Documentation Grafana Cloud Instrument and send data Grafana Alloy Reference Components discovery discovery.docker

discovery.docker

discovery.docker discovers Docker Engine containers and exposes them as targets.

Usage

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discovery.docker "LABEL" {
  host = DOCKER_ENGINE_HOST
}

Arguments

The following arguments are supported:

At most, one of the following can be provided:

• bearer_token argument.
• bearer_token_file argument.
• basic_auth block.
• authorization 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:

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.

Refer to List containers from the Docker Engine API documentation for the list of supported filters and their meaning.

basic_auth block

password and password_file are mutually exclusive, and only one can be provided inside a basic_auth block.

authorization block

credential and credentials_file are mutually exclusive, and only one can be provided inside an authorization block.

oauth2 block

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

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:

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_<labelname>: 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_<labelname>: 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:

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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:

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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