extract env vars from file system

Author: james-elicx

packages/cloudflare/package.json

@@ -59,11 +59,14 @@
     "tsup": "catalog:",
     "typescript": "catalog:",
     "typescript-eslint": "catalog:",
-    "vitest": "catalog:"
+    "vitest": "catalog:",
+    "mock-fs": "catalog:",
+    "@types/mock-fs": "catalog:"
   },
   "dependencies": {
     "@opennextjs/aws": "https://pkg.pr.new/@opennextjs/aws@674",
-    "ts-morph": "catalog:"
+    "ts-morph": "catalog:",
+    "@dotenvx/dotenvx": "catalog:"
   },
   "peerDependencies": {
     "wrangler": "catalog:"

packages/cloudflare/src/cli/build/utils/extract-project-env-vars.spec.ts

@@ -0,0 +1,57 @@
+import { writeFileSync } from "node:fs";
+
+import { BuildOptions } from "@opennextjs/aws/build/helper.js";
+import mockFs from "mock-fs";
+import { afterEach, beforeEach, describe, expect, it } from "vitest";
+
+import { extractProjectEnvVars } from "./extract-project-env-vars";
+
+const options = { monorepoRoot: "", appPath: "" } as BuildOptions;
+
+describe("extractProjectEnvVars", () => {
+  beforeEach(() => {
+    mockFs({
+      ".env": "ENV_VAR=value",
+      ".env.local": "ENV_LOCAL_VAR=value",
+      ".env.development": "ENV_DEV_VAR=value",
+      ".env.development.local": "ENV_DEV_LOCAL_VAR=value",
+      ".env.production": "ENV_PROD_VAR=value",
+      ".env.production.local": "ENV_PROD_LOCAL_VAR=value",
+    });
+  });
+
+  afterEach(() => mockFs.restore());
+
+  it("should extract production env vars", () => {
+    const result = extractProjectEnvVars(options);
+    expect(result).toEqual({
+      ENV_LOCAL_VAR: "value",
+      ENV_PROD_LOCAL_VAR: "value",
+      ENV_PROD_VAR: "value",
+      ENV_VAR: "value",
+    });
+  });
+
+  it("should extract development env vars", () => {
+    writeFileSync(".dev.vars", 'NEXTJS_ENV = "development"');
+
+    const result = extractProjectEnvVars(options);
+    expect(result).toEqual({
+      ENV_LOCAL_VAR: "value",
+      ENV_DEV_LOCAL_VAR: "value",
+      ENV_DEV_VAR: "value",
+      ENV_VAR: "value",
+    });
+  });
+
+  it("should override env vars with those in a local file", () => {
+    writeFileSync(".env.production.local", "ENV_PROD_VAR=overridden");
+
+    const result = extractProjectEnvVars(options);
+    expect(result).toEqual({
+      ENV_LOCAL_VAR: "value",
+      ENV_PROD_VAR: "overridden",
+      ENV_VAR: "value",
+    });
+  });
+});

packages/cloudflare/src/cli/build/utils/extract-project-env-vars.ts

@@ -0,0 +1,38 @@
+import * as fs from "node:fs";
+import * as path from "node:path";
+
+import { parse } from "@dotenvx/dotenvx";
+import type { BuildOptions } from "@opennextjs/aws/build/helper.js";
+
+function readEnvFiles(fileNames: string[], { monorepoRoot, appPath }: BuildOptions) {
+  return fileNames
+    .flatMap((fileName) => [
+      ...(monorepoRoot !== appPath ? [path.join(monorepoRoot, fileName)] : []),
+      path.join(appPath, fileName),
+    ])
+    .filter((filePath) => fs.statSync(filePath, { throwIfNoEntry: false })?.isFile())
+    .map((filePath) => parse(fs.readFileSync(filePath).toString()))
+    .reduce<Record<string, string>>((acc, overrides) => ({ ...acc, ...overrides }), {});
+}
+
+/**
+ * Extracts the environment variables defined in various .env files for a project.
+ *
+ * The `NEXTJS_ENV` environment variable in `.dev.vars` determines the mode.
+ *
+ * Merged variables respect the following priority order.
+ * 1. `.env.{mode}.local`
+ * 2. `.env.local`
+ * 3. `.env.{mode}`
+ * 4. `.env`
+ *
+ * In a monorepo, the env files in an app's directory will take precedence over
+ * the env files at the root of the monorepo.
+ */
+export function extractProjectEnvVars(options: BuildOptions) {
+  const wranglerDevVars = readEnvFiles([".dev.vars"], options);
+
+  const mode = wranglerDevVars["NEXTJS_ENV"] ?? "production";
+
+  return readEnvFiles([".env", `.env.${mode}`, ".env.local", `.env.${mode}.local`], options);
+}

packages/cloudflare/src/cli/build/utils/index.ts

@@ -1,3 +1,4 @@
 export * from "./copy-prerendered-routes";
+export * from "./extract-project-env-vars";
 export * from "./normalize-path";
 export * from "./ts-parse-file";