Danube CLI

Skill: danube-cli — Data Plane Operations

Objective

Complete reference for danube-cli — the command-line tool for producing, consuming, and testing messages with Danube. This is the fastest way to interact with Danube without writing code.

Quick Start

Terminal 1 — produce 5 messages:

danube-cli produce \
  -s http://localhost:6650 \
  -t /default/demo \
  -m "Hello from Danube CLI!" \
  --count 5

✅ Producer 'test_producer' created successfully
📤 Message 1/5 sent successfully (ID: ...)
📤 Message 2/5 sent successfully (ID: ...)
📤 Message 3/5 sent successfully (ID: ...)
📤 Message 4/5 sent successfully (ID: ...)
📤 Message 5/5 sent successfully (ID: ...)
📊 Summary:
   ✅ Success: 5

Terminal 2 — consume those messages:

danube-cli consume \
  -s http://localhost:6650 \
  -t /default/demo \
  -m my-first-subscription

🔍 Checking for schema associated with topic...
ℹ️  Topic has no schema - consuming raw bytes
Received message: Hello from Danube CLI!
Size: 24 bytes, Total received: 24 bytes

Producing Messages

Text and JSON

# Text message
danube-cli produce -s http://localhost:6650 -t /default/events -m "Hello!"

# JSON message
danube-cli produce -s http://localhost:6650 -t /default/events \
  -m '{"user_id":"123","action":"login","timestamp":"2024-01-15T10:30:00Z"}'

Multiple Messages

# 10 messages with 500ms interval
danube-cli produce -s http://localhost:6650 \
  -m "Message" --count 10 --interval 500

# Rapid fire (100ms minimum interval)
danube-cli produce -s http://localhost:6650 \
  -m "Fast" --count 1000 --interval 100

Message Attributes

danube-cli produce -s http://localhost:6650 \
  -m "Alert!" \
  --attributes "priority:high,region:us-west,env:production"

Reliable Delivery

danube-cli produce -s http://localhost:6650 \
  -m "Critical message" --reliable

Partitioned Topics

danube-cli produce -s http://localhost:6650 \
  -t /default/events --partitions 4 \
  -m "Partitioned message"

Schema-Validated Producing

# Use latest schema version
danube-cli produce -s http://localhost:6650 \
  -t /default/orders --schema-subject orders \
  -m '{"order_id":"ord_123","amount":99.99}'

# Pin to specific version
danube-cli produce -s http://localhost:6650 \
  -t /default/orders --schema-subject orders --schema-version 2 \
  -m '{"order_id":"ord_456","amount":149.99}'

# Auto-register schema from file
danube-cli produce -s http://localhost:6650 \
  -t /default/events --schema-file event-schema.json --schema-type json_schema \
  -m '{"event":"signup","user_id":"u_789"}'

Consuming Messages

Basic Consumer

danube-cli consume \
  -s http://localhost:6650 \
  -t /default/orders \
  -m order-processors

The consumer automatically detects and validates against the topic's schema if one is configured.

Subscription Types

# Shared (default): load balanced across consumers
danube-cli consume -s http://localhost:6650 \
  -t /default/events -m shared-sub --sub-type shared

# Exclusive: single consumer, ordered processing
danube-cli consume -s http://localhost:6650 \
  -t /default/orders -m exclusive-sub --sub-type exclusive

# Failover: active/standby with automatic failover
danube-cli consume -s http://localhost:6650 \
  -t /default/critical -m ha-sub --sub-type fail-over

Worker Pool Pattern (Shared Subscription)

for i in {1..4}; do
  danube-cli consume \
    -s http://localhost:6650 \
    -t /default/tasks \
    -n "worker-$i" \
    -m task-workers \
    --sub-type shared &
done

Fan-Out Pattern (Multiple Subscriptions)

Multiple subscriptions on the same topic for different processing pipelines:

danube-cli consume -t /default/orders -m order-processing &
danube-cli consume -t /default/orders -m order-analytics &
danube-cli consume -t /default/orders -m order-notifications &

Consumer Output Formats

# Raw text message
Received message: Hello, World!
Size: 13 bytes, Total received: 13 bytes

# JSON message with schema validation
🔍 Checking for schema associated with topic...
✅ Topic has schema: orders (json_schema, version 2)
📥 Consuming with schema validation...
✅ Message validated against schema 'orders' (version 2)
Received message: {"order_id":"ord_123","amount":99.99}
Size: 42 bytes, Total received: 42 bytes

Schema Management

Supported Schema Types

Register a Schema

# JSON Schema (most common)
danube-cli schema register user-events \
  --schema-type json_schema \
  --file user-schema.json

# Avro schema
danube-cli schema register payment-events \
  --schema-type avro \
  --file payment.avsc

# Inline schema
danube-cli schema register simple \
  --schema-type json_schema \
  --schema '{"type":"object","properties":{"id":{"type":"string"}}}'

Get Schema Details

danube-cli schema get user-events
danube-cli schema get user-events --output json

List Versions

danube-cli schema versions user-events

Check Compatibility

danube-cli schema check user-events \
  --schema-type json_schema \
  --file user-schema-v2.json

Schema Evolution Workflow

# 1. Check current schema
danube-cli schema get orders

# 2. Check compatibility of new version
danube-cli schema check orders \
  --schema-type json_schema \
  --file orders-v2.json

# 3. Register if compatible
danube-cli schema register orders \
  --schema-type json_schema \
  --file orders-v2.json

# 4. Verify
danube-cli schema versions orders

Command Reference

Producer Flags

Consumer Flags

Schema Commands

danube-cli vs danube-admin Operations

Troubleshooting

• Schema not found: danube-cli schema get my-subject — if not found, register it first
• Validation failures: Check message matches schema's required fields: danube-cli schema get my-subject --output json | jq .
• Every command supports --help: danube-cli produce --help, danube-cli consume --help, danube-cli schema --help