Plugins - Bifrost

The plugins array only controls explicitly opt-in plugins: semantic_cache, otel, maxim, datadog (enterprise), and custom plugins.Telemetry, logging, and governance are auto-loaded built-ins - they are always active and configured via the client block and dedicated top-level keys, not the plugins array.

Auto-Loaded Built-ins

These plugins start automatically. You do not add them to the plugins array.

Plugin	Always active?	How to configure
Telemetry (Prometheus `/metrics`)	Yes, always	`client.prometheus_labels` for custom labels; push gateway via `plugins` entry once DB-backed mode is running
Logging	When `client.enable_logging: true` and `logs_store` is configured	`client.enable_logging`, `client.disable_content_logging`, `client.logging_headers`
Governance	Yes, always (OSS)	`client.enforce_auth_on_inference` for VK enforcement; `governance.*` for virtual keys / budgets / routing rules

See Client Configuration and Governance for full details.

Plugin Array Structure

Every entry in the plugins array supports these common fields:

Field	Type	Required	Description
`name`	string	Yes	Plugin name
`enabled`	boolean	Yes	Enable or disable this plugin
`config`	object	Varies	Plugin-specific configuration
`path`	string	No	Path to a custom plugin binary or WASM file
`version`	integer	No	🛑 DB-Backed Only. Plugin metadata persisted on `TablePlugin`. In DB-backed sync, higher values trigger replacement/reload. Valid range: `1` to `32767`.
`placement`	string	No	🛑 DB-Backed Only. Execution metadata (`"pre_builtin"`, `"builtin"`, `"post_builtin"`) persisted on `TablePlugin` and used for ordering behavior.
`order`	integer	No	🛑 DB-Backed Only. Execution metadata persisted on `TablePlugin`; within a placement group, lower values run earlier.

name, enabled, path, and config are the core plugin config fields. In DB-backed mode, version, placement, and order are persisted on TablePlugin and used during sync/runtime ordering.

Semantic Cache
OpenTelemetry
Maxim
Datadog

Semantic Cache

Caches LLM responses by semantic similarity. Returns a cached response when an incoming request is semantically close enough to a previous one.Requires a vector store to be configured.

Field	Required	Default	Description
`config.dimension`	Yes	-	Embedding dimension. Use `1` for hash-based (exact) caching without an embedding provider
`config.provider`	No	-	Provider for generating embeddings (required for semantic mode)
`config.embedding_model`	No	-	Model for embeddings (required when `provider` is set)
`config.threshold`	No	`0.8`	Cosine similarity threshold for a cache hit (0.0–1.0)
`config.ttl`	No	`300`	Cache entry TTL in seconds (or a duration string like `"1h"`)
`config.cache_by_model`	No	`true`	Include model in cache key
`config.cache_by_provider`	No	`true`	Include provider in cache key
`config.exclude_system_prompt`	No	`false`	Exclude system prompt from cache key
`config.conversation_history_threshold`	No	`3`	Skip caching for requests with more messages than this
`config.default_cache_key`	No	-	Default cache key when no `x-bf-cache-key` header is sent

Semantic mode (embedding-based similarity search):

{
  "plugins": [
    {
      "name": "semantic_cache",
      "enabled": true,
      "config": {
        "provider": "openai",
        "embedding_model": "text-embedding-3-small",
        "dimension": 1536,
        "threshold": 0.85,
        "ttl": 300,
        "cache_by_model": true,
        "cache_by_provider": true
      }
    }
  ]
}

Hash mode (exact-match caching, no embedding provider needed):

{
  "plugins": [
    {
      "name": "semantic_cache",
      "enabled": true,
      "config": {
        "dimension": 1,
        "ttl": 1800
      }
    }
  ]
}

You must also configure a vector_store in config.json. See Storage - vector_store.

OpenTelemetry (OTel)

Exports distributed traces to any OTel-compatible collector (Jaeger, Zipkin, Tempo, Datadog via OTLP, etc.).

Field	Required	Default	Description
`config.collector_url`	Yes	-	OTLP collector endpoint
`config.trace_type`	Yes	-	Trace format: `"genai_extension"`, `"vercel"`, or `"open_inference"`
`config.protocol`	Yes	-	`"http"` or `"grpc"`
`config.service_name`	No	`"bifrost"`	Service name reported to the collector
`config.metrics_enabled`	No	`false`	Enable push-based OTLP metrics export
`config.metrics_endpoint`	No	-	OTLP metrics endpoint URL
`config.metrics_push_interval`	No	`15`	Metrics push interval in seconds
`config.headers`	No	-	Custom headers for the collector (supports `env.` prefix)
`config.insecure`	No	`false`	Skip TLS verification
`config.tls_ca_cert`	No	-	Path to TLS CA certificate
`config.plugin_span_filter`	No	-	Filter which plugin hook spans are exported. See Filtering Plugin Spans

{
  "plugins": [
    {
      "name": "otel",
      "enabled": true,
      "config": {
        "collector_url": "http://otel-collector:4318",
        "trace_type": "genai_extension",
        "protocol": "http",
        "service_name": "bifrost-gateway"
      }
    }
  ]
}

With authentication headers:

{
  "plugins": [
    {
      "name": "otel",
      "enabled": true,
      "config": {
        "collector_url": "https://otel.example.com:4318",
        "trace_type": "open_inference",
        "protocol": "http",
        "service_name": "bifrost",
        "headers": {
          "Authorization": "env.OTEL_AUTH_HEADER"
        }
      }
    }
  ]
}

With OTLP metrics export:

{
  "plugins": [
    {
      "name": "otel",
      "enabled": true,
      "config": {
        "collector_url": "http://otel-collector:4318",
        "trace_type": "genai_extension",
        "protocol": "http",
        "metrics_enabled": true,
        "metrics_endpoint": "http://otel-collector:4318/v1/metrics",
        "metrics_push_interval": 30
      }
    }
  ]
}

Maxim Observability

Sends request traces to the Maxim observability platform.

Field	Required	Description
`config.api_key`	Yes	Maxim API key (use `env.` prefix)
`config.log_repo_id`	No	Default Maxim logger repository ID

{
  "plugins": [
    {
      "name": "maxim",
      "enabled": true,
      "config": {
        "api_key": "env.MAXIM_API_KEY",
        "log_repo_id": "your-log-repo-id"
      }
    }
  ]
}

Datadog

Datadog is an enterprise-only plugin and is silently ignored in OSS builds.

Sends APM traces and metrics to a Datadog Agent.

Field	Default	Description
`config.agent_addr`	`"localhost:8126"`	Datadog Agent address for APM traces
`config.service_name`	`"bifrost"`	Service name in Datadog
`config.env`	-	Environment tag (e.g. `"production"`, `"staging"`)
`config.version`	-	Service version tag
`config.enable_traces`	`true`	Enable APM trace collection
`config.custom_tags`	`{}`	Additional key/value tags for all traces and metrics

{
  "plugins": [
    {
      "name": "datadog",
      "enabled": true,
      "config": {
        "agent_addr": "datadog-agent:8126",
        "service_name": "bifrost",
        "env": "production",
        "enable_traces": true,
        "custom_tags": {
          "team": "platform",
          "region": "us-east-1"
        }
      }
    }
  ]
}

Custom / Dynamic Plugins

Load a custom Go plugin binary or WASM plugin at startup using the path field. Custom plugins must implement one of the Bifrost plugin interfaces.

{
  "plugins": [
    {
      "name": "my-custom-auth",
      "enabled": true,
      "path": "/app/plugins/my-custom-auth.so",
      "config": {
        "auth_endpoint": "env.AUTH_SERVICE_URL"
      }
    }
  ]
}

WASM plugin:

{
  "plugins": [
    {
      "name": "my-wasm-plugin",
      "enabled": true,
      "path": "/app/plugins/my-plugin.wasm",
      "config": {}
    }
  ]
}

See Writing Go Plugins for new plugin development. The WASM plugin guide is deprecated and retained for existing deployments while webhook-based plugins are being added. Placement and ordering (DB-backed only): In DB-backed mode, plugin metadata such as version (1 to 32767), placement, and order can be managed via config sync and DB/UI workflows:

`placement`	When it runs
`pre_builtin`	Before all built-in plugins
`builtin`	Alongside built-in plugins (by `order`)
`post_builtin`	After all built-in plugins (default)

Within a placement group, lower order values run earlier.

​Auto-Loaded Built-ins

​Plugin Array Structure

​Semantic Cache

​OpenTelemetry (OTel)

​Maxim Observability

​Datadog

​Custom / Dynamic Plugins

Auto-Loaded Built-ins

Plugin Array Structure

Semantic Cache

OpenTelemetry (OTel)

Maxim Observability

Datadog

Custom / Dynamic Plugins