chore: remove dead code (hydra) by chronark · Pull Request #4062 · unkeyed/unkey

chronark · 2025-10-03T16:27:26Z

What does this PR do?

we're not using this anymore

Fixes # (issue)

If there is not an issue for this, please create one first. This is used to tracking purposes and also helps use understand why this PR exists

Type of change

Bug fix (non-breaking change which fixes an issue)
Chore (refactoring code, technical debt, workflow improvements)
Enhancement (small improvements)
New feature (non-breaking change which adds functionality)
Breaking change (fix or feature that would cause existing functionality to not work as expected)
This change requires a documentation update

How should this be tested?

Test A
Test B

Checklist

Required

Appreciated

If a UI change was made: Added a screen recording or screenshots to this PR
Updated the Unkey Docs if changes were necessary

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vercel · 2025-10-03T16:27:30Z

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2 Skipped Deployments

Project	Deployment	Preview	Comments	Updated (UTC)
dashboard	Ignored	Preview		Oct 6, 2025 7:40am
engineering	Ignored	Preview		Oct 6, 2025 7:40am

chronark · 2025-10-03T16:27:43Z

chore: remove dead code (hydra) #4062 👈 (View in Graphite)
chore: deleting dead code (kv package) #4061
main

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coderabbitai · 2025-10-03T16:27:56Z

📝 Walkthrough

Walkthrough

This PR removes the entire Hydra workflow system (engine, worker, steps, sleep, cron, marshalling, metrics, store/SQLC, tests, docs) and related initialization from deployment. It also updates infra/docs to reflect the absence of Hydra, including Docker setup and database schema docs. One CLI doc file receives formatting-only tweaks.

Changes

Cohort / File(s)	Summary
Docs formatting (CLI) `apps/engineering/content/docs/cli/run/ctrl/index.mdx`	Formatting-only MDX adjustments; no semantic changes.
Infra and schema docs `apps/engineering/content/docs/infrastructure/database-schema.mdx`	Removes Hydra mention; adds file structure and init order examples.
Deployment init and config `deployment/Dockerfile.mysql`, `deployment/docker-compose.yaml`, `deployment/init-databases.sql`	Drops Hydra schema copy, removes UNKEY_DATABASE_HYDRA env, and stops creating/granting the hydra DB.
Hydra package: core runtime removed `go/pkg/hydra/engine.go`, `go/pkg/hydra/worker.go`, `go/pkg/hydra/workflow.go`, `go/pkg/hydra/step.go`, `go/pkg/hydra/sleep.go`, `go/pkg/hydra/cron.go`, `go/pkg/hydra/marshaller.go`	Deletes engine, worker, workflow APIs, step/sleep execution, cron, and marshalling.
Hydra store (SQLC) removed `go/pkg/hydra/store/db.go`, `.../querier.go`, `.../models.go`, `.../workflows.sql.go`, `.../queries/workflows.sql`, `.../schema.sql`, `.../sqlc.json`, `.../generate.go`, `.../queries/*`	Removes store models, interfaces, generated queries, SQL schema and config.
Hydra metrics removed `go/pkg/hydra/metrics/metrics.go`, `go/pkg/hydra/metrics/example_usage.go`	Deletes all Prometheus metrics and examples.
Hydra tests and harness removed `go/pkg/hydra/*_test.go`, `go/pkg/hydra/test_helpers.go`, `go/pkg/hydra/testharness/events.go`	Removes all tests (engine, steps, consistency, polling, heartbeats, performance) and test utilities/event collector.
Hydra docs removed `go/pkg/hydra/README.md`, `go/pkg/hydra/doc.go`	Deletes Hydra package README and package docs.

Sequence Diagram(s)

sequenceDiagram
  autonumber
  participant Client
  participant Engine
  participant DB
  participant Worker
  participant Cron

  rect rgb(230,245,255)
  note over Engine,Worker: Before (Hydra present)
  Client->>Engine: StartWorkflow(payload)
  Engine->>DB: Insert workflow + payload
  Worker->>DB: Poll pending workflows
  Worker->>DB: Acquire lease
  Worker->>Worker: Execute steps (idempotent)
  Worker->>DB: Update step/workflow state
  Cron->>DB: List due cron jobs
  Cron->>Engine: Trigger StartWorkflow
  end

  rect rgb(255,235,230)
  note over Client,DB: After (Hydra removed)
  Client--X Engine: (API removed)
  Worker--X DB: (Polling/leases removed)
  Cron--X Engine: (Cron registration removed)
  end

Estimated code review effort

🎯 4 (Complex) | ⏱️ ~60 minutes

Possibly related PRs

feat: hydra #3420 — Introduces the Hydra implementation now being removed here; direct inverse of these changes.
refactor: remove hydra in favor of restate #4053 — Refactors to replace Hydra with Restate; aligns with removing Hydra code, schema, and wiring.

Suggested reviewers

mcstepp
perkinsjr
MichaelUnkey

Pre-merge checks and finishing touches

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Description Check	⚠️ Warning	The description uses the template headings but provides only a one-line justification without any detailed summary of changes, no specific issue linkage, and placeholder sections for testing and checkboxes that remain unfilled, leaving critical required information missing.	Please expand the description to include a clear summary of what dead code is removed and why, fill in the issue number in “Fixes #”, select the appropriate change type, and provide concrete testing instructions and completed checklist items.

✅ Passed checks (2 passed)

Check name	Status	Explanation
Title Check	✅ Passed	The title accurately and concisely describes the primary change of removing unused Hydra code, matching the main intent and scope of the PR.
Docstring Coverage	✅ Passed	No functions found in the changes. Docstring coverage check skipped.

✨ Finishing touches

📝 Generate docstrings

🧪 Generate unit tests (beta)

Create PR with unit tests
Post copyable unit tests in a comment
Commit unit tests in branch 10-03-chore_remove_dead_code_hydra_

📜 Recent review details

Configuration used: CodeRabbit UI

Review profile: CHILL

Plan: Pro

📥 Commits

Reviewing files that changed from the base of the PR and between 441fb9b and c949ddf.

📒 Files selected for processing (40)

apps/engineering/content/docs/cli/run/ctrl/index.mdx (11 hunks)
apps/engineering/content/docs/infrastructure/database-schema.mdx (1 hunks)
deployment/Dockerfile.mysql (0 hunks)
deployment/docker-compose.yaml (0 hunks)
deployment/init-databases.sql (0 hunks)
go/pkg/hydra/README.md (0 hunks)
go/pkg/hydra/circuit_breaker_test.go (0 hunks)
go/pkg/hydra/complex_workflows_test.go (0 hunks)
go/pkg/hydra/cron.go (0 hunks)
go/pkg/hydra/data_consistency_test.go (0 hunks)
go/pkg/hydra/debug_test.go (0 hunks)
go/pkg/hydra/doc.go (0 hunks)
go/pkg/hydra/engine.go (0 hunks)
go/pkg/hydra/engine_test.go (0 hunks)
go/pkg/hydra/marshaller.go (0 hunks)
go/pkg/hydra/marshaller_test.go (0 hunks)
go/pkg/hydra/metrics/example_usage.go (0 hunks)
go/pkg/hydra/metrics/metrics.go (0 hunks)
go/pkg/hydra/simple_consistency_test.go (0 hunks)
go/pkg/hydra/sleep.go (0 hunks)
go/pkg/hydra/step.go (0 hunks)
go/pkg/hydra/step_atomicity_test.go (0 hunks)
go/pkg/hydra/step_idempotency_test.go (0 hunks)
go/pkg/hydra/store/db.go (0 hunks)
go/pkg/hydra/store/generate.go (0 hunks)
go/pkg/hydra/store/models.go (0 hunks)
go/pkg/hydra/store/querier.go (0 hunks)
go/pkg/hydra/store/queries.go (0 hunks)
go/pkg/hydra/store/queries/workflows.sql (0 hunks)
go/pkg/hydra/store/schema.sql (0 hunks)
go/pkg/hydra/store/sqlc.json (0 hunks)
go/pkg/hydra/store/workflows.sql.go (0 hunks)
go/pkg/hydra/store_coverage_test.go (0 hunks)
go/pkg/hydra/test_helpers.go (0 hunks)
go/pkg/hydra/testharness/events.go (0 hunks)
go/pkg/hydra/worker.go (0 hunks)
go/pkg/hydra/worker_heartbeat_test.go (0 hunks)
go/pkg/hydra/worker_polling_test.go (0 hunks)
go/pkg/hydra/workflow.go (0 hunks)
go/pkg/hydra/workflow_performance_test.go (0 hunks)

💤 Files with no reviewable changes (38)

go/pkg/hydra/store/generate.go
deployment/docker-compose.yaml
go/pkg/hydra/store/sqlc.json
go/pkg/hydra/store/querier.go
go/pkg/hydra/sleep.go
go/pkg/hydra/marshaller.go
go/pkg/hydra/step.go
go/pkg/hydra/worker.go
go/pkg/hydra/engine.go
go/pkg/hydra/store/queries.go
go/pkg/hydra/store_coverage_test.go
go/pkg/hydra/store/models.go
deployment/Dockerfile.mysql
go/pkg/hydra/store/schema.sql
go/pkg/hydra/engine_test.go
go/pkg/hydra/testharness/events.go
deployment/init-databases.sql
go/pkg/hydra/workflow.go
go/pkg/hydra/README.md
go/pkg/hydra/complex_workflows_test.go
go/pkg/hydra/metrics/metrics.go
go/pkg/hydra/workflow_performance_test.go
go/pkg/hydra/simple_consistency_test.go
go/pkg/hydra/data_consistency_test.go
go/pkg/hydra/doc.go
go/pkg/hydra/store/queries/workflows.sql
go/pkg/hydra/circuit_breaker_test.go
go/pkg/hydra/worker_heartbeat_test.go
go/pkg/hydra/test_helpers.go
go/pkg/hydra/cron.go
go/pkg/hydra/worker_polling_test.go
go/pkg/hydra/marshaller_test.go
go/pkg/hydra/store/db.go
go/pkg/hydra/step_idempotency_test.go
go/pkg/hydra/step_atomicity_test.go
go/pkg/hydra/metrics/example_usage.go
go/pkg/hydra/store/workflows.sql.go
go/pkg/hydra/debug_test.go

🧰 Additional context used

🧠 Learnings (1)

📚 Learning: 2025-04-22T14:43:11.724Z

Learnt from: chronark
PR: unkeyed/unkey#3161
File: go/pkg/clickhouse/schema/databases/002_ratelimits/006_ratelimits_per_day_v1.sql:1-13
Timestamp: 2025-04-22T14:43:11.724Z
Learning: In the unkey project, the SQL files in clickhouse/schema/databases represent the current production schema and shouldn't be modified directly in PRs. Schema changes require dedicated migration scripts.

Applied to files:

apps/engineering/content/docs/infrastructure/database-schema.mdx

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imeyer

LGTM

it failed to build otherwise

github-actions · 2025-10-03T17:15:49Z

Thank you for following the naming conventions for pull request titles! 🙏

ogzhanolguncu

I thought hydra was unkillable

graphite-app · 2025-10-03T18:42:38Z

graphite-app · 2025-10-03T18:45:13Z

Graphite Automations

"Post a GIF when PR approved" took an action on this PR • (10/03/25)

1 gif was posted to this PR based on Andreas Thomas's automation.

chronark added 2 commits October 3, 2025 18:13

chore: deleting dead code (kv package)

197ecd4

chore: remove dead code (hydra)

0552d93

chronark mentioned this pull request Oct 3, 2025

chore: deleting dead code (kv package) #4061

Merged

12 tasks

vercel bot temporarily deployed to Preview – dashboard October 3, 2025 16:28 Inactive

chronark marked this pull request as ready for review October 3, 2025 16:28

chronark requested review from Flo4604, MichaelUnkey, imeyer, mcstepp, ogzhanolguncu and perkinsjr as code owners October 3, 2025 16:28

vercel bot temporarily deployed to Preview – engineering October 3, 2025 16:28 Inactive

imeyer approved these changes Oct 3, 2025

View reviewed changes

fix: idk why but this fixes the component

32e9645

it failed to build otherwise

vercel bot temporarily deployed to Preview – engineering October 3, 2025 17:18 Inactive

ogzhanolguncu approved these changes Oct 3, 2025

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Base automatically changed from 10-03-chore_deleting_dead_code_kv_package_ to main October 3, 2025 18:51

Flo4604 approved these changes Oct 6, 2025

View reviewed changes

Merge branch 'main' into 10-03-chore_remove_dead_code_hydra_

c949ddf

Flo4604 enabled auto-merge October 6, 2025 07:40

Flo4604 added this pull request to the merge queue Oct 6, 2025

Merged via the queue into main with commit 9ffae88 Oct 6, 2025
17 checks passed

Flo4604 deleted the 10-03-chore_remove_dead_code_hydra_ branch October 6, 2025 07:53

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