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Execute any script in a GitHub issue comment
TypeScript JavaScript
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Execute any script in a GitHub issue comment

Say "hello, world"

You can make GitHub Actions Bot to say "hello, world".

Post comment below on your issue or pull request.

For shorter, you can use as follows.

@github-actions run

await postComment("hello, world");

Introduce this action

Put .github/workflows/comment-run.yml to introduce comment-run.

# .github/workflows/comment-run.yml
name: "Comment run"
    types: [created, edited]

    runs-on: ubuntu-18.04
    - uses: actions/checkout@v2
        # 0 indicates all history
        fetch-depth: 0
    - uses: nwtgck/actions-comment-run@v1.1
        github-token: ${{ secrets.GITHUB_TOKEN }}
        allowed-associations: '["OWNER"]'

You can introduce comment-run with the following command.

mkdir -p .github/workflows && cd .github/workflows && wget && cd -

After introducing this, create new issue or pull request and post @github-actions run comment.

Comment author who can run scripts

Only accounts who have admin or write permission can execute the comment on your repository. (ref: Collaborators | GitHub Developer Guide)

By default, only owner can execute the scripts. You can change allowed-associations: '["OWNER"]' in the yaml above.

Here are examples.

  • allowed-associations: '["OWNER"]'
  • allowed-associations: '["OWNER", "MEMBER"]'
  • allowed-associations: '["OWNER", "COLLABORATOR"]'

Learn more: CommentAuthorAssociation | GitHub Developer Guide

Available variables in the js-comment-context

Here are available variables and functions in the ```js code block.

variable examples type or reference
context context.repo.owner, context.payload.comment toolkit/context.ts at @actions/github@1.1.0 · actions/toolkit
githubToken new GitHub(githubToken)
githubClient await githubClient.pulls.create(...), await githubClient.graphql(...) toolkit/packages/github at master · actions/toolkit
execSync execSync("ls -l") child_process.execSync()
postComment await postComment("**hey!**") (markdown: string) => Promise<void>, post GitHub issue/pull request comment
GitHub new GitHub(githubToken) toolkit/packages/github at master · actions/toolkit
fetch await fetch("") node-fetch/node-fetch: A light-weight module that brings window.fetch to Node.js
core core.debug('my message') toolkit/packages/core at master · actions/toolkit
exec await exec.exec("git status") toolkit/packages/exec at master · actions/toolkit

Other built-in variables and functions in Node.js such as process and require(...) are also available. This means you can use process.env for environment variables and require('fs') for file access.

Although other variables not in the list can be used on the comment, comment-run guarantees use of the variables list above and non-listed variables are not guaranteed to use.

Useful examples

LGTM Image

Post random LGTM image with

@github-actions run

<summary>LGTM 👍 </summary>

const res = await fetch("", {
  redirect: 'manual'
const webSiteUrl = res.headers.get('location');
const picUrl = new URL(webSiteUrl);
picUrl.pathname = picUrl.pathname.replace("/i/", "/p/");

Update all npm packages

Although Dependabot is useful, sometimes you might think bump all packages up. This comment allows you to do this.

@github-actions run

function exec(cmd) {

// Config
const gitUserEmail = "github-actions[bot]";
const gitUserName = "github-actions[bot]";
const prBranchName = "comment-run/npm-update";

const baseBranchName = context.payload.repository.default_branch";
exec(`git config --global "${gitUserEmail}"`);
exec(`git config --global "${gitUserName}"`);
exec(`git fetch --all`);
exec(`git checkout ${baseBranchName}`);
exec(`git checkout -b ${prBranchName}`);

const packageJson = JSON.parse(require('fs').readFileSync('package.json'));
const depStr = Object.keys(packageJson.dependencies || {}).join(' ');
const devDepStr = Object.keys(packageJson.devDependencies || {}).join(' ');
exec(`npm i ${depStr} ${devDepStr}`);

exec("git status");
exec("git add package*json");
exec(`git commit -m "chore(deps): update npm dependencies"`);
exec(`git push -fu origin ${prBranchName}`);

await githubClient.pulls.create({
  base: baseBranchName,
  head: prBranchName,
  owner: context.repo.owner,
  repo: context.repo.repo,
  title: "chore(deps): update npm dependencies",
  body: "update npm dependencies",

PR merge preview

GitHub Actions do not pass secrets to pull request from forked repositories. This security feature may restricts GitHub Actions usages. This comment is created to resolve the problem

@github-actions run

<summary>🚀 Merge preview</summary>

// Get pull-req URL like ""
const pullReqUrl = context.payload.issue.pull_request.url;
const githubUser = context.payload.repository.owner.login;
const res = await fetch(pullReqUrl, {
  headers: [
    ['Authorization', `Basic ${Buffer.from(`${githubUser}:${githubToken}`).toString('base64')}`]
const resJson = await res.json();
const prUserName = resJson.head.user.login;
const baseBranchName = resJson.base.ref;
const branchName = resJson.head.ref;
const fullRepoName = resJson.head.repo.full_name;
const previewBranchName = `actions-merge-preview/${prUserName}-${branchName}`;
execSync(`git config --global "github-actions[bot]"`);
execSync(`git config --global "github-actions[bot]"`);
// (from:
execSync(`git fetch --all`);
console.log(execSync(`git checkout ${baseBranchName}`).toString());
console.log(execSync(`git checkout -b ${previewBranchName} ${baseBranchName}`).toString());
console.log(execSync(`git pull${fullRepoName}.git ${branchName}`).toString());
// Push preview branch
// NOTE: Force push (should be safe because preview branch always start with "actions-merge-preview/")
execSync(`git push -fu origin ${previewBranchName}`);
const baseRepoFullName = context.payload.repository.full_name;
// Comment body
const commentBody = `🚀 Preview branch:  \n<${baseRepoFullName}/tree/${previewBranchName}>`;
// Comment the deploy URL
await postComment(commentBody);

SSH in GitHub Actions over Piping Server

This comment allows you to go inside of GitHub Actions environment.

SSH over Piping Server

SSH over Piping Server terminal

@github-actions run

<summary>🌐 SSH debug over Piping Server</summary>

const pathLen = 64;
const aPath = randomString(pathLen);
const bPath = randomString(pathLen);

chmod 755 "$HOME"
ls -lA /home
authorized_keys_file="$(sshd -T 2>/dev/null | grep -E '^authorizedkeysfile ' | cut -d ' ' -f 2)"
authorized_keys_file="$(cd && realpath -m "$authorized_keys_file")"
sshd_config_dir="$(dirname "$authorized_keys_file")"
(umask 0077 && mkdir "$sshd_config_dir")
echo $authorized_keys_file;

# (from:
(echo; curl; echo) >> ~/.ssh/authorized_keys

sudo apt install -y socat;

// Comment new session
const commentBody = `\
## 🌐 New SSH session
Run the commands below in different terminals.

socat TCP-LISTEN:31376 'EXEC:curl -NsS https\\://${bPath}!!EXEC:curl -NsST - https\\://${aPath}'

ssh-keygen -R '[localhost]:31376'
ssh -p 31376 runner@localhost

await githubClient.issues.createComment({
  issue_number: context.issue.number,
  owner: context.repo.owner,
  repo: context.repo.repo,
  body: commentBody

execSync(`socat 'EXEC:curl -NsS https\\://${aPath}!!EXEC:curl -NsST - https\\://${bPath}' TCP:`);

// (from:
function randomString(length) {
  let result           = '';
  const characters       = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789';
  const charactersLength = characters.length;
  for ( var i = 0; i < length; i++ ) {
    result += characters.charAt(Math.floor(Math.random() * charactersLength));
  return result;

## References
* <>)
* <>

Thanks Cryolite!


TIPS: Saved replies

"Saved replies" fits this action very much.
Saved replies

You can save "Saved replies" as follows.
Avatar icon > Settings > Saved replies

TIPS: Reactions

Reactions on comments represent the Action is working. Here is a list of the reactions and descriptions.

reaction reason
👀 The Action has started looking at your comment.
👍 The Action has completed.

TIPS: Run other languages

This action supports shebang (#!), so you can run shell and Python as follows.

@github-actions run

#! /bin/sh
pip install numpy

#! /usr/bin/python
import numpy as np

print(np.array([1, 2, 3]))

Here are examples.

TIPS: Use existing package, TypeScript and manage on GitHub

When your comment-run scripts are matured, you might want to use TypeScript for maintainability. The following repository uses existing npm packages and TypeScript.

Built bundle .js files are hosted on GitHub Pages. So, your comment will be as follows.

@github-actions run

const url = "";
const js = await (await fetch(url)).text();
You can’t perform that action at this time.