Connection Management

Connections are named endpoints for databases, file systems, and APIs. Sling stores them in ~/.sling/env.yaml.

Connection Types

MCP Operations

List Connections

{"action": "list", "input": {}}

Test Connection

{
  "action": "test",
  "input": {
    "connection": "MY_POSTGRES",
    "debug": true
  }
}

Discover Streams

{
  "action": "discover",
  "input": {
    "connection": "MY_POSTGRES",
    "pattern": "public.*",
    "columns": true
  }
}

Create Connection

{
  "action": "set",
  "input": {
    "name": "MY_POSTGRES",
    "properties": {
      "type": "postgres",
      "host": "localhost",
      "user": "myuser",
      "database": "mydb"
    }
  }
}

CLI Operations

sling conns list                              # List all
sling conns test MY_POSTGRES --debug          # Test
sling conns discover MY_POSTGRES --pattern "public.*"  # Discover
sling conns exec MY_POSTGRES -q "SELECT 1"    # Execute SQL

Configuration Methods

1. Environment Variable

export MY_POSTGRES='host=localhost user=postgres dbname=mydb'

2. URL Format

export MY_POSTGRES='postgresql://user:pass@host:5432/dbname'

3. YAML in env.yaml

# ~/.sling/env.yaml
connections:
  MY_POSTGRES:
    type: postgres
    host: localhost
    user: postgres
    password: ${PG_PASSWORD}
    database: mydb

  MY_S3:
    type: s3
    bucket: my-bucket
    access_key_id: ${AWS_ACCESS_KEY}
    secret_access_key: ${AWS_SECRET_KEY}

  MY_API:
    type: api
    spec: stripe
    secrets:
      api_key: ${STRIPE_API_KEY}

Common Connection Properties

Database Connections

File System Connections

API Connections

Discovery Patterns

sling conns discover MY_PG --pattern "public.*"           # All in schema
sling conns discover MY_PG --pattern "sales.customer_*"   # With prefix
sling conns discover MY_S3 --pattern "data/*.csv"         # Files
sling conns discover MY_S3 --pattern "**/*.parquet" --recursive
sling conns discover MY_PG --pattern "public.users" --columns

Security Best Practices

1. Use environment variables for sensitive credentials
2. Never commit env.yaml with real credentials to git
3. Use IAM roles when possible (AWS, GCP)
4. Test connections before running replications
5. Use SSH tunnels for database access through bastion hosts

Troubleshooting

Connection refused

• Check host/port accessibility: telnet host port
• Verify firewall rules
• Confirm database is running

Authentication failed

• Verify username/password
• Check user permissions
• Review database logs

SSL/TLS errors

• Add sslmode=disable for testing (not production)
• Verify certificate validity

Full Documentation

See https://docs.slingdata.io/connections.md for complete reference.