262 lines
12 KiB
Markdown
262 lines
12 KiB
Markdown
---
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stage: Enablement
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group: Database
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info: To determine the technical writer assigned to the Stage/Group associated with this page, see https://about.gitlab.com/handbook/engineering/ux/technical-writing/#assignments
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type: reference
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---
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# Working with the bundled PgBouncer service **(PREMIUM SELF)**
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[PgBouncer](http://www.pgbouncer.org/) is used to seamlessly migrate database
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connections between servers in a failover scenario. Additionally, it can be used
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in a non-fault-tolerant setup to pool connections, speeding up response time
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while reducing resource usage.
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GitLab Premium includes a bundled version of PgBouncer that can be managed
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through `/etc/gitlab/gitlab.rb`.
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## PgBouncer as part of a fault-tolerant GitLab installation
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This content has been moved to a [new location](replication_and_failover.md#configuring-the-pgbouncer-node).
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## PgBouncer as part of a non-fault-tolerant GitLab installation
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1. Generate PGBOUNCER_USER_PASSWORD_HASH with the command `gitlab-ctl pg-password-md5 pgbouncer`
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1. Generate SQL_USER_PASSWORD_HASH with the command `gitlab-ctl pg-password-md5 gitlab`. Enter the plaintext SQL_USER_PASSWORD later.
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1. On your database node, ensure the following is set in your `/etc/gitlab/gitlab.rb`
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```ruby
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postgresql['pgbouncer_user_password'] = 'PGBOUNCER_USER_PASSWORD_HASH'
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postgresql['sql_user_password'] = 'SQL_USER_PASSWORD_HASH'
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postgresql['listen_address'] = 'XX.XX.XX.Y' # Where XX.XX.XX.Y is the ip address on the node postgresql should listen on
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postgresql['md5_auth_cidr_addresses'] = %w(AA.AA.AA.B/32) # Where AA.AA.AA.B is the IP address of the pgbouncer node
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```
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1. Run `gitlab-ctl reconfigure`
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NOTE:
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If the database was already running, it needs to be restarted after reconfigure by running `gitlab-ctl restart postgresql`.
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1. On the node you are running PgBouncer on, make sure the following is set in `/etc/gitlab/gitlab.rb`
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```ruby
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pgbouncer['enable'] = true
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pgbouncer['databases'] = {
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gitlabhq_production: {
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host: 'DATABASE_HOST',
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user: 'pgbouncer',
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password: 'PGBOUNCER_USER_PASSWORD_HASH'
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}
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}
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```
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You can pass additional configuration parameters per database, for example:
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```ruby
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pgbouncer['databases'] = {
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gitlabhq_production: {
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...
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pool_mode: 'transaction'
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}
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}
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```
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Use these parameters with caution. For the complete list of parameters refer to the
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[PgBouncer documentation](https://www.pgbouncer.org/config.html#section-databases).
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1. Run `gitlab-ctl reconfigure`
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1. On the node running Puma, make sure the following is set in `/etc/gitlab/gitlab.rb`
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```ruby
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gitlab_rails['db_host'] = 'PGBOUNCER_HOST'
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gitlab_rails['db_port'] = '6432'
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gitlab_rails['db_password'] = 'SQL_USER_PASSWORD'
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```
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1. Run `gitlab-ctl reconfigure`
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1. At this point, your instance should connect to the database through PgBouncer. If you are having issues, see the [Troubleshooting](#troubleshooting) section
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## Backups
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Do not backup or restore GitLab through a PgBouncer connection: it causes a GitLab outage.
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[Read more about this and how to reconfigure backups](../../raketasks/backup_restore.md#backup-and-restore-for-installations-using-pgbouncer).
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## Enable Monitoring
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> [Introduced](https://gitlab.com/gitlab-org/omnibus-gitlab/-/issues/3786) in GitLab 12.0.
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If you enable Monitoring, it must be enabled on **all** PgBouncer servers.
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1. Create/edit `/etc/gitlab/gitlab.rb` and add the following configuration:
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```ruby
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# Enable service discovery for Prometheus
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consul['enable'] = true
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consul['monitoring_service_discovery'] = true
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# Replace placeholders
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# Y.Y.Y.Y consul1.gitlab.example.com Z.Z.Z.Z
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# with the addresses of the Consul server nodes
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consul['configuration'] = {
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retry_join: %w(Y.Y.Y.Y consul1.gitlab.example.com Z.Z.Z.Z),
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}
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# Set the network addresses that the exporters will listen on
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node_exporter['listen_address'] = '0.0.0.0:9100'
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pgbouncer_exporter['listen_address'] = '0.0.0.0:9188'
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```
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1. Run `sudo gitlab-ctl reconfigure` to compile the configuration.
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## Administrative console
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As part of Omnibus GitLab, a command is provided to automatically connect to the
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PgBouncer administrative console. See the
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[PgBouncer documentation](https://www.pgbouncer.org/usage.html#admin-console)
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for detailed instructions on how to interact with the console.
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To start a session run the following and provide the password for the `pgbouncer`
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user:
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```shell
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sudo gitlab-ctl pgb-console
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```
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To get some basic information about the instance:
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```shell
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pgbouncer=# show databases; show clients; show servers;
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name | host | port | database | force_user | pool_size | reserve_pool | pool_mode | max_connections | current_connections
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---------------------+-----------+------+---------------------+------------+-----------+--------------+-----------+-----------------+---------------------
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gitlabhq_production | 127.0.0.1 | 5432 | gitlabhq_production | | 100 | 5 | | 0 | 1
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pgbouncer | | 6432 | pgbouncer | pgbouncer | 2 | 0 | statement | 0 | 0
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(2 rows)
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type | user | database | state | addr | port | local_addr | local_port | connect_time | request_time | ptr | link
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| remote_pid | tls
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------+-----------+---------------------+--------+-----------+-------+------------+------------+---------------------+---------------------+-----------+------
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+------------+-----
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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 |
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| 0 |
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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 |
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| 0 |
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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 |
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| 0 |
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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 |
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| 0 |
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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 |
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| 0 |
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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 |
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| 0 |
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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 |
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| 0 |
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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 |
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| 0 |
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(8 rows)
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type | user | database | state | addr | port | local_addr | local_port | connect_time | request_time | ptr | link | rem
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ote_pid | tls
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------+--------+---------------------+-------+-----------+------+------------+------------+---------------------+---------------------+-----------+------+----
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--------+-----
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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 | |
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19980 |
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(1 row)
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```
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## Procedure for bypassing PgBouncer
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Some database changes have to be done directly, and not through PgBouncer.
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Read more about the affected tasks: [database restores](../../raketasks/backup_restore.md#backup-and-restore-for-installations-using-pgbouncer)
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and [GitLab upgrades](../../update/zero_downtime.md#use-postgresql-ha).
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1. To find the primary node, run the following on a database node:
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```shell
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sudo gitlab-ctl patroni members
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```
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1. Edit `/etc/gitlab/gitlab.rb` on the application node you're performing the task on, and update
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`gitlab_rails['db_host']` and `gitlab_rails['db_port']` with the database
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primary's host and port.
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1. Run reconfigure:
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```shell
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sudo gitlab-ctl reconfigure
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```
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Once you've performed the tasks or procedure, switch back to using PgBouncer:
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1. Change back `/etc/gitlab/gitlab.rb` to point to PgBouncer.
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1. Run reconfigure:
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```shell
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sudo gitlab-ctl reconfigure
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```
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## Fine tuning
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PgBouncer's default settings suit the majority of installations.
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In specific cases you may want to change the performance-specific and resource-specific variables to either increase possible
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throughput or to limit resource utilization that could cause memory exhaustion on the database.
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You can find the parameters and respective documentation on the [official PgBouncer documentation](https://www.pgbouncer.org/config.html).
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Listed below are the most relevant ones and their defaults on an Omnibus GitLab installation:
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- `pgbouncer['max_client_conn']` (default: `2048`, depends on server file descriptor limits)
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This is the "frontend" pool in PgBouncer: connections from Rails to PgBouncer.
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- `pgbouncer['default_pool_size']` (default: `100`)
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This is the "backend" pool in PgBouncer: connections from PgBouncer to the database.
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The ideal number for `default_pool_size` must be enough to handle all provisioned services that need to access
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the database. Each of the listed services below use the following formula to define database pool size:
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- `puma` : `max_threads + headroom` (default `14`)
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- `max_threads` is configured via: `gitlab['puma']['max_threads']` (default: `4`)
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- `headroom` can be configured via `DB_POOL_HEADROOM` env variable (default to `10`)
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- `sidekiq` : `max_concurrency + 1 + headroom` (default: `61`)
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- `max_concurrency` is configured via: `sidekiq['max_concurrency']` (default: `50`)
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- `headroom` can be configured via `DB_POOL_HEADROOM` env variable (default to `10`)
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- `geo-logcursor`: `1+headroom` (default: `11`)
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- `headroom` can be configured via `DB_POOL_HEADROOM` env variable (default to `10`)
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To calculate the `default_pool_size`, multiply the number of instances of `puma`, `sidekiq` and `geo-logcursor` by the
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number of connections each can consume as per listed above. The total will be the suggested `default_pool_size`.
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If you are using more than one PgBouncer with an internal Load Balancer, you may be able to divide the
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`default_pool_size` by the number of instances to guarantee an evenly distributed load between them.
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The `pgbouncer['max_client_conn']` is the hard-limit of connections PgBouncer can accept. It's unlikely you will need
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to change this. If you are hitting that limit, you may want to consider adding additional PgBouncers with an internal
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Load Balancer.
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When setting up the limits for a PgBouncer that points to the Geo Tracking Database,
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you can likely ignore `puma` from the equation, as it is only accessing that database sporadically.
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## Troubleshooting
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In case you are experiencing any issues connecting through PgBouncer, the first
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place to check is always the logs:
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```shell
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sudo gitlab-ctl tail pgbouncer
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```
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Additionally, you can check the output from `show databases` in the
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[administrative console](#administrative-console). In the output, you would expect
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to see values in the `host` field for the `gitlabhq_production` database.
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Additionally, `current_connections` should be greater than 1.
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### Message: `LOG: invalid CIDR mask in address`
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See the suggested fix [in Geo documentation](../geo/replication/troubleshooting.md#message-log--invalid-cidr-mask-in-address).
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### Message: `LOG: invalid IP mask "md5": Name or service not known`
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See the suggested fix [in Geo documentation](../geo/replication/troubleshooting.md#message-log--invalid-ip-mask-md5-name-or-service-not-known).
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