Detect if testnet is up / down

.env.example

@@ -0,0 +1 @@
+ETHERSCAN_API_KEY=

README.md

@@ -7,7 +7,9 @@ cd speedrun-grader
 yarn install
 ```
 
-you need a 12 word seed phrase as a deployer in a file called `mnemonic.txt`
+Copy `.env.example` to `.env` and put in your [Etherscan API Key](https://etherscan.io/apis).
+
+You also need a 12 word seed phrase as a deployer in a file called `mnemonic.txt`
 
 (you could use this eth.build to create one: https://eth.build/build#6f1ab054a3e274128914fdfd3e0e0868245816059ee4cb0b2a4f608e57bddea8)
 

index.js

@@ -6,6 +6,7 @@ const bodyParser = require("body-parser");
 const app = express();
 const util = require('util');
 const exec = util.promisify(require('child_process').exec);
+const { isNetworkRunning } = require("./utils/network");
 
 let challenges = JSON.parse(fs.readFileSync("challenges.json").toString())
 
@@ -101,7 +102,7 @@ app.get("/pretty/:challenge/:network/:address", async function(req, res) {
 
 // Main API endpoint.
 app.post('/', async function(req, res){
-  console.log("POST", req.body);
+  console.log("⏩ POST", req.body);
   const challengeId = req.body.challenge;
   const network = req.body.network;
   const address = req.body.address;
@@ -111,6 +112,13 @@ app.post('/', async function(req, res){
     return res.sendStatus(404);
   }
 
+  if (!(await isNetworkRunning(network))) {
+    console.error(`❌📡❌ ${network} is down.`);
+    return res.status(503).json({ error: `${network} is down.` })
+  }
+
+  console.log(`📡 ${network} is UP.`);
+
   const challenge = challenges[challengeId];
   const result = await testChallenge({ challenge, network, address })
 

package.json

@@ -1,7 +1,9 @@
 {
   "dependencies": {
+    "axios": "^0.24.0",
     "body-parser": "^1.19.1",
     "cors": "^2.8.5",
+    "dotenv": "^11.0.0",
     "express": "^4.17.2",
     "https": "^1.0.0",
     "nodemon": "^2.0.15"

utils/network.js

@@ -0,0 +1,35 @@
+require('dotenv').config();
+const axios = require('axios');
+
+const allowedNetworks = ["rinkeby", "ropsten", "kovan"];
+const API_KEY = process.env.ETHERSCAN_API_KEY;
+
+/**
+ * Checks if "network" is up.
+ * @param network a supported Ethereum network
+ * @returns {Promise<boolean>}
+ */
+const isNetworkRunning = async (network) => {
+  if (!allowedNetworks.includes(network)) return false;
+
+  const API_URL = `https://api-${network}.etherscan.io/api`;
+  const currentTimestamp = Math.round(Date.now() / 1000);
+  // We assume the network is Down that if not valid block in the last 2 minutes
+  const aliveFromTimestamp = currentTimestamp - 120;
+
+  const paramString = `?module=block&action=getblocknobytime&timestamp=${aliveFromTimestamp}&closest=after&apikey=${API_KEY}`;
+
+  try {
+    const response = await axios.get(API_URL + paramString);
+    // The Etherscan API returns OK / NOTOK
+    return response.data.message === "OK";
+  } catch (e) {
+    // Issue with the Request.
+    console.error(e);
+    return false;
+  }
+}
+
+module.exports = {
+  isNetworkRunning
+}

yarn.lock

@@ -59,6 +59,13 @@ [email protected]:
   resolved "https://registry.yarnpkg.com/array-flatten/-/array-flatten-1.1.1.tgz#9a5f699051b1e7073328f2a008968b64ea2955d2"
   integrity sha1-ml9pkFGx5wczKPKgCJaLZOopVdI=
 
+axios@^0.24.0:
+  version "0.24.0"
+  resolved "https://registry.yarnpkg.com/axios/-/axios-0.24.0.tgz#804e6fa1e4b9c5288501dd9dff56a7a0940d20d6"
+  integrity sha512-Q6cWsys88HoPgAaFAVUb0WpPk0O8iTeisR9IMqy9G8AbO4NlpVknrnQS03zzF9PGAWgO3cgletO3VjV/P7VztA==
+  dependencies:
+    follow-redirects "^1.14.4"
+
 balanced-match@^1.0.0:
   version "1.0.2"
   resolved "https://registry.yarnpkg.com/balanced-match/-/balanced-match-1.0.2.tgz#e83e3a7e3f300b34cb9d87f615fa0cbf357690ee"
@@ -289,6 +296,11 @@ dot-prop@^5.2.0:
   dependencies:
     is-obj "^2.0.0"
 
+dotenv@^11.0.0:
+  version "11.0.0"
+  resolved "https://registry.yarnpkg.com/dotenv/-/dotenv-11.0.0.tgz#ee37feddf8ada6d348a79e198312d4a8abfd1c1e"
+  integrity sha512-Fp/b504Y5W+e+FpCxTFMUZ7ZEQkQYF0rx+KZtmwixJxGQbLHrhCwo3FjZgNC8vIfrSi29PABNbMoCGD9YoiXbQ==
+
 duplexer3@^0.1.4:
   version "0.1.4"
   resolved "https://registry.yarnpkg.com/duplexer3/-/duplexer3-0.1.4.tgz#ee01dd1cac0ed3cbc7fdbea37dc0a8f1ce002ce2"
@@ -387,6 +399,11 @@ finalhandler@~1.1.2:
     statuses "~1.5.0"
     unpipe "~1.0.0"
 
+follow-redirects@^1.14.4:
+  version "1.14.7"
+  resolved "https://registry.yarnpkg.com/follow-redirects/-/follow-redirects-1.14.7.tgz#2004c02eb9436eee9a21446a6477debf17e81685"
+  integrity sha512-+hbxoLbFMbRKDwohX8GkTataGqO6Jb7jGwpAlwgy2bIz25XtRm7KEzJM76R1WiNT5SwZkX4Y75SwBolkpmE7iQ==
+
 [email protected]:
   version "0.2.0"
   resolved "https://registry.yarnpkg.com/forwarded/-/forwarded-0.2.0.tgz#2269936428aad4c15c7ebe9779a84bf0b2a81811"