--- title: "discovery.docker | Grafana Agent documentation" description: "Learn about discovery.docker" --- # discovery.docker `discovery.docker` discovers [Docker Engine](https://docs.docker.com/engine/) containers and exposes them as targets. ## Usage Alloy ![Copy code to clipboard](/media/images/icons/icon-copy-small-2.svg) Copy ```alloy discovery.docker "LABEL" { host = DOCKER_ENGINE_HOST } ``` ## Arguments The following arguments are supported: Expand table | Name | Type | Description | Default | Required | |--------------------------|---------------------|--------------------------------------------------------------------------------------------------|---------------|----------| | `host` | `string` | Address of the Docker Daemon to connect to. | | yes | | `port` | `number` | Port to use for collecting metrics when containers don’t have any port mappings. | `80` | no | | `host_networking_host` | `string` | Host to use if the container is in host networking mode. | `"localhost"` | no | | `refresh_interval` | `duration` | Frequency to refresh list of containers. | `"1m"` | no | | `bearer_token_file` | `string` | File containing a bearer token to authenticate with. | | no | | `bearer_token` | `secret` | Bearer token to authenticate with. | | no | | `enable_http2` | `bool` | Whether HTTP2 is supported for requests. | `true` | no | | `follow_redirects` | `bool` | Whether redirects returned by the server should be followed. | `true` | no | | `proxy_url` | `string` | HTTP proxy to send requests through. | | no | | `no_proxy` | `string` | Comma-separated list of IP addresses, CIDR notations, and domain names to exclude from proxying. | | no | | `proxy_from_environment` | `bool` | Use the proxy URL indicated by environment variables. | `false` | no | | `proxy_connect_header` | `map(list(secret))` | Specifies headers to send to proxies during CONNECT requests. | | no | At most, one of the following can be provided: - [`bearer_token` argument](#arguments). - [`bearer_token_file` argument](#arguments). - [`basic_auth` block](#basic_auth-block). - [`authorization` block](#authorization-block). - [`oauth2` block](#oauth2-block). `no_proxy` can contain IPs, CIDR notations, and domain names. IP and domain names can contain port numbers. `proxy_url` must be configured if `no_proxy` is configured. `proxy_from_environment` uses the environment variables HTTP\_PROXY, HTTPS\_PROXY and NO\_PROXY (or the lowercase versions thereof). Requests use the proxy from the environment variable matching their scheme, unless excluded by NO\_PROXY. `proxy_url` and `no_proxy` must not be configured if `proxy_from_environment` is configured. `proxy_connect_header` should only be configured if `proxy_url` or `proxy_from_environment` are configured. ## Blocks The following blocks are supported inside the definition of `discovery.docker`: Expand table | Hierarchy | Block | Description | Required | |-------------------------|---------------------------------------|-----------------------------------------------------------|----------| | filter | [filter](#filter-block) | Filters discoverable resources. | no | | basic\_auth | [basic\_auth](#basic_auth-block) | Configure basic\_auth for authenticating to the endpoint. | no | | authorization | [authorization](#authorization-block) | Configure generic authorization to the endpoint. | no | | oauth2 | [oauth2](#oauth2-block) | Configure OAuth2 for authenticating to the endpoint. | no | | oauth2 > tls\_config | [tls\_config](#tls_config-block) | Configure TLS settings for connecting to the endpoint. | no | | tls\_config | [tls\_config](#tls_config-block) | Configure TLS settings for connecting to the endpoint. | no | The `>` symbol indicates deeper levels of nesting. For example, `oauth2 > tls_config` refers to a `tls_config` block defined inside an `oauth2` block. ### filter block The `filter` block configures a filter to pass to the Docker Engine to limit the amount of containers returned. The `filter` block can be specified multiple times to provide more than one filter. Expand table | Name | Type | Description | Default | Required | |----------|----------------|-------------------------------|---------|----------| | `name` | `string` | Filter name to use. | | yes | | `values` | `list(string)` | Values to pass to the filter. | | yes | Refer to [List containers](https://docs.docker.com/engine/api/v1.41/#tag/Container/operation/ContainerList) from the Docker Engine API documentation for the list of supported filters and their meaning. ### basic\_auth block Expand table | Name | Type | Description | Default | Required | |-----------------|----------|------------------------------------------|---------|----------| | `password_file` | `string` | File containing the basic auth password. | | no | | `password` | `secret` | Basic auth password. | | no | | `username` | `string` | Basic auth username. | | no | `password` and `password_file` are mutually exclusive, and only one can be provided inside a `basic_auth` block. ### authorization block Expand table | Name | Type | Description | Default | Required | |--------------------|----------|--------------------------------------------|---------|----------| | `credentials_file` | `string` | File containing the secret value. | | no | | `credentials` | `secret` | Secret value. | | no | | `type` | `string` | Authorization type, for example, “Bearer”. | | no | `credential` and `credentials_file` are mutually exclusive, and only one can be provided inside an `authorization` block. ### oauth2 block Expand table | Name | Type | Description | Default | Required | |--------------------------|---------------------|--------------------------------------------------------------------------------------------------|---------|----------| | `client_id` | `string` | OAuth2 client ID. | | no | | `client_secret_file` | `string` | File containing the OAuth2 client secret. | | no | | `client_secret` | `secret` | OAuth2 client secret. | | no | | `endpoint_params` | `map(string)` | Optional parameters to append to the token URL. | | no | | `proxy_url` | `string` | HTTP proxy to send requests through. | | no | | `no_proxy` | `string` | Comma-separated list of IP addresses, CIDR notations, and domain names to exclude from proxying. | | no | | `proxy_from_environment` | `bool` | Use the proxy URL indicated by environment variables. | `false` | no | | `proxy_connect_header` | `map(list(secret))` | Specifies headers to send to proxies during CONNECT requests. | | no | | `scopes` | `list(string)` | List of scopes to authenticate with. | | no | | `token_url` | `string` | URL to fetch the token from. | | no | `client_secret` and `client_secret_file` are mutually exclusive, and only one can be provided inside an `oauth2` block. The `oauth2` block may also contain a separate `tls_config` sub-block. `no_proxy` can contain IPs, CIDR notations, and domain names. IP and domain names can contain port numbers. `proxy_url` must be configured if `no_proxy` is configured. `proxy_from_environment` uses the environment variables HTTP\_PROXY, HTTPS\_PROXY and NO\_PROXY (or the lowercase versions thereof). Requests use the proxy from the environment variable matching their scheme, unless excluded by NO\_PROXY. `proxy_url` and `no_proxy` must not be configured if `proxy_from_environment` is configured. `proxy_connect_header` should only be configured if `proxy_url` or `proxy_from_environment` are configured. ### tls\_config block Expand table | Name | Type | Description | Default | Required | |------------------------|----------|----------------------------------------------------------|---------|----------| | `ca_pem` | `string` | CA PEM-encoded text to validate the server with. | | no | | `ca_file` | `string` | CA certificate to validate the server with. | | no | | `cert_pem` | `string` | Certificate PEM-encoded text for client authentication. | | no | | `cert_file` | `string` | Certificate file for client authentication. | | no | | `insecure_skip_verify` | `bool` | Disables validation of the server certificate. | | no | | `key_file` | `string` | Key file for client authentication. | | no | | `key_pem` | `secret` | Key PEM-encoded text for client authentication. | | no | | `min_version` | `string` | Minimum acceptable TLS version. | | no | | `server_name` | `string` | ServerName extension to indicate the name of the server. | | no | The following pairs of arguments are mutually exclusive and can’t both be set simultaneously: - `ca_pem` and `ca_file` - `cert_pem` and `cert_file` - `key_pem` and `key_file` When configuring client authentication, both the client certificate (using `cert_pem` or `cert_file`) and the client key (using `key_pem` or `key_file`) must be provided. When `min_version` is not provided, the minimum acceptable TLS version is inherited from Go’s default minimum version, TLS 1.2. If `min_version` is provided, it must be set to one of the following strings: - `"TLS10"` (TLS 1.0) - `"TLS11"` (TLS 1.1) - `"TLS12"` (TLS 1.2) - `"TLS13"` (TLS 1.3) ## Exported fields The following fields are exported and can be referenced by other components: Expand table | Name | Type | Description | |-----------|---------------------|----------------------------------------------------| | `targets` | `list(map(string))` | The set of targets discovered from the docker API. | Each target includes the following labels: - `__meta_docker_container_id`: ID of the container. - `__meta_docker_container_name`: Name of the container. - `__meta_docker_container_network_mode`: Network mode of the container. - `__meta_docker_container_label_`: Each label from the container. - `__meta_docker_network_id`: ID of the Docker network the container is in. - `__meta_docker_network_name`: Name of the Docker network the container is in. - `__meta_docker_network_ingress`: Set to `true` if the Docker network is an ingress network. - `__meta_docker_network_internal`: Set to `true` if the Docker network is an internal network. - `__meta_docker_network_label_`: Each label from the network the container is in. - `__meta_docker_network_scope`: The scope of the network the container is in. - `__meta_docker_network_ip`: The IP of the container in the network. - `__meta_docker_port_private`: The private port on the container. - `__meta_docker_port_public`: The publicly exposed port from the container, if a port mapping exists. - `__meta_docker_port_public_ip`: The public IP of the container, if a port mapping exists. Each discovered container maps to one target per unique combination of networks and port mappings used by the container. ## Component health `discovery.docker` is only reported as unhealthy when given an invalid configuration. In those cases, exported fields retain their last healthy values. ## Debug information `discovery.docker` does not expose any component-specific debug information. ## Debug metrics `discovery.docker` does not expose any component-specific debug metrics. ## Examples ### Linux or macOS hosts This example discovers Docker containers when the host machine is macOS or Linux: Alloy ![Copy code to clipboard](/media/images/icons/icon-copy-small-2.svg) Copy ```alloy discovery.docker "containers" { host = "unix:///var/run/docker.sock" } prometheus.scrape "demo" { targets = discovery.docker.containers.targets forward_to = [prometheus.remote_write.demo.receiver] } prometheus.remote_write "demo" { endpoint { url = PROMETHEUS_REMOTE_WRITE_URL basic_auth { username = USERNAME password = PASSWORD } } } ``` Replace the following: - `PROMETHEUS_REMOTE_WRITE_URL`: The URL of the Prometheus remote\_write-compatible server to send metrics to. - `USERNAME`: The username to use for authentication to the remote\_write API. - `PASSWORD`: The password to use for authentication to the remote\_write API. ### Windows hosts This example discovers Docker containers when the host machine is Windows: Alloy ![Copy code to clipboard](/media/images/icons/icon-copy-small-2.svg) Copy ```alloy discovery.docker "containers" { host = "tcp://localhost:2375" } prometheus.scrape "demo" { targets = discovery.docker.containers.example.targets forward_to = [prometheus.remote_write.demo.receiver] } prometheus.remote_write "demo" { endpoint { url = PROMETHEUS_REMOTE_WRITE_URL basic_auth { username = USERNAME password = PASSWORD } } } ``` Replace the following: - `PROMETHEUS_REMOTE_WRITE_URL`: The URL of the Prometheus remote\_write-compatible server to send metrics to. - `USERNAME`: The username to use for authentication to the remote\_write API. - `PASSWORD`: The password to use for authentication to the remote\_write API. > **NOTE**: This example requires the “Expose daemon on tcp://localhost:2375 without TLS” setting to be enabled in the Docker Engine settings. ## Compatible components `discovery.docker` has exports that can be consumed by the following components: - Components that consume [Targets](../../compatibility/#targets-consumers) > Note > > Connecting some components may not be sensible or components may require further configuration to make the connection work correctly. Refer to the linked documentation for more details.