Pass env from system to api routes

Dockerfile

@@ -36,9 +36,14 @@ COPY --from=builder /app/public ./public
 COPY --from=builder /app/.next/standalone ./
 COPY --from=builder /app/.next/static ./.next/static
 
+COPY --from=builder /app/bin/dumpEnv.js ./bin/dumpEnv.js
+COPY --from=builder /app/dockerEntrypoint.sh .
+RUN ["chmod", "+x", "./dockerEntrypoint.sh"]
+
 EXPOSE 3000
 
 ENV PORT 3000
 ENV HOSTNAME localhost
 
+ENTRYPOINT ["./dockerEntrypoint.sh"]
 CMD ["node", "server.js"]

bin/dumpEnv.js

@@ -0,0 +1,29 @@
+const fs = require("fs");
+const path = require("path");
+
+// NOTE: Next.js does something super weird in production/standalone mode where process.env is cleared
+// of system process.env. The only reasonable workaround I found for this is to dump an .env file
+// in the deployment directory before running server (next.js loads this into process.env automatically)
+const envVars = [
+  "DATA_PATH",
+  // TODO: more
+];
+
+console.log("Preparing env variables…");
+
+const envDeclarations = envVars
+  .map((name) => {
+    const val = process.env[name];
+    if (!val) {
+      throw new Error(`Missing env variable ${name}`);
+    }
+    return `${name}=${val}`;
+  })
+  .join("\n");
+
+const shouldOutputHere = process.argv.includes('--docker')
+const outputDir = shouldOutputHere ? '' : '.next/standalone'
+
+console.log(`Dumping env variables to ${outputDir}...`);
+const envPath = path.join(__dirname, "..", outputDir, ".env");
+fs.writeFileSync(envPath, envDeclarations);

dockerEntrypoint.sh

@@ -0,0 +1,6 @@
+#!/bin/sh
+# no verbose
+set +x
+node bin/dumpEnv.js --docker
+echo "Starting Nextjs"
+exec "$@"

package.json

@@ -2,7 +2,9 @@
   "private": true,
   "scripts": {
     "dev": "next dev",
-    "build": "next build"
+    "build": "next build",
+    "build-prod": "npm run build && cp -r public .next/standalone && cp -r .next/static .next/standalone/.next",
+    "start-prod": "node bin/dumpEnv.js && node .next/standalone/server.js"
   },
   "dependencies": {
     "next": "latest",

pages/api/hello.js

@@ -2,16 +2,10 @@
 import fs from 'fs'
 import path from 'path'
 import getConfig from 'next/config';
-// const { serverRuntimeConfig } = getConfig();
 
-// console.log({
-//   env: process.env,
-//   serverRuntimeConfig,
-// })
+console.log(`Note: data path is ${process.env.DATA_PATH}`)
 
-// TODO: Why don't env variables propagate to here?
-// const messagePath = path.join(serverRuntimeConfig.dataPath, 'message')
-const messagePath = '/data/message'
+const messagePath = path.join(process.env.DATA_PATH, 'message')
 
 function getFileData() {
   try {