Simplify the argument passing

Assuming you know how to use packer, we don't need to setup an argument
template for this. This also makes the whole action more flexible.

README.md

@@ -1,17 +1,19 @@
 # Packer AMI Builder
-Use GitHub Action to execute Packer AMI build. This supports both HCL and JSON packer template files.
+Use GitHub Action to execute Packer build commands. This supports both HCL and
+JSON packer template files.
 
-For HCL Mode, set `templateFile` to `.` to read all `pkr.hcl` files within your working directory.
+For HCL Mode, set `packerArgs` to `build .` to load all `.pkr.hcl` files within
+the dir. To use the override variable file, set `packerArgs` to
+`build -var-file=overrides.pkrvars.hcl`
 
 ## Input Parameters
-| Name           | Description                            | Mandatory | Default |
-| -------------- | -------------------------------------- | --------- | ------- |
-| `templateFile` | Packer template file name              | Yes       |         |
-| `varFile`      | Optional user variables file           | No        | `NULL`  |
-| `workDir`      | Working directory inside the container | No        | `.`     |
+| Name         | Description                                              | Mandatory | Default |
+| ------------ | -------------------------------------------------------- | --------- | ------- |
+| `packerArgs` | Arguments that will be passed down to the packer command | Yes       |         |
+| `workDir`    | Working directory inside the container                   | No        | `.`     |
 
 ## Example
-Create a workflow file (`.github/workflows/ami-build.yaml`)like below:
+Create a workflow file (e.g `.github/workflows/ami-build.yaml`) like below:
 
 ```yaml
 name: Build an AMI using Packer
@@ -28,8 +30,7 @@ jobs:
       - name: Packer AMI Build
         uses: zmingxie/packer-ami-builder@master
         with:
-          templateFile: 'packer-template.json'
-          varFile: 'packer-vars.json'
+          packerArgs: 'build template.json'
           workDir: '.'
         env:
           AWS_ACCESS_KEY_ID: ${{ secrets.AWS_ACCESS_KEY_ID }}

action.yml

@@ -6,13 +6,9 @@ branding:
   icon: 'anchor'
 
 inputs:
-  templateFile:
-    description: 'Packer template file name'
+  packerArgs:
+    description: 'Arguments that will be passed down to the packer command'
     required: true
-  varFile:
-    description: 'Optional user variables file'
-    required: false
-    default: NULL
   workDir:
     description: 'Working directory inside the container'
     required: false

entrypoint.sh

@@ -1,34 +1,7 @@
 #!/bin/bash
-set -e
+set -ex
 
 cd "${INPUT_WORKDIR:-.}"
 
-# By default, HCL_MODE is disabled
-HCL_MODE=false
-if [[ ${INPUT_TEMPLATEFILE} == '.' || ${INPUT_TEMPLATEFILE} =~ '*.pkr.hcl' ]]; then
-  HCL_MODE=true
-fi
-echo "[INFO] HCL_MODE is ${HCL_MODE}"
-
-if [[ "${HCL_MODE}" == false && ! -f "${INPUT_TEMPLATEFILE}" ]]; then
-  echo "Error! Template file [${INPUT_TEMPLATEFILE}] is not found!"
-  exit 1
-fi
-
-# Validate the template (Currently doesn't work with HCL files)
-if [[ "${HCL_MODE}" == false ]]; then
-  packer validate ${INPUT_TEMPLATEFILE}
-  if [[ $? -ne 0 ]]; then
-    echo "Error! Packer template is not valid"
-    exit 1
-  fi
-fi
-
-if [[ -f "${INPUT_VARFILE}" ]]; then
-  VAR_FILE_FLAG="-var-file=${INPUT_VARFILE}"
-else
-  VAR_FILE_FLAG=""
-fi
-
-# Run packer build
-packer build ${VAR_FILE_FLAG} ${INPUT_TEMPLATEFILE}
+# Run packer with the given arguments
+packer ${INPUT_PACKERARGS}