537 lines
11 KiB
Markdown
537 lines
11 KiB
Markdown
---
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title: "Nomad Service Discovery"
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description: "Learn how to use Nomad as a provider for configuration discovery in Traefik Proxy. Read the technical documentation."
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---
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# Traefik & Nomad Service Discovery
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A Story of Tags, Services & Nomads
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{: .subtitle }
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Attach tags to your Nomad services and let Traefik do the rest!
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## Configuration Examples
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??? example "Configuring Nomad & Deploying Services"
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Enabling the nomad provider
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```yaml tab="File (YAML)"
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providers:
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nomad: {}
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```
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```toml tab="File (TOML)"
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[providers.nomad]
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```
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```bash tab="CLI"
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--providers.nomad=true
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```
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Attaching tags to services:
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```
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...
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service {
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name = "myService"
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tags = [
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"traefik.http.routers.my-router.rule=Host(`example.com`)",
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]
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}
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...
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```
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## Routing Configuration
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See the dedicated section in [routing](../routing/providers/nomad.md).
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## Provider Configuration
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### `refreshInterval`
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_Optional, Default=15s_
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Defines the polling interval.
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```yaml tab="File (YAML)"
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providers:
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nomad:
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refreshInterval: 30s
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# ...
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```
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```toml tab="File (TOML)"
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[providers.nomad]
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refreshInterval = "30s"
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# ...
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```
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```bash tab="CLI"
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--providers.nomad.refreshInterval=30s
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# ...
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```
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### `prefix`
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_required, Default="traefik"_
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The prefix for Nomad service tags defining Traefik labels.
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```yaml tab="File (YAML)"
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providers:
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nomad:
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prefix: test
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# ...
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```
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```toml tab="File (TOML)"
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[providers.nomad]
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prefix = "test"
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# ...
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```
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```bash tab="CLI"
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--providers.nomad.prefix=test
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# ...
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```
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### `stale`
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_Optional, Default=false_
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Use stale consistency for Nomad service API reads.
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!!! note ""
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This makes reads very fast and scalable at the cost of a higher likelihood of stale values.
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For more information, see the Nomad [documentation on consistency](https://www.nomadproject.io/api-docs#consistency-modes).
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```yaml tab="File (YAML)"
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providers:
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nomad:
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stale: true
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# ...
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```
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```toml tab="File (TOML)"
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[providers.nomad]
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stale = true
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# ...
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```
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```bash tab="CLI"
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--providers.nomad.stale=true
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# ...
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```
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### `endpoint`
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Defines the Nomad server endpoint.
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#### `address`
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Defines the address of the Nomad server.
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_Optional, Default="http://127.0.0.1:4646"_
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```yaml tab="File (YAML)"
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providers:
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nomad:
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endpoint:
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address: http://127.0.0.1:4646
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# ...
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```
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```toml tab="File (TOML)"
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[providers.nomad]
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[providers.nomad.endpoint]
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address = "http://127.0.0.1:4646"
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# ...
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```
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```bash tab="CLI"
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--providers.nomad.endpoint.address=http://127.0.0.1:4646
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# ...
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```
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#### `token`
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_Optional, Default=""_
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Token is used to provide a per-request ACL token, if Nomad ACLs are enabled.
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```yaml tab="File (YAML)"
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providers:
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nomad:
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endpoint:
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token: test
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# ...
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```
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```toml tab="File (TOML)"
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[providers.nomad]
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[providers.nomad.endpoint]
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token = "test"
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# ...
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```
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```bash tab="CLI"
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--providers.nomad.endpoint.token=test
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# ...
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```
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#### `endpointWaitTime`
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_Optional, Default=""_
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Limits the duration for which a Watch can block.
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If not provided, the agent default values will be used.
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```yaml tab="File (YAML)"
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providers:
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nomad:
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endpoint:
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endpointWaitTime: 15s
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# ...
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```
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```toml tab="File (TOML)"
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[providers.nomad]
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[providers.nomad.endpoint]
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endpointWaitTime = "15s"
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# ...
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```
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```bash tab="CLI"
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--providers.nomad.endpoint.endpointwaittime=15s
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# ...
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```
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#### `tls`
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_Optional_
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Defines the TLS configuration used for the secure connection to the Nomad API.
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##### `ca`
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_Optional_
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`ca` is the path to the certificate authority used for the secure connection to Nomad,
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it defaults to the system bundle.
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```yaml tab="File (YAML)"
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providers:
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nomad:
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endpoint:
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tls:
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ca: path/to/ca.crt
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```
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```toml tab="File (TOML)"
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[providers.nomad.endpoint.tls]
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ca = "path/to/ca.crt"
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```
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```bash tab="CLI"
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--providers.nomad.endpoint.tls.ca=path/to/ca.crt
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```
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##### `cert`
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_Optional_
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`cert` is the path to the public certificate used for the secure connection to the Nomad API.
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When using this option, setting the `key` option is required.
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```yaml tab="File (YAML)"
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providers:
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nomad:
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endpoint:
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tls:
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cert: path/to/foo.cert
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key: path/to/foo.key
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```
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```toml tab="File (TOML)"
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[providers.nomad.endpoint.tls]
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cert = "path/to/foo.cert"
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key = "path/to/foo.key"
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```
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```bash tab="CLI"
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--providers.nomad.endpoint.tls.cert=path/to/foo.cert
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--providers.nomad.endpoint.tls.key=path/to/foo.key
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```
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##### `key`
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_Optional_
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`key` is the path to the private key used for the secure connection to the Nomad API.
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When using this option, setting the `cert` option is required.
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```yaml tab="File (YAML)"
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providers:
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nomad:
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endpoint:
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tls:
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cert: path/to/foo.cert
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key: path/to/foo.key
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```
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```toml tab="File (TOML)"
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[providers.nomad.endpoint.tls]
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cert = "path/to/foo.cert"
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key = "path/to/foo.key"
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```
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```bash tab="CLI"
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--providers.nomad.endpoint.tls.cert=path/to/foo.cert
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--providers.nomad.endpoint.tls.key=path/to/foo.key
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```
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##### `insecureSkipVerify`
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_Optional, Default=false_
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If `insecureSkipVerify` is `true`, the TLS connection to Nomad accepts any certificate presented by the server regardless of the hostnames it covers.
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```yaml tab="File (YAML)"
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providers:
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nomad:
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endpoint:
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tls:
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insecureSkipVerify: true
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```
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```toml tab="File (TOML)"
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[providers.nomad.endpoint.tls]
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insecureSkipVerify = true
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```
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```bash tab="CLI"
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--providers.nomad.endpoint.tls.insecureskipverify=true
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```
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### `exposedByDefault`
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_Optional, Default=true_
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Expose Nomad services by default in Traefik.
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If set to `false`, services that do not have a `traefik.enable=true` tag will be ignored from the resulting routing configuration.
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For additional information, refer to [Restrict the Scope of Service Discovery](./overview.md#restrict-the-scope-of-service-discovery).
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```yaml tab="File (YAML)"
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providers:
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nomad:
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exposedByDefault: false
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# ...
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```
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```toml tab="File (TOML)"
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[providers.nomad]
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exposedByDefault = false
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# ...
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```
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```bash tab="CLI"
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--providers.nomad.exposedByDefault=false
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# ...
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```
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### `defaultRule`
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_Optional, Default=```Host(`{{ normalize .Name }}`)```_
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The default host rule for all services.
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For a given service, if no routing rule was defined by a tag, it is defined by this `defaultRule` instead.
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The `defaultRule` must be set to a valid [Go template](https://pkg.go.dev/text/template/),
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and can include [sprig template functions](https://masterminds.github.io/sprig/).
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The service name can be accessed with the `Name` identifier,
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and the template has access to all the labels (i.e. tags beginning with the `prefix`) defined on this service.
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The option can be overridden on an instance basis with the `traefik.http.routers.{name-of-your-choice}.rule` tag.
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```yaml tab="File (YAML)"
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providers:
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nomad:
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defaultRule: "Host(`{{ .Name }}.{{ index .Labels \"customLabel\"}}`)"
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# ...
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```
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```toml tab="File (TOML)"
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[providers.nomad]
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defaultRule = "Host(`{{ .Name }}.{{ index .Labels \"customLabel\"}}`)"
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# ...
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```
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```bash tab="CLI"
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--providers.nomad.defaultRule="Host(`{{ .Name }}.{{ index .Labels \"customLabel\"}}`)"
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# ...
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```
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??? info "Default rule and Traefik service"
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The exposure of the Traefik container, combined with the default rule mechanism,
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can lead to create a router targeting itself in a loop.
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In this case, to prevent an infinite loop,
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Traefik adds an internal middleware to refuse the request if it comes from the same router.
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### `constraints`
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_Optional, Default=""_
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The `constraints` option can be set to an expression that Traefik matches against the service tags to determine whether
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to create any route for that service. If none of the service tags match the expression, no route for that service is
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created. If the expression is empty, all detected services are included.
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The expression syntax is based on the ```Tag(`tag`)```, and ```TagRegex(`tag`)``` functions,
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as well as the usual boolean logic, as shown in examples below.
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??? example "Constraints Expression Examples"
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```toml
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# Includes only services having the tag `a.tag.name=foo`
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constraints = "Tag(`a.tag.name=foo`)"
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```
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```toml
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# Excludes services having any tag `a.tag.name=foo`
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constraints = "!Tag(`a.tag.name=foo`)"
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```
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```toml
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# With logical AND.
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constraints = "Tag(`a.tag.name`) && Tag(`another.tag.name`)"
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```
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```toml
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# With logical OR.
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constraints = "Tag(`a.tag.name`) || Tag(`another.tag.name`)"
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```
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```toml
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# With logical AND and OR, with precedence set by parentheses.
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constraints = "Tag(`a.tag.name`) && (Tag(`another.tag.name`) || Tag(`yet.another.tag.name`))"
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```
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```toml
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# Includes only services having a tag matching the `a\.tag\.t.+` regular expression.
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constraints = "TagRegex(`a\.tag\.t.+`)"
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```
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```yaml tab="File (YAML)"
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providers:
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nomad:
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constraints: "Tag(`a.tag.name`)"
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# ...
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```
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```toml tab="File (TOML)"
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[providers.nomad]
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constraints = "Tag(`a.tag.name`)"
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# ...
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```
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```bash tab="CLI"
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--providers.nomad.constraints="Tag(`a.tag.name`)"
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# ...
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```
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For additional information, refer to [Restrict the Scope of Service Discovery](./overview.md#restrict-the-scope-of-service-discovery).
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### `namespaces`
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??? warning "Deprecated in favor of the [`namespaces`](#namespaces) option."
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_Optional, Default=""_
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The `namespace` option defines the namespace in which the Nomad services will be discovered.
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!!! warning
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One should only define either the `namespaces` option or the `namespace` option.
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```yaml tab="File (YAML)"
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providers:
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nomad:
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namespace: "production"
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# ...
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```
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```toml tab="File (TOML)"
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[providers.nomad]
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namespace = "production"
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# ...
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```
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```bash tab="CLI"
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--providers.nomad.namespace=production
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# ...
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```
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### `namespaces`
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_Optional, Default=""_
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The `namespaces` option defines the namespaces in which the nomad services will be discovered.
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When using the `namespaces` option, the discovered object names will be suffixed as shown below:
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```text
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<resource-name>@nomad-<namespace>
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```
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!!! warning
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One should only define either the `namespaces` option or the `namespace` option.
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```yaml tab="File (YAML)"
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providers:
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nomad:
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namespaces:
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- "ns1"
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- "ns2"
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# ...
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```
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```toml tab="File (TOML)"
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[providers.nomad]
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namespaces = ["ns1", "ns2"]
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# ...
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```
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```bash tab="CLI"
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--providers.nomad.namespaces=ns1,ns2
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# ...
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```
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### `allowEmptyServices`
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_Optional, Default: false_
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If the parameter is set to `true`,
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it allows the creation of an empty [servers load balancer](../routing/services/index.md#servers-load-balancer) if the targeted Nomad service has no endpoints available. This results in a `503` HTTP response instead of a `404`.
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```yaml tab="File (YAML)"
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providers:
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nomad:
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allowEmptyServices: true
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# ...
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```
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```toml tab="File (TOML)"
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[providers.nomad]
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allowEmptyServices = true
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# ...
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```
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```bash tab="CLI"
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--providers.nomad.allowEmptyServices=true
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```
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