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Open source

discovery.dockerswarm

discovery.dockerswarm allows you to retrieve scrape targets from Docker Swarm.

Usage

Alloy 
discovery.dockerswarm "LABEL" {
  host = "DOCKER_DAEMON_HOST"
  role = "SWARM_ROLE"
}

Arguments

The following arguments are supported:

NameTypeDescriptionDefaultRequired
hoststringAddress of the Docker daemon.yes
rolestringRole of the targets to retrieve. Must be services, tasks, or nodes.yes
portnumberThe port to scrape metrics from, when role is nodes, and for discovered tasks and services that don’t have published ports.80no
refresh_intervaldurationInterval at which to refresh the list of targets."60s"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.dockerswarm:

HierarchyBlockDescriptionRequired
filterfilterOptional filter to limit the discovery process to a subset of available 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

Filters can be used to limit the discovery process to a subset of available resources. It is possible to define multiple filter blocks within the discovery.dockerswarm block. The list of available filters depends on the role:

The following arguments can be used to configure a filter.

NameTypeDescriptionDefaultRequired
namestringName of the filter.yes
valueslist(string)List of values associated with the filter.yes

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 Swarm.

Roles

The role attribute decides the role of the targets to retrieve.

services

The services role discovers all Swarm services and exposes their ports as targets. For each published port of a service, a single target is generated. If a service has no published ports, a target per service is created using the port attribute defined in the arguments.

Available meta labels:

  • __meta_dockerswarm_service_id: the ID of the service.
  • __meta_dockerswarm_service_name: the name of the service.
  • __meta_dockerswarm_service_mode: the mode of the service.
  • __meta_dockerswarm_service_endpoint_port_name: the name of the endpoint port, if available.
  • __meta_dockerswarm_service_endpoint_port_publish_mode: the publish mode of the endpoint port.
  • __meta_dockerswarm_service_label_<labelname>: each label of the service.
  • __meta_dockerswarm_service_task_container_hostname: the container hostname of the target, if available.
  • __meta_dockerswarm_service_task_container_image: the container image of the target.
  • __meta_dockerswarm_service_updating_status: the status of the service, if available.
  • __meta_dockerswarm_network_id: the ID of the network.
  • __meta_dockerswarm_network_name: the name of the network.
  • __meta_dockerswarm_network_ingress: whether the network is ingress.
  • __meta_dockerswarm_network_internal: whether the network is internal.
  • __meta_dockerswarm_network_label_<labelname>: each label of the network.
  • __meta_dockerswarm_network_scope: the scope of the network.

tasks

The tasks role discovers all Swarm tasks and exposes their ports as targets. For each published port of a task, a single target is generated. If a task has no published ports, a target per task is created using the port attribute defined in the arguments.

Available meta labels:

  • __meta_dockerswarm_container_label_<labelname>: each label of the container.
  • __meta_dockerswarm_task_id: the ID of the task.
  • __meta_dockerswarm_task_container_id: the container ID of the task.
  • __meta_dockerswarm_task_desired_state: the desired state of the task.
  • __meta_dockerswarm_task_slot: the slot of the task.
  • __meta_dockerswarm_task_state: the state of the task.
  • __meta_dockerswarm_task_port_publish_mode: the publish mode of the task port.
  • __meta_dockerswarm_service_id: the ID of the service.
  • __meta_dockerswarm_service_name: the name of the service.
  • __meta_dockerswarm_service_mode: the mode of the service.
  • __meta_dockerswarm_service_label_<labelname>: each label of the service.
  • __meta_dockerswarm_network_id: the ID of the network.
  • __meta_dockerswarm_network_name: the name of the network.
  • __meta_dockerswarm_network_ingress: whether the network is ingress.
  • __meta_dockerswarm_network_internal: whether the network is internal.
  • __meta_dockerswarm_network_label_<labelname>: each label of the network.
  • __meta_dockerswarm_network_label: each label of the network.
  • __meta_dockerswarm_network_scope: the scope of the network.
  • __meta_dockerswarm_node_id: the ID of the node.
  • __meta_dockerswarm_node_hostname: the hostname of the node.
  • __meta_dockerswarm_node_address: the address of the node.
  • __meta_dockerswarm_node_availability: the availability of the node.
  • __meta_dockerswarm_node_label_<labelname>: each label of the node.
  • __meta_dockerswarm_node_platform_architecture: the architecture of the node.
  • __meta_dockerswarm_node_platform_os: the operating system of the node.
  • __meta_dockerswarm_node_role: the role of the node.
  • __meta_dockerswarm_node_status: the status of the node.

The __meta_dockerswarm_network_* meta labels are not populated for ports which are published with mode=host.

nodes

The nodes role is used to discover Swarm nodes.

Available meta labels:

  • __meta_dockerswarm_node_address: the address of the node.
  • __meta_dockerswarm_node_availability: the availability of the node.
  • __meta_dockerswarm_node_engine_version: the version of the node engine.
  • __meta_dockerswarm_node_hostname: the hostname of the node.
  • __meta_dockerswarm_node_id: the ID of the node.
  • __meta_dockerswarm_node_label_<labelname>: each label of the node.
  • __meta_dockerswarm_node_manager_address: the address of the manager component of the node.
  • __meta_dockerswarm_node_manager_leader: the leadership status of the manager component of the node (true or false).
  • __meta_dockerswarm_node_manager_reachability: the reachability of the manager component of the node.
  • __meta_dockerswarm_node_platform_architecture: the architecture of the node.
  • __meta_dockerswarm_node_platform_os: the operating system of the node.
  • __meta_dockerswarm_node_role: the role of the node.
  • __meta_dockerswarm_node_status: the status of the node.

Component health

discovery.dockerswarm is only reported as unhealthy when given an invalid configuration. In those cases, exported fields retain their last healthy values.

Debug information

discovery.dockerswarm does not expose any component-specific debug information.

Debug metrics

discovery.dockerswarm does not expose any component-specific debug metrics.

Example

This example discovers targets from Docker Swarm tasks:

Alloy 
discovery.dockerswarm "example" {
  host = "unix:///var/run/docker.sock"
  role = "tasks"

  filter {
    name = "id"
    values = ["0kzzo1i0y4jz6027t0k7aezc7"]
  }

  filter {
    name = "desired-state"
    values = ["running", "accepted"]
  }
}

prometheus.scrape "demo" {
  targets    = discovery.dockerswarm.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.

Compatible components

discovery.dockerswarm 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.