# PieFed Database Migration Setup

## Overview

Database migrations are now handled by a **dedicated Kubernetes Job** that runs before web and worker pods start. This eliminates race conditions and follows Kubernetes best practices.

## Architecture

```
1. piefed-db-init Job (runs once)
   ├── Uses entrypoint-init.sh
   ├── Waits for DB and Redis
   ├── Runs: flask db upgrade
   └── Exits on completion

2. Web/Worker Deployments (wait for Job)
   ├── Init Container: wait-for-migrations
   │   ├── Watches Job status
   │   └── Blocks until Job completes
   └── Main Container: starts after init passes
```

## Components

### 1. Database Init Job
**File**: `job-db-init.yaml`
- Runs migrations using `entrypoint-init.sh`
- Must complete before any pods start
- Retries up to 3 times on failure
- Kept for 24h after completion (for debugging)

### 2. Init Containers (Web & Worker)
**Files**: `deployment-web.yaml`, `deployment-worker.yaml`
- Wait for `piefed-db-init` Job to complete
- Timeout after 10 minutes
- Show migration logs if Job fails
- Block pod startup until migrations succeed

### 3. RBAC Permissions
**File**: `rbac-init-checker.yaml`
- ServiceAccount: `piefed-init-checker`
- Permissions to read Job status and logs
- Scoped to `piefed-application` namespace only

## Deployment Flow

```mermaid
sequenceDiagram
    participant Flux
    participant RBAC as RBAC Resources
    participant Job as DB Init Job
    participant Init as Init Containers
    participant Pods as Web/Worker Pods

    Flux->>RBAC: 1. Create ServiceAccount + Role
    Flux->>Job: 2. Create Job
    Job->>Job: 3. Run migrations
    Flux->>Init: 4. Start Deployments
    Init->>Job: 5. Wait for Job complete
    Job-->>Init: 6. Job successful
    Init->>Pods: 7. Start main containers
```

## First-Time Setup

### 1. Build New Container Images
The base image now includes `entrypoint-init.sh`:

```bash
cd build/piefed
./build-all.sh
```

### 2. Apply Manifests
Flux will automatically pick up changes, or apply manually:

```bash
# Apply everything
kubectl apply -k manifests/applications/piefed/

# Watch the migration Job
kubectl logs -f -n piefed-application job/piefed-db-init

# Watch pods waiting for migrations
kubectl get pods -n piefed-application -w
```

## Upgrade Process (New Versions)

When upgrading PieFed to a new version with schema changes:

```bash
# 1. Build and push new images
cd build/piefed
./build-all.sh

# 2. Delete old Job (so it re-runs with new image)
kubectl delete job piefed-db-init -n piefed-application

# 3. Apply manifests (Job will recreate)
kubectl apply -k manifests/applications/piefed/

# 4. Watch migration progress
kubectl logs -f -n piefed-application job/piefed-db-init

# 5. Verify Job completed
kubectl wait --for=condition=complete --timeout=300s \
  job/piefed-db-init -n piefed-application

# 6. Restart deployments to pick up new image
kubectl rollout restart deployment piefed-web -n piefed-application
kubectl rollout restart deployment piefed-worker -n piefed-application
```

## Troubleshooting

### Migration Job Failed

```bash
# Check Job status
kubectl get job piefed-db-init -n piefed-application

# View full logs
kubectl logs -n piefed-application job/piefed-db-init

# Check database connection
kubectl exec -n piefed-application deployment/piefed-web -- \
  flask db current
```

### Pods Stuck in Init

```bash
# Check init container logs
kubectl logs -n piefed-application <pod-name> -c wait-for-migrations

# Check if Job is running
kubectl get job piefed-db-init -n piefed-application

# Manual Job completion check
kubectl get job piefed-db-init -n piefed-application \
  -o jsonpath='{.status.conditions[?(@.type=="Complete")].status}'
```

### RBAC Permissions Issue

```bash
# Verify ServiceAccount exists
kubectl get sa piefed-init-checker -n piefed-application

# Check Role binding
kubectl get rolebinding piefed-init-checker -n piefed-application

# Test permissions from a pod
kubectl auth can-i get jobs \
  --as=system:serviceaccount:piefed-application:piefed-init-checker \
  -n piefed-application
```

## Benefits

✅ **No Race Conditions**: Single Job runs migrations sequentially  
✅ **Proper Ordering**: Init containers enforce dependencies  
✅ **Clean Separation**: Web/worker focus on their primary roles  
✅ **Easy Debugging**: Clear logs for each stage  
✅ **GitOps Compatible**: Works perfectly with Flux CD  
✅ **Idempotent**: Safe to re-run, Jobs handle completion state  
✅ **Fast Scaling**: Web/worker pods start immediately after migrations  

## Migration from Old Setup

The old setup had `PIEFED_INIT_CONTAINER=true` on all pods, causing race conditions.

**Changes Made**:
1. ✅ Removed `PIEFED_INIT_CONTAINER` env var from all pods
2. ✅ Removed migration logic from `entrypoint-common.sh`
3. ✅ Created dedicated `entrypoint-init.sh` for Job
4. ✅ Added init containers to wait for Job
5. ✅ Created RBAC for Job status checking

**Before deploying**, ensure you rebuild images with the new entrypoint script!