How-to: Resolving 502 Errors for Instance Web Applications

Verify that the Instance is Running

To verify the instance is running:

• In OCI console main menu go to Compute then Instances.
• Select the instance and verify that the instance is in a running state.
• If status is stopped, start the instance.

Verify Application is Running

Next, verify the application is running on the instance.

• Use ssh to connect to the instance.
• Check the application listening port.

  netstat -tulnp | grep LISTEN | grep <PORT>

  Substitute <PORT> with the application's port number.

• If the command returns no matches, this indicates the application isn't running. Start the application.

Verify Connectivity on the Same Network

Use a VM on the same network to test connectivity.

• Use ssh to connect to an instance on the same network.
  Note
  
  In this example, the IP address of the machine to test is 10.0.0.5.
• Use curl to test the target VM. For example:

  curl -Ik https://10.0.0.5:8443

  If no response is returned, this could indicate a firewall configuration issue on the instance.

Check Load Balancer Configuration

If you're using a Load Balancer, ensure the backend sets are in a healthy state and attached.

Option 1

From the main menu go to Networking under Load Balancers select Load Balancer.

• Select the load balancer to review.
• On the Load Balancer Details page, check Backend set health status.

Option 2

From the main menu go to Networking under Load Balancers select Load Balancer.

• Select the load balancer to review.
• On the Load Balancer Details page, under resources, select Backend Sets.
• Select the backend set to review.
• Check Backend health status.

For more information, see Troubleshooting Load Balancer.