Connection Management

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

Connection Types

Type	Examples	Kind
Database	postgres, mysql, snowflake, bigquery	`database`
File System	s3, gcs, azure, sftp, local	`file`
API	Custom REST APIs via specs	`api`

MCP Operations

List Connections

json

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

Test Connection

json

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

Discover Streams

json

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

Create Connection

json

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

CLI Operations

bash

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

bash

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

2. URL Format

bash

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

3. YAML in env.yaml

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

Property	Description
`type`	Database type (postgres, mysql, etc.)
`host`	Hostname or IP
`port`	Port number
`user`	Username
`password`	Password
`database`	Database name
`schema`	Default schema
`ssh_tunnel`	SSH tunnel URL

File System Connections

Property	Description
`type`	File system type (s3, gcs, etc.)
`bucket`	Bucket/container name
`access_key_id`	Access key
`secret_access_key`	Secret key
`region`	Cloud region

API Connections

Property	Description
`type`	Must be `api`
`spec`	API spec name or path
`secrets`	Authentication credentials
`inputs`	Optional configuration

Discovery Patterns

bash

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

•Use environment variables for sensitive credentials
•Never commit env.yaml with real credentials to git
•Use IAM roles when possible (AWS, GCP)
•Test connections before running replications
•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.