Add source_pr_number input

README.md

@@ -263,6 +263,14 @@ Placeholders can be used to define variable values.
 These are indicated by a dollar sign and curly braces (`${placeholder}`).
 Please refer to this action's README for all available [placeholders](#placeholders).
 
+### `source_pr_number`
+
+Default: `''` (not set)
+
+Specifies the pull request (by its number) to backport, i.e. the source pull request.
+When set, the action will backport the specified pull request to each target branch.
+When not set, the action determines the source pull request from the event payload.
+
 ### `target_branches`
 
 Default: `''` (disabled)

action.yml

@@ -5,7 +5,7 @@ author: korthout
 inputs:
   branch_name:
     description: >
-      Template used as the name for branches created by this action. 
+      Template used as the name for branches created by this action.
       Placeholders can be used to define variable values.
       These are indicated by a dollar sign and curly braces (`${placeholder}`).
       Please refer to this action's README for all available placeholders.
@@ -52,23 +52,23 @@ inputs:
 
       #### `conflict_resolution`
 
-      Specifies how the action will handle a conflict occuring during the cherry-pick. 
+      Specifies how the action will handle a conflict occuring during the cherry-pick.
       In all cases, the action will stop the cherry-pick at the first conflict encountered.
 
       Behavior is defined by the option selected.
       - When set to `fail` the backport fails when the cherry-pick encounters a conflict.
       - When set to `draft_commit_conflicts` the backport will always create a draft pull request with the first conflict encountered committed.
 
       Instructions are provided on the original pull request on how to resolve the conflict and continue the cherry-pick.
-      
+
       #### `downstream_repo`
-      
+
       Define if you want to backport to a repository other than where the workflow runs.
 
       By default, the action always backports to the repository in which the workflow runs.
-      
+
       #### `downstream_owner`
-      
+
       Define if you want to backport to another owner than the owner of the repository the workflow runs on.
       Only takes effect if the `downstream_repo` property is also defined.
 
@@ -116,6 +116,11 @@ inputs:
       Please refer to this action's README for all available placeholders.
     default: >-
       [Backport ${target_branch}] ${pull_title}
+  source_pr_number:
+    description: >
+      Specifies the pull request (by its number) to backport, i.e. the source pull request.
+      When set, the action will backport the specified pull request to each target branch.
+      When not set, the action determines the source pull request from the event payload.
   target_branches:
     description: >
       The action will backport the pull request to each specified target branch (space-delimited).

dist/index.js

@@ -94,7 +94,9 @@ class Backport {
                     : workflowRepo;
                 if (repo === undefined)
                     throw new Error("No repository defined!");
-                const pull_number = this.github.getPullNumber();
+                const pull_number = this.config.source_pr_number === undefined
+                    ? this.github.getPullNumber()
+                    : this.config.source_pr_number;
                 const mainpr = yield this.github.getPullRequest(pull_number);
                 if (!(yield this.github.isMerged(mainpr))) {
                     const message = "Only merged pull requests can be backported.";
@@ -467,7 +469,7 @@ class Backport {
         const suggestionToResolve = this.composeMessageToResolveCommittedConflicts(target, branchname, commitShasToCherryPick, conflictResolution);
         return (0, dedent_1.default) `Created backport PR for \`${target}\`:
                   - ${downstream}#${pr_number} with remaining conflicts!
-                  
+
                   ${suggestionToResolve}`;
     }
     createOutput(successByTarget, createdPullRequestNumbers) {
@@ -1078,6 +1080,7 @@ function run() {
         const copy_milestone = core.getInput("copy_milestone");
         const copy_requested_reviewers = core.getInput("copy_requested_reviewers");
         const experimental = JSON.parse(core.getInput("experimental"));
+        const source_pr_number = core.getInput("source_pr_number");
         if (cherry_picking !== "auto" && cherry_picking !== "pull_request_head") {
             const message = `Expected input 'cherry_picking' to be either 'auto' or 'pull_request_head', but was '${cherry_picking}'`;
             console.error(message);
@@ -1124,6 +1127,7 @@ function run() {
             copy_milestone: copy_milestone === "true",
             copy_requested_reviewers: copy_requested_reviewers === "true",
             experimental: Object.assign(Object.assign({}, backport_1.experimentalDefaults), experimental),
+            source_pr_number: source_pr_number === "" ? undefined : parseInt(source_pr_number),
         };
         const backport = new backport_1.Backport(github, config, git);
         return backport.run();

src/backport.ts

@@ -20,6 +20,7 @@ export type Config = {
   labels: {
     pattern?: RegExp;
   };
+  source_pr_number?: number;
   pull: {
     description: string;
     title: string;
@@ -104,7 +105,10 @@ export class Backport {
 
       if (repo === undefined) throw new Error("No repository defined!");
 
-      const pull_number = this.github.getPullNumber();
+      const pull_number =
+        this.config.source_pr_number === undefined
+          ? this.github.getPullNumber()
+          : this.config.source_pr_number;
       const mainpr = await this.github.getPullRequest(pull_number);
 
       if (!(await this.github.isMerged(mainpr))) {
@@ -677,7 +681,7 @@ export class Backport {
     );
     return dedent`Created backport PR for \`${target}\`:
                   - ${downstream}#${pr_number} with remaining conflicts!
-                  
+
                   ${suggestionToResolve}`;
   }
 

src/main.ts

@@ -30,6 +30,7 @@ async function run(): Promise<void> {
   const copy_milestone = core.getInput("copy_milestone");
   const copy_requested_reviewers = core.getInput("copy_requested_reviewers");
   const experimental = JSON.parse(core.getInput("experimental"));
+  const source_pr_number = core.getInput("source_pr_number");
 
   if (cherry_picking !== "auto" && cherry_picking !== "pull_request_head") {
     const message = `Expected input 'cherry_picking' to be either 'auto' or 'pull_request_head', but was '${cherry_picking}'`;
@@ -85,6 +86,8 @@ async function run(): Promise<void> {
     copy_milestone: copy_milestone === "true",
     copy_requested_reviewers: copy_requested_reviewers === "true",
     experimental: { ...experimentalDefaults, ...experimental },
+    source_pr_number:
+      source_pr_number === "" ? undefined : parseInt(source_pr_number),
   };
   const backport = new Backport(github, config, git);