
# Docker Backend

Træfik can be configured to use Docker as a backend configuration.

## Docker

```toml
################################################################
# Docker configuration backend
################################################################

# Enable Docker configuration backend.
[docker]

# Docker server endpoint. Can be a tcp or a unix socket endpoint.
#
# Required
#
endpoint = "unix:///var/run/docker.sock"

# Default domain used.
# Can be overridden by setting the "traefik.domain" label on a container.
#
# Required
#
domain = "docker.localhost"

# Enable watch docker changes.
#
# Optional
#
watch = true

# Override default configuration template.
# For advanced users :)
#
# Optional
#
# filename = "docker.tmpl"

# Expose containers by default in Traefik.
# If set to false, containers that don't have `traefik.enable=true` will be ignored.
#
# Optional
# Default: true
#
exposedbydefault = true

# Use the IP address from the binded port instead of the inner network one.
# For specific use-case :)
#
# Optional
# Default: false
#
usebindportip = true

# Use Swarm Mode services as data provider.
#
# Optional
# Default: false
#
swarmmode = false

# Enable docker TLS connection.
#
# Optional
#
#  [docker.tls]
#  ca = "/etc/ssl/ca.crt"
#  cert = "/etc/ssl/docker.crt"
#  key = "/etc/ssl/docker.key"
#  insecureskipverify = true
```

To enable constraints see [backend-specific constraints section](/configuration/commons/#backend-specific).


## Docker Swarm Mode

```toml
################################################################
# Docker Swarmmode configuration backend
################################################################

# Enable Docker configuration backend.
[docker]

# Docker server endpoint.
# Can be a tcp or a unix socket endpoint.
#
# Required
# Default: "unix:///var/run/docker.sock"
#
endpoint = "tcp://127.0.0.1:2375"

# Default domain used.
# Can be overridden by setting the "traefik.domain" label on a services.
#
# Optional
# Default: ""
#
domain = "docker.localhost"

# Enable watch docker changes.
#
# Optional
# Default: true
#
watch = true

# Use Docker Swarm Mode as data provider.
#
# Optional
# Default: false
#
swarmmode = true

# Override default configuration template.
# For advanced users :)
#
# Optional
#
# filename = "docker.tmpl"

# Expose services by default in Traefik.
#
# Optional
# Default: true
#
exposedbydefault = false

# Enable docker TLS connection.
#
# Optional
#
#  [docker.tls]
#  ca = "/etc/ssl/ca.crt"
#  cert = "/etc/ssl/docker.crt"
#  key = "/etc/ssl/docker.key"
#  insecureskipverify = true
```

To enable constraints see [backend-specific constraints section](/configuration/commons/#backend-specific).

## Labels: overriding default behaviour

!!! note
    If you use a compose file, labels should be defined in the `deploy` part of your service.

    This behavior is only enabled for docker-compose version 3+ ([Compose file reference](https://docs.docker.com/compose/compose-file/#labels-1)).

```yaml
version: "3"
services:
  whoami:
    deploy:
      labels:
        traefik.docker.network: traefik
```

### On Containers

Labels can be used on containers to override default behaviour.

| Label                                                      | Description                                                                                                                                                                                                                                                                                                                                                                                                                     |
|------------------------------------------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| `traefik.backend=foo`                                      | Give the name `foo` to the generated backend for this container.                                                                                                                                                                                                                                                                                                                                                                |
| `traefik.backend.maxconn.amount=10`                        | Set a maximum number of connections to the backend. Must be used in conjunction with the below label to take effect.                                                                                                                                                                                                                                                                                                            |
| `traefik.backend.maxconn.extractorfunc=client.ip`          | Set the function to be used against the request to determine what to limit maximum connections to the backend by. Must be used in conjunction with the above label to take effect.                                                                                                                                                                                                                                              |
| `traefik.backend.loadbalancer.method=drr`                  | Override the default `wrr` load balancer algorithm                                                                                                                                                                                                                                                                                                                                                                              |
| `traefik.backend.loadbalancer.stickiness=true`             | Enable backend sticky sessions                                                                                                                                                                                                                                                                                                                                                                                                  |
| `traefik.backend.loadbalancer.stickiness.cookieName=NAME`  | Manually set the cookie name for sticky sessions                                                                                                                                                                                                                                                                                                                                                                                |
| `traefik.backend.loadbalancer.sticky=true`                 | Enable backend sticky sessions (DEPRECATED)                                                                                                                                                                                                                                                                                                                                                                                     |
| `traefik.backend.loadbalancer.swarm=true`                  | Use Swarm's inbuilt load balancer (only relevant under Swarm Mode).                                                                                                                                                                                                                                                                                                                                                             |
| `traefik.backend.circuitbreaker.expression=EXPR`           | Create a [circuit breaker](/basics/#backends) to be used against the backend                                                                                                                                                                                                                                                                                                                                                    |
| `traefik.port=80`                                          | Register this port. Useful when the container exposes multiples ports.                                                                                                                                                                                                                                                                                                                                                          |
| `traefik.protocol=https`                                   | Override the default `http` protocol                                                                                                                                                                                                                                                                                                                                                                                            |
| `traefik.weight=10`                                        | Assign this weight to the container                                                                                                                                                                                                                                                                                                                                                                                             |
| `traefik.enable=false`                                     | Disable this container in Træfik                                                                                                                                                                                                                                                                                                                                                                                                |
| `traefik.frontend.rule=EXPR`                               | Override the default frontend rule. Default: `Host:{containerName}.{domain}` or `Host:{service}.{project_name}.{domain}` if you are using `docker-compose`.                                                                                                                                                                                                                                                                     |
| `traefik.frontend.passHostHeader=true`                     | Forward client `Host` header to the backend.                                                                                                                                                                                                                                                                                                                                                                                    |
| `traefik.frontend.priority=10`                             | Override default frontend priority                                                                                                                                                                                                                                                                                                                                                                                              |
| `traefik.frontend.entryPoints=http,https`                  | Assign this frontend to entry points `http` and `https`. Overrides `defaultEntryPoints`                                                                                                                                                                                                                                                                                                                                         |
| `traefik.frontend.auth.basic=EXPR`                         | Sets basic authentication for that frontend in CSV format: `User:Hash,User:Hash`                                                                                                                                                                                                                                                                                                                                                |
| `traefik.frontend.whitelistSourceRange:RANGE`              | List of IP-Ranges which are allowed to access. An unset or empty list allows all Source-IPs to access. If one of the Net-Specifications are invalid, the whole list is invalid and allows all Source-IPs to access.                                                                                                                                                                                                             |
| `traefik.docker.network`                                   | Set the docker network to use for connections to this container. If a container is linked to several networks, be sure to set the proper network name (you can check with `docker inspect <container_id>`) otherwise it will randomly pick one (depending on how docker is returning them). For instance when deploying docker `stack` from compose files, the compose defined networks will be prefixed with the `stack` name. |
| `traefik.frontend.redirect.entryPoint=https`               | Enables Redirect to another entryPoint for that frontend (e.g. HTTPS)                                                                                                                                                                                                                                                                                                                                                           |
| `traefik.frontend.redirect.regex=^http://localhost/(.*)`   | Redirect to another URL for that frontend. Must be set with `traefik.frontend.redirect.replacement`.                                                                                                                                                                                                                                                                                                                            |
| `traefik.frontend.redirect.replacement=http://mydomain/$1` | Redirect to another URL for that frontend. Must be set with `traefik.frontend.redirect.regex`.                                                                                                                                                                                                                                                                                                                                  |



#### Security Headers

| Label                                                    | Description                                                                                                                                                                                         |
|----------------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| `traefik.frontend.headers.allowedHosts=EXPR`             | Provides a list of allowed hosts that requests will be processed. Format: `Host1,Host2`                                                                                                             |
| `traefik.frontend.headers.customRequestHeaders=EXPR `    | Provides the container with custom request headers that will be appended to each request forwarded to the container. Format: <code>HEADER:value&vert;&vert;HEADER2:value2</code>                    |
| `traefik.frontend.headers.customResponseHeaders=EXPR`    | Appends the headers to each response returned by the container, before forwarding the response to the client. Format: <code>HEADER:value&vert;&vert;HEADER2:value2</code>                           |
| `traefik.frontend.headers.hostsProxyHeaders=EXPR `       | Provides a list of headers that the proxied hostname may be stored. Format:  `HEADER1,HEADER2`                                                                                                      |
| `traefik.frontend.headers.SSLRedirect=true`              | Forces the frontend to redirect to SSL if a non-SSL request is sent.                                                                                                                                |
| `traefik.frontend.headers.SSLTemporaryRedirect=true`     | Forces the frontend to redirect to SSL if a non-SSL request is sent, but by sending a 302 instead of a 301.                                                                                         |
| `traefik.frontend.headers.SSLHost=HOST`                  | This setting configures the hostname that redirects will be based on. Default is "", which is the same host as the request.                                                                         |
| `traefik.frontend.headers.SSLProxyHeaders=EXPR`          | Header combinations that would signify a proper SSL Request (Such as `X-Forwarded-For:https`). Format:  <code>HEADER:value&vert;&vert;HEADER2:value2</code>                                         |
| `traefik.frontend.headers.STSSeconds=315360000`          | Sets the max-age of the STS header.                                                                                                                                                                 |
| `traefik.frontend.headers.STSIncludeSubdomains=true`     | Adds the `IncludeSubdomains` section of the STS  header.                                                                                                                                            |
| `traefik.frontend.headers.STSPreload=true`               | Adds the preload flag to the STS  header.                                                                                                                                                           |
| `traefik.frontend.headers.forceSTSHeader=false`          | Adds the STS  header to non-SSL requests.                                                                                                                                                           |
| `traefik.frontend.headers.frameDeny=false`               | Adds the `X-Frame-Options` header with the value of `DENY`.                                                                                                                                         |
| `traefik.frontend.headers.customFrameOptionsValue=VALUE` | Overrides the `X-Frame-Options` header with the custom value.                                                                                                                                       |
| `traefik.frontend.headers.contentTypeNosniff=true`       | Adds the `X-Content-Type-Options` header with the value `nosniff`.                                                                                                                                  |
| `traefik.frontend.headers.browserXSSFilter=true`         | Adds the X-XSS-Protection header with the value `1; mode=block`.                                                                                                                                    |
| `traefik.frontend.headers.contentSecurityPolicy=VALUE`   | Adds CSP Header with the custom value.                                                                                                                                                              |
| `traefik.frontend.headers.publicKey=VALUE`               | Adds pinned HTST public key header.                                                                                                                                                                 |
| `traefik.frontend.headers.referrerPolicy=VALUE`          | Adds referrer policy  header.                                                                                                                                                                       |
| `traefik.frontend.headers.isDevelopment=false`           | This will cause the `AllowedHosts`, `SSLRedirect`, and `STSSeconds`/`STSIncludeSubdomains` options to be ignored during development.<br>When deploying to production, be sure to set this to false. |

### On Service

Services labels can be used for overriding default behaviour

| Label                                                                     | Description                                                                                      |
|---------------------------------------------------------------------------|--------------------------------------------------------------------------------------------------|
| `traefik.<service-name>.port=PORT`                                        | Overrides `traefik.port`. If several ports need to be exposed, the service labels could be used. |
| `traefik.<service-name>.protocol`                                         | Overrides `traefik.protocol`.                                                                    |
| `traefik.<service-name>.weight`                                           | Assign this service weight. Overrides `traefik.weight`.                                          |
| `traefik.<service-name>.frontend.backend=BACKEND`                         | Assign this service frontend to `BACKEND`. Default is to assign to the service backend.          |
| `traefik.<service-name>.frontend.entryPoints`                             | Overrides `traefik.frontend.entrypoints`                                                         |
| `traefik.<service-name>.frontend.auth.basic`                              | Sets a Basic Auth for that frontend                                                              |
| `traefik.<service-name>.frontend.passHostHeader`                          | Overrides `traefik.frontend.passHostHeader`.                                                     |
| `traefik.<service-name>.frontend.priority`                                | Overrides `traefik.frontend.priority`.                                                           |
| `traefik.<service-name>.frontend.rule`                                    | Overrides `traefik.frontend.rule`.                                                               |
| `traefik.<service-name>.frontend.redirect`                                | Overrides `traefik.frontend.redirect`.                                                           |
| `traefik.<service-name>.frontend.redirect.entryPoint=https`               | Overrides `traefik.frontend.redirect.entryPoint`.                                                |
| `traefik.<service-name>.frontend.redirect.regex=^http://localhost/(.*)`   | Overrides `traefik.frontend.redirect.regex`.                                                     |
| `traefik.<service-name>.frontend.redirect.replacement=http://mydomain/$1` | Overrides `traefik.frontend.redirect.replacement`.                                               |


!!! note
    If a label is defined both as a `container label` and a `service label` (for example `traefik.<service-name>.port=PORT` and `traefik.port=PORT` ), the `service label` is used to defined the `<service-name>` property (`port` in the example).

    It's possible to mix `container labels` and `service labels`, in this case `container labels` are used as default value for missing `service labels` but no frontends are going to be created with the `container labels`.

    More details in this [example](/user-guide/docker-and-lets-encrypt/#labels).

!!! warning
    When running inside a container, Træfik will need network access through:

    `docker network connect <network> <traefik-container>`
