Add custom RuleSet support (#38)

README.md

@@ -81,6 +81,10 @@ The default value is `ktlint`.
 Optional. Defines a file glob to identify files to be checked.
 The default value is an empty string.
 
+### `custom_rule_path`
+
+Optional. Provides path to JAR file with custom rules. The default value is an empty string.
+
 ## Example usage
 
 ```yml

action.yml

@@ -52,6 +52,10 @@ inputs:
     description: Optionally defines a file glob to identify files to be checked
     required: false
     default: ''
+  custom_rule_path:
+    description: Path to custom rule set JAR
+    required: false
+    default: ''
 runs:
   using: 'docker'
   image: 'Dockerfile'
@@ -66,6 +70,7 @@ runs:
     - ${{ inputs.baseline }}
     - ${{ inputs.ktlint_version }}
     - ${{ inputs.name }}
+    - ${{ inputs.custom_rule_path }}
 branding:
   icon: 'edit'
   color: 'blue'

entrypoint.sh

@@ -3,6 +3,7 @@
 export RELATIVE=
 export ANDROID=
 export BASELINE=
+export CUSTOM_RULE_PATH=
 
 if [ "$INPUT_KTLINT_VERSION" = "latest" ]; then
   curl -sSL https://api.github.com/repos/pinterest/ktlint/releases/latest --header "authorization: Bearer ${INPUT_GITHUB_TOKEN}" |
@@ -30,6 +31,10 @@ if [ "$INPUT_ANDROID" = true ]; then
   export ANDROID=--android
 fi
 
+if [ "$INPUT_CUSTOM_RULE_PATH" ]; then
+  export CUSTOM_RULE_PATH="--ruleset=${INPUT_CUSTOM_RULE_PATH}"
+fi
+
 cd "$GITHUB_WORKSPACE"
 
 git config --global --add safe.directory $GITHUB_WORKSPACE
@@ -38,7 +43,7 @@ export REVIEWDOG_GITHUB_API_TOKEN="${INPUT_GITHUB_TOKEN}"
 
 echo ktlint version: "$(ktlint --version)"
 
-ktlint --reporter=checkstyle $RELATIVE $ANDROID $BASELINE $INPUT_FILE_GLOB |
+ktlint --reporter=checkstyle $CUSTOM_RULE_PATH $RELATIVE $ANDROID $BASELINE $INPUT_FILE_GLOB |
   reviewdog -f=checkstyle \
     -name="${INPUT_NAME}" \
     -reporter="${INPUT_REPORTER}" \