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Prometheus exporter for PgBouncer
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README.md

Prometheus exporter for PgBouncer

How to use it

You have two options to use it:

  1. Manually install and run the prometheus-pgbouncer-exporter Python package
  2. Use the Docker image available on Docker hub (see instructions on Docker hub)

How to manually install and run it

The following will install the exporter whose entrypoint binary is called pgbouncer-exporter:

pip3 install prometheus-pgbouncer-exporter

The exporter accepts configuration via config file, you can specify with --config argument:

pgbouncer-exporter --config ./config.yml

Available arguments:

--config CONFIG         Path to config file
--log-level LOG_LEVEL   Minimum log level. Accepted values are: DEBUG, INFO,
                        WARNING, ERROR, CRITICAL
--log-file LOG_FILE     Path to log file or 'stdout' to log on console. Signal
                        with -HUP to re-open log file descriptor

Features

  • Supports multiple pgbouncer instances
  • Allow to configure extra labels for each pgbouncer instance
  • Allow to configure timeouts on pgbouncer connections
  • Allow to filter databases for which metrics are exported with include_databases and exclude_databases

Why supporting multiple pgbouncer instances?

PgBouncer is a single thread application and so can only saturate a single CPU core on high load. In high load environments, it's common practice to run multiple pgbouncer processes per machine (one for each CPU core) and load balance traffic among them. Ideally we want to run a single exporter instance per machine, capable to monitor 1+ pgbouncer(s) running on the machine itself.

Exported metrics

The exporter exports the following metrics for each monitored pgbouncer instance:

Metric name Type PgBouncer Description
pgbouncer_stats_requests_total counter <= 1.7 Total number of requests pooled. Could be transactions or queries, depending on pool mode. (labels: database)
pgbouncer_stats_queries_total counter >= 1.8 Total number of SQL queries pooled by pgbouncer (labels: database)
pgbouncer_stats_queries_duration_microseconds counter all Total number of microseconds spent waiting for a server to return a query response. Includes time spent waiting for an available connection. (labels: database)
pgbouncer_stats_waiting_duration_microseconds counter >= 1.8 Total number of microseconds spent waiting for an available connection. (labels: database)
pgbouncer_stats_received_bytes_total counter all Total volume in bytes of network traffic received by pgbouncer (labels: database)
pgbouncer_stats_sent_bytes_total counter all Total volume in bytes of network traffic sent by pgbouncer (labels: database)
pgbouncer_stats_transactions_total counter >= 1.8 Total number of SQL transactions pooled by pgbouncer (labels: database)
pgbouncer_stats_transactions_duration_microseconds counter >= 1.8 Total number of microseconds spent in a transaction. Includes time spent waiting for an available connection. (labels: database)
pgbouncer_pools_client_active_connections gauge all Client connections that are linked to server connection and can process queries (labels: database, user)
pgbouncer_pools_client_waiting_connections gauge all Client connections have sent queries but have not yet got a server connection (labels: database, user)
pgbouncer_pools_server_active_connections gauge all Server connections that linked to client (labels: database, user)
pgbouncer_pools_server_idle_connections gauge all Server connections that unused and immediately usable for client queries (labels: database, user)
pgbouncer_pools_server_used_connections gauge all Server connections that have been idle more than server_check_delay, so they needs server_check_query to run on it before it can be used (labels: database, user)
pgbouncer_pools_server_testing_connections gauge all Server connections that are currently running either server_reset_query or server_check_query (labels: database, user)
pgbouncer_pools_server_login_connections gauge all Server connections currently in logging in process (labels: database, user)
pgbouncer_pools_client_maxwait_seconds gauge all How long the first (oldest) client in queue has waited, in seconds (labels: database, user)
pgbouncer_databases_database_pool_size gauge all Configured pool size limit (labels: database, backend_database)
pgbouncer_databases_database_reserve_pool_size gauge all Configured reserve limit (labels: database, backend_database)
pgbouncer_databases_database_current_connections gauge all Total number of per-database Database connections count (labels: database, backend_database)

Configuration file

The exporter read the configuration from a yaml config file with the following syntax:

# The host on which the exporter should listen to (defaults to 127.0.0.1)
exporter_host: 0.0.0.0

# The port on which the exporter should listen to (defaults to 9100)
exporter_port: 9100

# The list of pgbouncer instances to monitor
pgbouncers:
  -
    # The pgbouncer connection string. Supports environment variables replacement
    # Ie. $(PGBOUNCER_PASS) is replaced with the content of "PGBOUNCER_PASS" environment
    #     variable if exist, or left untouched if doesn't exist
    dsn: postgresql://pgbouncer:$(PGBOUNCER_PASS)@localhost:6431/pgbouncer

    # The pgbouncer connection timeout in seconds (defaults to 5 seconds)
    connect_timeout: 5

    # Databases to report metrics for. If omitted or empty, all databases
    # will be reported.
    include_databases:

    # Databases to exclude from metrics reporting. If omitted or empty, all
    # databases matching "include_databases" will be reported.
    exclude_databases:
      - pgbouncer

    # Extra labels to add to all metrics exported for this pgbouncer
    # instance. Required if you have configured multiple pgbouncers,
    # in order to export an unique set of metrics.
    extra_labels:
      pool_id: 1

  - dsn: postgresql://pgbouncer:$(PGBOUNCER_PASS)@localhost:6432/pgbouncer
    exclude_databases:
      - pgbouncer
    extra_labels:
      pool_id: 2

Environment variables replacement

The configuration file supports environment variables replacement. If you use the syntax $(NAME) in any setting value, it gets replaced by the content of NAME environment variable or left untouched if the NAME environment variable does not exist.

How to contribute

Run the development environment:

docker-compose build && docker-compose run dev

Then inside the container:

# Run tests
python -m unittest

# Run exporter
python -m prometheus_pgbouncer_exporter.cli --config ./config.yml

# Run linter
pycodestyle --max-line-length=300 prometheus_pgbouncer_exporter/*.py

How to publish a new version

Release python package:

  1. Update version in setup.py
  2. Update CHANGELOG.md
  3. Release new version on GitHub
  4. Run python3 setup.py sdist
  5. Upload it with twine upload dist/*
  6. Upload the files to the Github release

Release Docker image:

  1. Update package version in Dockerfile
  2. Build image
    docker rmi -f prometheus-pgbouncer-exporter && \
    docker build -t prometheus-pgbouncer-exporter .
    
  3. Tag the image and push it to Docker Hub
    docker tag prometheus-pgbouncer-exporter spreaker/prometheus-pgbouncer-exporter:latest && \
    docker push spreaker/prometheus-pgbouncer-exporter:latest
    
    docker tag prometheus-pgbouncer-exporter spreaker/prometheus-pgbouncer-exporter:2.0.3 && \
    docker push spreaker/prometheus-pgbouncer-exporter:2.0.3
    

License

This software is released under the MIT license.

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