Reduce Docker build memory use on small VPS

scripts/build-docker.mjs

@@ -0,0 +1,43 @@
+import { spawnSync } from "node:child_process";
+
+// Release each child's memory before starting the next expensive build phase.
+// In particular, do not type-check while a compiled bundler is still resident.
+function run(label, args, typechecked = false) {
+  console.log(`[build:docker] ${label}`);
+  const started = Date.now();
+  const child = spawnSync(process.execPath, args, {
+    stdio: "inherit",
+    env: {
+      ...process.env,
+      NODE_OPTIONS: "--max-old-space-size=640",
+      NEXT_TELEMETRY_DISABLED: "1",
+      MINEGEO_DOCKER_TYPECHECKED: typechecked ? "1" : "0",
+    },
+  });
+  if (child.error) throw child.error;
+  if (child.status !== 0) {
+    console.error(
+      `[build:docker] ${label} failed (${child.signal || `exit ${child.status}`}).`,
+    );
+    process.exit(child.status || 1);
+  }
+  console.log(
+    `[build:docker] ${label} finished in ${Math.round((Date.now() - started) / 1000)}s.`,
+  );
+}
+
+run("Clean build cache", ["scripts/clean-build.mjs"]);
+run("Generate route types", ["node_modules/next/dist/bin/next", "typegen"]);
+run("Check TypeScript", [
+  "node_modules/typescript/bin/tsc",
+  "--noEmit",
+  "--incremental",
+  "false",
+]);
+// Type errors fail the preceding step. Only this invocation skips the duplicate
+// check; regular npm run build still performs Next.js's normal type checking.
+run(
+  "Compile production application",
+  ["node_modules/next/dist/bin/next", "build", "--webpack"],
+  true,
+);