how to use Cloud Builder for NodeJS application - Virtual Machine

[dontknow]

I am trying from last two days and not a big success yet, I am not sure if I am on right path: Here is my scenario:

Created a VM in google cloud compute engine and enabled http & https

Enabled CLOUD BUILDER API and created trigger for GitHub push in main branch

Also enabled the compute instance admin v1 (compute engine) inside settings -> Service account permissions

So I am developing an sample test NodeJS app to check how to automate everything from push to live deployment and I can see examples and guide for push and deployment via cloud run , app engine, GKE etc. but didn't find any guide for deploying to compute engine virtual machine;

here are some of files how I am trying to deploy my NodeJS application

index.js

const express = require('express');

const app = express()

const port=3000;

app.get('/',(req,res)=>{

    res.send('Hello World')

});

app.listen(port,()=>{

    console.log('sample app is running on port ${port}')

})

------------------------------------------------------

Dockerfile

FROM node:16

RUN mkdir -p /usr/src/app

# Create app directory

WORKDIR /usr/src/app

COPY package.json /usr/src/app/

RUN npm install

# Bundle app source

COPY . /usr/src/app

EXPOSE 3000

CMD [ "npm", "start" ]

--------------------------------------------------

cloudbuild.yaml

steps:

    - name: 'gcr.io/cloud-builders/docker'

      args: ['build','-t', 'eu.gcr.io/mysample-app/sampletestapp:latest','.']

    - name: 'gcr.io/cloud-builders/docker'

      args: ['push','eu.gcr.io/mysample-app/sampletestapp:latest',]

    - name: 'gcr.io/cloud-builders/docker'

      args: ['run','--publish', '3000:3000','eu.gcr.io/mysample-app/sampletestapp:latest']

    images: ['eu.gcr.io/mysample-app/sampletestapp:latest']

-----------------------------------------------------------

With all above setup when I commit some changes, i can see trigger is running and it build the application successfully, and it fails at docker run 

Finished Step #1

Starting Step #2

Step #2: Already have image (with digest): gcr.io/cloud-builders/docker

Step #2: 

Step #2: > testapp@1.0.0 start

Step #2: > dist/index.js

Step #2: 

Step #2: sh: 1: dist/index.js: Permission denied

Finished Step #2

ERROR

ERROR: build step 2 "gcr.io/cloud-builders/docker" failed: step exited with non-zero status: 126

But even after successfully build I am unable to access my API (which is simple / root) Also when login to VM via SSH I don't see anything on that WORKDIR (/usr/src/app) /app directory doesn't exist, also found that docker is not installed

So I need help in these :

How cloud builder know where to build and deploy because I didn't mentioned any linking with my virtual machine in cloudbuilder.yml, which VM it will use to deploy or if we don't mention then it choose the first running VM

Is it possible to build and run automatically on VM via this approach ?, if not what I can do?

Is something wrong in my code ?

sorry for my bad explanation, Any help would be much appreciated

Thanks