Code files

Chapter11/deploying-to-the-cloud/micro/auditservice/service.js

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+'use strict'
+
+const { MongoClient } = require('mongodb')
+const { dns } = require('concordant')()
+
+module.exports = service 
+
+function service () {
+
+  var db
+
+  setup()
+  
+  function setup () {
+    const mongo = '_main._tcp.mongo.micro.svc.cluster.local'
+
+    dns.resolve(mongo, (err, locs) => {
+      if (err) { 
+        console.error(err)
+        return
+      }
+      const { host, port } = locs[0]
+      const url = `mongodb://${host}:${port}/audit`
+      MongoClient.connect(url, (err, client) => {
+        if (err) { 
+          console.log('failed to connect to MongoDB retrying in 100ms')
+          setTimeout(setup, 100)
+          return
+        }
+        db = client
+        db.on('close', () => db = null)
+      }) 
+    })
+  }
+
+  function append (args, cb) {
+    if (!db) {
+      cb(Error('No database connection'))
+      return
+    }
+    const audit = db.collection('audit')
+    const data = { 
+      ts: Date.now(),
+      calc: args.calc,
+      result: args.calcResult 
+    }
+
+    audit.insert(data, (err, result) => {
+      if (err) {
+        cb(err)
+        return
+      }
+      cb(null, {result: result.toString()})
+    })
+  }
+
+  function list (args, cb) {
+    if (!db) {
+      cb(Error('No database connection'))
+      return
+    }
+    const audit = db.collection('audit')
+    audit.find({}, {limit: 10}).toArray((err, docs) => {
+      if (err) {
+        cb(err)
+        return
+      }
+      cb(null, {list: docs})
+    })
+  }
+
+  return { append, list }
+}
+