Merge pull request #439 from hongaar/feature/configurable-commit-message

feat: configurable commit message

README.md

@@ -194,6 +194,24 @@ For more information see https://help.github.com/articles/about-pull-request-mer
 mergeMethod: merge
 ```
 
+### `mergeCommitMessage` (default: none)
+
+Optionally specify the merge commit message format. The following template tags
+are supported:
+
+* `{title}`: The pull request title at the moment it is merged
+* `{body}`: The pull request body at the moment it is merged
+* `{number}`: The pull request number
+* `{branch}`: The name of the source branch
+* `{commits}`: A list of merged commits
+
+When this option is not set, the merge commit message is controlled by
+GitHub and uses a combination of the title of the pull request when it was
+opened (note that later changes to the title are ignored) and a list of
+commits.
+
+This settings is ignored when `mergeMethod` is set to `rebase`.
+
 ### `rules` (default: none)
 
 Rules allow more flexiblity configuring conditions for automatically merging. Each rule is defined by

auto-merge.example.yml

@@ -37,6 +37,23 @@ deleteBranchAfterMerge: true
 # For more information see https://help.github.com/articles/about-pull-request-merges/
 mergeMethod: merge
 
+# Optionally specify the merge commit message format. The following template
+# tags are supported:
+# * {title}: The pull request title at the moment it is merged
+# * {body}: The pull request body at the moment it is merged
+# * {number}: The pull request number
+# * {branch}: The name of the source branch
+# * {commits}: A list of merged commits
+# When this option is not set, the merge commit message is controlled by
+# GitHub and uses a combination of the title of the pull request when it was
+# opened (note that later changes to the title are ignored) and a list of
+# commits.
+# This settings is ignored when `mergeMethod` is set to `rebase`.
+mergeCommitMessage: |
+  {title} (#{number})
+
+  {body}
+
 # Blocking labels are the labels that can be attached to a pull request to make sure the pull request
 # is not being automatically merged.
 blockingLabels:

query.graphql

@@ -24,6 +24,7 @@ query PullRequestQuery($owner:String!, $repo:String!, $pullRequestNumber:Int!) {
         }
       }
       title
+      body
       authorAssociation
       baseRef {
         repository {
@@ -61,6 +62,14 @@ query PullRequestQuery($owner:String!, $repo:String!, $pullRequestNumber:Int!) {
           }
         }
       }
+      allCommits: commits(last: 100) {
+        nodes {
+          commit {
+            abbreviatedOid
+            messageHeadline
+          }
+        }
+      }
       headRef {
         repository {
           owner {
@@ -74,6 +83,7 @@ query PullRequestQuery($owner:String!, $repo:String!, $pullRequestNumber:Int!) {
         name
       }
       headRefOid
+      headRefName
       repository {
         branchProtectionRules(last: 100) {
           nodes {

src/commit-message.ts

@@ -0,0 +1,50 @@
+import { PullRequestInfo } from './models'
+import { Config } from './config'
+
+export function getCommitMessage (
+  pullRequestInfo: PullRequestInfo,
+  config: Config
+) {
+  return config.mergeCommitMessage
+    ? getCustomCommitMessage(pullRequestInfo, config.mergeCommitMessage)
+    : null
+}
+
+export function splitCommitMessage (message: string) {
+  const [title, ...body] = message.trim().split('\n')
+
+  return {
+    title: title.trim(),
+    body: body.join('\n').trim()
+  }
+}
+
+type Tag = 'title' | 'body' | 'number' | 'branch' | 'commits'
+
+type Tags = {
+  [key in Tag]: (pullRequestInfo: PullRequestInfo) => string
+}
+
+function getCustomCommitMessage (
+  pullRequestInfo: PullRequestInfo,
+  template: string
+) {
+  const tagResolvers: Tags = {
+    title: pullRequestInfo => pullRequestInfo.title,
+    body: pullRequestInfo => pullRequestInfo.body,
+    number: pullRequestInfo => pullRequestInfo.number.toString(),
+    branch: pullRequestInfo => pullRequestInfo.headRefName,
+    commits: pullRequestInfo => pullRequestInfo.allCommits.nodes
+      .map(node => `* ${node.commit.messageHeadline} (${node.commit.abbreviatedOid})`)
+      .join('\n')
+  }
+
+  return template.replace(/\{(\w+)\}/g, (match, tagName: Tag) => {
+    const tagResolver = tagResolvers[tagName]
+    if (tagResolver) {
+      return tagResolver(pullRequestInfo)
+    } else {
+      return match
+    }
+  })
+}

src/config.ts

@@ -38,6 +38,7 @@ export type Config = {
   updateBranch: boolean,
   deleteBranchAfterMerge: boolean,
   mergeMethod: 'merge' | 'rebase' | 'squash'
+  mergeCommitMessage?: string
   reportStatus: boolean
 } & ConditionConfig
 
@@ -93,7 +94,8 @@ const configDecoder: Decoder<Config> = object({
     constant<'merge'>('merge'),
     constant<'rebase'>('rebase'),
     constant<'squash'>('squash')
-  )
+  ),
+  mergeCommitMessage: optional(string())
 })
 
 export function validateConfig (config: any) {

src/github-models.ts

@@ -63,6 +63,8 @@ export function validatePullRequestQuery (pullRequestQuery: PullRequestQuery) {
               labels: assertNotNullNodes(pullRequest.labels, 'No permission to labels of pull request',
                 labels => removeTypename(labels)
               ),
+              title: pullRequest.title,
+              body: pullRequest.body,
               reviews: assertNotNullNodes(pullRequest.reviews, 'No permission to fetch reviews',
                 review => ({
                   ...removeTypename(review),
@@ -96,6 +98,7 @@ export function validatePullRequestQuery (pullRequestQuery: PullRequestQuery) {
                 })
               ),
               headRefOid: pullRequest.headRefOid as string,
+              headRefName: pullRequest.headRefName,
               commits: assertNotNullNodes(pullRequest.commits, 'No permission to fetch commits',
                 commit => ({
                   ...removeTypename(commit),
@@ -116,6 +119,16 @@ export function validatePullRequestQuery (pullRequestQuery: PullRequestQuery) {
                   }
                 })
               ),
+              allCommits: assertNotNullNodes(pullRequest.allCommits, 'No permission to fetch commits',
+                commit => ({
+                  ...removeTypename(commit),
+                  commit: {
+                    ...removeTypename(commit.commit),
+                    abbreviatedOid: commit.commit.abbreviatedOid,
+                    messageHeadline: commit.commit.messageHeadline
+                  }
+                })
+              ),
               repository: {
                 ...removeTypename(pullRequest.repository),
                 branchProtectionRules: assertNotNullNodes(pullRequest.repository.branchProtectionRules, 'No permission to fetch branchProtectionRules',

src/pull-request-handler.ts

@@ -6,6 +6,8 @@ import { getPullRequestStatus, PullRequestStatus } from './pull-request-status'
 import { queryPullRequest } from './pull-request-query'
 import { updateStatusReportCheck } from './status-report'
 import { MergeStateStatus } from './query.graphql'
+import { Config } from './config'
+import { getCommitMessage, splitCommitMessage } from './commit-message'
 
 export interface PullRequestContext extends HandlerContext {
   reschedulePullRequest: () => void,
@@ -55,11 +57,11 @@ export type PullRequestAction = 'reschedule' | 'update_branch' | 'merge' | 'dele
 export type PullRequestActions
   = (
     []
-  | ['reschedule']
-  | ['update_branch', 'reschedule']
-  | ['merge']
-  | ['merge', 'delete_branch']
-) & Array<PullRequestAction>
+    | ['reschedule']
+    | ['update_branch', 'reschedule']
+    | ['merge']
+    | ['merge', 'delete_branch']
+  ) & Array<PullRequestAction>
 
 export type PullRequestPlanCode
   = 'closed'
@@ -81,6 +83,11 @@ export type PullRequestPlan = {
   actions: PullRequestActions
 }
 
+type ExtraMergeParams = {
+  commit_title?: string
+  commit_message?: string
+}
+
 function getChecksMarkdown (pullRequestStatus: PullRequestStatus) {
   return Object.entries(pullRequestStatus)
     .map(([name, result]) => {
@@ -98,6 +105,27 @@ function getChecksMarkdown (pullRequestStatus: PullRequestStatus) {
     .join('\n')
 }
 
+function markdownParagraphs (paragraphs: string[]) {
+  return paragraphs
+    .filter(paragraph => paragraph)
+    .join('\n\n')
+}
+
+function getCommitMessageMarkdown (pullRequestInfo: PullRequestInfo, config: Config) {
+  const commitMessage = getCommitMessage(pullRequestInfo, config)
+
+  if (commitMessage === null) {
+    return ''
+  }
+
+  const quotedCommitMessage = commitMessage.split('\n').map(line => `> ${line}`).join('\n')
+
+  return markdownParagraphs([
+    'Commit message preview:',
+    quotedCommitMessage
+  ])
+}
+
 /**
  * Determines which actions to take based on the pull request and the condition results
  */
@@ -123,15 +151,23 @@ export function getPullRequestPlan (
   if (pendingConditions.length > 0) {
     return {
       code: 'pending_condition',
-      message: `There are pending conditions:\n\n${getChecksMarkdown(pullRequestStatus)}`,
+      message: markdownParagraphs([
+        'There are pending conditions:',
+        getChecksMarkdown(pullRequestStatus),
+        getCommitMessageMarkdown(pullRequestInfo, config)
+      ]),
       actions: ['reschedule']
     }
   }
 
   if (failingConditions.length > 0) {
     return {
       code: 'failing_condition',
-      message: `There are failing conditions:\n\n${getChecksMarkdown(pullRequestStatus)}`,
+      message: markdownParagraphs([
+        'There are failing conditions:',
+        getChecksMarkdown(pullRequestStatus),
+        getCommitMessageMarkdown(pullRequestInfo, config)
+      ]),
       actions: []
     }
   }
@@ -181,13 +217,19 @@ export function getPullRequestPlan (
       if (config.deleteBranchAfterMerge && !isInFork(pullRequestInfo)) {
         return {
           code: 'merge_and_delete',
-          message: 'Will merge the pull request and delete its branch',
+          message: markdownParagraphs([
+            'Will merge the pull request and delete its branch.',
+            getCommitMessageMarkdown(pullRequestInfo, config)
+          ]),
           actions: ['merge', 'delete_branch']
         }
       } else {
         return {
           code: 'merge',
-          message: 'Will merge the pull request',
+          message: markdownParagraphs([
+            'Will merge the pull request.',
+            getCommitMessageMarkdown(pullRequestInfo, config)
+          ]),
           actions: ['merge']
         }
       }
@@ -313,35 +355,47 @@ async function mergePullRequest (
   pullRequestInfo: PullRequestInfo
 ) {
   const { config } = context
+  const extraParams: ExtraMergeParams = {}
   const pullRequestReference = getPullRequestReference(pullRequestInfo)
+  const commitMessage = getCommitMessage(pullRequestInfo, config)
+
+  if (commitMessage !== null) {
+    const commitMessageParams = splitCommitMessage(commitMessage)
+    extraParams.commit_title = commitMessageParams.title
+    extraParams.commit_message = commitMessageParams.body
+  }
+
   // This presses the merge button.
   result(
     await context.github.pulls.merge({
       owner: pullRequestReference.owner,
       repo: pullRequestReference.repo,
       pull_number: pullRequestReference.number,
-      merge_method: config.mergeMethod
+      merge_method: config.mergeMethod,
+      ...extraParams
     })
   )
 }
 
+function getPlanTitle (plan: PullRequestPlan) {
+  return plan.actions.some(action => action === 'merge')
+    ? 'Merging'
+    : plan.actions.some(action => action === 'update_branch')
+      ? 'Updating branch'
+      : plan.actions.some(action => action === 'reschedule')
+        ? 'Waiting'
+        : 'Not merging'
+}
+
 export async function handlePullRequestStatus (
   context: PullRequestContext,
   pullRequestInfo: PullRequestInfo,
   pullRequestStatus: PullRequestStatus
 ) {
   const plan = getPullRequestPlan(context, pullRequestInfo, pullRequestStatus)
+  const title = getPlanTitle(plan)
 
-  await updateStatusReportCheck(context, pullRequestInfo,
-    plan.actions.some(action => action === 'merge')
-      ? 'Merging'
-      : plan.actions.some(action => action === 'update_branch')
-        ? 'Updating branch'
-        : plan.actions.some(action => action === 'reschedule')
-          ? 'Waiting'
-          : 'Not merging',
-    plan.message
-  )
+  await updateStatusReportCheck(context, pullRequestInfo, title, plan.message)
 
   const { actions } = plan
   context.log.debug('Actions:', actions)