Documentation Grafana Cloud Instrument and send data Grafana Alloy Reference Components local local.file_match

local.file_match

local.file_match discovers files on the local filesystem using glob patterns and the doublestar library.

Usage

alloy Copy

local.file_match "LABEL" {
  path_targets = [{"__path__" = DOUBLESTAR_PATH}]
}

Arguments

The following arguments are supported:

path_targets uses doublestar style paths.

• /tmp/**/*.log will match all subfolders of tmp and include any files that end in *.log.
• /tmp/apache/*.log will match only files in /tmp/apache/ that end in *.log.
• /tmp/** will match all subfolders of tmp, tmp itself, and all files.

Exported fields

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

Each target includes the following labels:

• __path__: Absolute path to the file.

Component health

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

Debug information

local.file_match does not expose any component-specific debug information.

Debug metrics

local.file_match does not expose any component-specific debug metrics.

Examples

Send /tmp/logs/*.log files to Loki

This example discovers all files and folders under /tmp/logs. The absolute paths are used by loki.source.file.files targets.

alloy Copy

local.file_match "tmp" {
  path_targets = [{"__path__" = "/tmp/logs/**/*.log"}]
}

loki.source.file "files" {
  targets    = local.file_match.tmp.targets
  forward_to = [loki.write.endpoint.receiver]
}

loki.write "endpoint" {
  endpoint {
      url = LOKI_URL
      basic_auth {
          username = USERNAME
          password = PASSWORD
      }
  }
}

Replace the following:

• LOKI_URL: The URL of the Loki server to send logs to.
• USERNAME: The username to use for authentication to the Loki API.
• PASSWORD: The password to use for authentication to the Loki API.

Send Kubernetes pod logs to Loki

This example finds all the logs on pods and monitors them.

alloy Copy

discovery.kubernetes "k8s" {
  role = "pod"
}

discovery.relabel "k8s" {
  targets = discovery.kubernetes.k8s.targets

  rule {
    source_labels = ["__meta_kubernetes_namespace", "__meta_kubernetes_pod_label_name"]
    target_label  = "job"
    separator     = "/"
  }

  rule {
    source_labels = ["__meta_kubernetes_pod_uid", "__meta_kubernetes_pod_container_name"]
    target_label  = "__path__"
    separator     = "/"
    replacement   = "/var/log/pods/*$1/*.log"
  }
}

local.file_match "pods" {
  path_targets = discovery.relabel.k8s.output
}

loki.source.file "pods" {
  targets = local.file_match.pods.targets
  forward_to = [loki.write.endpoint.receiver]
}

loki.write "endpoint" {
  endpoint {
      url = LOKI_URL
      basic_auth {
          username = USERNAME
          password = PASSWORD
      }
  }
}

Replace the following:

• LOKI_URL: The URL of the Loki server to send logs to.
• USERNAME: The username to use for authentication to the Loki API.
• PASSWORD: The password to use for authentication to the Loki API.

Compatible components

local.file_match can accept arguments from the following components:

• Components that export Targets

local.file_match has exports that can be consumed by the following components:

• Components that consume Targets