Documentation Grafana Alloy Reference Components prometheus prometheus.exporter.postgres

prometheus.exporter.postgres

The prometheus.exporter.postgres component embeds the postgres_exporter for collecting metrics from a PostgreSQL database.

You can specify multiple prometheus.exporter.postgres components by giving them different labels.

Usage

alloy Copy

prometheus.exporter.postgres "<LABEL>" {
    data_source_names = "<DATA_SOURCE_NAMES_LIST>"
}

Arguments

You can use the following arguments with prometheus.exporter.postgres:

Refer to the PostgreSQL documentation for more information about the format of the connection strings in data_source_names.

Refer to the examples for the custom_queries_config_path file in the postgres_exporter repository.

By default, the same set of metrics is enabled as in the upstream postgres_exporter. If custom_queries_config_path is set, additional metrics defined in the given configuration file will be exposed. If disable_default_metrics is set to true, only the metrics defined in the custom_queries_config_path file will be exposed.

A subset of metrics collectors can be controlled by setting the enabled_collectors argument. The following collectors are available for selection:

By default, the following collectors are enabled:

Blocks

You can use the following block with prometheus.exporter.postgres:

autodiscovery

The autodiscovery block configures discovery of databases, outside of any specified in data_source_names.

The following arguments are supported:

If enabled is set to true and no allowlist or denylist is specified, the exporter scrapes from all databases.

If autodiscovery is disabled, neither database_allowlist nor database_denylist has any effect.

Exported fields

Component health

prometheus.exporter.postgres is only reported as unhealthy if given an invalid configuration.

Debug information

prometheus.exporter.postgres doesn’t expose any component-specific debug information.

Debug metrics

prometheus.exporter.postgres doesn’t expose any component-specific debug metrics.

Examples

Collect metrics from a PostgreSQL server

The following example uses a prometheus.exporter.postgres component to collect metrics from a PostgreSQL server running locally with all default settings:

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// Because no autodiscovery is defined, this will only scrape the 'database_name' database, as defined
// in the DSN below.
prometheus.exporter.postgres "example" {
  data_source_names = ["postgresql://username:password@localhost:5432/database_name?sslmode=disable"]
}

prometheus.scrape "default" {
  targets    = prometheus.exporter.postgres.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.

Collect custom metrics from an allowlisted set of databases

The following example uses a prometheus.exporter.postgres component to collect custom metrics from a set of specific databases, replacing default metrics with custom metrics derived from queries in /etc/alloy/custom-postgres-metrics.yaml:

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prometheus.exporter.postgres "example" {
  data_source_names = ["postgresql://username:password@localhost:5432/database_name?sslmode=disable"]

  // This block configures autodiscovery to check for databases outside of the 'database_name' db
  // specified in the DSN above. The database_allowlist field means that only the 'frontend_app' and 'backend_app'
  // databases will be scraped.
  autodiscovery {
    enabled            = true
    database_allowlist = ["frontend_app", "backend_app"]
  }

  disable_default_metrics    = true
  custom_queries_config_path = "/etc/alloy/custom-postgres-metrics.yaml"
}

prometheus.scrape "default" {
  targets    = prometheus.exporter.postgres.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.

Collect metrics from all databases except for a denylisted database

This example uses a prometheus.exporter.postgres component to collect custom metrics from all databases except for the secrets database.

alloy Copy

prometheus.exporter.postgres "example" {
  data_source_names = ["postgresql://username:password@localhost:5432/database_name?sslmode=disable"]

  // The database_denylist field will filter out those databases from the list of databases to scrape,
  // meaning that all databases *except* these will be scraped.
  //
  // In this example it will scrape all databases except for the one named 'secrets'.
  autodiscovery {
    enabled           = true
    database_denylist = ["secrets"]
  }
}

prometheus.scrape "default" {
  targets    = prometheus.exporter.postgres.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>"
    }
  }
}

Escape special characters in postgres url

If your PostgreSQL connection string includes special characters for e.g. password (@, :, /, etc.), you should wrap the password using encoding.url_encode.

alloy Copy

prometheus.exporter.postgres "example" {
  data_source_names = [
    "postgresql://username:" + encoding.url_encode("p@ss/w:ord!") + "@localhost:5432/dbname?sslmode=disable"
  ]
}

This ensures the DSN remains valid and correctly parsed.

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

prometheus.exporter.postgres has exports that can be consumed by the following components:

• Components that consume Targets