My valid workflow file is :

env:
  TF_BACKEND_BUCKET: ${{ secrets.TF_BACKEND_BUCKET }}
  TF_BACKEND_KEY: ${{ secrets.TF_BACKEND_KEY }}
  TF_FILENAME: ${{ vars.TF_FILENAME }}
  TF_VAR_FILENAME: ${{ vars.TF_VAR_FILENAME }}


jobs:
  prepare_env:
    name: Prepare AWS Environment
    runs-on: ubuntu-latest
    environment:  ${{ inputs.cloud_provider }}
    steps:
      - name: Checkout code
        uses: actions/checkout@v3

      - name: Apply Variables and Secrets
        working-directory: deploy/terraform-aws
        ## Set AK/SK and terraform s3 backend info
        run: |
          echo "current path is: $(pwd)"
          ls -l provision-kafka-aws.tf
          sed -i "s/TF_BACKEND_BUCKET/$TF_BACKEND_BUCKET/g" provision-kafka-aws.tf

My invalid workflow file is :

env:
  TF_BACKEND_BUCKET: ${{ secrets.TF_BACKEND_BUCKET }}
  TF_BACKEND_KEY: ${{ secrets.TF_BACKEND_KEY }}
  TF_FILENAME: ${{ vars.TF_FILENAME }}
  TF_VAR_FILENAME: ${{ vars.TF_VAR_FILENAME }}


jobs:
  prepare_env:
    name: Prepare AWS Environment
    runs-on: ubuntu-latest
    environment:  ${{ inputs.cloud_provider }}
    steps:
      - name: Checkout code
        uses: actions/checkout@v3

      - name: Apply Variables and Secrets
        working-directory: deploy/terraform-aws
        ## Set AK/SK and terraform s3 backend info
        run: |
          echo "current path is: $(pwd)"
          ls -l provision-kafka-aws.tf
          sed -i "s/TF_BACKEND_BUCKET/$TF_BACKEND_BUCKET/g" $TF_VAR_FILENAME

The error output is :

sed: can't read provision-kafka-aws.tf
: No such file or directory

My question is : I am sure the file exists and ls is print out correcly. But github can’t find file when use variables. How to solve this?