feat: Allow the use of project-level external config file for js-compute-runtime CLI behavior

README.md

@@ -30,6 +30,108 @@ addEventListener("fetch", event => {
 });
 ```
 
+### CLI Flags and configuration
+
+The CLI is typically invoked by the `build` script defined in your project's `package.json` scripts.
+
+```json
+{
+  "scripts": {
+    "build": "js-compute-runtime src/index.js bin/main.wasm"
+  }
+}
+```
+
+The CLI is invoked as follows:
+
+```sh
+js-compute-runtime [OPTIONS] <input-js-file> <output-wasm-file>
+```
+
+Options can be specified on the command line or added to a persistent configuration file for the project.  The CLI will search for a configuration starting from the current directory in the following order:
+
+* A `fastlycompute` property in `package.json`
+* `.fastlycomputerc.json`
+* `fastlycompute.config.js`
+
+<details>
+<summary>Click here to see full list</summary>
+
+The CLI will search for a configuration starting from the current directory in the following order:
+
+- A `fastlycompute` property in `package.json`
+- `.fastlycomputerc` (JSON or YAML)
+- `.fastlycomputerc.json`, `.fastlycomputerc.yaml`, `.fastlycomputerc.yml`
+- `.fastlycomputerc.js`, `.fastlycomputerc.mjs`
+- `fastlycompute.config.js`, `fastlycompute.config.mjs`
+
+</details>
+
+If an option is defined in both the command line and the configuration file, the command line option takes precedence.
+
+#### Supported Options
+
+| Config Key                                    | CLI Flag                                             | Type                        | Description                                                                                                                                               | 
+|:----------------------------------------------|:-----------------------------------------------------|:----------------------------|:----------------------------------------------------------------------------------------------------------------------------------------------------------|
+| `enableAOT`                                   | `--enable-aot`                                       | `boolean`                   | Enable AOT compilation for performance                                                                                                                    |
+| `aotCache`                                    | `--aot-cache`                                        | `string` (path)             | Specify a path to the AOT cache file                                                                                                                      |
+| `enableHttpCache`                             | `--enable-http-cache`                                | `boolean`                   | Enable the [HTTP cache hook API](https://www.fastly.com/documentation/guides/concepts/cache/#modifying-a-request-as-it-is-forwarded-to-a-backend)         |
+| `enableExperimentalHighResolutionTimeMethods` | `--enable-experimental-high-resolution-time-methods` | `boolean`                   | Enable experimental fastly.now() method                                                                                                                   |
+| `enableExperimentalTopLevelAwait`             | `--enable-experimental-top-level-await`              | `boolean`                   | Enable experimental top level await                                                                                                                       |
+| `enableStackTraces`                           | `--enable-stack-traces`                              | `boolean`                   | Enable stack traces                                                                                                                                       |
+| `excludeSources`                              | `--exclude-sources`                                  | `boolean`                   | Don't include sources in stack traces                                                                                                                     |
+| `debugIntermediateFiles`                      | `--debug-intermediate-files`                         | `string` (path)             | Output intermediate files in directory                                                                                                                    |
+| `debugBuild`                                  | `--debug-build`                                      | `boolean`                   | Use debug build of the SDK runtime                                                                                                                        |
+| `engineWasm`                                  | `--engine-wasm`                                      | `string` (path)             | Specify a custom Wasm engine (advanced)                                                                                                                   |
+| `wevalBin`                                    | `--weval-bin`                                        | `string` (path)             | Specify a custom weval binary (advanced)                                                                                                                  |
+| `env`                                         | `--env`                                              | `string \| object \| array` | Set environment variables, possibly inheriting from the current environment. Multiple variables can be comma-separated (e.g., --env ENV_VAR,OVERRIDE=val) |
+
+NOTE: The `env` field is additive. Values defined on the command-line values append to, rather than replace, the values defined in any configuration file. 
+
+#### Example command-line options
+
+```sh
+js-compute-runtime --enable-aot --enable-stack-traces --enable-top-level-await --env=LOG_LEVEL=debug ./src/index.js ./bin/main.wasm
+```
+
+#### Example `.fastlycomputerc.json`
+
+```json
+{
+  "enableAOT": true,
+  "enableStackTraces": true,
+  "enableTopLevelAwait": true,
+  "env": {
+    "LOG_LEVEL": "debug"
+  }
+}
+```
+
+#### Example `package.json`
+
+```json
+{
+  "name": "my-fastly-service",
+  "type": "module",
+  "dependencies": {
+    "@fastly/cli": "^13.0.0"
+  },
+  "scripts": {
+    "build": "js-compute-runtime ./src/index.js ./bin/main.wasm",
+    "dev": "fastly compute serve",
+    "deploy": "fastly compute publish"
+  },
+  "fastlycompute": {
+    "enableAOT": true,
+    "enableStackTraces": true,
+    "enableTopLevelAwait": true,
+    "env": {
+      "LOG_LEVEL": "debug"
+    }
+  }
+}
+```
+
 ### API documentation
 
 The API documentation for the JavaScript SDK is located at [https://js-compute-reference-docs.edgecompute.app](https://js-compute-reference-docs.edgecompute.app).

package.json

@@ -63,6 +63,7 @@
     "@jridgewell/trace-mapping": "^0.3.31",
     "acorn": "^8.13.0",
     "acorn-walk": "^8.3.4",
+    "cosmiconfig": "^9.0.1",
     "esbuild": "^0.25.0",
     "magic-string": "^0.30.12",
     "picomatch": "^4.0.3",

src/cli/js-compute-runtime-cli.ts

@@ -3,8 +3,11 @@
 import { parseInputs } from '../parseInputs.js';
 import { printHelp, printVersion } from '../printHelp.js';
 import { addSdkMetadataField } from '../addSdkMetadataField.js';
+import { readConfigFileAndCliArguments } from '../config.js';
 
-const parsedInputs = await parseInputs(process.argv.slice(2));
+const argv = await readConfigFileAndCliArguments(process.argv.slice(2));
+
+const parsedInputs = await parseInputs(argv);
 
 if (parsedInputs === 'version') {
   await printVersion();