Repository: twitchdev/extensions-hello-world
Branch: main
Commit: 78bc797cec55
Files: 18
Total size: 41.2 KB
Directory structure:
gitextract_vzvjms3c/
├── .gitignore
├── LICENSE
├── README.html
├── README.md
├── bin/
│ ├── generate_cert.cmd
│ ├── generate_cert.js
│ └── generate_cert.sh
├── package.json
├── public/
│ ├── config.html
│ ├── config.js
│ ├── helper.js
│ ├── live_config.html
│ ├── mobile.html
│ ├── panel.html
│ ├── video_component.html
│ ├── video_overlay.html
│ └── viewer.js
└── services/
└── backend.js
================================================
FILE CONTENTS
================================================
================================================
FILE: .gitignore
================================================
# Temporary files
*.sw[op]
# Configuration
conf/*
.DS_Store
# Logs
logs
*.log
npm-debug.log*
yarn-debug.log*
yarn-error.log*
# Runtime data
pids
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*.seed
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# Directory for instrumented libs generated by jscoverage/JSCover
lib-cov
# Coverage directory used by tools like istanbul
coverage
# nyc test coverage
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# Grunt intermediate storage (http://gruntjs.com/creating-plugins#storing-task-files)
.grunt
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bower_components
# node-waf configuration
.lock-wscript
# Compiled binary addons (http://nodejs.org/api/addons.html)
build/Release
# Dependency directories
node_modules/
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# Typescript v1 declaration files
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# Optional npm cache directory
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# Optional eslint cache
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# Optional REPL history
.node_repl_history
# Output of 'npm pack'
*.tgz
# Yarn Integrity file
.yarn-integrity
# dotenv environment variables file
.env
# IntelliJ IDE files
.idea
================================================
FILE: LICENSE
================================================
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================================================
FILE: README.html
================================================
Extensions-Hello-World
Extensions-Hello-World
The Simplest Extension in the (Hello) World.
Motivation
The Hello World sample is designed to get you started building a Twitch Extension quickly. It contains all the key parts of a functioning Extension and can be immediately run in the Developer Rig. For a fast guide to get started, visit the Developer Rig documentation.
What's in the Sample
The Hello World Extension provides a simple scenario that demonstrates the end-to-end flow of an Extension. On the frontend, a user clicks a button that can change the color of a circle. Instead of changing the CSS locally, it calls its Extension Backend Service (EBS) to update the color of the circle. That message is then sent via Twitch PubSub to update all clients listening to the PubSub topic.
The sample is broken into two main components:
The Frontend of the Extension, comprised of HTML files for the different extension views and corresponding Javascript files and CSS. The frontend has the following functionality:
A button and script that makes a POST call to the EBS to request a color change for the circle
A GET call when the Extension is initialized to change the circle to the current color stored on the EBS
A listener to Twitch PubSub, that receives color change updates and then updates the circle color
A lightweight EBS that performs the following functionality:
Spins up a simple HTTPS server with a POST handler for changing color
Validates an Extension JWT
Sends a new color message via Twitch PubSub for a specific channel
Using the Sample
The recommended path to using this sample is with the Developer Rig. Use the Developer Rig's extension-init command to clone this repository.
The Developer Rig is able to host the frontend Hello World files, but the EBS must be run and hosted separately.
Setting Up Your Backend Certificates
Twitch Extensions require SSL (TLS).
If you're using the Developer Rig and used it to create this extension, it will have already configured the certificates. Otherwise, you'll need to set up a certificate for local development. This will generate a new certificate (server.crt and server.key) for you and place it in the conf/ directory. This certificate is different from the one used for the Developer Rig.
On MacOS
Navigate to the root of the Hello World extension folder and run npm install and then npm run cert
On Windows
Run the following commands to generate the necessary certificates for your Hello World backend
If you're using the Developer Rig, it has buttons in its UI to perform the following actions.
To run the EBS, run node services/backend, with the following command line arguments: -c <client id>, -s <secret>, -o <owner id>.
This provides the EBS with your Extension client ID, Extension secret and the user ID of the Extension owner (likely you). These are necessary to validate calls to your EBS and make calls to Twitch services such as PubSub.
If you do not want to pass in command line arguments, you can also directly set the following environment variables: EXT_SECRET, EXT_CLIENT_ID, EXT_OWNER_ID in your code.
To get the owner ID, you will need to execute a simple CURL command against the Twitch /users endpoint. You'll need your extension client ID as part of the query (this will be made consistent with the Developer Rig shortly, by using owner name).
curl -H "Client-ID: <client id>" -X GET "https://api.twitch.tv/helix/users?login=<owner name>"
Note - If you haven't yet created an extension, you can start that process here.
================================================
FILE: README.md
================================================
# Extensions-Hello-World
The Simplest Extension in the (Hello) World.
## Motivation
The Hello World sample is designed to get you started building a Twitch Extension quickly. It contains all the key parts of a functioning Extension and can be immediately run in the [Developer Rig](https://github.com/twitchdev/developer-rig). For a fast guide to get started, visit the Developer Rig documentation.
## What's in the Sample
The Hello World Extension provides a simple scenario that demonstrates the end-to-end flow of an Extension. On the frontend, a user clicks a button that can change the color of a circle. Instead of changing the CSS locally, it calls its Extension Backend Service (EBS) to update the color of the circle. That message is then sent via Twitch PubSub to update all clients listening to the PubSub topic.
__The sample is broken into two main components:__
1. The Frontend of the Extension, comprised of HTML files for the different extension views and corresponding Javascript files and CSS. The frontend has the following functionality:
* A button and script that makes a POST call to the EBS to request a color change for the circle
* A GET call when the Extension is initialized to change the circle to the current color stored on the EBS
* A listener to Twitch PubSub, that receives color change updates and then updates the circle color
2. A lightweight EBS that performs the following functionality:
* Spins up a simple HTTPS server with a POST handler for changing color
* Validates an Extension JWT
* Sends a new color message via Twitch PubSub for a specific channel
## Using the Sample
The recommended path to using this sample is with the [Developer Rig](https://github.com/twitchdev/developer-rig). Use the Developer Rig's `extension-init` command to clone this repository.
The Developer Rig is able to host the frontend Hello World files, but the EBS must be run and hosted separately.
### Setting Up Your Backend Certificates
Twitch Extensions require SSL (TLS).
If you're using the Developer Rig and used it to create this extension, it will have already configured the certificates. Otherwise, you'll need to set up a certificate for local development. This will generate a new certificate (`server.crt` and `server.key`) for you and place it in the `conf/` directory. This certificate is different from the one used for the Developer Rig.
#### On MacOS
Navigate to the root of the Hello World extension folder and run `npm install` and then `npm run cert`
#### On Windows
Run the following commands to generate the necessary certificates for your Hello World backend
1. `node scripts/ssl.js`
2. `mkdir ../my-extension/conf`
3. `mv ssl/selfsigned.crt ../my-extension/conf/server.crt`
4. `mv ssl/selfsigned.key ../my-extension/conf/server.key`
### Running Hello World
If you're using the Developer Rig, it has buttons in its UI to perform the following actions.
To run the EBS, run `node services/backend`, with the following command line arguments: `-c `, `-s `, `-o `.
This provides the EBS with your Extension client ID, Extension secret and the user ID of the Extension owner (likely you). These are necessary to validate calls to your EBS and make calls to Twitch services such as PubSub.
If you do not want to pass in command line arguments, you can also directly set the following environment variables: `EXT_SECRET`, `EXT_CLIENT_ID`, `EXT_OWNER_ID` in your code.
You can get your client ID and secret from your [Extension Dashboard](https://dev.twitch.tv/dashboard/extensions).
To get the owner ID, you will need to execute a simple CURL command against the Twitch `/users` endpoint. You'll need your extension client ID as part of the query (this will be made consistent with the Developer Rig shortly, by using _owner name_).
```bash
curl -H "Client-ID: " -X GET "https://api.twitch.tv/helix/users?login="
```
**Note -** If you haven't yet created an extension, you can start that process [here](https://dev.twitch.tv/extensions).
================================================
FILE: bin/generate_cert.cmd
================================================
@ECHO OFF
SETLOCAL
SET T=%TEMP%\%RANDOM%.cnf
SET GIT=%ProgramFiles%\Git
SET CONF=%~dp0..\conf
SET FILE_ROOT=%CONF%\%~1
IF EXIST "%CONF%" RD /Q /S "%CONF%"
MKDIR "%CONF%"
COPY /Y "%GIT%\usr\ssl\openssl.cnf" %T% > nul
ECHO [SAN]>> %T%
ECHO subjectAltName='DNS:localhost'>> %T%
"%GIT%\mingw64\bin\openssl" req -newkey rsa:4096 -days 1001 -nodes -x509 -subj "/C=US/ST=California/L=San Francisco/O=LULZCorp/OU=web/CN=localhost" -extensions SAN -config "%T%" -keyout "%FILE_ROOT%.key" -out "%FILE_ROOT%.crt"
SET EXIT_CODE=%ERRORLEVEL%
DEL /F /Q %T%
EXIT /B %EXIT_CODE%
================================================
FILE: bin/generate_cert.js
================================================
// Valiate the command line.
if(process.argv.length < 3) {
console.log(`usage: node ${process.argv[1]} file_root`);
process.exit(2);
}
// Spawn the process for the platform.
const { spawn } = require('child_process');
const cmd = process.platform !== 'win32' ?
spawn('bin/generate_cert.sh', [process.argv[2]]) :
spawn('cmd.exe', ['/c', 'bin\\generate_cert.cmd', process.argv[2]]);
let output = '';
// Handle process activity.
cmd.stdout.on('data', (data) => {
output += data.toString();
});
cmd.stderr.on('data', (data) => {
output += data.toString();
});
cmd.on('exit', (code) => {
console.log(output);
if(code) {
process.exit(code);
}
});
================================================
FILE: bin/generate_cert.sh
================================================
#!/usr/bin/env bash
NAME=${1:-server}
DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"
openssl req \
-newkey rsa:4096 \
-days 1001 \
-nodes \
-x509 \
-subj "/C=US/ST=California/L=San Francisco/O=LULZCorp/OU=web/CN=localhost" \
-extensions SAN \
-config <( cat $( [[ "Darwin" = "$(uname -s)" ]] && echo /System/Library/OpenSSL/openssl.cnf || echo /etc/ssl/openssl.cnf ) \
<(printf "[SAN]\nsubjectAltName='DNS:localhost'")) \
-keyout "${DIR}/${NAME}.key" \
-out "${DIR}/${NAME}.crt"
echo ""
echo "* Generated $NAME.key and $NAME.crt files in local directory"
echo ""
if [[ "$OSTYPE" == "darwin"* ]]; then
echo "* Installing cert into local Keychain."
echo "* To see or modify, run 'Keychain Access' app and look in the 'System' Folder"
sudo security add-trusted-cert -d -p ssl -r trustRoot -k "/Library/Keychains/System.keychain" "${DIR}/${NAME}.crt"
else
echo "* Please install and trust cert at conf/$NAME.crt"
fi
cd "$DIR"
if [[ ! -d "${DIR}/../conf/" ]]; then
mkdir "${DIR}/../conf/"
fi
mv ${NAME}.{key,crt} "${DIR}/../conf/"
================================================
FILE: package.json
================================================
{
"name": "extension-hello-world",
"version": "1.0.0",
"description": "Simple Hello World Twitch Extension",
"main": "index.js",
"scripts": {
"cert": "node bin/generate_cert.js server",
"start": "node services/backend"
},
"keywords": [
"twitch",
"extension"
],
"author": "Emily Rose ",
"license": "Apache-2.0",
"dependencies": {
"boom": "^7.2.0",
"color": "^3.0.0",
"commander": "^2.15.0",
"hapi": "^17.8.4",
"inert": "^5.1.0",
"jsonwebtoken": "^8.2.0",
"request": "^2.85.0",
"selfsigned": "^1.10.2"
}
}
================================================
FILE: public/config.html
================================================
Config Page
================================================
FILE: public/viewer.js
================================================
var token = "";
var tuid = "";
var ebs = "";
// because who wants to type this every time?
var twitch = window.Twitch.ext;
// create the request options for our Twitch API calls
var requests = {
set: createRequest('POST', 'cycle'),
get: createRequest('GET', 'query')
};
function createRequest(type, method) {
return {
type: type,
url: location.protocol + '//localhost:8081/color/' + method,
success: updateBlock,
error: logError
}
}
function setAuth(token) {
Object.keys(requests).forEach((req) => {
twitch.rig.log('Setting auth headers');
requests[req].headers = { 'Authorization': 'Bearer ' + token }
});
}
twitch.onContext(function(context) {
twitch.rig.log(context);
});
twitch.onAuthorized(function(auth) {
// save our credentials
token = auth.token;
tuid = auth.userId;
// enable the button
$('#cycle').removeAttr('disabled');
setAuth(token);
$.ajax(requests.get);
});
function updateBlock(hex) {
twitch.rig.log('Updating block color');
$('#color').css('background-color', hex);
}
function logError(_, error, status) {
twitch.rig.log('EBS request returned '+status+' ('+error+')');
}
function logSuccess(hex, status) {
// we could also use the output to update the block synchronously here,
// but we want all views to get the same broadcast response at the same time.
twitch.rig.log('EBS request returned '+hex+' ('+status+')');
}
$(function() {
// when we click the cycle button
$('#cycle').click(function() {
if(!token) { return twitch.rig.log('Not authorized'); }
twitch.rig.log('Requesting a color cycle');
$.ajax(requests.set);
});
// listen for incoming broadcast message from our EBS
twitch.listen('broadcast', function (target, contentType, color) {
twitch.rig.log('Received broadcast color');
updateBlock(color);
});
});
================================================
FILE: services/backend.js
================================================
/**
* Copyright 2018 Amazon.com, Inc. or its affiliates
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
const fs = require('fs');
const Hapi = require('hapi');
const path = require('path');
const Boom = require('boom');
const color = require('color');
const ext = require('commander');
const jsonwebtoken = require('jsonwebtoken');
const request = require('request');
// The developer rig uses self-signed certificates. Node doesn't accept them
// by default. Do not use this in production.
process.env.NODE_TLS_REJECT_UNAUTHORIZED = '0';
// Use verbose logging during development. Set this to false for production.
const verboseLogging = true;
const verboseLog = verboseLogging ? console.log.bind(console) : () => { };
// Service state variables
const initialColor = color('#6441A4'); // super important; bleedPurple, etc.
const serverTokenDurationSec = 30; // our tokens for pubsub expire after 30 seconds
const userCooldownMs = 1000; // maximum input rate per user to prevent bot abuse
const userCooldownClearIntervalMs = 60000; // interval to reset our tracking object
const channelCooldownMs = 1000; // maximum broadcast rate per channel
const bearerPrefix = 'Bearer '; // HTTP authorization headers have this prefix
const colorWheelRotation = 30;
const channelColors = {};
const channelCooldowns = {}; // rate limit compliance
let userCooldowns = {}; // spam prevention
const STRINGS = {
secretEnv: usingValue('secret'),
clientIdEnv: usingValue('client-id'),
ownerIdEnv: usingValue('owner-id'),
serverStarted: 'Server running at %s',
secretMissing: missingValue('secret', 'EXT_SECRET'),
clientIdMissing: missingValue('client ID', 'EXT_CLIENT_ID'),
ownerIdMissing: missingValue('owner ID', 'EXT_OWNER_ID'),
messageSendError: 'Error sending message to channel %s: %s',
pubsubResponse: 'Message to c:%s returned %s',
cyclingColor: 'Cycling color for c:%s on behalf of u:%s',
colorBroadcast: 'Broadcasting color %s for c:%s',
sendColor: 'Sending color %s to c:%s',
cooldown: 'Please wait before clicking again',
invalidAuthHeader: 'Invalid authorization header',
invalidJwt: 'Invalid JWT',
};
ext.
version(require('../package.json').version).
option('-s, --secret ', 'Extension secret').
option('-c, --client-id ', 'Extension client ID').
option('-o, --owner-id ', 'Extension owner ID').
parse(process.argv);
const ownerId = getOption('ownerId', 'EXT_OWNER_ID');
const secret = Buffer.from(getOption('secret', 'EXT_SECRET'), 'base64');
const clientId = getOption('clientId', 'EXT_CLIENT_ID');
const serverOptions = {
host: 'localhost',
port: 8081,
routes: {
cors: {
origin: ['*'],
},
},
};
const serverPathRoot = path.resolve(__dirname, '..', 'conf', 'server');
if (fs.existsSync(serverPathRoot + '.crt') && fs.existsSync(serverPathRoot + '.key')) {
serverOptions.tls = {
// If you need a certificate, execute "npm run cert".
cert: fs.readFileSync(serverPathRoot + '.crt'),
key: fs.readFileSync(serverPathRoot + '.key'),
};
}
const server = new Hapi.Server(serverOptions);
(async () => {
// Handle a viewer request to cycle the color.
server.route({
method: 'POST',
path: '/color/cycle',
handler: colorCycleHandler,
});
// Handle a new viewer requesting the color.
server.route({
method: 'GET',
path: '/color/query',
handler: colorQueryHandler,
});
// Start the server.
await server.start();
console.log(STRINGS.serverStarted, server.info.uri);
// Periodically clear cool-down tracking to prevent unbounded growth due to
// per-session logged-out user tokens.
setInterval(() => { userCooldowns = {}; }, userCooldownClearIntervalMs);
})();
function usingValue(name) {
return `Using environment variable for ${name}`;
}
function missingValue(name, variable) {
const option = name.charAt(0);
return `Extension ${name} required.\nUse argument "-${option} <${name}>" or environment variable "${variable}".`;
}
// Get options from the command line or the environment.
function getOption(optionName, environmentName) {
const option = (() => {
if (ext[optionName]) {
return ext[optionName];
} else if (process.env[environmentName]) {
console.log(STRINGS[optionName + 'Env']);
return process.env[environmentName];
}
console.log(STRINGS[optionName + 'Missing']);
process.exit(1);
})();
console.log(`Using "${option}" for ${optionName}`);
return option;
}
// Verify the header and the enclosed JWT.
function verifyAndDecode(header) {
if (header.startsWith(bearerPrefix)) {
try {
const token = header.substring(bearerPrefix.length);
return jsonwebtoken.verify(token, secret, { algorithms: ['HS256'] });
}
catch (ex) {
throw Boom.unauthorized(STRINGS.invalidJwt);
}
}
throw Boom.unauthorized(STRINGS.invalidAuthHeader);
}
function colorCycleHandler(req) {
// Verify all requests.
const payload = verifyAndDecode(req.headers.authorization);
const { channel_id: channelId, opaque_user_id: opaqueUserId } = payload;
// Store the color for the channel.
let currentColor = channelColors[channelId] || initialColor;
// Bot abuse prevention: don't allow a user to spam the button.
if (userIsInCooldown(opaqueUserId)) {
throw Boom.tooManyRequests(STRINGS.cooldown);
}
// Rotate the color as if on a color wheel.
verboseLog(STRINGS.cyclingColor, channelId, opaqueUserId);
currentColor = color(currentColor).rotate(colorWheelRotation).hex();
// Save the new color for the channel.
channelColors[channelId] = currentColor;
// Broadcast the color change to all other extension instances on this channel.
attemptColorBroadcast(channelId);
return currentColor;
}
function colorQueryHandler(req) {
// Verify all requests.
const payload = verifyAndDecode(req.headers.authorization);
// Get the color for the channel from the payload and return it.
const { channel_id: channelId, opaque_user_id: opaqueUserId } = payload;
const currentColor = color(channelColors[channelId] || initialColor).hex();
verboseLog(STRINGS.sendColor, currentColor, opaqueUserId);
return currentColor;
}
function attemptColorBroadcast(channelId) {
// Check the cool-down to determine if it's okay to send now.
const now = Date.now();
const cooldown = channelCooldowns[channelId];
if (!cooldown || cooldown.time < now) {
// It is.
sendColorBroadcast(channelId);
channelCooldowns[channelId] = { time: now + channelCooldownMs };
} else if (!cooldown.trigger) {
// It isn't; schedule a delayed broadcast if we haven't already done so.
cooldown.trigger = setTimeout(sendColorBroadcast, now - cooldown.time, channelId);
}
}
function sendColorBroadcast(channelId) {
// Set the HTTP headers required by the Twitch API.
const headers = {
'Client-ID': clientId,
'Content-Type': 'application/json',
'Authorization': bearerPrefix + makeServerToken(channelId),
};
// Create the POST body for the Twitch API request.
const currentColor = color(channelColors[channelId] || initialColor).hex();
const body = JSON.stringify({
content_type: 'application/json',
message: currentColor,
targets: ['broadcast'],
});
// Send the broadcast request to the Twitch API.
verboseLog(STRINGS.colorBroadcast, currentColor, channelId);
request(
`https://api.twitch.tv/extensions/message/${channelId}`,
{
method: 'POST',
headers,
body,
}
, (err, res) => {
if (err) {
console.log(STRINGS.messageSendError, channelId, err);
} else {
verboseLog(STRINGS.pubsubResponse, channelId, res.statusCode);
}
});
}
// Create and return a JWT for use by this service.
function makeServerToken(channelId) {
const payload = {
exp: Math.floor(Date.now() / 1000) + serverTokenDurationSec,
channel_id: channelId,
user_id: ownerId, // extension owner ID for the call to Twitch PubSub
role: 'external',
pubsub_perms: {
send: ['*'],
},
};
return jsonwebtoken.sign(payload, secret, { algorithm: 'HS256' });
}
function userIsInCooldown(opaqueUserId) {
// Check if the user is in cool-down.
const cooldown = userCooldowns[opaqueUserId];
const now = Date.now();
if (cooldown && cooldown > now) {
return true;
}
// Voting extensions must also track per-user votes to prevent skew.
userCooldowns[opaqueUserId] = now + userCooldownMs;
return false;
}