifiers, bastion connection details, rate limiting, distributor URLs, and intervals for various operations.

### Fields

- **WitnessKeys** ([]note.Signer)
  - Signing keys for the witness.
- **WitnessVerifier** (note.Verifier)
  - Verifier for one of the witness signers.
- **BastionAddr** (string)
  - The host:port of the bastion host to connect to.
- **BastionKey** (ed25519.PrivateKey)
  - The private key used to authenticate to the bastion host.
- **RateLimit** (float64)
  - The maximum number of update requests to serve per second.
- **RestDistributorBaseURL** (string)
  - Optional base URL for a distributor that accepts witnessed checkpoints.
- **FeedInterval** (time.Duration)
  - The interval for feeding operations.
- **DistributeInterval** (time.Duration)
  - The interval for distribution operations.
- **DistributeRateLimit** (float64)
  - The maximum number of calls per second to the configured distributor.
- **ServeMux** (*http.ServeMux)
  - An optional HTTP ServeMux for handling requests.
- **Logs** (LogConfig)
  - Provides the witness with the log configuration. If unset, uses the embedded default config.
- **Feeders** (func(context.Context) iter.Seq2[FeederConfig, error])
  - Provides access to feeder configurations.
- **WitnessNetworkConfigURLs** ([]string)
  - Optional URLs pointing to public witness network config resources.
- **WitnessNetworkConfigInterval** (time.Duration)
  - The time between attempts to fetch and merge configs from WitnessNetworkConfigURLs.
```

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

### Feeder String Method

Source: https://pkg.go.dev/github.com/transparency-dev/witness/omniwitness

Returns the string representation of the Feeder enum value.

```go
func (f Feeder) String() string
```

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

### SumDBClient Type Definition

Source: https://pkg.go.dev/github.com/transparency-dev/witness/internal/client

Provides access to information from the SumDB. It is used for querying log data.

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

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

### Witness Struct Definition

Source: https://pkg.go.dev/github.com/transparency-dev/witness/client/http

Defines the Witness client structure. It is used for interacting with tlog-witness compatible witnesses over HTTP.

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

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

### SumDBClient.TileData

Source: https://pkg.go.dev/github.com/transparency-dev/witness/internal/client

Retrieves raw tile data for a specific level and offset. Can fetch partial tiles.

```APIDOC
## TileData

### Description
TileHashes gets the raw tile data at the given level and offset. If partial > 0 then a partial tile will be fetched with the number of hashes.

### Signature
func (c *SumDBClient) TileData(level, offset, partial int) ([]byte, error)
```

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

### ParsePublicWitnessConfig

Source: https://pkg.go.dev/github.com/transparency-dev/witness/omniwitness

ParsePublicWitnessConfig implements a parser for the public witness config format.

```APIDOC
## ParsePublicWitnessConfig

### Description
Parses the public witness configuration from an io.Reader.

### Signature
```go
func ParsePublicWitnessConfig(r io.Reader) ([]Log, error)
```
```

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

### NewWitness

Source: https://pkg.go.dev/github.com/transparency-dev/witness/client/http

NewWitness returns a Witness accessed over http at the given URL using the client provided.

```APIDOC
## NewWitness

### Description
Creates a new Witness client.

### Method
`NewWitness`

### Parameters
- `url` (*url.URL) - The URL of the witness.
- `c` (*http.Client) - The HTTP client to use for requests.

### Returns
- `Witness` - An instance of the Witness client.
```

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

### LogYAML Struct Definition

Source: https://pkg.go.dev/github.com/transparency-dev/witness/omniwitness

Represents the structure for log details stored in YAML format. This includes origin, public key, URL, and feeder information.

```go
type LogYAML struct {
	Origin    string `yaml:"Origin"`
	PublicKey string `yaml:"PublicKey"`
	URL       string `yaml:"URL"`
	Feeder    Feeder `yaml:"Feeder"`
}
```

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

### InertMetricFactory Type - Witness Monitoring

Source: https://pkg.go.dev/github.com/transparency-dev/witness/monitoring

An empty struct used to create inert metrics, primarily for testing purposes. It implements the MetricFactory interface.

```go
type InertMetricFactory struct{}

```

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

### Witness GetCheckpoint Method

Source: https://pkg.go.dev/github.com/transparency-dev/witness/internal/witness

Retrieves a checkpoint for a specified log origin that is consistent with other checkpoints signed by this witness. Returns a nil checkpoint if none is stored.

```go
func (w *Witness) GetCheckpoint(ctx context.Context, origin string) ([]byte, error)
```

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

### SumDBClient.LatestCheckpoint

Source: https://pkg.go.dev/github.com/transparency-dev/witness/internal/client

Retrieves the most recent checkpoint from the SumDB log.

```APIDOC
## LatestCheckpoint

### Description
Gets the freshest Checkpoint.

### Signature
func (c *SumDBClient) LatestCheckpoint() (*Checkpoint, error)
```

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

### TestUpdate Function Signature

Source: https://pkg.go.dev/github.com/transparency-dev/witness/internal/persistence/testonly

This function signature is used for testing persistence implementations. It accepts a testing object and a factory function to create persistence instances.

```go
func TestUpdate(t *testing.T, lspFactory func() (persistence.LogStatePersistence, func() error))
```

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

### Feeder MarshalYAML Method

Source: https://pkg.go.dev/github.com/transparency-dev/witness/omniwitness

Serializes the Feeder enum to its string representation for YAML marshaling.

```go
func (f Feeder) MarshalYAML() (any, error)
```

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

### GetMetricFactory

Source: https://pkg.go.dev/github.com/transparency-dev/witness/monitoring

Retrieves the singleton MetricFactory instance used throughout the application.

```APIDOC
## GetMetricFactory

### Description
Returns the singleton MetricFactory for this application. Code should not call this during static initialization as the main program is unlikely to have configured the factory by this time. The recommended pattern is to call this in a `sync.Once` before initializing counters.

### Signature
```go
func GetMetricFactory() MetricFactory
```

### Returns
* `MetricFactory`: The singleton MetricFactory instance.
```

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

### NewStaticLogConfig

Source: https://pkg.go.dev/github.com/transparency-dev/witness/omniwitness

NewStaticLogConfig creates a new LogConfig based on the provided YAML data.

```APIDOC
## NewStaticLogConfig

### Description
Creates a new LogConfig from YAML data.

### Signature
```go
func NewStaticLogConfig(yamlCfg []byte) (*staticLogConfig, error)
```
```

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

### SetMetricFactory

Source: https://pkg.go.dev/github.com/transparency-dev/witness/monitoring

Sets a singleton instance of a MetricFactory. This function must be called, and only the first call will have any effect.

```APIDOC
## SetMetricFactory

### Description
Sets a singleton instance of a MetricFactory that will be used throughout the application. Only the first call to this method will have any effect and it _must_ be called.

### Signature
```go
func SetMetricFactory(imf MetricFactory)
```

### Parameters
* `imf` (MetricFactory) - The MetricFactory instance to set.
```

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

### UpdateFn Function Signature

Source: https://pkg.go.dev/github.com/transparency-dev/witness/omniwitness

Defines the signature for a function that updates a witness. It takes context, old size, new checkpoint data, and proof, returning updated data and size.

```go
type UpdateFn func(ctx context.Context, oldSize uint64, newCP []byte, proof [][]byte) ([]byte, uint64, error)
```

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

### LogYAML Structure

Source: https://pkg.go.dev/github.com/transparency-dev/witness/omniwitness

The LogYAML structure represents the details of a log, typically used for configuration.

```APIDOC
## LogYAML Structure

### Description
The `LogYAML` struct holds the configuration details for a specific log, including its origin, public key, URL, and associated feeder information.

### Fields

- **Origin** (string, `yaml:"Origin"`)
  - The origin of the log.
- **PublicKey** (string, `yaml:"PublicKey"`)
  - The public key associated with the log.
- **URL** (string, `yaml:"URL"`)
  - The URL for the log.
- **Feeder** (Feeder, `yaml:"Feeder"`)
  - The feeder configuration for this log.
```

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

### Witness Struct Definition

Source: https://pkg.go.dev/github.com/transparency-dev/witness/omniwitness

Represents a target witness for feeding, containing an update function and a name.

```go
type Witness struct {
	Update UpdateFn
	Name   string
}
```

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

### Persistence Type Alias

Source: https://pkg.go.dev/github.com/transparency-dev/witness/omniwitness

An alias for persistence.LogStatePersistence, describing the required functionality for persisting log state.

```go
type Persistence = persistence.LogStatePersistence
```

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

### InertMetricFactory

Source: https://pkg.go.dev/github.com/transparency-dev/witness/monitoring

A factory that creates inert (no-op) metrics, primarily used for testing purposes.

```APIDOC
## InertMetricFactory

### Description
Creates inert metrics for testing.

### Type
```go
type InertMetricFactory struct{}
```

### Methods
* `NewCounter(name, help string, labelNames ...string) Counter`: Creates a new inert Counter.
```

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

### MetricFactory.NewCounter

Source: https://pkg.go.dev/github.com/transparency-dev/witness/monitoring/prometheus

NewCounter creates a new Counter object backed by Prometheus. It takes a name, help text, and optional label names.

```APIDOC
## func (MetricFactory) NewCounter

### Description
NewCounter creates a new Counter object backed by Prometheus.

### Signature
```go
func (pmf MetricFactory) NewCounter(name, help string, labelNames ...string) monitoring.Counter
```

### Parameters
* `name` (string) - The name of the metric.
* `help` (string) - The help text for the metric.
* `labelNames` (...string) - Optional label names for the metric.
```

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

### NewFeedSource

Source: https://pkg.go.dev/github.com/transparency-dev/witness/internal/feeder/rekor_v1

NewFeedSource returns a populated FeedSource struct configured for Rekor v1 logs.

```APIDOC
## func NewFeedSource

### Description
NewFeedSource returns a populated FeedSource struct configured for Rekor v1 logs.

### Signature
```go
func NewFeedSource(origin string, verifier note.Verifier, logURL string, c *http.Client) (feeder.Source, error)
```

### Parameters
- **origin** (string) - Description not available.
- **verifier** (note.Verifier) - Description not available.
- **logURL** (string) - Description not available.
- **c** (*http.Client) - Description not available.

### Returns
- **feeder.Source** - Description not available.
- **error** - Description not available.
```

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

### RunFeeders

Source: https://pkg.go.dev/github.com/transparency-dev/witness/omniwitness

RunFeeders continually feeds checkpoints from logs to witnesses according to the provided config. This is a long-running function which will only return when the context is done.

```APIDOC
## RunFeeders

### Description
Continuously feeds checkpoints from logs to witnesses.

### Signature
```go
func RunFeeders(ctx context.Context, opts RunFeedOpts) error
```
```

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

### SumDBClient.ParseCheckpointNote

Source: https://pkg.go.dev/github.com/transparency-dev/witness/internal/client

Parses raw checkpoint note data into a Checkpoint struct.

```APIDOC
## ParseCheckpointNote

### Description
Parses a previously acquired raw checkpoint note data.

### Signature
func (c *SumDBClient) ParseCheckpointNote(checkpoint []byte) (*Checkpoint, error)
```

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

### MetricFactory Interface

Source: https://pkg.go.dev/github.com/transparency-dev/witness/monitoring

Defines the interface for creating different types of metrics, specifically focusing on creating counters.

```APIDOC
## MetricFactory

### Description
Allows the creation of different types of metric.

### Interface
```go
type MetricFactory interface {
	NewCounter(name, help string, labelNames ...string) Counter
}
```

### Methods
* `NewCounter(name, help string, labelNames ...string) Counter`: Creates a new Counter metric.
```
Tokens:
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