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discovery.docker

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

Usage

river
discovery.docker "LABEL" {
  host = DOCKER_ENGINE_HOST
}

Arguments

The following arguments are supported:

NameTypeDescriptionDefaultRequired
hoststringAddress of the Docker Daemon to connect to.yes
portnumberPort to use for collecting metrics when containers don’t have any port mappings.80no
host_networking_hoststringHost to use if the container is in host networking mode."localhost"no
refresh_intervaldurationFrequency to refresh list of containers."1m"no
bearer_token_filestringFile containing a bearer token to authenticate with.no
bearer_tokensecretBearer token to authenticate with.no
enable_http2boolWhether HTTP2 is supported for requests.trueno
follow_redirectsboolWhether redirects returned by the server should be followed.trueno
proxy_urlstringHTTP proxy to send requests through.no
no_proxystringComma-separated list of IP addresses, CIDR notations, and domain names to exclude from proxying.no
proxy_from_environmentboolUse the proxy URL indicated by environment variables.falseno
proxy_connect_headermap(list(secret))Specifies headers to send to proxies during CONNECT requests.no

At most, one of the following can be provided:

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:

HierarchyBlockDescriptionRequired
filterfilterFilters discoverable resources.no
basic_authbasic_authConfigure basic_auth for authenticating to the endpoint.no
authorizationauthorizationConfigure generic authorization to the endpoint.no
oauth2oauth2Configure OAuth2 for authenticating to the endpoint.no
oauth2 > tls_configtls_configConfigure TLS settings for connecting to the endpoint.no
tls_configtls_configConfigure 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.

NameTypeDescriptionDefaultRequired
namestringFilter name to use.yes
valueslist(string)Values to pass to the filter.yes

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

basic_auth block

NameTypeDescriptionDefaultRequired
password_filestringFile containing the basic auth password.no
passwordsecretBasic auth password.no
usernamestringBasic auth username.no

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

authorization block

NameTypeDescriptionDefaultRequired
credentials_filestringFile containing the secret value.no
credentialssecretSecret value.no
typestringAuthorization type, for example, “Bearer”.no

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

oauth2 block

NameTypeDescriptionDefaultRequired
client_idstringOAuth2 client ID.no
client_secret_filestringFile containing the OAuth2 client secret.no
client_secretsecretOAuth2 client secret.no
endpoint_paramsmap(string)Optional parameters to append to the token URL.no
proxy_urlstringHTTP proxy to send requests through.no
no_proxystringComma-separated list of IP addresses, CIDR notations, and domain names to exclude from proxying.no
proxy_from_environmentboolUse the proxy URL indicated by environment variables.falseno
proxy_connect_headermap(list(secret))Specifies headers to send to proxies during CONNECT requests.no
scopeslist(string)List of scopes to authenticate with.no
token_urlstringURL 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

NameTypeDescriptionDefaultRequired
ca_pemstringCA PEM-encoded text to validate the server with.no
ca_filestringCA certificate to validate the server with.no
cert_pemstringCertificate PEM-encoded text for client authentication.no
cert_filestringCertificate file for client authentication.no
insecure_skip_verifyboolDisables validation of the server certificate.no
key_filestringKey file for client authentication.no
key_pemsecretKey PEM-encoded text for client authentication.no
min_versionstringMinimum acceptable TLS version.no
server_namestringServerName 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:

NameTypeDescription
targetslist(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_<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:

river
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:

river
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:

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.