Add health + stats endpoint

README.md

@@ -71,3 +71,16 @@ for automation.
 
 This file browser is for development and test purposes only, for production, put a static webserver
 in front of this application & reverse proxy only the WebSocket (HTTP Upgrade) server.
+
+#### Monitoring
+
+A health check endpoint lives on `/health`, and returns e.g.:
+
+```json
+{  
+    "uptime": 44023,
+    "lastLedger": 41800244,
+    "lastLedgerTx": 41800238,
+    "txCount": 276
+}
+```

bin/webserver.mjs

@@ -5,6 +5,12 @@ import expressWs from 'express-ws'
 import autoindex from 'express-autoindex/dist/index.cjs.js'
 import 'dotenv/config'
 
+import { lastLedger } from '../lib/onLedger.mjs'
+import { txCount } from '../lib/onTransaction.mjs'
+
+const startDate = new Date()
+let lastLedgerTx
+
 let wss // WebSocket Server
 
 if (!wss) {
@@ -27,6 +33,15 @@ if (!wss) {
 
       app.use('/', express.static('./store/'))
 
+      app.use('/health', (req, res) => {
+        res.json({
+          uptime: new Date() - startDate,
+          lastLedger: lastLedger ?? null,
+          lastLedgerTx: lastLedgerTx ?? null,
+          txCount: txCount ?? null,
+        })
+      })
+
       app.use('/:networkId([0-9]{1,})', (req, res, next) => {
         return autoindex('./store/' + req.params.networkId + '/', { json: /application\/json/.test(req.get('accept')) })(req, res,  next)
       })
@@ -78,6 +93,8 @@ const emit = _data => {
           data.xpop.blob = undefined
         }
 
+        lastLedgerTx = data.origin.ledgerIndex
+
         if (account === '' || data.account === account) {
           client.send(JSON.stringify(data), { binary: false })
         }

lib/onLedger.mjs

@@ -9,6 +9,8 @@ import 'dotenv/config'
 const obtainedHumanReadableLedgers = []
 const obtainedBinaryTxLedgers = []
 
+let lastLedger
+
 const onLedger = async ({
   networkId,
   ledger,
@@ -19,6 +21,8 @@ const onLedger = async ({
       const relativeStoreDir = 'store/' + networkId + '/' + ledgerIndexToFolders(ledger.ledger_index)
       const storeDir = new URL('../' + relativeStoreDir, import.meta.url).pathname
 
+      lastLedger = ledger.ledger_index
+
       if (await dirExists(storeDir)) {
         const ledgerData = [
           ...(
@@ -148,4 +152,5 @@ const onLedger = async ({
 
 export {
   onLedger,
+  lastLedger,
 }

lib/onTransaction.mjs

@@ -6,6 +6,8 @@ import { waitForLedgerReady } from './events/ledgerReady.mjs'
 import { emit } from '../bin/webserver.mjs'
 import 'dotenv/config'
 
+let txCount = 0
+
 const xpopBinaryDir = new URL('../store/xpop', import.meta.url).pathname
 const lastSeenTransactions = []
 
@@ -81,6 +83,8 @@ const onTransaction = async ({
                 if (xpopWritten) {
                   console.log('   ### EMIT XPOP READY FOR', tx?.Account, Number(tx.Sequence), tx.hash)
 
+                  txCount++
+
                   return await emit({
                     account: tx?.Account,
                     sequence: tx.Sequence,
@@ -116,4 +120,5 @@ const onTransaction = async ({
 
 export {
   onTransaction,
+  txCount,
 }