github action pull request event is not running - github

Question

I have a GitHub action code with terraform and ECR, ECS now I have two branch master and feature and when I created Pull-request for feature to master
then only my terraform plan code will run but when i create a Pull-request and merge to master then my GitHub action running but that part is skipped i am not sure why it is happing please find the below attached code
---
name: "workflow"
on:
# Triggers the workflow on push or pull request events but only for the "master" branch
push:
branches: [ "master" ]
# Allows you to run this workflow manually from the Actions tab
workflow_dispatch:
jobs:
cd:
name: "Deployment"
runs-on: "ubuntu-latest"
#if: startsWith(github.ref, 'refs/tags/')
steps:
- name: "Checkout Code"
uses: "actions/checkout#v2"
- name: Set tag
id: vars
run: echo "::set-output name=tag::${GITHUB_REF#refs/*/}"
- name: Configure AWS credential
uses: aws-actions/configure-aws-credentials#v1
with:
aws-access-key-id: ${{ secrets.AWS_ACCESS_KEY_ID }}
aws-secret-access-key: ${{ secrets.AWS_SECRET_ACCESS_KEY }}
aws-region: ${{ secrets.AWS_REGION }}
- name: Login to Amazon ECR
id: login-ecr
uses: aws-actions/amazon-ecr-login#v1
- name: Build, tag, and push image to Amazon ECR
id: build-image
env:
ECR_REGISTRY: ${{ steps.login-ecr.outputs.registry }}
ECR_REPOSITORY: my_ecr_repi
IMAGE_TAG: ${{ github.event.head_commit.message }}
run: |
docker build -t $ECR_REGISTRY/$ECR_REPOSITORY:$IMAGE_TAG .
docker push $ECR_REGISTRY/$ECR_REPOSITORY:$IMAGE_TAG
echo "::set-output name=image::$ECR_REGISTRY/$ECR_REPOSITORY:$IMAGE_TAG"
- name: Setup Terraform
uses: hashicorp/setup-terraform#v1
with:
cli_config_credentials_token: ${{ secrets.TF_API_TOKEN }}
- name: Terraform Init
run: |
cd terraform_with_ALB
terraform init
- name: Terraform Format
id: fmt
run: |
cd terraform_with_ALB
terraform fmt -check
- name: Terraform Validate
id: validate
run: |
cd terraform_with_ALB
terraform validate -no-color
- name: Terraform Plan
id: plan
if: github.event_name == 'pull_request'
run: |
cd terraform_with_ALB
terraform plan -no-color -input=false
continue-on-error: true
till terraform valiate it wokring fine after that it skip terraform plan part

Answer 1

you are missing the pull_request element in the on section.
on:
# Triggers the workflow on push or pull request events but only for the "master" branch
push:
branches: [ "master" ]
pull_request:
branches: [ "master" ]