Commit 6c6c105f authored by Nailia Iskhakova's avatar Nailia Iskhakova 3️⃣ Committed by João Alexandre Cunha
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Update OAK considerations for multi-node with Omnibus PG cluster

parent b048bc7f

content/handbook/engineering/architecture/design-documents/omnibus_adjacent_kubernetes/decisions/004_multi_node_omnibus_support.md

+12 −9
Changes for content/handbook/engineering/architecture/design-documents/omnibus_adjacent_kubernetes/decisions/004_multi_node_omnibus_support.md: 12 added lines, 9 removed lines.
Original line number Diff line number Diff line
@@ -55,14 +55,18 @@ firewall rules, CIDR allowlisting, and `postgresql['md5_auth_cidr_addresses']`. 
For external PostgreSQL (PaaS or self-managed), standard network

configuration is sufficient.



For Omnibus PostgreSQL clusters using Patroni, customers must provision

a separate external database for advanced components.

The Patroni cluster exists solely to support

`gitlabhq_production`. After a failover, PgBouncer only updates that

connection pool — other logical databases on the same cluster will have

stale connections pointing to the old primary, causing silent failures.

This limitation is documented in

[ADR: No Omnibus HA support for databases beyond gitlabhq_production](https://gitlab.com/gitlab-com/content-sites/handbook/-/merge_requests/18927).

For Omnibus PostgreSQL clusters using Patroni, advanced components can

provision their own databases within the Omnibus cluster alongside the

main GitLab application database, and failovers propagate to those

databases automatically, as long as the component database usage is designed

to support a PostgreSQL WAL-based replication. The registry metadata database is

an example of a database that does not support PostgreSQL WAL-based replication

because it does its own database replication via application logic. So

components desiring to take advantage of the Omnibus support for multiple

databases in HA mode, must be PostgreSQL Wall replication compliant.

The same network access pattern as single-node Omnibus

PostgreSQL applies — firewall rules, CIDR allowlisting, and

`postgresql['md5_auth_cidr_addresses']`.



**Gitaly**
@@ -157,4 +161,3 @@ PostgreSQL. 
- [OAK design document](../_index.md)

- [Multi-node Omnibus PoC — work item #9691](https://gitlab.com/gitlab-org/omnibus-gitlab/-/work_items/9691)

- PoC: [demo (internal link)](https://drive.google.com/file/d/1ZriEHz1Sjg-9rJLSi0EpUurmaHVscPTP/view) and [implementation details](https://gitlab.com/-/snippets/5974860)
 
- [ADR: No Omnibus HA support for databases beyond `gitlabhq_production`](https://gitlab.com/gitlab-com/content-sites/handbook/-/merge_requests/18927)