Documentation Grafana Alloy Reference Components discovery discovery.http

discovery.http

discovery.http provides a flexible way to define targets by querying an external http endpoint.

It fetches targets from an HTTP endpoint containing a list of zero or more target definitions. The target must reply with an HTTP 200 response. The HTTP header Content-Type must be application/json, and the body must be valid JSON.

Example response body:

json Copy

[
  {
    "targets": [ "<host>", ... ],
    "labels": {
      "<labelname>": "<labelvalue>", ...
    }
  },
  ...
]

It is possible to use additional fields in the JSON to pass parameters to prometheus.scrape such as the metricsPath and scrape_interval.

As an example, the following will provide a target with a custom metricsPath, scrape interval, and timeout value:

json Copy

[
   {
      "labels" : {
         "__metrics_path__" : "/api/prometheus",
         "__scheme__" : "https",
         "__scrape_interval__" : "60s",
         "__scrape_timeout__" : "10s",
         "service" : "custom-api-service"
      },
      "targets" : [
         "custom-api:443"
      ]
   },
]

It’s also possible to append query parameters to the metrics path with the __param_<name> syntax.

For example, the following will call a metrics path of /health?target_data=prometheus:

json Copy

[
   {
      "labels" : {
         "__metrics_path__" : "/health",
         "__scheme__" : "https",
         "__scrape_interval__" : "60s",
         "__scrape_timeout__" : "10s",
         "__param_target_data": "prometheus",
         "service" : "custom-api-service"
      },
      "targets" : [
         "custom-api:443"
      ]
   },
]

For more information on the potential labels you can use, see the prometheus.scrape technical details section, or the Prometheus Configuration documentation.

Usage

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discovery.http "LABEL" {
  url = URL
}

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.http:

The > symbol indicates deeper levels of nesting. For example, oauth2 > tls_config refers to a tls_config block defined inside an oauth2 block.

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_url: URL the target was obtained from.

Component health

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

Debug information

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

Debug metrics

• prometheus_sd_http_failures_total (counter): Total number of refresh failures.

Examples

This example will query a URL every 15 seconds and expose targets that it finds:

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discovery.http "dynamic_targets" {
  url = "https://example.com/scrape_targets"
  refresh_interval = "15s"
}

Compatible components

discovery.http has exports that can be consumed by the following components:

• Components that consume Targets