feat(terrascan): Add support for __GIT_WORKING_DIR__ in hooks arguments (#943)

Author: GSokol

README.md

@@ -1123,6 +1123,14 @@ If the generated name is incorrect, set them by providing the `module-repo-short
 
     See the `terrascan run -h` command line help for available options.
 
+    To pass the config file path, use the `__GIT_WORKING_DIR__` placeholder. It will be replaced with the Git working directory (repo root) at run time. For example:
+
+    ```yaml
+    - id: terrascan
+      args:
+        - --args=--config-path=__GIT_WORKING_DIR__/.terrascan.toml
+    ```
+
 2. Use the `--args=--verbose` parameter to see the rule ID in the scanning output. Useful to skip validations.
 3. Use `--skip-rules="ruleID1,ruleID2"` parameter to skip one or more rules globally while scanning (e.g.: `--args=--skip-rules="ruleID1,ruleID2"`).
 4. Use the syntax `#ts:skip=RuleID optional_comment` inside a resource to skip the rule for that resource.

hooks/terrascan.sh

@@ -12,6 +12,10 @@ function main {
   common::parse_cmdline "$@"
   common::export_provided_env_vars "${ENV_VARS[@]}"
   common::parse_and_export_env_vars
+  # Support for setting PATH to repo root.
+  for i in "${!ARGS[@]}"; do
+    ARGS[i]=${ARGS[i]/__GIT_WORKING_DIR__/$(pwd)\/}
+  done
   # JFYI: terrascan color already suppressed via PRE_COMMIT_COLOR=never
 
   # shellcheck disable=SC2153 # False positive