Awesome
universal-github-app-jwt
Calculate GitHub App bearer tokens for Node, Deno, and modern browsers
Usage
<table> <tbody valign=top align=left> <tr><th> Browsers </th><td width=100%> Load <code>universal-github-app-jwt</code> directly from <a href="https://esm.sh">esm.sh</a><script type="module">
import githubAppJwt from "https://esm.sh/universal-github-app-jwt";
</script>
Install with <code>npm install universal-github-app-jwt</code>
import githubAppJwt from "universal-github-app-jwt";
Load <code>universal-github-app-jwt</code> directly from <a href="https://esm.sh">esm.sh</a>, including types.
import githubAppJwt from "https://esm.sh/universal-github-app-jwt";
const { token, appId, expiration } = await githubAppJwt({
id: APP_ID,
privateKey: PRIVATE_KEY,
});
The retrieved token can now be used in Authorization request header, e.g. with @octokit/request:
request("GET /app", {
headers: {
authorization: `bearer ${token}`,
},
});
For a complete implementation of GitHub App authentication strategies, see @octokit/auth-app.js.
githubAppJwt(options)
<table width="100%">
<thead align=left>
<tr>
<th width=150>
name
</th>
<th width=70>
type
</th>
<th>
description
</th>
</tr>
</thead>
<tbody align=left valign=top>
<tr>
<th>
<code>options.id</code>
</th>
<th>
<code>number | string</code>
</th>
<td>
<strong>Required</strong>. The GitHub App's ID or Client ID. For <code>github.com</code> and GHES 3.14+, it is recommended to use the Client ID.
</td>
</tr>
<tr>
<th>
<code>options.privateKey</code>
</th>
<th>
<code>string</code>
</th>
<td>
<strong>Required</strong>. Content of the <code>*.pem</code> file you downloaded from the app’s about page. You can generate a new private key if needed. Make sure to preserve the line breaks. If your private key contains escaped newlines (`\\n`), they will be automatically replaced with actual newlines.
</td>
</tr>
<tr>
<th>
<code>options.now</code>
</th>
<th>
<code>number</code>
</th>
<td>
An optional override for the current time in seconds since the UNIX epoch. Defaults to <code>Math.floor(Date.now() / 1000))</code>. This value can be overridden to account for a time skew between the local machine and the authentication server.
</td>
</tr>
</tbody>
</table>
githubAppJwt(options) resolves with an object with the following keys
<a name="private-key-formats"></a>
About Private Key formats
When downloading a private-key.pem file from GitHub, the format is in PKCS#1 format. Unfortunately, the WebCrypto API only supports PKCS#8.
If you use 1Password to store a private key as an SSH key, it will be transformed to the OpenSSH format, which is also not supported by WebCrypto.
You can identify the format based on the the first line
| First Line | Format |
|---|---|
-----BEGIN RSA PRIVATE KEY----- | PKCS#1 |
-----BEGIN PRIVATE KEY----- | PKCS#8 |
-----BEGIN OPENSSH PRIVATE KEY----- | OpenSSH |
Converting PKCS#1 to PKCS#8
-
Using an Online Private Key Converter
Convert quickly using the Web interface at https://private-key-converter.vercel.app
-
Using Node.js
If you use Node.js, you can convert the format before passing it to universal-github-app-jwt:
import crypto from "node:crypto";
import githubAppJwt from "universal-github-app-jwt";
const privateKeyPkcs8 = crypto
.createPrivateKey(process.env.PRIVATE_KEY)
.export({
type: "pkcs8",
format: "pem",
});
const { token, appId, expiration } = await githubAppJwt({
id: process.env.APP_ID,
privateKey: privateKeyPkcs8,
});
-
Using OpenSSL
Convert the format using openssl before passing it to your app.
openssl pkcs8 -topk8 -inform PEM -outform PEM -nocrypt -in private-key.pem -out private-key-pkcs8.key
Converting OpenSSH to PKCS#8
cp private-key.pem private-key-pkcs8.key && ssh-keygen -m PKCS8 -N "" -f private-key-pkcs8.key
I'm looking for help to create a minimal OpenSSH to PKCS convert library that I can recommend people to use before passing the private key to githubAppJwt. Please create an issue if you'd like to help.