headerssetterextension

README

Headers Setter Extension

Status
Stability	alpha
Distributions	contrib, k8s
Issues
Code coverage
Code Owners	@VihasMakwana | Seeking more code owners!

The headers_setter extension implements ClientAuthenticator and is used to set requests headers in gRPC / HTTP exporters with values provided via extension configurations or requests metadata (context).

Use cases include but are not limited to enabling multi-tenancy for observability backends such as Tempo, Mimir, Loki and others by setting the X-Scope-OrgID header to the value extracted from the context.

Configuration

The following settings are available:

• additional_auth (Optional): The ID of another auth extension to chain with. When specified, this extension will call the additional auth extension first, then apply its own headers on top. This allows combining multiple authentication methods, such as OAuth2 for authorization and custom headers for additional metadata.

• headers: a list of header configuration objects that specify headers and their value sources. Each configuration object has the following properties:

  • key: The header name.
  • action (default: upsert): An action to perform on the header. Supported actions are:
    • insert: Inserts the new header if it does not exist.
    • update: Updates the header value if it exists.
    • upsert: Inserts a header if it does not exist and updates the header if it exists.
    • delete: Deletes the header.
  • value: The header value is looked up from the value property of the extension configuration.
  • value_file: The header value is read from a file. The file is watched for changes and the header value is automatically updated when the file changes. This is useful for credentials that are rotated, such as Kubernetes secrets.
  • default_value: (Optional) Value used if no entry for header key specified in from_context is present in request metadata.
  • from_context: The header value is looked up from the request metadata, such as HTTP headers, using the property value as the key (likely a header name).
  • from_attribute: The header value is taken from the request's authentication data (the client.Info.Auth attributes produced by a server-side authenticator extension configured on the receiver), and may include attributes like subject and membership. This is not the resource, scope, span, metric, log, or any other attribute on the telemetry payload itself.

The value, value_file, from_context,default_value and from_attribute,default_value properties are mutually exclusive.

In order for from_context to work, other components in the pipeline also need to be configured appropriately:

• If a batch processor is present in the pipeline, it must be configured to preserve client metadata. Add the value which from_context needs to the metadata_keys of the batch processor.
• Receivers must be configured with include_metadata: true so that metadata keys are available to the pipeline.

Configuration Example

extensions:
  headers_setter:
    headers:
      - action: insert
        key: X-Scope-OrgID
        from_context: tenant_id
        default_value: Org-ID
      - action: upsert
        key: User-ID
        value: user_id
      - action: update
        key: User-ID
        value: user_id
      - action: delete
        key: Some-Header

receivers:
  otlp:
    protocols:
      http:
        include_metadata: true

processors:
  batch:
    # Preserve the tenant-id metadata.
    metadata_keys:
    - tenant_id

exporters:
  loki:
    labels:
      resource:
        container_id: ""
        container_name: ""
    endpoint: https://localhost:<port>/loki/api/v1/push
    auth:
      authenticator: headers_setter

service:
  extensions: [ headers_setter ]
  pipelines:
    traces:
      receivers: [ otlp ]
      processors: [ batch ]
      exporters: [ loki ]

File-Based Credentials Example

The value_file option allows reading header values from files, which is useful for credentials that are rotated, such as Kubernetes secrets or other dynamic credentials:

extensions:
  headers_setter:
    headers:
      - key: X-API-Key
        value_file: /var/secrets/api-key
        action: upsert
      - key: X-Tenant-ID
        value_file: /etc/tenant/id
        action: insert

exporters:
  otlphttp:
    endpoint: https://api.example.com/v1/traces
    auth:
      authenticator: headers_setter

service:
  extensions: [headers_setter]
  pipelines:
    traces:
      receivers: [otlp]
      exporters: [otlphttp]

The files are watched for changes, and header values are automatically updated when the files are modified. This is particularly useful in Kubernetes environments where secrets are mounted as files and can be rotated without restarting the collector.

Chaining with other Auth Extensions

The headers_setter extension can be chained with another authentication extension using the additional_auth parameter. This allows combining multiple authentication methods, such as OAuth2 for bearer token authentication and custom headers for additional metadata or routing information.

Example: Combining OAuth2 and Custom Headers

extensions:
  oauth2client:
    client_id: someclientid
    client_secret: someclientsecret
    token_url: https://example.com/oauth2/default/v1/token
    scopes: ["api.metrics"]
    # The timeout parameter is optional
    timeout: 2s

  headers_setter:
    # Chain with the oauth2client extension
    additional_auth: oauth2client
    headers:
      - key: X-Scope-OrgID
        value: acme-tenant
      - key: X-Custom-Header
        from_context: custom_metadata

receivers:
  otlp:
    protocols:
      http:
        include_metadata: true

exporters:
  prometheus_remote_write:
    endpoint: https://prometheus.example.com/api/v1/write
    auth:
      # Use headers_setter as the authenticator
      # This will apply both OAuth2 and custom headers
      authenticator: headers_setter

service:
  extensions: [oauth2client, headers_setter]
  pipelines:
    metrics:
      receivers: [otlp]
      exporters: [prometheus_remote_write]

In this configuration:

1. The oauth2client extension provides OAuth2 bearer token authentication
2. The headers_setter extension adds custom headers on top of the OAuth2 authentication
3. When the exporter sends data, both authentication methods are applied:
   • OAuth2 adds the Authorization: Bearer <token> header
   • Headers setter adds X-Scope-OrgID and X-Custom-Header headers
4. The collector ensures the oauth2client extension starts before headers_setter due to the dependency relationship

Documentation

Index

• func NewFactory() extension.Factory
• type ActionValue
• type Config
  • func (cfg *Config) Validate() error
• type HeaderConfig

Functions

func NewFactory

func NewFactory() extension.Factory

NewFactory creates a factory for the headers setter extension.

Types

type ActionValue

type ActionValue string

ActionValue is the enum to capture the four types of actions to perform on a header

const (
	// INSERT inserts the new header if it does not exist
	INSERT ActionValue = "insert"

	// UPDATE updates the header value if it exists
	UPDATE ActionValue = "update"

	// UPSERT inserts a header if it does not exist and updates the header
	// if it exists
	UPSERT ActionValue = "upsert"

	// DELETE deletes the header
	DELETE ActionValue = "delete"
)

type Config

type Config struct {
	HeadersConfig  []HeaderConfig `mapstructure:"headers"`
	AdditionalAuth *component.ID  `mapstructure:"additional_auth"`
	// contains filtered or unexported fields
}

func (*Config) Validate

func (cfg *Config) Validate() error

Validate checks if the extension configuration is valid

type HeaderConfig

type HeaderConfig struct {
	Action        ActionValue          `mapstructure:"action"`
	Key           *string              `mapstructure:"key"`
	Value         *string              `mapstructure:"value"`
	ValueFile     *string              `mapstructure:"value_file"`
	FromContext   *string              `mapstructure:"from_context"`
	FromAttribute *string              `mapstructure:"from_attribute"`
	DefaultValue  *configopaque.String `mapstructure:"default_value"`
}