chore: adds write config file on startup

Dockerfile

@@ -55,4 +55,8 @@ ENV PORT 3000
 
 VOLUME /app/data
 
+# Allow passing through the RPC_CONFIG JSON configuration environment variable.
+ARG RPC_CONFIG
+ENV RPC_CONFIG="$RPC_CONFIG"
+
 CMD ["node", "server.js"]

next.config.js

@@ -1,7 +1,30 @@
+const fs = require("fs");
+const { env } = require("process");
+const { PHASE_PRODUCTION_SERVER } = require("next/constants");
+const CONFIG_ENV_VAR_NAME = "RPC_CONFIG";
+const CONFIG_JSON = env[CONFIG_ENV_VAR_NAME];
+
 /** @type {import('next').NextConfig} */
 const nextConfig = {
   reactStrictMode: true,
   output: "standalone"
 };
 
-module.exports = nextConfig;
+module.exports = (phase) => {
+  const isProduction = phase === PHASE_PRODUCTION_SERVER;
+  const saveConfigFile = isProduction && Boolean(CONFIG_JSON);
+
+  if (saveConfigFile) {
+    saveConfig(config);
+  }
+
+  return nextConfig;
+};
+
+function saveConfig() {
+  console.log(
+    `Saving config file from '${CONFIG_ENV_VAR_NAME}' env variable value`
+  );
+
+  fs.writeFileSync("./data/config.json", CONFIG_JSON);
+}

package.json

@@ -1,6 +1,6 @@
 {
   "name": "raspberry-pi-client",
-  "version": "1.0.0-rc.1",
+  "version": "1.0.0-rc.2",
   "private": true,
   "scripts": {
     "dev": "next dev",