traefik/docs/content/providers/file.md

# Traefik & File

Good Old Configuration File
{: .subtitle } 

The file provider lets you define the [dynamic configuration](./overview.md) in a TOML or YAML file.
You can write one of these mutually exclusive configuration elements:

* In [a dedicated file](#filename)
* In [several dedicated files](#directory)

!!! info
    The file provider is the default format used throughout the documentation to show samples of the configuration for many features. 

!!! tip
    The file provider can be a good location for common elements you'd like to re-use from other providers; e.g. declaring whitelist middlewares, basic authentication, ...

## Configuration Examples

??? example "Declaring Routers, Middlewares & Services"

    Enabling the file provider:
    
    ```toml tab="File (TOML)"
    [providers.file]
      directory = "/path/to/dynamic/conf"
    ```
    
    ```yaml tab="File (YAML)"
    providers:
      file:
        directory: "/path/to/dynamic/conf"
    ```
    
    ```bash tab="CLI"
    --providers.file.directory=/path/to/dynamic/conf
    ```
    
    Declaring Routers, Middlewares & Services:
    
    ```toml tab="TOML"
    [http]
      # Add the router
      [http.routers]
        [http.routers.router0]
          entryPoints = ["web"]
          middlewares = ["my-basic-auth"]
          service = "service-foo"
          rule = "Path(`/foo`)"
      
      # Add the middleware
      [http.middlewares]    
        [http.middlewares.my-basic-auth.basicAuth]
          users = ["test:$apr1$H6uskkkW$IgXLP6ewTrSuBkTrqE8wj/", 
                    "test2:$apr1$d9hr9HBB$4HxwgUir3HP4EsggP/QNo0"]
          usersFile = "etc/traefik/.htpasswd"
      
      # Add the service
      [http.services]
        [http.services.service-foo]
          [http.services.service-foo.loadBalancer]
            [[http.services.service-foo.loadBalancer.servers]]
              url = "http://foo/"
            [[http.services.service-foo.loadBalancer.servers]]
              url = "http://bar/"
    ```
    
    ```yaml tab="YAML"
    http:
      # Add the router
      routers:
        router0:
          entryPoints:
          - web
          middlewares:
          - my-basic-auth
          service: service-foo
          rule: Path(`/foo`)
      
      # Add the middleware
      middlewares:
        my-basic-auth:
          basicAuth:
            users:
            - test:$apr1$H6uskkkW$IgXLP6ewTrSuBkTrqE8wj/
            - test2:$apr1$d9hr9HBB$4HxwgUir3HP4EsggP/QNo0
            usersFile: etc/traefik/.htpasswd
      
      # Add the service
      services:
        service-foo:
          loadBalancer:
            servers:
            - url: http://foo/
            - url: http://bar/
            passHostHeader: false
    ```

## Provider Configuration

If you're in a hurry, maybe you'd rather go through the [dynamic configuration](../reference/dynamic-configuration/file.md) references and the [static configuration](../reference/static-configuration/overview.md).

!!! warning "Limitations"

    With the file provider, Traefik listens for file system notifications to update the dynamic configuration.
    
    If you use a mounted/bound file system in your orchestrator (like docker or kubernetes), the way the files are linked may be a source of errors.
    If the link between the file systems is broken, when a source file/directory is changed/renamed, nothing will be reported to the linked file/directory, so the file system notifications will be neither triggered nor caught. 
    
    For example, in docker, if the host file is renamed, the link to the mounted file will be broken and the container's file will not be updated.
    To avoid this kind of issue, a good practice is to:
        
    * set the Traefik [**directory**](#directory) configuration with the parent directory
    * mount/bind the parent directory

    As it is very difficult to listen to all file system notifications, Traefik use [fsnotify](https://github.com/fsnotify/fsnotify).
    If using a directory with a mounted directory does not fix your issue, please check your file system compatibility with fsnotify.
    
### `filename`

Defines the path to the configuration file.

!!! warning ""
    `filename` and `directory` are mutually exclusive.
    The recommendation is to use `directory`.

```toml tab="File (TOML)"
[providers]
  [providers.file]
    filename = "/path/to/config/dynamic_conf.toml"
```

```yaml tab="File (YAML)"
providers:
  file:
    filename: /path/to/config/dynamic_conf.yml
```

```bash tab="CLI"
--providers.file.filename=/path/to/config/dynamic_conf.toml
```

### `directory`

Defines the path to the directory that contains the configuration files.

!!! warning ""
    `filename` and `directory` are mutually exclusive.
    The recommendation is to use `directory`.

```toml tab="File (TOML)"
[providers]
  [providers.file]
    directory = "/path/to/config"
```

```yaml tab="File (YAML)"
providers:
  file:
    directory: /path/to/config
```

```bash tab="CLI"
--providers.file.directory=/path/to/config
```

### `watch`

Set the `watch` option to `true` to allow Traefik to automatically watch for file changes.  
It works with both the `filename` and the `directory` options.

```toml tab="File (TOML)"
[providers]
  [providers.file]
    directory = "/path/to/dynamic/conf"
    watch = true
```

```yaml tab="File (YAML)"
providers:
  file:
    directory: /path/to/dynamic/conf
    watch: true
```

```bash tab="CLI"
--providers.file.directory=/my/path/to/dynamic/conf
--providers.file.watch=true
```

### Go Templating

!!! warning
    Go Templating only works with dedicated dynamic configuration files.
    Templating does not work in the Traefik main static configuration file.

Traefik supports using Go templating to automatically generate repetitive portions of configuration files.
These sections must be valid [Go templates](https://golang.org/pkg/text/template/),
augmented with the [Sprig template functions](http://masterminds.github.io/sprig/).

To illustrate, it's possible to easily define multiple routers, services, and TLS certificates as described in the following examples:

??? example "Configuring Using Templating"
    
    ```toml tab="TOML"
    # template-rules.toml
    [http]
    
      [http.routers]
      {{ range $i, $e := until 100 }}
        [http.routers.router{{ $e }}-{{ env "MY_ENV_VAR" }}]
        # ...
      {{ end }}  
      
      
      [http.services]
      {{ range $i, $e := until 100 }}
          [http.services.service{{ $e }}]
          # ...
      {{ end }}  
      
    [tcp]
    
      [tcp.routers]
      {{ range $i, $e := until 100 }}
        [tcp.routers.router{{ $e }}]
        # ...
      {{ end }}  
      
      
      [tcp.services]
      {{ range $i, $e := until 100 }}
          [http.services.service{{ $e }}]
          # ...
      {{ end }}  
    
    {{ range $i, $e := until 10 }}
    [[tls.certificates]]
      certFile = "/etc/traefik/cert-{{ $e }}.pem"
      keyFile = "/etc/traefik/cert-{{ $e }}.key"
      store = ["my-store-foo-{{ $e }}", "my-store-bar-{{ $e }}"]
    {{ end }}
    
    [tls.config]
    {{ range $i, $e := until 10 }}
      [tls.config.TLS{{ $e }}]
      # ...
    {{ end }}
    ```
    
    ```yaml tab="YAML"
    http:
      routers:
        {{range $i, $e := until 100 }}
        router{{ $e }}-{{ env "MY_ENV_VAR" }}:
          # ...
        {{end}}
    
      services:
        {{range $i, $e := until 100 }}
        application{{ $e }}:
          # ...
        {{end}}
    
    tcp:
      routers:
        {{range $i, $e := until 100 }}
        router{{ $e }}:
          # ...
        {{end}}
    
      services:
        {{range $i, $e := until 100 }}
        service{{ $e }}:
          # ...
        {{end}}
    
    tls:
      certificates:
      {{ range $i, $e := until 10 }}
      - certFile: "/etc/traefik/cert-{{ $e }}.pem"
        keyFile: "/etc/traefik/cert-{{ $e }}.key"
        store:
        - "my-store-foo-{{ $e }}"
        - "my-store-bar-{{ $e }}"
      {{end}}
    ```