feat: Replace config at runtime

Dockerfile

@@ -1,5 +1,4 @@
-FROM node:10-alpine as builder
-LABEL maintainer="Niranjan Rajendran <[email protected]>"
+FROM node:12-alpine as builder
 
 WORKDIR /app
 
@@ -25,16 +24,18 @@ FROM node:10-alpine
 
 WORKDIR /fastboot
 
-COPY scripts/fastboot-server.js .
-COPY --from=builder /app/dist/ app/
+COPY --from=builder /app/dist/ dist/
 
 RUN apk add --no-cache ca-certificates && \
-    cp app/package.json . && \
+    cp dist/package.json . && \
     yarn install && \
-    yarn add fastboot-app-server && \
+    yarn add fastboot-app-server dotenv lodash safe-eval && \
     rm -rf yarn.lock && \
     yarn cache clean
 
+COPY scripts/* ./scripts/
+COPY config/environment.js ./config/
+
 EXPOSE 4000
 
-CMD ["node", "fastboot-server.js"]
+CMD ["node", "./scripts/fastboot-server.js"]

scripts/fastboot-server.js

@@ -1,7 +1,10 @@
+require('dotenv').config()
+
 const FastBootAppServer = require('fastboot-app-server');
+const { injectEnvironment } = require('./replace-config');
 
 const enableGzip = process.env.FASTBOOT_GZIP || 'true';
-const fastbootDistPath = process.env.FASTBOOT_DIST_PATH || '/fastboot/app';
+const fastbootDistPath = process.env.FASTBOOT_DIST_PATH || './dist';
 const enableChunkedResponse = process.env.FASTBOOT_CHUNKED_RESPONSE || 'true';
 const fastbootHost = process.env.FASTBOOT_HOST || '0.0.0.0';
 const fastbootPort = process.env.FASTBOOT_PORT || process.env.PORT || '4000';
@@ -16,4 +19,10 @@ let fastbootServer = new FastBootAppServer({
   workerCount     : parseInt(fastbootWorkers)
 });
 
-fastbootServer.start();
+(async () => {
+  if (process.env.INJECT_ENV === 'true') {
+    await injectEnvironment();
+  }
+
+  fastbootServer.start();
+})();

scripts/replace-config.js

@@ -0,0 +1,132 @@
+require('dotenv').config()
+
+const fs = require('fs');
+const promisify = require('util').promisify
+const { merge } = require('lodash')
+const safeEval = require('safe-eval')
+
+const env = require('../config/environment')
+const appName = 'open-event-frontend'
+
+const environment = env('production')
+
+async function replaceFastbootConfig() {
+  const packagePath = './dist/package.json'
+  const packageInfo = require('.' + packagePath)
+
+  const old = packageInfo.fastboot.config[appName]
+  packageInfo.fastboot.config[appName] = merge(old, environment);
+  await promisify(fs.writeFile)(packagePath, JSON.stringify(packageInfo))
+
+  console.log('Transformed package.json with new environment')
+}
+
+function findObject(js, objectStart) {
+  let braceCount = 1;
+
+  const start = js.indexOf("{", objectStart);
+
+  if (start < 0) {
+    return null;
+  }
+
+  let index = start + 1;
+  let parseBlocker = null;
+  let parseBlockerBuffer = null;
+
+  while (index < js.length) {
+    const c = js[index];
+
+    if (!parseBlocker && !parseBlockerBuffer) {
+      if (c == "{") {
+        braceCount += 1;
+      } else if (c == "}") {
+        braceCount -= 1;
+      } else if (c === '"' || c === "'" || c === "`") {
+        parseBlocker = c;
+      } else if (js[index - 1] == "/") {
+        if (c == "/") parseBlocker = "\n";
+        else if (c == "*") parseBlockerBuffer = "*/";
+      }
+
+      if (braceCount === 0) {
+        break;
+      }
+    } else {
+      if (c === parseBlocker) {
+        parseBlocker = null;
+      } else if (c == '/' && js[index - 1] == '*') {
+        parseBlockerBuffer = null;
+      }
+    }
+
+    index++;
+  }
+
+  if (index >= js.length) return null;
+
+  return {
+    start,
+    end: index
+  };
+}
+
+function replace(str, start, end, replacement) {
+  return str.substring(0, start) + replacement + str.substring(end + 1, str.length)
+}
+
+async function replaceWebConfig() {
+  const pattern = new RegExp(`^${appName}.*\.js$`)
+  const basePath = './dist/assets/'
+  const appJs = (await promisify(fs.readdir)(basePath)).filter(name => name.match(pattern))
+
+  const envDefinition = 'define("open-event-frontend/config/environment"'
+
+  for (const js of appJs) {
+    const jsPath = basePath + js;
+    const code = (await promisify(fs.readFile)(jsPath)).toString()
+    let defineIndex = code.indexOf(envDefinition)
+
+    if (defineIndex < 0) {
+      defineIndex = code.indexOf(envDefinition.replace(/"/g, "'"))
+      if (defineIndex < 0)
+        continue;
+    }
+
+    const defaultIndex = code.indexOf('default', defineIndex + 1)
+
+    if (defaultIndex < 0)
+      continue;
+
+    // File with environment definition found
+
+    console.log('Transforming ' + js)
+
+    const object = findObject(code, defaultIndex)
+
+    console.log('Environment Object Found', object)
+
+    const webEnvJson = code.substring(object.start, object.end + 1)
+    const old = safeEval('(' + webEnvJson + ')')
+
+    const newEnv = JSON.stringify(merge(old, environment))
+    const newCode = replace(code, object.start, object.end, newEnv)
+
+    console.log('Injected new environment')
+
+    await promisify(fs.writeFile)(jsPath, newCode)
+
+    console.log('Transformation Complete')
+
+    break;
+  }
+}
+
+async function injectEnvironment() {
+  await replaceFastbootConfig()
+  await replaceWebConfig()
+}
+
+module.exports = {
+  injectEnvironment
+}