Configuration

Overview

The Sink gateway is the main interface between users and the platform. Through gateway configuration, you can control:

• The port and address the service listens on
• Logging level and frontend feature toggles
• Optional AI capability settings

This guide covers common gateway configuration tasks.

Configuration File Location

The gateway configuration file is located at:

~/.sink/gateway.json

Here ~/.sink corresponds to SINK_HOME/.sink, with a default value of ~/.sink.

Quick Start: Basic Configuration

Scenario 1: Change the Service Port

# Edit ~/.sink/gateway.json

{
  "port": 8080,
  "host": "127.0.0.1"
}

The change takes effect after restarting the gateway. Access the Web UI at http://127.0.0.1:8080.

Scenario 2: Allow Remote Access

{
  "port": 5000,
  "host": "0.0.0.0"
}

This allows other machines to access via http://<your-ip>:5000.

Scenario 3: Configure Port Using Environment Variables

Use environment variable interpolation syntax in gateway.json:

{
  "port": "${PORT:-5000}",
  "host": "127.0.0.1"
}

This means: use the PORT environment variable, or default to 5000 if not set.

On startup:

PORT=8080 sink gateway start

Authentication Configuration

Static Bearer Token (Additional Authentication)

In addition to the primary authentication method, you can configure additional Bearer tokens:

{
  "authTokens": [
    "token-1",
    "token-2"
  ]
}

Use them in the Authorization header when sending requests:

curl -H "Authorization: Bearer token-1" http://localhost:5000/api/config

This is useful for integration scripts or CI/CD pipelines.

Logging Configuration

Log Level

{
  "logLevel": "info"
}

Possible values:

• fatal - Only fatal errors
• error - Errors only
• warn - Warnings and above
• info - General information (default)
• debug - Detailed debug information
• trace - All logs (most verbose)
• silent - Disable all log output

Viewing Logs

Logs are printed to standard output. When running the gateway, you can:

# View logs directly
sink gateway start

# Or redirect to a file
sink gateway start > sink.log 2>&1

Frontend Feature Toggles

Control which feature menus are visible in the Web UI through uiConfig:

{
  "uiConfig": {
    "showProfiles": true,
    "showRuntimes": true,
    "showSkills": true,
    "showMcp": true,
    "showInstructions": true,
    "showVscode": true,
    "showCanvas": true,
    "simpleMode": false
  }
}

Available Feature Toggles

Use Case

Scenario: Present different UI to different users

You can dynamically control feature toggles using environment variables:

{
  "uiConfig": {
    "showProfiles": "${SHOW_PROFILES:-true}",
    "showVscode": "${SHOW_VSCODE:-false}",
    "simpleMode": "${SIMPLE_MODE:-false}"
  }
}

On startup:

# Hide VS Code menu and enable simple mode
SHOW_VSCODE=false SIMPLE_MODE=true sink gateway start

Settings Configuration

In addition to gateway.json, Sink has a global settings.json configuration that supports three layers.

Location: ~/.sink/settings.json and <workspace>/.sink/settings.json

Common Configuration Items

{
  "env": {
    "ANTHROPIC_API_KEY": "sk-...",
    "CUSTOM_VAR": "value"
  },
  "logLevel": "info",
  "agentLifecycle": {
    "maxConcurrent": 4,
    "idleSwapOutMs": 300000
  },
  "sandbox": {
    "enabled": true
  }
}

Troubleshooting

Gateway Startup Failure

Check for JSON syntax errors in the configuration file:

cat ~/.sink/gateway.json | jq .

If there’s an error, fix the JSON format and retry.

Environment Variable Interpolation Not Working

Check:

1. If the environment variable is actually set: echo $VAR_NAME
2. If the configuration file is being read correctly: startup logs should show configuration loading information
3. If the interpolation syntax in gateway.json is correct

Authentication Issues

• 403 Unauthorized: Check if the Bearer token is correct (if authTokens is configured)

Performance Issues

• Increase agentLifecycle.maxConcurrent to allow more Agents to run in parallel
• Increase agentLifecycle.idleSwapOutMs to reduce Agent suspension frequency
• Adjust logLevel to warn or error to reduce logging I/O

Next Steps

• Managing Profiles: Define Agent personas
• Configuring Runtimes: Set up Agent runtimes
• Managing Skills: Add capabilities to Agents