feat: allow array for headers option

examples/headers/array/README.md

@@ -0,0 +1,36 @@
+# headers option as an object
+
+Adds headers to all responses.
+
+**webpack.config.js**
+
+```js
+module.exports = {
+  // ...
+  devServer: {
+    headers: [
+      {
+        key: "X-Foo",
+        value: "value1",
+      },
+      {
+        key: "X-Bar",
+        value: "value2",
+      },
+    ],
+  },
+};
+```
+
+To run this example use the following command:
+
+```console
+npx webpack serve --open
+```
+
+## What should happen
+
+1. The script should open `http://localhost:8080/`.
+2. You should see the text on the page itself change to read `Success!`.
+3. Open the console in your browser's devtools and select the _Network_ tab.
+4. Find `main.js`. The response headers should contain `X-Foo: value1` and `X-Bar: value2`.

examples/headers/array/app.js

@@ -0,0 +1,6 @@
+"use strict";
+
+const target = document.querySelector("#target");
+
+target.classList.add("pass");
+target.innerHTML = "Success!";

examples/headers/array/webpack.config.js

@@ -0,0 +1,22 @@
+"use strict";
+
+// our setup function adds behind-the-scenes bits to the config that all of our
+// examples need
+const { setup } = require("../../util");
+
+module.exports = setup({
+  context: __dirname,
+  entry: "./app.js",
+  devServer: {
+    headers: [
+      {
+        key: "X-Foo",
+        value: "value1",
+      },
+      {
+        key: "X-Bar",
+        value: "value2",
+      },
+    ],
+  },
+});

lib/Server.js

@@ -1845,10 +1845,19 @@ class Server {
         headers = headers(req, res, this.middleware.context);
       }
 
-      // eslint-disable-next-line guard-for-in
-      for (const name in headers) {
-        res.setHeader(name, headers[name]);
+      const allHeaders = [];
+
+      if (typeof headers === "object" && !Array.isArray(headers)) {
+        // eslint-disable-next-line guard-for-in
+        for (const name in headers) {
+          allHeaders.push({ key: name, value: headers[name] });
+        }
+        headers = allHeaders;
       }
+
+      headers.forEach((header) => {
+        res.setHeader(header.key, header.value);
+      });
     }
 
     next();

lib/options.json

@@ -369,8 +369,32 @@
       "description": "Allows to configure the server's listening socket for TLS (by default, dev server will be served over HTTP).",
       "link": "https://webpack.js.org/configuration/dev-server/#devserverhttps"
     },
+    "HeaderObject": {
+      "type": "object",
+      "additionalProperties": false,
+      "properties": {
+        "key": {
+          "description": "key of header.",
+          "type": "string"
+        },
+        "value": {
+          "description": "value of header.",
+          "type": "string"
+        }
+      },
+      "cli": {
+        "exclude": true
+      }
+    },
     "Headers": {
       "anyOf": [
+        {
+          "type": "array",
+          "items": {
+            "$ref": "#/definitions/HeaderObject"
+          },
+          "minItems": 1
+        },
         {
           "type": "object"
         },

test/__snapshots__/validate-options.test.js.snap.webpack4

@@ -223,13 +223,26 @@ exports[`options validate should throw an error on the "devMiddleware" option wi
    -> Read more at https://webpack.js.org/configuration/dev-server/#devserverdevmiddleware"
 `;
 
+exports[`options validate should throw an error on the "headers" option with '[]' value 1`] = `
+"ValidationError: Invalid options object. Dev Server has been initialized using an options object that does not match the API schema.
+ - options.headers should be a non-empty array."
+`;
+
+exports[`options validate should throw an error on the "headers" option with '[{"foo":"bar"}]' value 1`] = `
+"ValidationError: Invalid options object. Dev Server has been initialized using an options object that does not match the API schema.
+ - options.headers[0] has an unknown property 'foo'. These properties are valid:
+   object { key?, value? }"
+`;
+
 exports[`options validate should throw an error on the "headers" option with '1' value 1`] = `
 "ValidationError: Invalid options object. Dev Server has been initialized using an options object that does not match the API schema.
  - options.headers should be one of these:
-   object { … } | function
+   [object { key?, value? }, ...] (should not have fewer than 1 item) | object { … } | function
    -> Allows to set custom headers on response.
    -> Read more at https://webpack.js.org/configuration/dev-server/#devserverheaders
    Details:
+    * options.headers should be an array:
+      [object { key?, value? }, ...] (should not have fewer than 1 item)
     * options.headers should be an object:
       object { … }
     * options.headers should be an instance of function."
@@ -238,10 +251,12 @@ exports[`options validate should throw an error on the "headers" option with '1'
 exports[`options validate should throw an error on the "headers" option with 'false' value 1`] = `
 "ValidationError: Invalid options object. Dev Server has been initialized using an options object that does not match the API schema.
  - options.headers should be one of these:
-   object { … } | function
+   [object { key?, value? }, ...] (should not have fewer than 1 item) | object { … } | function
    -> Allows to set custom headers on response.
    -> Read more at https://webpack.js.org/configuration/dev-server/#devserverheaders
    Details:
+    * options.headers should be an array:
+      [object { key?, value? }, ...] (should not have fewer than 1 item)
     * options.headers should be an object:
       object { … }
     * options.headers should be an instance of function."

test/__snapshots__/validate-options.test.js.snap.webpack5

@@ -223,13 +223,26 @@ exports[`options validate should throw an error on the "devMiddleware" option wi
    -> Read more at https://webpack.js.org/configuration/dev-server/#devserverdevmiddleware"
 `;
 
+exports[`options validate should throw an error on the "headers" option with '[]' value 1`] = `
+"ValidationError: Invalid options object. Dev Server has been initialized using an options object that does not match the API schema.
+ - options.headers should be a non-empty array."
+`;
+
+exports[`options validate should throw an error on the "headers" option with '[{"foo":"bar"}]' value 1`] = `
+"ValidationError: Invalid options object. Dev Server has been initialized using an options object that does not match the API schema.
+ - options.headers[0] has an unknown property 'foo'. These properties are valid:
+   object { key?, value? }"
+`;
+
 exports[`options validate should throw an error on the "headers" option with '1' value 1`] = `
 "ValidationError: Invalid options object. Dev Server has been initialized using an options object that does not match the API schema.
  - options.headers should be one of these:
-   object { … } | function
+   [object { key?, value? }, ...] (should not have fewer than 1 item) | object { … } | function
    -> Allows to set custom headers on response.
    -> Read more at https://webpack.js.org/configuration/dev-server/#devserverheaders
    Details:
+    * options.headers should be an array:
+      [object { key?, value? }, ...] (should not have fewer than 1 item)
     * options.headers should be an object:
       object { … }
     * options.headers should be an instance of function."
@@ -238,10 +251,12 @@ exports[`options validate should throw an error on the "headers" option with '1'
 exports[`options validate should throw an error on the "headers" option with 'false' value 1`] = `
 "ValidationError: Invalid options object. Dev Server has been initialized using an options object that does not match the API schema.
  - options.headers should be one of these:
-   object { … } | function
+   [object { key?, value? }, ...] (should not have fewer than 1 item) | object { … } | function
    -> Allows to set custom headers on response.
    -> Read more at https://webpack.js.org/configuration/dev-server/#devserverheaders
    Details:
+    * options.headers should be an array:
+      [object { key?, value? }, ...] (should not have fewer than 1 item)
     * options.headers should be an object:
       object { … }
     * options.headers should be an instance of function."

test/e2e/__snapshots__/headers.test.js.snap.webpack4

@@ -1,5 +1,15 @@
 // Jest Snapshot v1, https://goo.gl/fbAQLP
 
+exports[`headers option as a function returning an array should handle GET request with headers: console messages 1`] = `Array []`;
+
+exports[`headers option as a function returning an array should handle GET request with headers: page errors 1`] = `Array []`;
+
+exports[`headers option as a function returning an array should handle GET request with headers: response headers x-bar 1`] = `"value2"`;
+
+exports[`headers option as a function returning an array should handle GET request with headers: response headers x-foo 1`] = `"value1"`;
+
+exports[`headers option as a function returning an array should handle GET request with headers: response status 1`] = `200`;
+
 exports[`headers option as a function should handle GET request with headers as a function: console messages 1`] = `Array []`;
 
 exports[`headers option as a function should handle GET request with headers as a function: page errors 1`] = `Array []`;
@@ -19,6 +29,16 @@ exports[`headers option as a string should handle GET request with headers: resp
 
 exports[`headers option as a string should handle GET request with headers: response status 1`] = `200`;
 
+exports[`headers option as an array of objects should handle GET request with headers: console messages 1`] = `Array []`;
+
+exports[`headers option as an array of objects should handle GET request with headers: page errors 1`] = `Array []`;
+
+exports[`headers option as an array of objects should handle GET request with headers: response headers x-bar 1`] = `"value2"`;
+
+exports[`headers option as an array of objects should handle GET request with headers: response headers x-foo 1`] = `"value1"`;
+
+exports[`headers option as an array of objects should handle GET request with headers: response status 1`] = `200`;
+
 exports[`headers option as an array should handle GET request with headers as an array: console messages 1`] = `Array []`;
 
 exports[`headers option as an array should handle GET request with headers as an array: page errors 1`] = `Array []`;

test/e2e/__snapshots__/headers.test.js.snap.webpack5

@@ -1,5 +1,15 @@
 // Jest Snapshot v1, https://goo.gl/fbAQLP
 
+exports[`headers option as a function returning an array should handle GET request with headers: console messages 1`] = `Array []`;
+
+exports[`headers option as a function returning an array should handle GET request with headers: page errors 1`] = `Array []`;
+
+exports[`headers option as a function returning an array should handle GET request with headers: response headers x-bar 1`] = `"value2"`;
+
+exports[`headers option as a function returning an array should handle GET request with headers: response headers x-foo 1`] = `"value1"`;
+
+exports[`headers option as a function returning an array should handle GET request with headers: response status 1`] = `200`;
+
 exports[`headers option as a function should handle GET request with headers as a function: console messages 1`] = `Array []`;
 
 exports[`headers option as a function should handle GET request with headers as a function: page errors 1`] = `Array []`;
@@ -19,6 +29,16 @@ exports[`headers option as a string should handle GET request with headers: resp
 
 exports[`headers option as a string should handle GET request with headers: response status 1`] = `200`;
 
+exports[`headers option as an array of objects should handle GET request with headers: console messages 1`] = `Array []`;
+
+exports[`headers option as an array of objects should handle GET request with headers: page errors 1`] = `Array []`;
+
+exports[`headers option as an array of objects should handle GET request with headers: response headers x-bar 1`] = `"value2"`;
+
+exports[`headers option as an array of objects should handle GET request with headers: response headers x-foo 1`] = `"value1"`;
+
+exports[`headers option as an array of objects should handle GET request with headers: response status 1`] = `200`;
+
 exports[`headers option as an array should handle GET request with headers as an array: console messages 1`] = `Array []`;
 
 exports[`headers option as an array should handle GET request with headers as an array: page errors 1`] = `Array []`;