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prometheus.exporter.postgres

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

Multiple prometheus.exporter.postgres components can be specified by giving them different labels.

Usage

alloy
prometheus.exporter.postgres "LABEL" {
    data_source_names = DATA_SOURCE_NAMES_LIST
}

Arguments

The following arguments are supported:

NameTypeDescriptionDefaultRequired
data_source_nameslist(secret)Specifies the PostgreSQL servers to connect to.yes
disable_settings_metricsboolDisables collection of metrics from pg_settings.falseno
disable_default_metricsboolWhen true, only exposes metrics supplied from custom_queries_config_path.falseno
custom_queries_config_pathstringPath to YAML file containing custom queries to expose as metrics.""no
enabled_collectorslist(string)List of collectors to enable. Refer to the information below for more detail.[]no

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.

Note

There are a number of environment variables that aren’t recommended for use, as they will affect all prometheus.exporter.postgres components. Refer to the postgres_exporter repository for a full list of environment variables.

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:

  • database
  • database_wraparound
  • locks
  • long_running_transactions
  • postmaster
  • process_idle
  • replication
  • replication_slot
  • stat_activity_autovacuum
  • stat_bgwriter
  • stat_database
  • stat_statements
  • stat_user_tables
  • stat_wal_receiver
  • statio_user_indexes
  • statio_user_tables
  • wal
  • xlog_location

By default, the following collectors are enabled:

  • database
  • locks
  • replication
  • replication_slot
  • stat_bgwriter
  • stat_database
  • stat_user_tables
  • statio_user_tables
  • wal

Note

Due to a limitation of the upstream exporter, when multiple data_source_names are used, the collectors that are controlled via the enabled_collectors argument will only be applied to the first data source in the list.

Blocks

The following blocks are supported:

HierarchyBlockDescriptionRequired
autodiscoveryautodiscoveryDatabase discovery settings.no

autodiscovery block

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

The following arguments are supported:

NameTypeDescriptionDefaultRequired
enabledboolWhether to automatically discover other databases.falseno
database_allowlistlist(string)List of databases to filter for, meaning only these databases will be scraped.no
database_denylistlist(string)List of databases to filter out, meaning all other databases will be scraped.no

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

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

Exported fields

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

NameTypeDescription
targetslist(map(string))The targets that can be used to collect exporter metrics.

For example, the targets can either be passed to a discovery.relabel component to rewrite the targets’ label sets or to a prometheus.scrape component that collects the exposed metrics.

The exported targets use the configured in-memory traffic address specified by the run command.

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

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

alloy
// 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

This 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:

alloy
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
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
    }
  }
}

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:

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.