Ensure json var-files have a .json extension

Otherwise it is assumed to be hcl

Author: dflook

.github/workflows/test-plan.yaml

@@ -844,6 +844,28 @@ jobs:
             my_var="single"
           var_file: tests/workflows/test-plan/test.tfvars
 
+  plan_json_tfvars:
+    runs-on: ubuntu-24.04
+    name: Plan JSON tfvars
+    permissions:
+      contents: read
+      pull-requests: write
+    env:
+      GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+        with:
+          persist-credentials: false
+
+      - name: Plan
+        uses: ./terraform-plan
+        with:
+          path: tests/workflows/test-plan/vars
+          variables: |
+            my_var="single"
+          var_file: tests/workflows/test-plan/test.tfvars.json
+
   plan_single_sensitive_variable:
     runs-on: ubuntu-24.04
     name: Plan single sensitive variable

image/actions.sh

@@ -399,10 +399,16 @@ function create-auto-tfvars() {
             fi
 
             local file_name="${file_path##*/}"
-            local name="${file_name%.tfvars}"
+            local extension="${file_name##*.}"
 
-            debug_log "Creating autoloading tfvars file for $file_path: zzzz-dflook-terraform-github-actions-$AUTO_TFVARS_COUNTER.$name.auto.tfvars"
-            cp "$file_path" "$INPUT_PATH/zzzz-dflook-terraform-github-actions-$AUTO_TFVARS_COUNTER.$name.auto.tfvars"
+            if [[ "$extension" == "json" ]]; then
+                link_name="zzzz-dflook-terraform-github-actions-$AUTO_TFVARS_COUNTER.${file_name%.json}.auto.tfvars.json"
+            else
+                link_name="zzzz-dflook-terraform-github-actions-$AUTO_TFVARS_COUNTER.${file_name%.tfvars}.auto.tfvars"
+            fi
+
+            debug_log "Creating autoloading tfvars file for $file_path: $link_name"
+            cp "$file_path" "$INPUT_PATH/$link_name"
             AUTO_TFVARS_COUNTER=$(printf "%02d\n" "$((AUTO_TFVARS_COUNTER + 1))")
         done
     fi

tests/workflows/test-plan/test.tfvars.json

@@ -0,0 +1,4 @@
+{
+  "my_var_from_file": "monkey",
+  "my_var": "this should be overridden"
+}