Debug your Openshift Node.js Apps locally with Visual Studio Code (VS Code)

VS Code has built-in debugging support for the Node.js runtime. But how do you remote debug a Node.js application running on Openshift.

Setup Node debugger on Openshift

On Openshift in the browser open the project your app is running on

Select the Pod

Select Terminal for the pod

Node v6 LTS has an inbuilt debugger and can be run in the Terminal enter

node debug app.js 

where app.js will be the starting point for running your app (typically app.js or index.js). This exposes your app in debug mode on port 5858 by default.

Note: Node v8 LTS uses inspect so the command would be node inspect app.js

From the command line login to Openshift and change to your project

oc login https://your-openshift-instance:8443

oc project your-project-name

oc set probe dc your-app-name --liveness --readiness --remove=true

This disables the liveness and readiness checks so your pod doesn’t restart during remote debugging. Returns the similar to the following

deploymentconfig "your-app-name" updated
oc port-forward $(oc get po | grep your-app-name | grep Running | awk '{print $1}') 8888:5858

This will forward port 5858 from the running Pod to a local port 8888 (8888 is an example you can use any free port). Returns the following

Forwarding from 127.0.0.1:8888 -> 5858
Forwarding from [::1]:8888 -> 5858

So now you have debug started in Openshift and forwarded to localhost:8888

Connect Vs Code to the remote

Open Visual Studio Code

Open the Application you wish to debug.

Select Debug option and select Configure ‘launch.json.

Set the launch.json file similar to the following, using the port 8888 from the port forward command, the “program” :”${workspaceRoot}/app.js” variable should match your node.js starting point.

{
    "version": "0.2.0",
    "configurations": [
        {
            "type": "node",
            "request": "attach", 
            "name": "Attach to Remote",
            "address": "localhost",
            "protocol": "legacy",
            "port": 8888,
            "localRoot": "${workspaceRoot}",
            "remoteRoot": "/opt/app-root/src/"
        },
        {
            "type": "node",
            "request": "launch",
            "protocol": "legacy",
            "name": "Launch Program",
            "program": "${workspaceRoot}/app.js"
        }
    ]
}

Click the drop down beside the play button and select Attach to Remote

Click on the play button or Select from drop down to start debugging

That it you can now use the debugger as normal

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