github.com/Ilhicas/nomad@v1.0.4-0.20210304152020-e86851182bc3/website/content/docs/job-specification/expose.mdx

---
layout: docs
page_title: expose Stanza - Job Specification
sidebar_title: expose
description: |-
  The "expose" stanza allows specifying options for configuring Envoy expose
  paths used in Consul Connect integration
---

# `expose` Stanza

<Placement
  groups={[
    'job',
    'group',
    'service',
    'connect',
    'sidecar_service',
    'proxy',
    'expose',
  ]}
/>

The `expose` stanza allows configuration of additional listeners for the default
Envoy sidecar proxy managed by Nomad for [Consul Connect][learn-consul-connect].
These listeners create a bypass of the Connect TLS and network namespace
isolation, enabling non-Connect enabled services to make requests to specific
HTTP paths through the sidecar proxy.

The `expose` configuration is valid within the context of a `proxy` stanza.
Additional information about Expose Path configurations for Envoy can be found
in Consul's [Expose Paths Configuration Reference][consul-expose-path-config].

Service [check][] configurations can use their [expose][] parameter to
automatically generate expose path configurations for HTTP and gRPC checks.

```hcl
job "expose-check-example" {
  datacenters = ["dc1"]

  group "api" {
    network {
      mode = "bridge"
    }

    service {
      name = "count-api"
      port = "9001"

      connect {
        sidecar_service {}
      }

      check {
        expose   = true
        name     = "api-health"
        type     = "http"
        path     = "/health"
        interval = "10s"
        timeout  = "3s"
      }
    }

    task "web" {
      driver = "docker"

      config {
        image = "hashicorpnomad/counter-api:v3"
      }
    }
  }
}
```

For uses other than Consul service checks, use the `expose` configuration in the
`proxy` stanza. The example below effectively demonstrates exposing the
`/health` endpoint similar to the example above, but using the fully flexible
`expose` configuration.

```hcl
job "expose-example" {
  datacenters = ["dc1"]

  group "api" {
    network {
      mode = "bridge"

      port "api_expose_healthcheck" {
        to = -1
      }
    }

    service {
      name = "count-api"
      port = "9001"

      connect {
        sidecar_service {
          proxy {
            expose {
              path {
                path            = "/health"
                protocol        = "http"
                local_path_port = 9001
                listener_port   = "api_expose_healthcheck"
              }
            }
          }
        }
      }

      check {
        name     = "api-health"
        type     = "http"
        path     = "/health"
        port     = "api_expose_healthcheck"
        interval = "10s"
        timeout  = "3s"
      }
    }

    task "web" {
      driver = "docker"

      config {
        image = "hashicorpnomad/counter-api:v3"
      }

      # e.g. reference ${NOMAD_PORT_api_expose_healthcheck} for other uses
    }
  }
}
```

## `expose` Parameters

- `path` <code>([Path]: nil)</code> - A list of [Envoy Expose Path Configurations][expose_path]
  to expose through Envoy.

### `path` Parameters

- `path` `(string: required)` - The HTTP or gRPC path to expose. The path must be prefixed
  with a slash.

- `protocol` `(string: required)` - Sets the protocol of the listener. Must be
  `http` or `http2`. For gRPC use `http2`.

- `local_path_port` `(int: required)` - The port the service is listening to for connections to
  the configured `path`. Typically this will be the same as the `service.port` value, but
  could be different if for example the exposed path is intended to resolve to another task
  in the task group.

- `listener_port` <code>([Port]: required)</code> - The name of the port to use
  for the exposed listener. The port should be configured to [map inside][network-to]
  the task's network namespace.

## `expose` Examples

The following example is configured to expose the `/metrics` endpoint of the
Connect-enabled `count-dashboard` service, using the `HTTP` protocol.
`count-dashboard` is expected to listen inside its namespace to port `9001`, and
external services will be able to reach its `/metrics` endpoint by connecting to
the [network interface][network_interface] of the node on the allocated
`metrics` [Port][].

```hcl
service {
  name = "count-dashboard"
  port = "9001"

  connect {
    sidecar_service {
      proxy {
        expose {
          path {
            path            = "/metrics"
            protocol        = "http"
            local_path_port = 9001
            listener_port   = "metrics"
          }
        }
      }
    }
  }
}
```

## `path` Examples

The following example is an expose configuration that exposes a `/metrics`
endpoint using the `http2` protocol (typical for gRPC), and an HTTP `/v2/health`
endpoint.

```hcl
proxy {
  expose {
    path {
      path            = "/metrics"
      protocol        = "http2"
      local_path_port = 9001
      listener_port   = "expose"
    }
    path {
      path            = "/v2/health"
      protocol        = "http"
      local_path_port = 9001
      listener_port   = "expose"
    }
  }
}
```

### Exposing Service Checks

A common use case for `expose` is for exposing endpoints used in Consul service
check definitions. For these cases the [expose][] parameter in the service check
stanza can be used to automatically generate the expose path configuration.
Configuring a port for use by the check is optional, as a dynamic port will be
automatically generated if not provided.

```hcl
check {
  expose   = true
  type     = "http"
  name     = "dashboard-health"
  path     = "/health"
  interval = "10s"
  timeout  = "3s"
}
```

[network-to]: /docs/job-specification/network#to
[consul-expose-path-config]: https://www.consul.io/docs/connect/registration/service-registration#expose-paths-configuration-reference
[expose-path]: /docs/job-specification/expose#path-1
[expose]: /docs/job-specification/service#expose
[path]: /docs/job-specification/expose#path-parameters 'Nomad Expose Path Parameters'
[port]: /docs/job-specification/network#port-parameters 'Nomad Port Parameters'
[network_interface]: /docs/configuration/client#network_interface
[learn-consul-connect]: https://learn.hashicorp.com/tutorials/nomad/consul-service-mesh
[check]: /docs/job-specification/service#check-parameters