Providers

A provider is the source of dynamic configuration. Each provider is its own subpackage under pkg/provider/. They all implement a small interface in pkg/provider/provider.go:

type Provider interface {
    Init() error
    Provide(configurationChan chan<- dynamic.Message, pool *safe.Pool) error
}

Provide is expected to run forever (or until the routines pool is stopped) and emit dynamic.Message values whenever the source produces a new configuration.

Built-in providers

Provider	Package	Best for
File / Directory	pkg/provider/file	Static or hand-edited configurations.
Docker / Swarm	pkg/provider/docker	Single-host Docker, Docker Compose, Swarm mode.
Kubernetes Ingress	pkg/provider/kubernetes/ingress	Standard Kubernetes Ingress resources.
Kubernetes IngressRoute (CRD)	pkg/provider/kubernetes/crd	Traefik-specific Kubernetes CRDs.
Kubernetes Gateway API	pkg/provider/kubernetes/gateway	Gateway API standard.
Kubernetes Ingress-NGINX shim	pkg/provider/kubernetes/ingress-nginx	Migration from the Ingress-NGINX controller.
Knative Serving	pkg/provider/kubernetes/knative	Knative-managed routes.
Consul (KV)	pkg/provider/kv/consul	Consul KV.
etcd	pkg/provider/kv/etcd	etcd KV.
Redis	pkg/provider/kv/redis	Redis hash-based configuration.
ZooKeeper	pkg/provider/kv/zk	ZooKeeper KV.
Consul Catalog	pkg/provider/consulcatalog	Consul service registry.
Nomad	pkg/provider/nomad	Nomad job catalog.
Amazon ECS	pkg/provider/ecs	ECS task definitions.
HTTP	pkg/provider/http	Pull configuration from a URL.
REST	pkg/provider/rest	Push configuration to Traefik's API.
Tailscale	pkg/provider/tailscale	Tailscale-issued certificates.
ACME	pkg/provider/acme	Automatic Let's Encrypt certificates.
Internal	pkg/provider/traefik	Built-in routes for the dashboard / ping / Prometheus.

How providers register themselves

pkg/config/static/static_config.go declares a fixed precedence list:

var providerNames = []string{
    gateway.ProviderName,
    crd.ProviderName,
    ingress.ProviderName,
    ingressnginx.ProviderName,
    docker.SwarmName,
    docker.DockerName,
    file.ProviderName,
    redis.ProviderName,
    knative.ProviderName,
    consul.ProviderName,
    consulcatalog.ProviderName,
    nomad.ProviderName,
    etcd.ProviderName,
    ecs.ProviderName,
    http.ProviderName,
    zk.ProviderName,
    rest.ProviderName,
}

This is the order in which providers are wrapped by the aggregator (pkg/provider/aggregator/aggregator.go) and the order used as the tie-breaker when an object name appears in multiple providers.

Any provider that is not enabled in static config is simply not constructed.

Conventions across providers

• Name constant. Each provider exports a ProviderName constant. The Docker package exports two (DockerName and SwarmName) since Swarm mode is a separate provider configuration block.
• exposedByDefault. Most discovery providers default to opting containers/services in. Setting exposedByDefault: false flips the polarity — only items annotated with traefik.enable=true are exposed.
• Constraints. A constraints expression filters discovered items. Implementation lives in pkg/provider/constraints/.
• Default rule. Each provider can produce a router rule from a Go template if no rule was supplied. Default rules use template variables like {{ .Name }}, {{ index .Labels "namespace" }}.
• Reconnection. Watch-style providers (Kubernetes, Docker events, Consul watch) use cenkalti/backoff/v4 to reconnect indefinitely on failure.

Anatomy of a provider

A typical provider has these files:

File	Role
<provider>.go	The Provider struct, configuration fields, Init() and Provide() implementation.
config.go	The mapping from labels/annotations/CRDs to dynamic.Configuration.
data.go (Docker) / client.go (Kubernetes)	The interface to the upstream API, mockable for tests.
<provider>_test.go	Unit tests, often using a fixture file.
fixtures/...	Recorded API responses for table-driven tests.

Adding a provider is mostly:

1. Define configuration fields with description, json, yaml, toml tags.
2. Implement Init() (validation, defaults) and Provide() (the long-running loop).
3. Register the provider's name and configuration in pkg/config/static/static_config.go.
4. Add it to pkg/provider/aggregator/aggregator.go so it gets started.
5. Run make generate to refresh the documentation reference.
6. Add an integration test in integration/<name>_test.go.

The provider pages below cover the larger or more frequently asked-about ones in more detail.