Troubleshooting SDK connection to Relay

Affected: All SDKs (client-side and server-side) attempting to connect to the Relay Proxy

Symptoms

When attempting to establish a connection between the SDK and the Relay Proxy, you might encounter the following symptoms:

1. Delayed Initialization: The SDK takes an unusually long time to initialize.

2. Unexpected Flag Values: The application utilizes unexpected default values instead of the ones defined in LaunchDarkly.

3. Initialization Errors: Errors associated with connection, environment, or authentication pop up during SDK initialization.

4. Delayed Feature Flag Updates: Changes to feature flags in the LaunchDarkly UI don't reflect in the application in real-time.

5. Connection Timeout Errors: SDK throws errors related to connection timeouts or unreachable endpoints.

Cause

An understanding of what might be causing the issue can be pivotal for troubleshooting. Here are some potential reasons:

1. SDK Configuration: Incorrect setup of the SDK to interface with the Relay Proxy.

2. Relay Proxy Issues: The Relay Proxy itself may be facing connectivity issues with LaunchDarkly.

3. Network Disruptions: Temporary network instabilities between the SDK and the Relay Proxy.

4. Invalid SDK Keys: The use of outdated, revoked, or incorrect SDK keys.

5. Version Mismatches: Outdated versions of the SDK or Relay Proxy that aren't compatible with each other.

Solution

To address these causes, follow these detailed steps:

1. SDK Configuration:

   1. Confirm that the SDK is properly configured to connect to the Relay Proxy's address and port.

   2. Cross-check environment-specific variables and endpoints.

   3. If using a client-side SDK, ensure the Relay Proxy is set to support client-side SDKs.

2. Test Connection:

   1. Verify the SDK's connection to the Relay Proxy, by execute a feature flag evaluation:

    curl -X REPORT localhost:8030/sdk/evalx/context \
         -H "Authorization: sdk-key-123abc" \
         -H "Content-Type: application/json" \
         -d '{"key": "context-key-123abc", "email":"sandy@example.com"}'

   • An unsuccessful evaluation or timeout may indicate connection issues.

3. Network Stability:

   1. Ensure a stable network connection between the SDK and the Relay Proxy.

   2. Utilize network diagnostic tools to check for dropped packets or high latency.

   3. Investigate potential network firewalls, proxies, or blocks hindering the connection.

4. SDK Key Validation:

   1. Double-check the SDK key. Ensure it's the correct key for the environment you're connecting to.

   2. Make sure the key hasn't been revoked or replaced in LaunchDarkly.

5. Version Check:

   1. Confirm you're using supported versions of both the SDK and the Relay Proxy.

   2. Consider updating to the latest versions if not already on them.

6. Relay Proxy Monitoring:

   1. Monitor the health and performance of the Relay Proxy.

   2. If it's overwhelmed with requests, consider optimizing its configuration or scaling the setup.

   3. Examine Relay Proxy logs for any evident issues or errors.

Resources

• Relay Proxy GitHub Repository - Status Health Check
• Relay Proxy GitHub Repository - Service Endpoints
• Configuring SDKs for the Relay Proxy