[jonbamber]

Context

DO NOT MERGE UNTIL AFTER MANUAL DATABASE UPGRADE

This work is related to upgrading the PostgreSQL version for this service from version 16 to version 18.

https://trello.com/c/64RX275N/3087-upgrade-drd-postgres-version

This change updates the Test environment configuration to use PostgreSQL 18. There is no review app for this change.

The upgrade of the flexible server will be performed manually (due to azurerm Terraform provider limitations) and this PR should be merged after that manual upgrade.

Changes proposed in this pull request

• New postgres_server_version variable in terraform/application/variables.tf, defaulting to "18".
• terraform/application/database.tf passes the variable to the postgres module as server_version instead of the hardcoded "16".

Guidance to review

Before manual upgrade

• make test terraform-plan DOCKER_IMAGE_TAG=41e68678726d036aa4e2dd8e2ea0fc5f9fd95908 will show:
  • module.postgres.azurerm_postgresql_flexible_server.main[0].version: 16 -> 18
  • module.postgres.azurerm_postgresql_flexible_server_configuration.connection_throttling[0] will be destroyed (not supported in v18)

After manual upgrade

• make test terraform-plan DOCKER_IMAGE_TAG=600761fa0d15e571d6891c97740e578380478454 should show no changes.

Checklist

• I have performed a self-review of my code, including formatting and typos
• I have cleaned the commit history
• I have attached the pull request to the Trello card

[Copilot]

🔵 Needs a closer look

Human confirmation is required that the Test server’s manual PostgreSQL 16→18 upgrade is complete and the post-upgrade Terraform plan shows no changes, since live infrastructure state cannot be verified from this snapshot.

No open issues 🎉

What changed in this PR

Prepares the service’s Terraform configuration for PostgreSQL 18 by making the server version configurable. This PR must be merged only after the manual database upgrade.

Changes:

• Adds postgres_server_version with a default of "18".
• Passes the variable to the PostgreSQL module instead of hardcoding "16".

File	Description
terraform/​application/​variables.tf	Defines the PostgreSQL version variable, defaulting to 18.
terraform/​application/​database.tf	Uses the version variable in the PostgreSQL module.

_{Review effort: Balanced}

[Copilot]

🔵 Needs a closer look

A human must confirm the Test server’s manual upgrade to PostgreSQL 18 and a post-upgrade Terraform plan showing no changes, neither of which can be verified from this review.

No open issues 🎉

_{Review effort: Balanced}