From eff36ec856be5f47230fdce47d74ac44ba620091 Mon Sep 17 00:00:00 2001
From: Kunal Kotwani <kkotwani@amazon.com>
Date: Wed, 21 Sep 2022 14:04:06 -0700
Subject: [PATCH] Add support for skipping certain files for backporting

Signed-off-by: Kunal Kotwani <kkotwani@amazon.com>
---
 action.yml               |  3 +++
 src/backport.ts          | 12 +++++++++++-
 src/get-files-to-skip.ts | 14 ++++++++++++++
 src/index.ts             |  4 ++++
 4 files changed, 32 insertions(+), 1 deletion(-)
 create mode 100644 src/get-files-to-skip.ts

diff --git a/action.yml b/action.yml
index cbe0c96..7b15b01 100644
--- a/action.yml
+++ b/action.yml
@@ -5,6 +5,9 @@ inputs:
   add_labels:
     description: Comma separated list of labels to add to the backport PR.
     required: false
+  files_to_skip:
+    description: Comma seperated list of files to be skipped from the backport
+    required: false
   branch_name:
     description: Custom branch name for the backport PR.
     required: false
diff --git a/src/backport.ts b/src/backport.ts
index afce466..1414f62 100644
--- a/src/backport.ts
+++ b/src/backport.ts
@@ -88,6 +88,7 @@ const backportOnce = async ({
   base,
   body,
   commitToBackport,
+  filesToSkip,
   github,
   head,
   labelsToAdd,
@@ -98,6 +99,7 @@ const backportOnce = async ({
   base: string;
   body: string;
   commitToBackport: string;
+  filesToSkip: string[];
   github: InstanceType<typeof GitHub>;
   head: string;
   labelsToAdd: string[];
@@ -112,7 +114,12 @@ const backportOnce = async ({
   await git("switch", base);
   await git("switch", "--create", head);
   try {
-    await git("cherry-pick", "-x", commitToBackport);
+    await git("cherry-pick", "-x", "-n", commitToBackport);
+    for (const file of filesToSkip) {
+      await git("checkout", "HEAD", file);
+    }
+
+    await git("commit", "--no-edit", "-s");
   } catch (error: unknown) {
     await git("cherry-pick", "--abort");
     throw error;
@@ -221,6 +228,7 @@ const deleteBackportBranchIfMerged = async ({
 const backport = async ({
   branchName,
   deleteBranch,
+  filesToSkip,
   labelsToAdd,
   payload: {
     action,
@@ -242,6 +250,7 @@ const backport = async ({
 }: {
   branchName: string;
   deleteBranch: boolean;
+  filesToSkip: string[];
   labelsToAdd: string[];
   payload: EventPayloads.WebhookPayloadPullRequest;
   titleTemplate: string;
@@ -304,6 +313,7 @@ const backport = async ({
           base,
           body,
           commitToBackport,
+          filesToSkip,
           github,
           head,
           labelsToAdd,
diff --git a/src/get-files-to-skip.ts b/src/get-files-to-skip.ts
new file mode 100644
index 0000000..3bb456b
--- /dev/null
+++ b/src/get-files-to-skip.ts
@@ -0,0 +1,14 @@
+/**
+ * Get an array of files to be skipped from the backport PR.
+ * Filtering out empty strings.
+ */
+const getFilesToSkip = (input: string | undefined): string[] => {
+  if (input === undefined || input === "") {
+    return [];
+  }
+
+  const files_to_skip = input.split(",");
+  return files_to_skip.map((v) => v.trim()).filter((v) => v !== "");
+};
+
+export { getFilesToSkip };
diff --git a/src/index.ts b/src/index.ts
index b3c3c81..07201fc 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -4,6 +4,7 @@ import { EventPayloads } from "@octokit/webhooks";
 
 import { backport } from "./backport";
 import { getLabelsToAdd } from "./get-labels-to-add";
+import { getFilesToSkip } from "./get-files-to-skip";
 
 const run = async () => {
   try {
@@ -14,9 +15,12 @@ const run = async () => {
     debug(JSON.stringify(context, undefined, 2));
     const labelsInput = getInput("add_labels");
     const labelsToAdd = getLabelsToAdd(labelsInput);
+    const filesInput = getInput("files_to_skip");
+    const filesToSkip = getFilesToSkip(filesInput);
     await backport({
       branchName,
       deleteBranch,
+      filesToSkip,
       labelsToAdd,
       payload: context.payload as EventPayloads.WebhookPayloadPullRequest,
       titleTemplate,