# Traefik & Docker

A Story of Labels & Containers
{: .subtitle }

![Docker](../assets/img/providers/docker.png)

Attach labels to your containers and let Traefik do the rest!

!!! tip "The Quick Start Uses Docker"
    If you haven't already, maybe you'd like to go through the [quick start](../getting-started/quick-start.md) that uses the docker provider!

## Configuration Examples

??? example "Configuring Docker & Deploying / Exposing Services"

    Enabling the docker provider
    
    ```toml tab="File (TOML)"
    [providers.docker]
    ```
    
    ```yaml tab="File (YAML)"
    providers:
      docker: {}
    ```
    
    ```bash tab="CLI"
    --providers.docker=true
    ```

    Attaching labels to containers (in your docker compose file)

    ```yaml
    version: "3"
    services:
      my-container:
        # ...
        labels:
          - traefik.http.routers.my-container.rule=Host(`mydomain.com`)
    ```

??? example "Configuring Docker Swarm & Deploying / Exposing Services"

    Enabling the docker provider (Swarm Mode)

    ```toml tab="File (TOML)"
    [providers.docker]
      # swarm classic (1.12-)
      # endpoint = "tcp://127.0.0.1:2375"
      # docker swarm mode (1.12+)
      endpoint = "tcp://127.0.0.1:2377"
      swarmMode = true
    ```
    
    ```yaml tab="File (YAML)"
    providers:
      docker:
        # swarm classic (1.12-)
        # endpoint = "tcp://127.0.0.1:2375"
        # docker swarm mode (1.12+)
        endpoint: "tcp://127.0.0.1:2375"
        swarmMode: true
    ```
    
    ```bash tab="CLI"
    --providers.docker.endpoint="tcp://127.0.0.1:2375"
    --providers.docker.swarmMode=true
    ```

    Attach labels to services (not to containers) while in Swarm mode (in your docker compose file)

    ```yaml
    version: "3"
    services:
      my-container:
        deploy:
          labels:
            - traefik.http.routers.my-container.rule=Host(`mydomain.com`)
            - traefik.http.services.my-container-service.loadbalancer.server.port=8080
    ```

    !!! important "Labels in Docker Swarm Mode"
        While in Swarm Mode, Traefik uses labels found on services, not on individual containers.
        
        Therefore, if you use a compose file with 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)).

## Routing Configuration

See the dedicated section in [routing](../routing/providers/docker.md).

## Provider Configuration

### `endpoint`

_Required, Default="unix:///var/run/docker.sock"_

```toml tab="File (TOML)"
[providers.docker]
  endpoint = "unix:///var/run/docker.sock"
```

```yaml tab="File (YAML)"
providers:
  docker:
    endpoint: "unix:///var/run/docker.sock"
```

```bash tab="CLI"
--providers.docker.endpoint="unix:///var/run/docker.sock"
```

Traefik requires access to the docker socket to get its dynamic configuration.

??? warning "Security Notes"

    Depending on your context, accessing the Docker API without any restriction can be a security concern: If Traefik is attacked, then the attacker might get access to the Docker (or Swarm Mode) backend.

    As explained in the Docker documentation: ([Docker Daemon Attack Surface page](https://docs.docker.com/engine/security/security/#docker-daemon-attack-surface)):

    `[...] only **trusted** users should be allowed to control your Docker daemon [...]`

    !!! tip "Improved Security"

        [TraefikEE](https://containo.us/traefikee) solves this problem by separating the control plane (connected to Docker) and the data plane (handling the requests).

    ??? info "Resources about Docker's Security"

        - [KubeCon EU 2018 Keynote, Running with Scissors, from Liz Rice](https://www.youtube.com/watch?v=ltrV-Qmh3oY)
        - [Don't expose the Docker socket (not even to a container)](https://www.lvh.io/posts/dont-expose-the-docker-socket-not-even-to-a-container/)
        - [A thread on Stack Overflow about sharing the `/var/run/docker.sock` file](https://news.ycombinator.com/item?id=17983623)
        - [To DinD or not to DinD](https://blog.loof.fr/2018/01/to-dind-or-not-do-dind.html)

??? tip "Security Compensation"

    Expose the Docker socket over TCP, instead of the default Unix socket file.
    It allows different implementation levels of the [AAA (Authentication, Authorization, Accounting) concepts](https://en.wikipedia.org/wiki/AAA_(computer_security)), depending on your security assessment:

    - Authentication with Client Certificates as described in ["Protect the Docker daemon socket."](https://docs.docker.com/engine/security/https/)
    - Authorization with the [Docker Authorization Plugin Mechanism](https://docs.docker.com/engine/extend/plugins_authorization/)
    - Accounting at networking level, by exposing the socket only inside a Docker private network, only available for Traefik.
    - Accounting at container level, by exposing the socket on a another container than Traefik's.
      With Swarm mode, it allows scheduling of Traefik on worker nodes, with only the "socket exposer" container on the manager nodes.
    - Accounting at kernel level, by enforcing kernel calls with mechanisms like [SELinux](https://en.wikipedia.org/wiki/Security-Enhanced_Linux), to only allows an identified set of actions for Traefik's process (or the "socket exposer" process).

    ??? info "Additional Resources"

        - [Traefik issue GH-4174 about security with Docker socket](https://github.com/containous/traefik/issues/4174)
        - [Inspecting Docker Activity with Socat](https://developers.redhat.com/blog/2015/02/25/inspecting-docker-activity-with-socat/)
        - [Letting Traefik run on Worker Nodes](https://blog.mikesir87.io/2018/07/letting-traefik-run-on-worker-nodes/)
        - [Docker Socket Proxy from Tecnativa](https://github.com/Tecnativa/docker-socket-proxy)

!!! info "Traefik & Swarm Mode"
    To let Traefik access the Docker Socket of the Swarm manager, it is mandatory to schedule Traefik on the Swarm manager nodes.

??? example "Using the docker.sock"

    The docker-compose file shares the docker sock with the Traefik container

    ```yaml
    version: '3'

    services:
      traefik:
         image: traefik:v2.0 # The official v2.0 Traefik docker image
         ports:
           - "80:80"
         volumes:
           - /var/run/docker.sock:/var/run/docker.sock
    ```

    We specify the docker.sock in traefik's configuration file.

    ```toml tab="File (TOML)"
    [providers.docker]
      endpoint = "unix:///var/run/docker.sock"
      # ...
    ```
    
    ```yaml tab="File (YAML)"
    providers:
      docker:
        endpoint: "unix:///var/run/docker.sock"
         # ...
    ```
    
    ```bash tab="CLI"
    --providers.docker.endpoint="unix:///var/run/docker.sock"
    # ...
    ```

### `useBindPortIP`

_Optional, Default=false_

```toml tab="File (TOML)"
[providers.docker]
  useBindPortIP = true
  # ...
```

```yaml tab="File (YAML)"
providers:
  docker:
    useBindPortIP: true
    # ...
```

```bash tab="CLI"
--providers.docker.useBindPortIP=true
# ...
```

Traefik routes requests to the IP/Port of the matching container.
When setting `useBindPortIP=true`, you tell Traefik to use the IP/Port attached to the container's _binding_ instead of its inner network IP/Port.

When used in conjunction with the `traefik.http.services.<name>.loadbalancer.server.port` label (that tells Traefik to route requests to a specific port),
Traefik tries to find a binding on port `traefik.http.services.<name>.loadbalancer.server.port`.
If it can't find such a binding, Traefik falls back on the internal network IP of the container,
but still uses the `traefik.http.services.<name>.loadbalancer.server.port` that is set in the label.

??? example "Examples of `usebindportip` in different situations."

    | port label         | Container's binding                                | Routes to      |
    |--------------------|----------------------------------------------------|----------------|
    |          -         |           -                                        | IntIP:IntPort  |
    |          -         | ExtPort:IntPort                                    | IntIP:IntPort  |
    |          -         | ExtIp:ExtPort:IntPort                              | ExtIp:ExtPort  |
    | LblPort            |           -                                        | IntIp:LblPort  |
    | LblPort            | ExtIp:ExtPort:LblPort                              | ExtIp:ExtPort  |
    | LblPort            | ExtIp:ExtPort:OtherPort                            | IntIp:LblPort  |
    | LblPort            | ExtIp1:ExtPort1:IntPort1 & ExtIp2:LblPort:IntPort2 | ExtIp2:LblPort |

    !!! info ""
        In the above table:
        
        - `ExtIp` stands for "external IP found in the binding"
        - `IntIp` stands for "internal network container's IP",
        - `ExtPort` stands for "external Port found in the binding"
        - `IntPort` stands for "internal network container's port."

### `exposedByDefault`

_Optional, Default=true_

```toml tab="File (TOML)"
[providers.docker]
  exposedByDefault = false
  # ...
```

```yaml tab="File (YAML)"
providers:
  docker:
    exposedByDefault: false
    # ...
```

```bash tab="CLI"
--providers.docker.exposedByDefault=false
# ...
```

Expose containers by default through Traefik.
If set to false, containers that don't have a `traefik.enable=true` label will be ignored from the resulting routing configuration.

See also [Restrict the Scope of Service Discovery](./overview.md#restrict-the-scope-of-service-discovery).

### `network`

_Optional, Default=empty_

```toml tab="File (TOML)"
[providers.docker]
  network = "test"
  # ...
```

```yaml tab="File (YAML)"
providers:
  docker:
    network: test
    # ...
```

```bash tab="CLI"
--providers.docker.network=test
# ...
```

Defines a default docker network to use for connections to all containers.

This option can be overridden on a container basis with the `traefik.docker.network` label.

### `defaultRule`

_Optional, Default=```Host(`{{ normalize .Name }}`)```_

```toml tab="File (TOML)"
[providers.docker]
  defaultRule = "Host(`{{ .Name }}.{{ index .Labels \"customLabel\"}}`)"
  # ...
```

```yaml tab="File (YAML)"
providers:
  docker:
    defaultRule: "Host(`{{ .Name }}.{{ index .Labels \"customLabel\"}}`)"
    # ...
```

```bash tab="CLI"
--providers.docker.defaultRule="Host(`{{ .Name }}.{{ index .Labels \"customLabel\"}}`)"
# ...
```

For a given container if no routing rule was defined by a label, it is defined by this defaultRule instead.
It must be a valid [Go template](https://golang.org/pkg/text/template/),
augmented with the [sprig template functions](http://masterminds.github.io/sprig/).
The container service name can be accessed as the `Name` identifier,
and the template has access to all the labels defined on this container.

### `swarmMode`

_Optional, Default=false_

```toml tab="File (TOML)"
[providers.docker]
  swarmMode = true
  # ...
```

```yaml tab="File (YAML)"
providers:
  docker:
    swarmMode: true
    # ...
```

```bash tab="CLI"
--providers.docker.swarmMode=true
# ...
```

Activates the Swarm Mode.

### `swarmModeRefreshSeconds`

_Optional, Default=15_

```toml tab="File (TOML)"
[providers.docker]
  swarmModeRefreshSeconds = "30s"
  # ...
```

```yaml tab="File (YAML)"
providers:
  docker:
    swarmModeRefreshSeconds: "30s"
    # ...
```

```bash tab="CLI"
--providers.docker.swarmModeRefreshSeconds=30s
# ...
```

Defines the polling interval (in seconds) in Swarm Mode.

### `constraints`

_Optional, Default=""_

```toml tab="File (TOML)"
[providers.docker]
  constraints = "Label(`a.label.name`, `foo`)"
  # ...
```

```yaml tab="File (YAML)"
providers:
  docker:
    constraints: "Label(`a.label.name`, `foo`)"
    # ...
```

```bash tab="CLI"
--providers.docker.constraints="Label(`a.label.name`, `foo`)"
# ...
```

Constraints is an expression that Traefik matches against the container's labels to determine whether to create any route for that container.
That is to say, if none of the container's labels match the expression, no route for the container is created.
If the expression is empty, all detected containers are included.

The expression syntax is based on the `Label("key", "value")`, and `LabelRegex("key", "value")` functions, as well as the usual boolean logic, as shown in examples below.

??? example "Constraints Expression Examples"

    ```toml
    # Includes only containers having a label with key `a.label.name` and value `foo`
    constraints = "Label(`a.label.name`, `foo`)"
    ```
    
    ```toml
    # Excludes containers having any label with key `a.label.name` and value `foo`
    constraints = "!Label(`a.label.name`, `value`)"
    ```
    
    ```toml
    # With logical AND.
    constraints = "Label(`a.label.name`, `valueA`) && Label(`another.label.name`, `valueB`)"
    ```
    
    ```toml
    # With logical OR.
    constraints = "Label(`a.label.name`, `valueA`) || Label(`another.label.name`, `valueB`)"
    ```
    
    ```toml
    # With logical AND and OR, with precedence set by parentheses.
    constraints = "Label(`a.label.name`, `valueA`) && (Label(`another.label.name`, `valueB`) || Label(`yet.another.label.name`, `valueC`))"
    ```
    
    ```toml
    # Includes only containers having a label with key `a.label.name` and a value matching the `a.+` regular expression.
    constraints = "LabelRegex(`a.label.name`, `a.+`)"
    ```

See also [Restrict the Scope of Service Discovery](./overview.md#restrict-the-scope-of-service-discovery).

### `tls`

_Optional_

#### `tls.ca`

Certificate Authority used for the secured connection to Docker.

```toml tab="File (TOML)"
[providers.docker.tls]
  ca = "path/to/ca.crt"
```

```yaml tab="File (YAML)"
providers:
  docker:
    tls:
      ca: path/to/ca.crt
```

```bash tab="CLI"
--providers.docker.tls.ca=path/to/ca.crt
```

#### `tls.caOptional`

Policy followed for the secured connection with TLS Client Authentication to Docker.
Requires `tls.ca` to be defined.

- `true`: VerifyClientCertIfGiven
- `false`: RequireAndVerifyClientCert
- if `tls.ca` is undefined NoClientCert

```toml tab="File (TOML)"
[providers.docker.tls]
  caOptional = true
```

```yaml tab="File (YAML)"
providers:
  docker:
    tls:
      caOptional: true
```

```bash tab="CLI"
--providers.docker.tls.caOptional=true
```

#### `tls.cert`

Public certificate used for the secured connection to Docker.

```toml tab="File (TOML)"
[providers.docker.tls]
  cert = "path/to/foo.cert"
  key = "path/to/foo.key"
```

```yaml tab="File (YAML)"
providers:
  docker:
    tls:
      cert: path/to/foo.cert
      key: path/to/foo.key
```

```bash tab="CLI"
--providers.docker.tls.cert=path/to/foo.cert
--providers.docker.tls.key=path/to/foo.key
```

#### `tls.key`

Private certificate used for the secured connection to Docker.

```toml tab="File (TOML)"
[providers.docker.tls]
  cert = "path/to/foo.cert"
  key = "path/to/foo.key"
```

```yaml tab="File (YAML)"
providers:
  docker:
    tls:
      cert: path/to/foo.cert
      key: path/to/foo.key
```

```bash tab="CLI"
--providers.docker.tls.cert=path/to/foo.cert
--providers.docker.tls.key=path/to/foo.key
```

#### `tls.insecureSkipVerify`

If `insecureSkipVerify` is `true`, TLS for the connection to Docker accepts any certificate presented by the server and any host name in that certificate.

```toml tab="File (TOML)"
[providers.docker.tls]
  insecureSkipVerify = true
```

```yaml tab="File (YAML)"
providers:
  docker:
    tls:
      insecureSkipVerify: true
```

```bash tab="CLI"
--providers.docker.tls.insecureSkipVerify=true
```