Cloudflare Workers

Cloudflare Workers Deployment

You are now operating in Cloudflare Workers deployment mode using the wrangler CLI.

Prerequisites

# Install wrangler
npm install -g wrangler

# Authenticate (one-time, interactive)
wrangler login

# Or use API token (preferred for CI/automation)
export CLOUDFLARE_API_TOKEN="your-token-here"
# Generate at: https://dash.cloudflare.com/profile/api-tokens
# Required scopes: Workers Scripts:Edit, Workers KV Storage:Edit, D1:Edit, R2:Edit

# Verify authentication
wrangler whoami

Project Structure

my-worker/
├── wrangler.toml      # Configuration file
├── src/
│   └── index.ts       # Worker entrypoint
└── package.json

Minimal wrangler.toml

name = "my-worker"
main = "src/index.ts"
compatibility_date = "2024-01-01"

# Optional: bind KV namespace
[[kv_namespaces]]
binding = "MY_KV"
id = "abc123def456"

# Optional: bind D1 database
[[d1_databases]]
binding = "DB"
database_name = "my-database"
database_id = "abc123"

# Optional: bind R2 bucket
[[r2_buckets]]
binding = "MY_BUCKET"
bucket_name = "my-bucket"

Local Development

# Start local dev server (uses local emulation)
wrangler dev

# Dev against real Cloudflare network (remote bindings)
wrangler dev --remote

# Specify port
wrangler dev --port 8787

# Enable live reload on save
wrangler dev --watch

Deployment

# Deploy to production
wrangler deploy

# Dry run (validate without deploying)
wrangler deploy --dry-run

# Deploy to a named environment (requires [env.staging] in wrangler.toml)
wrangler deploy --env staging
wrangler deploy --env production

# Deploy and verify output
wrangler deploy 2>&1 | tee deploy.log
grep "Deployed" deploy.log

Multi-Environment Configuration

# wrangler.toml

name = "my-worker"
main = "src/index.ts"
compatibility_date = "2024-01-01"

[env.staging]
name = "my-worker-staging"
vars = { ENVIRONMENT = "staging" }

[env.production]
name = "my-worker-production"
vars = { ENVIRONMENT = "production" }

Monitoring: Live Log Tailing

# Tail logs in real-time
wrangler tail

# Always use --format json for parsing
wrangler tail --format json

# Tail a specific environment
wrangler tail --env production --format json

# Filter by status code (e.g., only errors)
wrangler tail --status error

# Filter by sampling rate (0.0 to 1.0)
wrangler tail --sampling-rate 0.1

Version Management and Rollback

# List deployed versions
wrangler versions list
wrangler versions list --json

# View a specific version's details
wrangler versions view <version-id>

# Upload a new version without activating
wrangler versions upload

# Activate a specific version (gradual rollout)
wrangler versions deploy <version-id>

# Deploy with percentage traffic split
wrangler versions deploy <version-id> --percentage 10

# Rollback to previous version
wrangler rollback

Secrets Management

# Set a secret (prompts for value, never logged)
wrangler secret put DATABASE_URL

# Set a secret for a specific environment
wrangler secret put DATABASE_URL --env production

# List all secret names (values are never shown)
wrangler secret list

# Delete a secret
wrangler secret delete DATABASE_URL

KV Namespace Operations

# Create a KV namespace
wrangler kv namespace create MY_NAMESPACE

# List all namespaces
wrangler kv namespace list

# Write a key-value pair
wrangler kv key put mykey "myvalue" --namespace-id <namespace-id>

# Read a value
wrangler kv key get mykey --namespace-id <namespace-id>

# List keys with prefix
wrangler kv key list --namespace-id <namespace-id> --prefix "user:"

# Delete a key
wrangler kv key delete mykey --namespace-id <namespace-id>

# Bulk upload from JSON file
wrangler kv bulk put data.json --namespace-id <namespace-id>

KV is eventually consistent (~60s). Best for: config, feature flags, cached reads.

D1 Database Operations

# Create a D1 database
wrangler d1 create my-database

# List all D1 databases
wrangler d1 list

# Execute SQL (local emulation)
wrangler d1 execute my-database --command "SELECT * FROM users LIMIT 10;"

# Execute SQL on production (always use --remote for production)
wrangler d1 execute my-database --remote --command "SELECT COUNT(*) FROM users;"

# Execute a SQL file
wrangler d1 execute my-database --remote --file ./schema.sql

# Apply migrations
wrangler d1 migrations apply my-database --remote

# Show migration status
wrangler d1 migrations list my-database

D1 is strongly consistent SQLite. Best for: structured data, relational queries.

R2 Bucket Operations

# Create an R2 bucket
wrangler r2 bucket create my-bucket

# List all buckets
wrangler r2 bucket list

# Upload an object
wrangler r2 object put my-bucket/path/to/file.txt --file ./local-file.txt

# Download an object
wrangler r2 object get my-bucket/path/to/file.txt --file ./downloaded.txt

# Delete an object
wrangler r2 object delete my-bucket/path/to/file.txt

R2 has zero egress fees. Best for: files, media, backups.

Queues Operations

# Create a queue
wrangler queues create my-queue

# List queues
wrangler queues list

# Send a message to a queue (for testing)
wrangler queues send my-queue '{"event": "test", "data": {}}'

Worker Deletion

# Delete a Worker (irreversible!)
wrangler delete

# Delete a specific environment's worker
wrangler delete --env staging

Deployment Patterns

Pattern 1: Standard Deploy and Verify

# 1. Deploy
wrangler deploy --env production

# 2. Tail logs to verify health (press Ctrl+C when satisfied)
wrangler tail --env production --format json &
TAIL_PID=$!

# 3. Wait a few seconds for traffic
sleep 10

# 4. Stop tailing
kill $TAIL_PID

# 5. Report deployment URL (from deploy output)

Pattern 2: Multi-Environment Pipeline

# 1. Deploy to staging first
wrangler deploy --env staging

# 2. Verify staging works
curl -f https://my-worker-staging.workers.dev/health

# 3. Deploy to production only if staging passes
wrangler deploy --env production

# 4. Verify production
curl -f https://my-worker-production.workers.dev/health

Pattern 3: Blue-Green with Traffic Splitting

# 1. Upload new version without activating
wrangler versions upload

# 2. Get the new version ID
NEW_VERSION=$(wrangler versions list --json | jq -r '.[0].id')

# 3. Route 10% of traffic to new version
wrangler versions deploy "$NEW_VERSION" --percentage 10

# 4. Monitor logs for errors
wrangler tail --format json | jq 'select(.outcome == "exception")'

# 5. Promote to 100% if healthy
wrangler versions deploy "$NEW_VERSION" --percentage 100

# OR rollback if problems found
wrangler rollback

Cloudflare Storage Binding Reference

Free Tier Limits

• 100,000 requests/day
• 10ms CPU time per invocation
• KV: 100k reads/day, 1k writes/day, 1 GB storage
• D1: 5M rows read/day, 100k rows written/day, 5 GB storage
• R2: 10 GB storage, 1M Class A ops, 10M Class B ops

Safety Rules

• Never commit CLOUDFLARE_API_TOKEN to source control — use environment variables or wrangler secret put.
• Always deploy to staging before production.
• Always tail logs after deployment to verify no errors.
• Use --dry-run to validate the deployment bundle before pushing to production.
• Use wrangler rollback immediately if errors spike after deployment.
• D1 migrations with --remote modify live production data — test locally first.