feat(lib): add datbase wrapper

Signed-off-by: Hans Kristian Flaatten <hans.kristian.flaatten@dnt.no>

lib/db.js

@@ -0,0 +1,26 @@
+'use strict';
+
+const mongoose = require('mongoose');
+
+if (mongoose.connection._hasOpened) {
+  module.exports = mongoose;
+} else {
+  let mongoUri = process.env.MONGO_URI;
+
+  if (typeof mongoUri === 'undefined' || !mongoUri) {
+    if (!process.env.MONGO_DB) {
+      throw new Error('Environment variable "MONGO_DB" is undefined');
+    }
+
+    const addr = process.env.MONGO_PORT_27017_TCP_ADDR;
+    const port = process.env.MONGO_PORT_27017_TCP_PORT;
+    const db = process.env.MONGO_DB;
+
+    mongoUri = `mongodb://${addr}:${port}/${db}`;
+  }
+
+  module.exports = mongoose.connect(mongoUri);
+  module.exports.connection.on('error', err => {
+    throw err;
+  });
+}