refactor(config.js): Extract config file

* Separate different config source to each files
* Freeze config object

lib/config/dockerSecret.js

@@ -0,0 +1,51 @@
+'use strict'
+
+const fs = require('fs')
+const path = require('path')
+
+const basePath = path.resolve('/var/run/secrets/')
+
+function getSecret (secret) {
+  const filePath = path.join(basePath, secret)
+  if (fs.existsSync(filePath)) return fs.readFileSync(filePath)
+  return undefined
+}
+
+if (fs.existsSync(basePath)) {
+  module.exports = {
+    sessionsecret: getSecret('sessionsecret'),
+    sslkeypath: getSecret('sslkeypath'),
+    sslcertpath: getSecret('sslcertpath'),
+    sslcapath: getSecret('sslcapath'),
+    dhparampath: getSecret('dhparampath'),
+    s3: {
+      accessKeyId: getSecret('s3_acccessKeyId'),
+      secretAccessKey: getSecret('s3_secretAccessKey')
+    },
+    facebook: {
+      clientID: getSecret('facebook_clientID'),
+      clientSecret: getSecret('facebook_clientSecret')
+    },
+    twitter: {
+      consumerKey: getSecret('twitter_consumerKey'),
+      consumerSecret: getSecret('twitter_consumerSecret')
+    },
+    github: {
+      clientID: getSecret('github_clientID'),
+      clientSecret: getSecret('github_clientSecret')
+    },
+    gitlab: {
+      clientID: getSecret('gitlab_clientID'),
+      clientSecret: getSecret('gitlab_clientSecret')
+    },
+    dropbox: {
+      clientID: getSecret('dropbox_clientID'),
+      clientSecret: getSecret('dropbox_clientSecret')
+    },
+    google: {
+      clientID: getSecret('google_clientID'),
+      clientSecret: getSecret('google_clientSecret')
+    },
+    imgur: getSecret('imgur_clientid')
+  }
+}