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Add simple authentication support #5

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merged 1 commit into from
Oct 10, 2023
Merged

Add simple authentication support #5

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5 changes: 4 additions & 1 deletion .env.example
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Original file line number Diff line number Diff line change
Expand Up @@ -2,4 +2,7 @@ ENABLE_CACHE = false
//Cache in ms
CACHE_TTL = 300000
BACKEND_SERVER_LIST = http://localhost:3000,http://localhost:3001
ROUND_ROBIN_STRATEGY = sequential
ROUND_ROBIN_STRATEGY = sequential
// (Optional, Default: false) Set if you want to enable simple auth token
LB_ENABLE_AUTH_TOKEN = false
LB_AUTH_TOKEN = myapitokenchangethislater
41 changes: 41 additions & 0 deletions package-lock.json
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1 change: 1 addition & 0 deletions package.json
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Expand Up @@ -15,6 +15,7 @@
"body-parser": "^1.20.2",
"dotenv": "^16.3.1",
"express": "^4.18.2",
"express-bearer-token": "^2.4.0",
"js-sha256": "^0.10.1",
"lru-cache": "^10.0.1",
"object-hash": "^3.0.0",
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197 changes: 115 additions & 82 deletions src/index.mjs
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Expand Up @@ -10,6 +10,7 @@ import { performance } from "node:perf_hooks";
import { exit } from "node:process";
import { handleFatalError } from "./util.mjs";
import { retry } from "@ultraq/promise-utils";
import bearerToken from 'express-bearer-token';

// Load env variable from .env
dotenv.config();
Expand All @@ -19,29 +20,31 @@ const ENABLE_CACHE = process.env.ENABLE_CACHE ? process.env.ENABLE_CACHE === 'tr
const CACHE_TTL = process.env.CACHE_TTL ? parseInt(process.env.CACHE_TTL) : 300000;
const BACKEND_SERVER_LIST = process.env.BACKEND_SERVER_LIST ? process.env.BACKEND_SERVER_LIST.split(',').map(s => s.trim()) : [];
const ROUND_ROBIN_STRATEGY = process.env.ROUND_ROBIN_STRATEGY || 'sequential';
const LB_ENABLE_AUTH_TOKEN = process.env.LB_ENABLE_AUTH_TOKEN ? process.env.LB_ENABLE_AUTH_TOKEN === 'true' : false;
const LB_AUTH_TOKEN = process.env.LB_AUTH_TOKEN || "myapitokenchangethislater";

if (BACKEND_SERVER_LIST.length == 0) {
handleFatalError(new Error("Backend server cannot be empty"));
handleFatalError(new Error("Backend server cannot be empty"));
}

// console.debug(BACKEND_SERVER_LIST);
// exit(1);

// Only retry failed request maximum 2 times
const retryStrategy = function (result, error, attempts) {
return !!error && attempts < 2 ? attempts * 250 : -1;
return !!error && attempts < 2 ? attempts * 250 : -1;
}

const responseCache = new LRUCache(
{
max: 500,
maxSize: 5000,
sizeCalculation: (value, key) => {
return value.toString().length;
},
// how long to live in ms
ttl: CACHE_TTL,
}
{
max: 500,
maxSize: 5000,
sizeCalculation: (value, key) => {
return value.toString().length;
},
// how long to live in ms
ttl: CACHE_TTL,
}
)

const app = express();
Expand All @@ -51,92 +54,122 @@ const servers = BACKEND_SERVER_LIST;
let availableServers;

switch (ROUND_ROBIN_STRATEGY) {
case 'sequential':
availableServers = new SequentialRoundRobin(servers);
break;
case 'random':
availableServers = new RandomRoundRobin(servers);
break;
default:
availableServers = new SequentialRoundRobin(servers);
break;
case 'sequential':
availableServers = new SequentialRoundRobin(servers);
break;
case 'random':
availableServers = new RandomRoundRobin(servers);
break;
default:
availableServers = new SequentialRoundRobin(servers);
break;
}

const PORT = process.env.PORT || 8081;

// Whenever receive new request will forward to application server
const loadBalancerHandler = async (req, res) => {

// Extract properties from request object
const { method, url, headers, body } = req;

const ip = req.headers['cf-connecting-ip'] || req.headers['x-forwarded-for'] || req.connection.remoteAddress;

const newHeaders = {};
const skipHeadersKey = ["content-length", "host"];
Object.keys(headers).forEach((key) => {
const existSkipHeaderKey = skipHeadersKey.includes(key.toLowerCase());
if (!existSkipHeaderKey) newHeaders[key] = headers[key];
});

console.debug(ip);
console.debug(headers);
// console.debug(newHeaders);
console.debug(url);
// exit();
// Extract properties from request object
const { method, url, headers, body } = req;

const ip = req.headers['cf-connecting-ip'] || req.headers['x-forwarded-for'] || req.connection.remoteAddress;

const newHeaders = {};
const skipHeadersKey = ["content-length", "host"];

if (LB_ENABLE_AUTH_TOKEN) {
// Don't forward current authorization header to backend
skipHeadersKey.push("authorization");
}
Object.keys(headers).forEach((key) => {
const existSkipHeaderKey = skipHeadersKey.includes(key.toLowerCase());
if (!existSkipHeaderKey) newHeaders[key] = headers[key];
});

console.debug(ip);
console.debug(headers);
// console.debug(newHeaders);
console.debug(url);
// exit();

// Make request key from combination of hash from url, method, and body object hash
const req_key = sha256(`${url} ${method} ` + hash.sha1(body));

// Return cached response immediately if it exists
if (ENABLE_CACHE && responseCache.has(req_key)) {
console.debug("Get from cache");
return res.send(responseCache.get(req_key));
}

// Select the server using round robin strategy to forward the request
const server = availableServers.next();
console.debug("Connect to " + server.value);

try {
const startTimeRequest = performance.now();

// Requesting to underlying application server
const response = await retry(() => axios({
url: `${server.value}${url}`,
method: method,
headers: newHeaders,
data: body
}), retryStrategy);

const endTimeRequest = performance.now();

console.debug("Request to " + server.value + " took " + (endTimeRequest - startTimeRequest) + " ms");

// Send cache if it is available
if (ENABLE_CACHE) responseCache.set(req_key, response.data);

// Send back the response data from application server to client
res.status(response.status).header(response.headers).send(response.data);
}
catch (err) {
// Send back the error message
console.error(err);
const statusCode = err.response ? err.response.status : 500;
const message = err.response ? typeof err.response.data.message ? err.response.data.message : err.response.reason.message || err.response.code || err.message || "Server error!" : "Server error!";
res.status(statusCode).header(err.response.headers).send(message);
}
}

// Make request key from combination of hash from url, method, and body object hash
const req_key = sha256(`${url} ${method} ` + hash.sha1(body));
app.use(bodyparser.json({ limit: '5mb' }));

// Return cached response immediately if it exists
if (ENABLE_CACHE && responseCache.has(req_key)) {
console.debug("Get from cache");
return res.send(responseCache.get(req_key));
if (LB_ENABLE_AUTH_TOKEN) {
// Extract auth token if it is exist
app.use(bearerToken());

// Simple authentication middleware
const authMiddleware = function (req, res, next) {
if (LB_ENABLE_AUTH_TOKEN) {
const token = typeof req.token !== 'undefined' ? req.token : null;
if (!token) {
const error = new Error('Missing API token');
error.statusCode = 401
return res.status(401).json({ "message": error.message });
}

if (LB_AUTH_TOKEN !== token) {
const error = new Error('Invalid API token');
error.statusCode = 401
return res.status(401).json({ "message": error.message });
}
}
next();
};

// Select the server using round robin strategy to forward the request
const server = availableServers.next();
console.debug("Connect to " + server.value);

try {
const startTimeRequest = performance.now();

// Requesting to underlying application server
const response = await retry(() => axios({
url: `${server.value}${url}`,
method: method,
headers: newHeaders,
data: body
}), retryStrategy);

const endTimeRequest = performance.now();

console.debug("Request to " + server.value + " took " + (endTimeRequest - startTimeRequest) + " ms");

// Send cache if it is available
if (ENABLE_CACHE) responseCache.set(req_key, response.data);

// Send back the response data from application server to client
res.status(response.status).header(response.headers).send(response.data);
}
catch (err) {
// Send back the error message
console.error(err);
const statusCode = err.response ? err.response.status : 500;
const message = err.response ? typeof err.response.data.message ? err.response.data.message : err.response.reason.message || err.response.code || err.message || "Server error!" : "Server error!";
res.status(statusCode).header(err.response.headers).send(message);
}
app.use(authMiddleware);
}

app.use(bodyparser.json({ limit: '5mb' }));

// Pass any request to loadBalancerHandler
app.use((req, res) => { loadBalancerHandler(req, res) });

// Listen on PORT 8080
app.listen(PORT, err => {
err ?
console.debug(`Failed to listen on PORT ${PORT}`) :
console.debug("Load Balancer Server "
+ `listening on PORT ${PORT}`);
err ?
console.debug(`Failed to listen on PORT ${PORT}`) :
console.debug("Load Balancer Server "
+ `listening on PORT ${PORT}`);
});
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