Firebase Deployer

When to Use

Activate this skill when:

• Firestore query errors indicate missing indexes
• User modifies firestore.rules or firestore.indexes.json
• User requests "deploy firebase rules" or "deploy indexes"
• Error messages mention "FAILED_PRECONDITION" or "composite index"
• User says "deploy firebase", "push rules", or "update firestore"
• New Firestore queries need composite indexes
• Security rules need updating for new features

Instructions

Step 1: Identify What Needs Deployment

1. Check for modified files:

git status | grep -E "(firestore.rules|firestore.indexes.json)"

2. If query error occurred, extract index requirements from error message:
   • Collection name
   • Fields being queried
   • Order direction (ASCENDING/DESCENDING)
   • Query filters (array-contains, etc.)

Step 2: Update Index Configuration (if needed)

If missing index detected:

1. Read current indexes:

cat firestore.indexes.json

2. Add new index to firestore.indexes.json:

{
  "indexes": [
    {
      "collectionGroup": "collection_name",
      "queryScope": "COLLECTION",
      "fields": [
        {
          "fieldPath": "field1",
          "order": "ASCENDING"
        },
        {
          "fieldPath": "field2",
          "order": "DESCENDING"
        }
      ]
    }
  ]
}

Step 3: Verify Firebase Project

1. Check current project:

firebase use

2. If project not set or wrong project:

firebase use project-id

3. Verify configuration:

firebase projects:list

Step 4: Deploy Rules and Indexes

Deploy both rules and indexes together:

firebase deploy --only firestore:rules,firestore:indexes

Or deploy separately:

# Deploy only indexes
firebase deploy --only firestore:indexes

# Deploy only rules
firebase deploy --only firestore:rules

Step 5: Verify Deployment

1. Check index status:

firebase firestore:indexes

2. Monitor index building (can take several minutes):

   • Indexes show as "Building" initially
   • Check Firebase Console for progress
   • Wait for "Ready" status before querying

3. Test the query that triggered the error

Examples

Example 1: Deploy After Query Error

# Error received:
# "The query requires an index. You can create it here: https://console.firebase.google.com/..."

# Step 1: Extract index requirements from error URL
# Collection: posts
# Fields: userId (ASCENDING), createdAt (DESCENDING)

# Step 2: Update firestore.indexes.json
# (use Edit tool to add index)

# Step 3: Deploy
firebase deploy --only firestore:indexes

# Step 4: Verify
firebase firestore:indexes

Example 2: Deploy Modified Security Rules

# User modified firestore.rules to add new collection rules

# Step 1: Verify changes
cat firestore.rules

# Step 2: Deploy rules only
firebase deploy --only firestore:rules

# Step 3: Verify in console
# Check Firebase Console > Firestore > Rules

Example 3: Deploy Both Rules and Indexes

# User updated both rules and indexes

# Deploy together for consistency
firebase deploy --only firestore:rules,firestore:indexes

# Verify both
firebase firestore:indexes
# Check console for rules

Example 4: Multi-Project Deployment

# Deploy to specific project
firebase deploy --only firestore:rules,firestore:indexes --project production-id

# Switch project for subsequent deploys
firebase use staging-id
firebase deploy --only firestore:rules,firestore:indexes

Best Practices

✅ DO:

• Always verify current Firebase project before deploying
• Deploy rules and indexes together when both changed
• Test queries after index deployment completes
• Check index status after deployment
• Read error messages carefully to extract index requirements
• Deploy to staging environment first (if available)
• Wait for indexes to finish building before testing
• Keep firestore.indexes.json in version control

❌ DON'T:

• Don't deploy without checking current project
• Don't assume indexes are ready immediately (they build asynchronously)
• Don't deploy rules that could break production
• Don't ignore index URL in error messages (contains exact requirements)
• Don't delete indexes still in use by queries
• Don't deploy without reviewing changes first
• Don't forget to commit firestore.indexes.json after adding indexes

Index Configuration Tips:

1. Query Scope:

   • COLLECTION: Index for specific collection
   • COLLECTION_GROUP: Index across all collections with same name

2. Field Order:

   • List fields in query order
   • Use ASCENDING or DESCENDING to match query
   • Array-contains queries need special handling

3. Compound Indexes:

   • Required for queries with multiple filters
   • Required for orderBy on different field than filter
   • Required for inequality filters on multiple fields

4. Index Exemptions:

   • Single field ascending/descending: Auto-indexed
   • Simple equality queries: Usually auto-indexed
   • Check Firestore docs for exemption list

Security Rules Best Practices:

1. Default Deny:

match /{document=**} {
  allow read, write: if false;
}

2. Authenticated Users:

match /users/{userId} {
  allow read, write: if request.auth != null && request.auth.uid == userId;
}

3. Field Validation:

match /posts/{postId} {
  allow create: if request.auth != null
    && request.resource.data.title is string
    && request.resource.data.title.size() <= 100;
}

Deployment Checklist

Before deploying:

• Verified correct Firebase project
• Reviewed changes to rules/indexes
• Tested rules in Firebase Console simulator (if changed)
• No breaking changes to production queries
• Index configuration matches query requirements
• Have backup of previous rules (git history)

After deploying:

• Verified deployment success message
• Checked index status (building/ready)
• Tested queries that use new indexes
• Monitored for errors in Firebase Console
• Committed firestore.indexes.json changes

Troubleshooting

Issue: "Project not found" error Solution: Run firebase use project-id or firebase projects:list

Issue: "Permission denied" during deployment Solution: Re-authenticate with firebase login or check IAM roles

Issue: Index still showing as "Building" after long time Solution: Normal for large collections. Check Firebase Console for progress.

Issue: Query still failing after index deployment Solution: Verify index matches exact query requirements (field order, direction)

Issue: Rules deployment breaks existing queries Solution: Review rules for overly restrictive conditions. Test in simulator first.

Issue: Multiple index errors for same query Solution: Create single composite index with all required fields

Firebase CLI Commands Reference

# Project management
firebase projects:list                    # List all projects
firebase use project-id                   # Switch to project
firebase use --add                        # Add project alias

# Deployment
firebase deploy --only firestore:rules    # Deploy rules only
firebase deploy --only firestore:indexes  # Deploy indexes only
firebase deploy --only firestore          # Deploy both

# Index management
firebase firestore:indexes                # List all indexes
firebase firestore:indexes --status       # Show build status

# Verification
firebase use                              # Show current project
firebase projects:list                    # Verify project access

# Authentication
firebase login                            # Re-authenticate
firebase logout                           # Sign out
firebase login:list                       # List authenticated accounts

Integration with Development Workflow

1. During Development:

   • Write Firestore queries
   • Note index errors
   • Add indexes to firestore.indexes.json
   • Deploy immediately

2. Before Committing:

   • Ensure all indexes deployed
   • Verify rules match new features
   • Test queries in development

3. Before Production Deploy:

   • Deploy indexes to production first
   • Wait for indexes to build
   • Then deploy application code
   • Verify queries work in production

Error Message Patterns

Common error messages that trigger this skill:

1. Missing Index:

The query requires an index. You can create it here: https://...

2. Failed Precondition:

FAILED_PRECONDITION: The query requires an index...

3. Permission Denied (rules issue):

Missing or insufficient permissions

4. Invalid Argument:

Cannot have inequality filters on multiple properties

Extract index requirements and deploy accordingly.