traefik/docs/configuration/backends/file.md

# File Backends

Like any other reverse proxy, Træfik can be configured with a file. You have three choices:

## Simple

Add your configuration at the end of the global configuration file `traefik.toml`:

```toml
# traefik.toml
logLevel = "DEBUG"
defaultEntryPoints = ["http", "https"]
[entryPoints]
  [entryPoints.http]
  address = ":80"
    [entryPoints.http.redirect]
      entryPoint = "https"
  [entryPoints.https]
  address = ":443"
    [entryPoints.https.tls]
      [[entryPoints.https.tls.certificates]]
      CertFile = "integration/fixtures/https/snitest.com.cert"
      KeyFile = "integration/fixtures/https/snitest.com.key"
      [[entryPoints.https.tls.certificates]]
      CertFile = "integration/fixtures/https/snitest.org.cert"
      KeyFile = "integration/fixtures/https/snitest.org.key"

[file]

# rules
[backends]
  [backends.backend1]
    [backends.backend1.circuitbreaker]
      expression = "NetworkErrorRatio() > 0.5"
    [backends.backend1.servers.server1]
    url = "http://172.17.0.2:80"
    weight = 10
    [backends.backend1.servers.server2]
    url = "http://172.17.0.3:80"
    weight = 1
  [backends.backend2]
    [backends.backend2.maxconn]
      amount = 10
      extractorfunc = "request.host"
    [backends.backend2.LoadBalancer]
      method = "drr"
    [backends.backend2.servers.server1]
    url = "http://172.17.0.4:80"
    weight = 1
    [backends.backend2.servers.server2]
    url = "http://172.17.0.5:80"
    weight = 2

[frontends]
  [frontends.frontend1]
  backend = "backend2"
    [frontends.frontend1.routes.test_1]
    rule = "Host:test.localhost"
  [frontends.frontend2]
  backend = "backend1"
  passHostHeader = true
  priority = 10

  # restrict access to this frontend to the specified list of IPv4/IPv6 CIDR Nets
  # 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.
  whitelistSourceRange = ["10.42.0.0/16", "152.89.1.33/32", "afed:be44::/16"]

  entrypoints = ["https"] # overrides defaultEntryPoints
    [frontends.frontend2.routes.test_1]
    rule = "Host:{subdomain:[a-z]+}.localhost"
  [frontends.frontend3]
  entrypoints = ["http", "https"] # overrides defaultEntryPoints
  backend = "backend2"
    rule = "Path:/test"
```

## Rules in a Separate File

Put your rules in a separate file, for example `rules.toml`:

```toml
# traefik.toml
logLevel = "DEBUG"
[entryPoints]
  [entryPoints.http]
  address = ":80"
    [entryPoints.http.redirect]
      entryPoint = "https"
  [entryPoints.https]
  address = ":443"
    [entryPoints.https.tls]
      [[entryPoints.https.tls.certificates]]
      CertFile = "integration/fixtures/https/snitest.com.cert"
      KeyFile = "integration/fixtures/https/snitest.com.key"
      [[entryPoints.https.tls.certificates]]
      CertFile = "integration/fixtures/https/snitest.org.cert"
      KeyFile = "integration/fixtures/https/snitest.org.key"

[file]
filename = "rules.toml"
```

```toml
# rules.toml
[backends]
  [backends.backend1]
    [backends.backend1.circuitbreaker]
      expression = "NetworkErrorRatio() > 0.5"
    [backends.backend1.servers.server1]
    url = "http://172.17.0.2:80"
    weight = 10
    [backends.backend1.servers.server2]
    url = "http://172.17.0.3:80"
    weight = 1
  [backends.backend2]
    [backends.backend2.maxconn]
      amount = 10
      extractorfunc = "request.host"
    [backends.backend2.LoadBalancer]
      method = "drr"
    [backends.backend2.servers.server1]
    url = "http://172.17.0.4:80"
    weight = 1
    [backends.backend2.servers.server2]
    url = "http://172.17.0.5:80"
    weight = 2

[frontends]
  [frontends.frontend1]
  backend = "backend2"
    [frontends.frontend1.routes.test_1]
    rule = "Host:test.localhost"
  [frontends.frontend2]
  backend = "backend1"
  passHostHeader = true
  priority = 10
  entrypoints = ["https"] # overrides defaultEntryPoints
    [frontends.frontend2.routes.test_1]
    rule = "Host:{subdomain:[a-z]+}.localhost"
  [frontends.frontend3]
  entrypoints = ["http", "https"] # overrides defaultEntryPoints
  backend = "backend2"
    rule = "Path:/test"
```

## Multiple .toml Files

You could have multiple `.toml` files in a directory:
 
```toml
[file]
directory = "/path/to/config/"
```

If you want Træfik to watch file changes automatically, just add:

```toml
[file]
watch = true
```

The configuration files can be also templates written using functions provided by [go template](https://golang.org/pkg/text/template/) as well as functions provided by the [sprig library](https://masterminds.github.io/sprig/), like this:

```tmpl
[backends]
  [backends.backend1]
  url = "http://firstserver"
  [backends.backend2]
  url = "http://secondserver"

{{$frontends := dict "frontend1" "backend1" "frontend2" "backend2"}}
[frontends]
{{range $frontend, $backend := $frontends}}
  [frontends.{{$frontend}}]
  backend = "{{$backend}}"
{{end}}
```