WPB-26487 backend background jobs hasql resource pool refactoring

[battermann]

https://wearezeta.atlassian.net/browse/WPB-26487

related to https://wearezeta.atlassian.net/browse/WPB-25325

Checklist

• Add a new entry in an appropriate subdirectory of changelog.d
• Read and follow the PR guidelines

[Copilot]

Pull request overview

This PR refactors the PostgreSQL connection pooling across multiple services/libraries by switching from hasql-pool to hasql-resource-pool, introducing a new Hasql.Pool.Extended.Pool wrapper that carries metrics and a rawPool accessor for code paths that still need the underlying pool (notably migrations).

Changes:

• Replace hasql-pool with hasql-resource-pool across Cabal and Nix, including pin/override updates.
• Update service/library effect stacks to use Hasql.Pool.Extended.Pool (and rawPool where a raw Hasql.Pool.Pool is required).
• Rework pool metrics collection (session/acquisition latency histograms + periodic pool stats snapshots).

Reviewed changes

Copilot reviewed 36 out of 36 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
services/galley/src/Galley/Run.hs	Use rawPool for migrations; adjust imports.
services/galley/src/Galley/Env.hs	Switch env pool type import to Hasql.Pool.Extended.
services/galley/src/Galley/App.hs	Update Polysemy Input pool type to the extended wrapper.
services/galley/galley.cabal	Swap dependency from hasql-pool to hasql-resource-pool.
services/galley/default.nix	Swap Nix dependency from hasql-pool to hasql-resource-pool.
services/brig/src/Brig/Run.hs	Use rawPool for migrations and in migration command.
services/brig/src/Brig/Index/Eval.hs	Introduce PostgresUsageException wrapper and updated interpreter for UsageError.
services/brig/src/Brig/CanonicalInterpreter.hs	Update Polysemy Input pool type to the extended wrapper.
services/brig/src/Brig/App.hs	Move Brig to Hasql.Pool.Extended import/aliasing.
services/brig/default.nix	Swap Nix dependency from hasql-pool to hasql-resource-pool.
services/brig/brig.cabal	Swap dependency from hasql-pool to hasql-resource-pool.
services/background-worker/src/Wire/Effects.hs	Update Polysemy Input pool type and wiring to the extended wrapper.
services/background-worker/src/Wire/BackgroundWorker/Env.hs	Update pool imports/aliases to Hasql.Pool.Extended.
services/background-worker/default.nix	Swap Nix dependency from hasql-pool to hasql-resource-pool.
services/background-worker/background-worker.cabal	Swap dependency from hasql-pool to hasql-resource-pool.
nix/manual-overrides.nix	Replace override of hasql-pool with hasql-resource-pool.
nix/haskell-pins.nix	Add pin for hasql-resource-pool.
libs/wire-subsystems/wire-subsystems.cabal	Swap dependency from hasql-pool to hasql-resource-pool.
libs/wire-subsystems/src/Wire/UserGroupStore/Postgres.hs	Replace explicit Hasql pool constraints with PGConstraints.
libs/wire-subsystems/src/Wire/TeamFeatureStore/Migration.hs	Switch to extended pool module aliasing.
libs/wire-subsystems/src/Wire/TeamCollaboratorsStore/Postgres.hs	Replace explicit Hasql pool constraints with PGConstraints.
libs/wire-subsystems/src/Wire/PostgresMigrations.hs	Wrap UsageError into PostgresMigrationError for throwing.
libs/wire-subsystems/src/Wire/Postgres.hs	Update pool usage and add observer-based metrics recording.
libs/wire-subsystems/src/Wire/MigrationLock.hs	Pull rawPool from the extended pool wrapper for lock sessions.
libs/wire-subsystems/src/Wire/MeetingsStore/Postgres.hs	Use runSession/PGConstraints instead of manual pool plumbing.
libs/wire-subsystems/src/Wire/Error.hs	Update UsageError pattern matching for new constructors.
libs/wire-subsystems/src/Wire/DomainRegistrationStore/Migration.hs	Switch to extended pool module aliasing.
libs/wire-subsystems/src/Wire/ConversationStore/Postgres.hs	Replace explicit Hasql pool constraints with PGConstraints.
libs/wire-subsystems/src/Wire/ConversationStore/Migration.hs	Switch to extended pool module aliasing.
libs/wire-subsystems/src/Wire/CodeStore/Migration.hs	Switch to extended pool module aliasing.
libs/wire-subsystems/src/Wire/AppStore/Postgres.hs	Replace explicit Hasql pool constraints with PGConstraints.
libs/wire-subsystems/default.nix	Swap Nix dependency from hasql-pool to hasql-resource-pool.
libs/extended/src/Hasql/Pool/Extended.hs	Reimplement pooling/metrics on top of hasql-resource-pool.
libs/extended/extended.cabal	Swap dependency from hasql-pool to hasql-resource-pool and remove uuid.
libs/extended/default.nix	Swap Nix dependency from hasql-pool to hasql-resource-pool and remove uuid.
changelog.d/0-release-notes/WPB-25325	Add release note describing the pool backend switch and metrics changes.

[Copilot]

Pull request overview

Copilot reviewed 44 out of 45 changed files in this pull request and generated 4 comments.

Comments suppressed due to low confidence (1)

services/brig/src/Brig/Index/Options.hs:376

• This PR removes the --pg-pool-aging-timeout CLI option, but make es-reindex still passes it (see Makefile:430). After this change, that make target will fail with an “unknown option” error. Either update the Makefile/docs to stop using the flag, or keep a deprecated alias flag that is accepted (and ignored) for backward compatibility.

[akshaymankar]

Overall looks good, minor changes requested.

The issues pointed out are resolved. Since Akshay is not available, this was approved by someone else.