PgBouncer Docker image

This is a minimal PgBouncer image, based on Alpine Linux.

Features:

Very small, quick to pull (just 15MB)
Using LibreSSL
Configurable using environment variables
Uses standard Postgres port 5432, to work transparently for applications.
Includes PostgreSQL client tools such as psql, pg_isready
MD5 authentication by default.
/etc/pgbouncer/pgbouncer.ini and /etc/pbbouncer/userlist.txt are auto-created if they don't exist.

Why using PgBouncer

PostgreSQL connections take up a lot of memory (about 10MB per connection). There is also a significant startup cost to establish a connection with TLS, hence web applications gain performance by using persistent connections.

By placing PgBouncer in between the web application and the actual PostgreSQL database, the memory and start-up costs are reduced. The web application can keep persistent connections to PgBouncer, while PgBouncer only keeps a few connections to the actual PostgreSQL server. It can reuse the same connection for multiple clients.

Available tags

Base images:

latest (Dockerfile) - Default and latest version.
1.9.0 (Dockerfile) - Latest version.
1.8.1 (Dockerfile) - Previous version.

Images are automatically rebuild on Alpine Linux updates.

Usage

docker run --rm \
    -e DATABASE_URL="postgres://user:pass@postgres-host/database" \
    -p 5432:5432 \
    edoburu/pgbouncer

Or using separate variables:

docker run --rm \
    -e DB_USER=user \
    -e DB_PASSWORD=pass \
    -e DB_HOST=postgres-host \
    -e DB_NAME=database \
    -p 5432:5432 \
    edoburu/pgbouncer

Connecting should work as expected:

psql 'postgresql://user:pass@localhost/dbname'

Configuration

Almost all settings found in the pgbouncer.ini can be defined as environment variables, except a few that make little sense in a Docker environment (like port numbers, syslog and pid settings). See the entrypoint script for details. For example:

docker run --rm \
    -e DATABASE_URL="postgres://user:pass@postgres-host/database" \
    -e POOL_MODE=session \
    -e SERVER_RESET_QUERY="DISCARD ALL" \
    -e MAX_CLIENT_CONN=100 \
    -p 5432:5432
    edoburu/pgbouncer

Kubernetes integration

For example in Kubernetes, see the examples/kubernetes folder.

PostgreSQL configuration

Make sure PostgreSQL at least accepts connections from the machine where PgBouncer runs! Update listen_addresses in postgresql.conf and accept incoming connections from your IP range (e.g. 10.0.0.0/8) in pg_hba.conf:

# TYPE  DATABASE        USER            ADDRESS                 METHOD
host    all             all             10.0.0.0/8              md5

Using a custom configuration

When the default pgbouncer.ini is not sufficient, or you'd like to let multiple users connect through a single PgBouncer instance, mount an updated configuration:

docker run --rm \
    -e DB_USER=user \
    -e DB_PASSWORD=pass \
    -e DB_HOST=postgres-host \
    -e DB_NAME=database \
    -v pgbouncer.ini:/etc/pgbouncer/pgbouncer.ini:ro
    -p 5432:5432
    edoburu/pgbouncer

Or extend the Dockerfile:

FROM edoburu/pgbouncer:1.9.0
COPY pgbouncer.ini userlist.txt /etc/pgbouncer/

When the pgbouncer.ini file exists, the startup script will not override it. An extra entry will be written to userlist.txt when DATABASE_URL contains credentials, or DB_USER and DB_PASSWORD are defined.

The userlist.txt file uses the following format:

"username" "plaintext-password"

or:

"username" "md5<md5 of password + username>"

Use examples/generate-userlist to generate this file:

examples/generate-userlist >> userlist.txt

Connecting to the admin console

When an admin user is defined, and it has a password in the userlist.txt, it can connect to the special pgbouncer database:

psql postgres://postgres@hostname-of-container/pgbouncer  # outside container
psql postgres://127.0.0.1/pgbouncer                       # inside container

Hence this requires a custom configuration, or a mount of a custom userlist.txt in the docker file. Various admin console commands can be executed, for example:

SHOW STATS;
SHOW SERVERS;
SHOW CLIENTS;
SHOW POOLS;

And it allows temporary disconnecting the backend database (e.g. for restarts) while the web applications keep a connection to PgBouncer:

PAUSE;
RESUME;

ealogar/docker-pgbouncer