config.yaml

# Copyright 2023 Canonical Ltd.
# See LICENSE file for licensing details.

options:
  listen_port:
    default: 6432
    description: |
      The port on which pgbouncer listens for traffic. Corresponds to
      listen_port in pgbouncer config.
    type: int

  pool_mode:
    default: session
    description: |
      Specifies when a server connection can be reused by other clients. Can
      be one of the following values:

      session
      Server is released back to pool after client disconnects. Default.

      transaction
      Server is released back to pool after transaction finishes.

      statement
      Server is released back to pool after query finishes. Transactions
      spanning multiple statements are disallowed in this mode.
    type: string

  max_db_connections:
    default: 100
    description: |
      Do not allow more than this many server connections per database
      (regardless of user). This considers the PgBouncer database that the
      client has connected to, not the PostgreSQL database of the outgoing
      connection.

      Note that when you hit the limit, closing a client connection to one pool
      will not immediately allow a server connection to be established for
      another pool, because the server connection for the first pool is still
      open. Once the server connection closes (due to idle timeout), a new
      server connection will immediately be opened for the waiting pool.

      This is used to calculate the following pgbouncer.ini config options,
      which are documented in the pgbouncer config docs here:
      https://www.pgbouncer.org/config.html.

      - Firstly, the number of pgbouncer instances is calculated based on the
        number of CPU cores in the current deployment.
      - effective DB connections = max_db_connections / pgbouncer instances
      - default_pool_size = effective connections / 2
      - min_pool_size = effective connections / 4
      - reserve_pool_size = effective connections / 4

      If max_db_connections is set to 0, the derivatives are set thusly, based
      on pgbouncer defaults:
      - default_pool_size = 20
      - min_pool_size = 10
      - reserve_pool_size = 10

      0 = unlimited.
    type: int