feat: Add 'infile' option

README.md

@@ -15,8 +15,9 @@ This action will bump version, tag commit and generate a changelog with conventi
 - **Optional** `git-path`: Path filter for the logs. If set, only commits that match the path filter will be considered. By default, we won't use this feature(empty string).
 - **Optional** `preset`: Preset that is used from conventional commits. Default `angular`.
 - **Optional** `tag-prefix`: Prefix for the git tags. Default `v`.
+- **Optional** `input-file`: Read the changelog from this file. This will prepend the newly generated changelogs to the file's content.
 - **Optional** `output-file`: File to output the changelog to. Default `CHANGELOG.md`, when providing `'false'` no file will be generated / updated.
-- **Optional** `release-count`: Number of releases to preserve in changelog. Default `5`, use `0` to regenerate all.
+- **Optional** `release-count`: Number of releases to preserve in changelog. Default `5`, use `0` to regenerate all. This input has no effect if `input-file` is used.
 - **Optional** `version-file`: The path to the file that contains the version to bump (supports comma-separated list of file paths). Default `./package.json`.
 - **Optional** `version-path`: The place inside the version file to bump. Default `version`.
 - **Optional** `skip-git-pull`: Do not pull the repo before tagging. Ensure you full cloned the repo in the first place to get tags. Default `'false'`.

action.yml

@@ -56,13 +56,17 @@ inputs:
     default: "v"
     required: false
 
+  input-file:
+    description: "Read the changelog from this file. This will prepend the newly generated changelogs to the file's content"
+    required: false
+
   output-file:
     description: "File to output the changelog to"
     default: "CHANGELOG.md"
     required: false
 
   release-count:
-    description: "Number of releases to preserve in changelog"
+    description: "Number of releases to preserve in changelog. Default `5`, use `0` to regenerate all. This input has no effect if input-file is used"
     default: "5"
     required: false
 

src/helpers/generateChangelog.js

@@ -1,4 +1,5 @@
 const fs = require('fs')
+const { Readable } = require('stream');
 const conventionalChangelog = require('conventional-changelog')
 
 /**
@@ -67,12 +68,45 @@ module.exports.generateStringChangelog = (tagPrefix, preset, version, releaseCou
  * @param releaseCount
  * @param config
  * @param gitPath
+ * @param infile
  * @returns {Promise<>}
  */
-module.exports.generateFileChangelog = (tagPrefix, preset, version, fileName, releaseCount, config, gitPath) => new Promise((resolve) => {
+module.exports.generateFileChangelog = (tagPrefix, preset, version, fileName, releaseCount, config, gitPath, infile) => new Promise((resolve) => {
-  const changelogStream = getChangelogStream(tagPrefix, preset, version, releaseCount, config, gitPath)
+  const changelogStream = getChangelogStream(tagPrefix, preset, version, infile ? 1 : releaseCount, config, gitPath)
+
+  // The default changelog output to be streamed first
+  const readStreams = [changelogStream]
+
+  // If an input-file is provided and release count is not 0
+  if (infile) {
+    // The infile is read synchronously to avoid repeatedly reading newly written content while it is being written
+    const buffer = fs.readFileSync(infile);
+    const readableStream = Readable.from(buffer);
+    // We add the stream as the next item for later pipe
+    readStreams.push(readableStream)
+  }
+
+  const writeStream = fs.createWriteStream(fileName)
+
+  let currentIndex = 0;
+
+  function pipeNextStream() {
+    if (currentIndex < readStreams.length) {
+      const currentStream = readStreams[currentIndex];
+
+      currentStream.pipe(writeStream, { end: false });
+
+      currentStream.once('end', () => {
+        currentIndex++;
+        pipeNextStream();
+      });
+    } else {
+      // All stream pipes have completed
+      writeStream.end();
+      resolve();
+    }
+  }
+
+  pipeNextStream();
 
-  changelogStream
-    .pipe(fs.createWriteStream(fileName))
-    .on('finish', resolve)
 })

src/index.js

@@ -46,6 +46,7 @@ async function run() {
     const preChangelogGenerationFile = core.getInput('pre-changelog-generation')
     const gitUrl = core.getInput('git-url')
     const gitPath = core.getInput('git-path')
+    const infile = core.getInput('input-file')
     const skipCi = core.getBooleanInput('skip-ci')
     const createSummary = core.getBooleanInput('create-summary')
     const prerelease = core.getBooleanInput('pre-release')
@@ -72,6 +73,10 @@ async function run() {
       core.info(`Using "${preCommitFile}" as pre-commit script`)
     }
 
+    if (infile) {
+      core.info(`Using "${infile}" as input file`)
+    }
+
     if (preChangelogGenerationFile) {
       core.info(`Using "${preChangelogGenerationFile}" as pre-changelog-generation script`)
     }
@@ -172,7 +177,7 @@ async function run() {
       // If output file === 'false' we don't write it to file
       if (outputFile !== 'false') {
         // Generate the changelog
-        await changelog.generateFileChangelog(tagPrefix, preset, newVersion, outputFile, releaseCount, config, gitPath)
+        await changelog.generateFileChangelog(tagPrefix, preset, newVersion, outputFile, releaseCount, config, gitPath, infile)
       }
 
       if (!skipCommit) {