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Documentation Grafana Alloy Reference Components discovery discovery.file

discovery.file

discovery.file discovers targets from a set of files, similar to the Prometheus file_sd_config.

Usage

alloy Copy

discovery.file "LABEL" {
  files = [FILE_PATH_1, FILE_PATH_2, ...]
}

Arguments

The following arguments are supported:

The last path segment of each element in files may contain a single * that matches any character sequence, e.g. my/path/tg_*.json.

Exported fields

The following fields are exported and can be referenced by other components:

Each target includes the following labels:

• __meta_filepath: The absolute path to the file the target was discovered from.

Component health

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

Debug information

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

Debug metrics

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

Examples

Example target files

json Copy

[
  {
    "targets": [ "127.0.0.1:9091", "127.0.0.1:9092" ],
    "labels": {
      "environment": "dev"
    }
  },
  {
    "targets": [ "127.0.0.1:9093" ],
    "labels": {
      "environment": "prod"
    }
  }
]

yaml Copy

- targets:
  - 127.0.0.1:9999
  - 127.0.0.1:10101
  labels:
    job: worker
- targets:
  - 127.0.0.1:9090
  labels:
    job: prometheus

Basic file discovery

This example discovers targets from a single file, scrapes them, and writes metrics to a Prometheus remote write endpoint.

alloy Copy

discovery.file "example" {
  files = ["/tmp/example.json"]
}

prometheus.scrape "default" {
  targets    = discovery.file.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.

File discovery with retained file path label

This example discovers targets from a wildcard file path, scrapes them, and writes metrics to a Prometheus remote write endpoint.

It also uses a relabeling rule to retain the file path as a label on each target.

alloy Copy

discovery.file "example" {
  files = ["/tmp/example_*.yaml"]
}

discovery.relabel "keep_filepath" {
  targets = discovery.file.example.targets
  rule {
    source_labels = ["__meta_filepath"]
    target_label = "filepath"
  }
}

prometheus.scrape "default" {
  targets    = discovery.relabel.keep_filepath.output
  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.file has exports that can be consumed by the following components:

• Components that consume Targets