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PostgreSQL Server Exporter

Prometheus exporter for PostgreSQL server metrics.

CI Tested PostgreSQL versions: 9.4, 9.5, 9.6, 10, 11, 12, 13, 14, 15

Quick Start

This package is available for Docker:

# Start an example database
docker run --net=host -it --rm -e POSTGRES_PASSWORD=password postgres
# Connect to it
docker run \
  --net=host \
  -e DATA_SOURCE_NAME="postgresql://postgres:password@localhost:5432/postgres?sslmode=disable" \
  quay.io/prometheuscommunity/postgres-exporter

Multi-Target Support (BETA)

This Feature is in beta and may require changes in future releases. Feedback is welcome.

This exporter supports the multi-target pattern. This allows running a single instance of this exporter for multiple postgres targets. Using the multi-target functionality of this exporter is optional and meant for cases where it is impossible to install the exporter as a sidecar, for example SaaS-managed services.

To use the multi-target functionality, send an http request to the endpoint /probe?target=foo:5432 where target is set to the DSN of the postgres instance to scrape metrics from.

To avoid putting sensitive information like username and password in the URL, preconfigured auth modules are supported via the auth_modules section of the config file. auth_modules for DSNs can be used with the /probe endpoint by specifying the ?auth_module=foo http parameter.

Configuration File

The configuration file controls the behavior of the exporter. It can be set using the --config.file command line flag and defaults to postgres_exporter.yml.

auth_modules

This section defines preset authentication and connection parameters for use in the multi-target endpoint. auth_modules is a map of modules with the key being the identifier which can be used in the /probe endpoint. Currently only the userpass type is supported.

Example:

auth_modules:
  foo1: # Set this to any name you want
    type: userpass
    userpass:
      username: first
      password: firstpass
    options:
      # options become key=value parameters of the DSN
      sslmode: disable

Building and running

git clone https://github.com/prometheus-community/postgres_exporter.git
cd postgres_exporter
make build
./postgres_exporter <flags>

To build the Docker image:

make promu
promu crossbuild -p linux/amd64 -p linux/armv7 -p linux/amd64 -p linux/ppc64le
make docker

This will build the docker image as prometheuscommunity/postgres_exporter:${branch}.

Flags

  • help Show context-sensitive help (also try --help-long and --help-man).

  • collector.database Enable the pg_database collector. Default is enabled

  • collector.bgwriter Enable the pg_stat_bgwriter collector. Default is enabled

  • web.listen-address Address to listen on for web interface and telemetry. Default is :9187.

  • web.telemetry-path Path under which to expose metrics. Default is /metrics.

  • disable-default-metrics Use only metrics supplied from queries.yaml via --extend.query-path. Default is false.

  • disable-settings-metrics Use the flag if you don't want to scrape pg_settings. Default is false.

  • auto-discover-databases Whether to discover the databases on a server dynamically. Default is false.

  • extend.query-path Path to a YAML file containing custom queries to run. Check out queries.yaml for examples of the format.

  • dumpmaps Do not run - print the internal representation of the metric maps. Useful when debugging a custom queries file.

  • constantLabels Labels to set in all metrics. A list of label=value pairs, separated by commas.

  • version Show application version.

  • exclude-databases A list of databases to remove when autoDiscoverDatabases is enabled.

  • include-databases A list of databases to only include when autoDiscoverDatabases is enabled.

  • log.level Set logging level: one of debug, info, warn, error.

  • log.format Set the log format: one of logfmt, json.

  • web.config.file Configuration file to use TLS and/or basic authentication. The format of the file is described in the exporter-toolkit repository.

Environment Variables

The following environment variables configure the exporter:

  • DATA_SOURCE_NAME the default legacy format. Accepts URI form and key=value form arguments. The URI may contain the username and password to connect with.

  • DATA_SOURCE_URI an alternative to DATA_SOURCE_NAME which exclusively accepts the hostname without a username and password component. For example, my_pg_hostname or my_pg_hostname?sslmode=disable.

  • DATA_SOURCE_URI_FILE The same as above but reads the URI from a file.

  • DATA_SOURCE_USER When using DATA_SOURCE_URI, this environment variable is used to specify the username.

  • DATA_SOURCE_USER_FILE The same, but reads the username from a file.

  • DATA_SOURCE_PASS When using DATA_SOURCE_URI, this environment variable is used to specify the password to connect with.

  • DATA_SOURCE_PASS_FILE The same as above but reads the password from a file.

  • PG_EXPORTER_WEB_TELEMETRY_PATH Path under which to expose metrics. Default is /metrics.

  • PG_EXPORTER_DISABLE_DEFAULT_METRICS Use only metrics supplied from queries.yaml. Value can be true or false. Default is false.

  • PG_EXPORTER_DISABLE_SETTINGS_METRICS Use the flag if you don't want to scrape pg_settings. Value can be true or false. Default is false.

  • PG_EXPORTER_AUTO_DISCOVER_DATABASES Whether to discover the databases on a server dynamically. Value can be true or false. Default is false.

  • PG_EXPORTER_EXTEND_QUERY_PATH Path to a YAML file containing custom queries to run. Check out queries.yaml for examples of the format.

  • PG_EXPORTER_CONSTANT_LABELS Labels to set in all metrics. A list of label=value pairs, separated by commas.

  • PG_EXPORTER_EXCLUDE_DATABASES A comma-separated list of databases to remove when autoDiscoverDatabases is enabled. Default is empty string.

  • PG_EXPORTER_INCLUDE_DATABASES A comma-separated list of databases to only include when autoDiscoverDatabases is enabled. Default is empty string, means allow all.

  • PG_EXPORTER_METRIC_PREFIX A prefix to use for each of the default metrics exported by postgres-exporter. Default is pg

Settings set by environment variables starting with PG_ will be overwritten by the corresponding CLI flag if given.

Setting the Postgres server's data source name

The PostgreSQL server's data source name must be set via the DATA_SOURCE_NAME environment variable.

For running it locally on a default Debian/Ubuntu install, this will work (transpose to init script as appropriate):

sudo -u postgres DATA_SOURCE_NAME="user=postgres host=/var/run/postgresql/ sslmode=disable" postgres_exporter

Also, you can set a list of sources to scrape different instances from the one exporter setup. Just define a comma separated string.

sudo -u postgres DATA_SOURCE_NAME="port=5432,port=6432" postgres_exporter

See the github.com/lib/pq module for other ways to format the connection string.

Adding new metrics

The exporter will attempt to dynamically export additional metrics if they are added in the future, but they will be marked as "untyped". Additional metric maps can be easily created from Postgres documentation by copying the tables and using the following Python snippet:

x = """tab separated raw text of a documentation table"""
for l in StringIO(x):
    column, ctype, description = l.split('\t')
    print """"{0}" : {{ prometheus.CounterValue, prometheus.NewDesc("pg_stat_database_{0}", "{2}", nil, nil) }}, """.format(column.strip(), ctype, description.strip())

Adjust the value of the resultant prometheus value type appropriately. This helps build rich self-documenting metrics for the exporter.

Adding new metrics via a config file

The -extend.query-path command-line argument specifies a YAML file containing additional queries to run. Some examples are provided in queries.yaml.

Disabling default metrics

To work with non-officially-supported postgres versions (e.g. 8.2.15), or variants of postgres (e.g. Greenplum), you can disable the default metrics with the --disable-default-metrics flag. This removes all built-in metrics, and uses only metrics defined by queries in the queries.yaml file you supply (so you must supply one, otherwise the exporter will return nothing but internal statuses and not your database).

Automatically discover databases

To scrape metrics from all databases on a database server, the database DSN's can be dynamically discovered via the --auto-discover-databases flag. When true, SELECT datname FROM pg_database WHERE datallowconn = true AND datistemplate = false and datname != current_database() is run for all configured DSN's. From the result a new set of DSN's is created for which the metrics are scraped.

In addition, the option --exclude-databases adds the possibily to filter the result from the auto discovery to discard databases you do not need.

If you want to include only subset of databases, you can use option --include-databases. Exporter still makes request to pg_database table, but do scrape from only if database is in include list.

Running as non-superuser

To be able to collect metrics from pg_stat* views as non-superuser in PostgreSQL server versions >= 10 you can grant the pg_monitor or pg_read_all_stats built-in roles to the user. If you need to monitor older PostgreSQL servers, you will have to create functions and views as a superuser, and assign permissions separately to those.

-- To use IF statements, hence to be able to check if the user exists before
-- attempting creation, we need to switch to procedural SQL (PL/pgSQL)
-- instead of standard SQL.
-- More: https://www.postgresql.org/docs/9.3/plpgsql-overview.html
-- To preserve compatibility with <9.0, DO blocks are not used; instead,
-- a function is created and dropped.
CREATE OR REPLACE FUNCTION __tmp_create_user() returns void as $$
BEGIN
  IF NOT EXISTS (
          SELECT                       -- SELECT list can stay empty for this
          FROM   pg_catalog.pg_user
          WHERE  usename = 'postgres_exporter') THEN
    CREATE USER postgres_exporter;
  END IF;
END;
$$ language plpgsql;

SELECT __tmp_create_user();
DROP FUNCTION __tmp_create_user();

ALTER USER postgres_exporter WITH PASSWORD 'password';
ALTER USER postgres_exporter SET SEARCH_PATH TO postgres_exporter,pg_catalog;

-- If deploying as non-superuser (for example in AWS RDS), uncomment the GRANT
-- line below and replace <MASTER_USER> with your root user.
-- GRANT postgres_exporter TO <MASTER_USER>;

GRANT CONNECT ON DATABASE postgres TO postgres_exporter;

Run following command if you use PostgreSQL versions >= 10

GRANT pg_monitor to postgres_exporter;

Run following SQL commands only if you use PostgreSQL versions older than 10. In PostgreSQL, views run with the permissions of the user that created them so they can act as security barriers. Functions need to be created to share this data with the non-superuser. Only creating the views will leave out the most important bits of data.

CREATE SCHEMA IF NOT EXISTS postgres_exporter;
GRANT USAGE ON SCHEMA postgres_exporter TO postgres_exporter;

CREATE OR REPLACE FUNCTION get_pg_stat_activity() RETURNS SETOF pg_stat_activity AS
$$ SELECT * FROM pg_catalog.pg_stat_activity; $$
LANGUAGE sql
VOLATILE
SECURITY DEFINER;

CREATE OR REPLACE VIEW postgres_exporter.pg_stat_activity
AS
  SELECT * from get_pg_stat_activity();

GRANT SELECT ON postgres_exporter.pg_stat_activity TO postgres_exporter;

CREATE OR REPLACE FUNCTION get_pg_stat_replication() RETURNS SETOF pg_stat_replication AS
$$ SELECT * FROM pg_catalog.pg_stat_replication; $$
LANGUAGE sql
VOLATILE
SECURITY DEFINER;

CREATE OR REPLACE VIEW postgres_exporter.pg_stat_replication
AS
  SELECT * FROM get_pg_stat_replication();

GRANT SELECT ON postgres_exporter.pg_stat_replication TO postgres_exporter;

CREATE EXTENSION IF NOT EXISTS pg_stat_statements;
CREATE OR REPLACE FUNCTION get_pg_stat_statements() RETURNS SETOF pg_stat_statements AS
$$ SELECT * FROM public.pg_stat_statements; $$
LANGUAGE sql
VOLATILE
SECURITY DEFINER;

CREATE OR REPLACE VIEW postgres_exporter.pg_stat_statements
AS
  SELECT * FROM get_pg_stat_statements();

GRANT SELECT ON postgres_exporter.pg_stat_statements TO postgres_exporter;

NOTE
Remember to use postgres database name in the connection string:

DATA_SOURCE_NAME=postgresql://postgres_exporter:password@localhost:5432/postgres?sslmode=disable

Running the tests

# Run the unit tests
make test
# Start the test database with docker
docker run -p 5432:5432 -e POSTGRES_DB=circle_test -e POSTGRES_USER=postgres -e POSTGRES_PASSWORD=test -d postgres
# Run the integration tests
DATA_SOURCE_NAME='postgresql://postgres:test@localhost:5432/circle_test?sslmode=disable' GOOPTS='-v -tags integration' make test