# 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"
# Override template version
# For advanced users :)
#
# Optional
# - "1": previous template version (must be used only with older custom templates, see "filename")
# - "2": current template version (must be used to force template version when "filename" is used)
#
# templateVersion = 2
# 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 Swarm Mode 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"
# Override template version
# For advanced users :)
#
# Optional
# - "1": previous template version (must be used only with older custom templates, see "filename")
# - "2": current template version (must be used to force template version when "filename" is used)
#
# templateVersion = 2
# 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 behavior
### Using Docker with Swarm Mode
If you use a compose file with the Swarm mode, 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
```
### Using Docker Compose
If you are intending to use only Docker Compose commands (e.g. `docker-compose up --scale whoami=2 -d`), labels should be under your service, otherwise they will be ignored.
```yaml
version: "3"
services:
whoami:
labels:
traefik.docker.network: traefik
```
### On Containers
Labels can be used on containers to override default behavior.
| Label | Description |
|------------------------------------------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| `traefik.docker.network` | Set the docker network to use for connections to this container. [1] |
| `traefik.domain` | Default domain used for frontend rules. |
| `traefik.enable=false` | Disable this container in Træfik |
| `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.backend=foo` | Give the name `foo` to the generated backend for this container. |
| `traefik.backend.buffering.maxRequestBodyBytes=0` | See [buffering](/configuration/commons/#buffering) section. |
| `traefik.backend.buffering.maxResponseBodyBytes=0` | See [buffering](/configuration/commons/#buffering) section. |
| `traefik.backend.buffering.memRequestBodyBytes=0` | See [buffering](/configuration/commons/#buffering) section. |
| `traefik.backend.buffering.memResponseBodyBytes=0` | See [buffering](/configuration/commons/#buffering) section. |
| `traefik.backend.buffering.retryExpression=EXPR` | See [buffering](/configuration/commons/#buffering) section. |
| `traefik.backend.circuitbreaker.expression=EXPR` | Create a [circuit breaker](/basics/#backends) to be used against the backend |
| `traefik.backend.healthcheck.path=/health` | Enable health check for the backend, hitting the container at `path`. |
| `traefik.backend.healthcheck.port=8080` | Allow to use a different port for the health check. |
| `traefik.backend.healthcheck.interval=1s` | Define the health check interval. |
| `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.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.frontend.auth.basic=EXPR` | Sets basic authentication for that frontend in CSV format: `User:Hash,User:Hash` |
| `traefik.frontend.entryPoints=http,https` | Assign this frontend to entry points `http` and `https`.
Overrides `defaultEntryPoints` |
| `traefik.frontend.errors..backend=NAME` | See [custom error pages](/configuration/commons/#custom-error-pages) section. |
| `traefik.frontend.errors..query=PATH` | See [custom error pages](/configuration/commons/#custom-error-pages) section. |
| `traefik.frontend.errors..status=RANGE` | See [custom error pages](/configuration/commons/#custom-error-pages) section. |
| `traefik.frontend.passHostHeader=true` | Forward client `Host` header to the backend. |
| `traefik.frontend.passTLSCert=true` | Forward TLS Client certificates to the backend. |
| `traefik.frontend.priority=10` | Override default frontend priority |
| `traefik.frontend.rateLimit.extractorFunc=EXP` | See [rate limiting](/configuration/commons/#rate-limiting) section. |
| `traefik.frontend.rateLimit.rateSet..period=6` | See [rate limiting](/configuration/commons/#rate-limiting) section. |
| `traefik.frontend.rateLimit.rateSet..average=6` | See [rate limiting](/configuration/commons/#rate-limiting) section. |
| `traefik.frontend.rateLimit.rateSet..burst=6` | See [rate limiting](/configuration/commons/#rate-limiting) section. |
| `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`. |
| `traefik.frontend.redirect.permanent=true` | Return 301 instead of 302. |
| `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.whiteList.sourceRange=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.frontend.whiteList.useXForwardedFor=true` | Use `X-Forwarded-For` header as valid source of IP for the white list. |
[1] `traefik.docker.network`:
If a container is linked to several networks, be sure to set the proper network name (you can check with `docker inspect `) 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.
Or if your service references external network use it's name instead.
#### Custom Headers
| Label | Description |
|-------------------------------------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| `traefik.frontend.headers.customRequestHeaders=EXPR ` | Provides the container with custom request headers that will be appended to each request forwarded to the container.
Format: HEADER:value||HEADER2:value2 |
| `traefik.frontend.headers.customResponseHeaders=EXPR` | Appends the headers to each response returned by the container, before forwarding the response to the client.
Format: HEADER:value||HEADER2:value2 |
#### 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.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: HEADER:value||HEADER2:value2 |
| `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.customBrowserXSSValue=VALUE` | Set custom value for X-XSS-Protection header. This overrides the BrowserXssFilter option. |
| `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.
When deploying to production, be sure to set this to false. |
### On containers with Multiple Ports (segment labels)
Segment labels are used to define routes to a container exposing multiple ports.
A segment is a group of labels that apply to a port exposed by a container.
You can define as many segments as ports exposed in a container.
Segment labels override the default behavior.
| Label | Description |
|---------------------------------------------------------------------------|--------------------------------------------------------------------------------------------------|
| `traefik..domain` | Default domain used for frontend rules. |
| `traefik..port=PORT` | Overrides `traefik.port`. If several ports need to be exposed, the segment labels could be used. |
| `traefik..protocol` | Overrides `traefik.protocol`. |
| `traefik..weight` | Assign this segment weight. Overrides `traefik.weight`. |
| `traefik..frontend.auth.basic` | Sets a Basic Auth for that frontend |
| `traefik..frontend.backend=BACKEND` | Assign this segment frontend to `BACKEND`. Default is to assign to the segment backend. |
| `traefik..frontend.entryPoints` | Overrides `traefik.frontend.entrypoints` |
| `traefik..frontend.errors..backend=NAME` | See [custom error pages](/configuration/commons/#custom-error-pages) section. |
| `traefik..frontend.errors..query=PATH` | See [custom error pages](/configuration/commons/#custom-error-pages) section. |
| `traefik..frontend.errors..status=RANGE` | See [custom error pages](/configuration/commons/#custom-error-pages) section. |
| `traefik..frontend.passHostHeader` | Overrides `traefik.frontend.passHostHeader`. |
| `traefik..frontend.passTLSCert` | Overrides `traefik.frontend.passTLSCert`. |
| `traefik..frontend.priority` | Overrides `traefik.frontend.priority`. |
| `traefik..frontend.rateLimit.extractorFunc=EXP` | See [rate limiting](/configuration/commons/#rate-limiting) section. |
| `traefik..frontend.rateLimit.rateSet..period=6` | See [rate limiting](/configuration/commons/#rate-limiting) section. |
| `traefik..frontend.rateLimit.rateSet..average=6` | See [rate limiting](/configuration/commons/#rate-limiting) section. |
| `traefik..frontend.rateLimit.rateSet..burst=6` | See [rate limiting](/configuration/commons/#rate-limiting) section. |
| `traefik..frontend.redirect.entryPoint=https` | Overrides `traefik.frontend.redirect.entryPoint`. |
| `traefik..frontend.redirect.regex=^http://localhost/(.*)` | Overrides `traefik.frontend.redirect.regex`. |
| `traefik..frontend.redirect.replacement=http://mydomain/$1` | Overrides `traefik.frontend.redirect.replacement`. |
| `traefik..frontend.redirect.permanent=true` | Return 301 instead of 302. |
| `traefik..frontend.rule` | Overrides `traefik.frontend.rule`. |
| `traefik..frontend.whiteList.sourceRange=RANGE` | Overrides `traefik.frontend.whiteList.sourceRange`. |
| `traefik..frontend.whiteList.useXForwardedFor=true` | Overrides `traefik.frontend.whiteList.useXForwardedFor`. |
#### Custom Headers
| Label | Description |
|----------------------------------------------------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| `traefik..frontend.headers.customRequestHeaders=EXPR ` | Provides the container with custom request headers that will be appended to each request forwarded to the container.
Format: HEADER:value||HEADER2:value2 |
| `traefik..frontend.headers.customResponseHeaders=EXPR` | Appends the headers to each response returned by the container, before forwarding the response to the client.
Format: HEADER:value||HEADER2:value2 |
#### 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.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: HEADER:value||HEADER2:value2 |
| `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.customBrowserXSSValue=VALUE` | Set custom value for X-XSS-Protection header. This overrides the BrowserXssFilter option. |
| `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.
When deploying to production, be sure to set this to false. |
!!! note
If a label is defined both as a `container label` and a `segment label` (for example `traefik..port=PORT` and `traefik.port=PORT` ), the `segment label` is used to defined the `` property (`port` in the example).
It's possible to mix `container labels` and `segment labels`, in this case `container labels` are used as default value for missing `segment 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 `