debian-mirror-gitlab/doc/administration/high_availability/pgbouncer.md

---
type: reference
---

# Working with the bundle Pgbouncer service

As part of its High Availability stack, GitLab Premium includes a bundled version of [Pgbouncer](https://pgbouncer.github.io/) that can be managed through `/etc/gitlab/gitlab.rb`.

In a High Availability setup, Pgbouncer is used to seamlessly migrate database connections between servers in a failover scenario.

Additionally, it can be used in a non-HA setup to pool connections, speeding up response time while reducing resource usage.

It is recommended to run pgbouncer alongside the `gitlab-rails` service, or on its own dedicated node in a cluster.

## Operations

### Running Pgbouncer as part of an HA GitLab installation

1. Make sure you collect [`CONSUL_SERVER_NODES`](database.md#consul-information), [`CONSUL_PASSWORD_HASH`](database.md#consul-information), and [`PGBOUNCER_PASSWORD_HASH`](database.md#pgbouncer-information) before executing the next step.

1. Edit `/etc/gitlab/gitlab.rb` replacing values noted in the `# START user configuration` section:

    ```ruby
    # Disable all components except Pgbouncer and Consul agent
    roles ['pgbouncer_role']

    # Configure Pgbouncer
    pgbouncer['admin_users'] = %w(pgbouncer gitlab-consul)

    # Configure Consul agent
    consul['watchers'] = %w(postgresql)

    # START user configuration
    # Please set the real values as explained in Required Information section
    # Replace CONSUL_PASSWORD_HASH with with a generated md5 value
    # Replace PGBOUNCER_PASSWORD_HASH with with a generated md5 value
    pgbouncer['users'] = {
      'gitlab-consul': {
        password: 'CONSUL_PASSWORD_HASH'
      },
      'pgbouncer': {
        password: 'PGBOUNCER_PASSWORD_HASH'
      }
    }
    # Replace placeholders:
    #
    # Y.Y.Y.Y consul1.gitlab.example.com Z.Z.Z.Z
    # with the addresses gathered for CONSUL_SERVER_NODES
    consul['configuration'] = {
      retry_join: %w(Y.Y.Y.Y consul1.gitlab.example.com Z.Z.Z.Z)
    }
    #
    # END user configuration
    ```

    > `pgbouncer_role` was introduced with GitLab 10.3

1.  Run `gitlab-ctl reconfigure`

1. Create a `.pgpass` file so Consul is able to
   reload pgbouncer. Enter the `PGBOUNCER_PASSWORD` twice when asked:

    ```sh
    gitlab-ctl write-pgpass --host 127.0.0.1 --database pgbouncer --user pgbouncer --hostuser gitlab-consul
    ```

#### PGBouncer Checkpoint

1. Ensure the node is talking to the current master:

    ```sh
    gitlab-ctl pgb-console # You will be prompted for PGBOUNCER_PASSWORD
    ```

    If there is an error `psql: ERROR:  Auth failed` after typing in the
    password, ensure you previously generated the MD5 password hashes with the correct
    format. The correct format is to concatenate the password and the username:
    `PASSWORDUSERNAME`. For example, `Sup3rS3cr3tpgbouncer` would be the text
    needed to generate an MD5 password hash for the `pgbouncer` user.

1. Once the console prompt is available, run the following queries:

    ```sh
    show databases ; show clients ;
    ```

    The output should be similar to the following:

    ```
            name         |  host       | port |      database       | force_user | pool_size | reserve_pool | pool_mode | max_connections | current_connections
    ---------------------+-------------+------+---------------------+------------+-----------+--------------+-----------+-----------------+---------------------
     gitlabhq_production | MASTER_HOST | 5432 | gitlabhq_production |            |        20 |            0 |           |               0 |                   0
     pgbouncer           |             | 6432 | pgbouncer           | pgbouncer  |         2 |            0 | statement |               0 |                   0
    (2 rows)

     type |   user    |      database       |  state  |   addr         | port  | local_addr | local_port |    connect_time     |    request_time     |    ptr    | link | remote_pid | tls
    ------+-----------+---------------------+---------+----------------+-------+------------+------------+---------------------+---------------------+-----------+------+------------+-----
     C    | pgbouncer | pgbouncer           | active  | 127.0.0.1      | 56846 | 127.0.0.1  |       6432 | 2017-08-21 18:09:59 | 2017-08-21 18:10:48 | 0x22b3880 |      |          0 |
    (2 rows)
    ```

### Running Pgbouncer as part of a non-HA GitLab installation

1. Generate PGBOUNCER_USER_PASSWORD_HASH with the command `gitlab-ctl pg-password-md5 pgbouncer`

1. Generate SQL_USER_PASSWORD_HASH with the command `gitlab-ctl pg-password-md5 gitlab`. We'll also need to enter the plaintext SQL_USER_PASSWORD later

1. On your database node, ensure the following is set in your `/etc/gitlab/gitlab.rb`

   ```ruby
   postgresql['pgbouncer_user_password'] = 'PGBOUNCER_USER_PASSWORD_HASH'
   postgresql['sql_user_password'] = 'SQL_USER_PASSWORD_HASH'
   postgresql['listen_address'] = 'XX.XX.XX.Y' # Where XX.XX.XX.Y is the ip address on the node postgresql should listen on
   postgresql['md5_auth_cidr_addresses'] = %w(AA.AA.AA.B/32) # Where AA.AA.AA.B is the IP address of the pgbouncer node
   ```

1. Run `gitlab-ctl reconfigure`

   **Note:** If the database was already running, it will need to be restarted after reconfigure by running `gitlab-ctl restart postgresql`.

1. On the node you are running pgbouncer on, make sure the following is set in `/etc/gitlab/gitlab.rb`

   ```ruby
   pgbouncer['enable'] = true
   pgbouncer['databases'] = {
     gitlabhq_production: {
       host: 'DATABASE_HOST',
       user: 'pgbouncer',
       password: 'PGBOUNCER_USER_PASSWORD_HASH'
     }
   }
   ```

1. Run `gitlab-ctl reconfigure`

1. On the node running unicorn, make sure the following is set in `/etc/gitlab/gitlab.rb`

   ```ruby
   gitlab_rails['db_host'] = 'PGBOUNCER_HOST'
   gitlab_rails['db_port'] = '6432'
   gitlab_rails['db_password'] = 'SQL_USER_PASSWORD'
   ```

1. Run `gitlab-ctl reconfigure`

1. At this point, your instance should connect to the database through pgbouncer. If you are having issues, see the [Troubleshooting](#troubleshooting) section

## Enable Monitoring

> [Introduced](https://gitlab.com/gitlab-org/omnibus-gitlab/issues/3786) in GitLab 12.0.

If you enable Monitoring, it must be enabled on **all** pgbouncer servers.

1. Create/edit `/etc/gitlab/gitlab.rb` and add the following configuration:

   ```ruby
   # Enable service discovery for Prometheus
   consul['enable'] = true
   consul['monitoring_service_discovery'] =  true

   # Replace placeholders
   # Y.Y.Y.Y consul1.gitlab.example.com Z.Z.Z.Z
   # with the addresses of the Consul server nodes
   consul['configuration'] = {
      retry_join: %w(Y.Y.Y.Y consul1.gitlab.example.com Z.Z.Z.Z),
   }

   # Set the network addresses that the exporters will listen on
   node_exporter['listen_address'] = '0.0.0.0:9100'
   pgbouncer_exporter['listen_address'] = '0.0.0.0:9188'
   ```

1. Run `sudo gitlab-ctl reconfigure` to compile the configuration.

### Interacting with pgbouncer

#### Administrative console

As part of omnibus-gitlab, we provide a command `gitlab-ctl pgb-console` to automatically connect to the pgbouncer administrative console. Please see the [pgbouncer documentation](https://pgbouncer.github.io/usage.html#admin-console) for detailed instructions on how to interact with the console.

To start a session, run

```shell
# gitlab-ctl pgb-console
Password for user pgbouncer:
psql (9.6.8, server 1.7.2/bouncer)
Type "help" for help.

pgbouncer=#
```

The password you will be prompted for is the PGBOUNCER_USER_PASSWORD

To get some basic information about the instance, run

```shell
pgbouncer=# show databases; show clients; show servers;
        name         |   host    | port |      database       | force_user | pool_size | reserve_pool | pool_mode | max_connections | current_connections
---------------------+-----------+------+---------------------+------------+-----------+--------------+-----------+-----------------+---------------------
 gitlabhq_production | 127.0.0.1 | 5432 | gitlabhq_production |            |       100 |            5 |           |               0 |                   1
 pgbouncer           |           | 6432 | pgbouncer           | pgbouncer  |         2 |            0 | statement |               0 |                   0
(2 rows)

 type |   user    |      database       | state  |   addr    | port  | local_addr | local_port |    connect_time     |    request_time     |    ptr    | link
| remote_pid | tls
------+-----------+---------------------+--------+-----------+-------+------------+------------+---------------------+---------------------+-----------+------
+------------+-----
 C    | gitlab    | gitlabhq_production | active | 127.0.0.1 | 44590 | 127.0.0.1  |       6432 | 2018-04-24 22:13:10 | 2018-04-24 22:17:10 | 0x12444c0 |
|          0 |
 C    | gitlab    | gitlabhq_production | active | 127.0.0.1 | 44592 | 127.0.0.1  |       6432 | 2018-04-24 22:13:10 | 2018-04-24 22:17:10 | 0x12447c0 |
|          0 |
 C    | gitlab    | gitlabhq_production | active | 127.0.0.1 | 44594 | 127.0.0.1  |       6432 | 2018-04-24 22:13:10 | 2018-04-24 22:17:10 | 0x1244940 |
|          0 |
 C    | gitlab    | gitlabhq_production | active | 127.0.0.1 | 44706 | 127.0.0.1  |       6432 | 2018-04-24 22:14:22 | 2018-04-24 22:16:31 | 0x1244ac0 |
|          0 |
 C    | gitlab    | gitlabhq_production | active | 127.0.0.1 | 44708 | 127.0.0.1  |       6432 | 2018-04-24 22:14:22 | 2018-04-24 22:15:15 | 0x1244c40 |
|          0 |
 C    | gitlab    | gitlabhq_production | active | 127.0.0.1 | 44794 | 127.0.0.1  |       6432 | 2018-04-24 22:15:15 | 2018-04-24 22:15:15 | 0x1244dc0 |
|          0 |
 C    | gitlab    | gitlabhq_production | active | 127.0.0.1 | 44798 | 127.0.0.1  |       6432 | 2018-04-24 22:15:15 | 2018-04-24 22:16:31 | 0x1244f40 |
|          0 |
 C    | pgbouncer | pgbouncer           | active | 127.0.0.1 | 44660 | 127.0.0.1  |       6432 | 2018-04-24 22:13:51 | 2018-04-24 22:17:12 | 0x1244640 |
|          0 |
(8 rows)

 type |  user  |      database       | state |   addr    | port | local_addr | local_port |    connect_time     |    request_time     |    ptr    | link | rem
ote_pid | tls
------+--------+---------------------+-------+-----------+------+------------+------------+---------------------+---------------------+-----------+------+----
--------+-----
 S    | gitlab | gitlabhq_production | idle  | 127.0.0.1 | 5432 | 127.0.0.1  |      35646 | 2018-04-24 22:15:15 | 2018-04-24 22:17:10 | 0x124dca0 |      |
  19980 |
(1 row)
```

## Troubleshooting

In case you are experiencing any issues connecting through pgbouncer, the first place to check is always the logs:

```shell
# gitlab-ctl tail pgbouncer
```

Additionally, you can check the output from `show databases` in the [Administrative console](#administrative-console). In the output, you would expect to see values in the `host` field for the `gitlabhq_production` database. Additionally, `current_connections` should be greater than 1.