Debugging a rails application in Minikube

Question

I'm running a rails service inside a minikube cluster on my local machine. I like to throw breakpoints into my code in order to interact with the process. This doesn't work while inside Minikube. I can attach to the pod running my rails container and hit the binding.pr statement in my code, and instead of getting an interactive breakpoint, I simply see the pry attempt to create a breakpoint, but ultimately move right past it. Anyone figure out how to get this working? I'm guessing the deployed pod itself isn't interactive.

Answer 1

You are trying to get interactive access to your application.

Your problem is caused by the fact that the k8s does not allocate a TTY and stdin buffer for the container by default.

I have replicated your issue and found a solution.

To get an interactive breakpoint you have to add 2 flags to your Deployment yaml to indicate that you need interactive session:

   stdin: true
   tty: true

Here is an example of a deployment:

   apiVersion: apps/v1
   kind: Deployment
   metadata:
     labels:
       run: test
     name: test
   spec:
     selector:
       matchLabels:
         run: test
     template:
       metadata:
         labels:
           run: test
       spec:
         containers:
         - image: test
           name: test
           stdin: true
           tty: true

You can find more info about it here.

Remember to use -it option when attaching to pod, like shown below:

   kubectl attach -it <pod_name>

Let me know if that helped.