feat: built in env files support

packages/dotenv-webpack-plugin/README.md

@@ -77,12 +77,15 @@ DotenvWebpackPlugin accepts the following configuration options:
 
 1. `prefixes`: An array of prefixes to prepend to the names of environment variables. By default, DotenvWebpackPlugin will prepend `process.env.` and `import.meta.env.` to the names of environment variables.
 
+1. `allowEmptyValues`: A boolean value indicating whether to allow empty values. By default this value is set to `false`, DotenvWebpackPlugin will throw an error if an environment variable is defined without a value.
+
 You can pass these options when creating an instance of DotenvWebpackPlugin:
 
 ```javascript
 new DotenvWebpackPlugin({
   envFiles: ["./.env", "./.env.local"],
   prefixes: ["process.env.", "import.meta.env."],
   envVarPrefix: "PUBLIC_",
+  allowEmptyValues: false,
 });
 ```

packages/dotenv-webpack-plugin/src/index.js

@@ -35,12 +35,14 @@ class DotenvWebpackPlugin {
       envFiles = this.defaultFileList,
       prefixes = ["process.env.", "import.meta.env."],
       envVarPrefix = "PUBLIC_",
+      allowEmptyValues = false,
     } = options;
 
     this.options = {
       envFiles,
       prefixes,
       envVarPrefix,
+      allowEmptyValues,
     };
   }
 
@@ -91,16 +93,43 @@ class DotenvWebpackPlugin {
     for (const [key, value] of Object.entries(envVariables)) {
       // only add variables starting with the provided prefix
       if (key.startsWith(this.options.envVarPrefix)) {
-        for (let index = 0; index < this.options.prefixes.length; index++) {
-          const prefix = this.options.prefixes[index];
-          filteredEnvVariables[`${prefix}${key}`] = value;
-        }
+        filteredEnvVariables[key] = value;
       }
     }
 
     return filteredEnvVariables;
   }
 
+  assignPrefixes(envVariables) {
+    const prefixedEnvVariables = {};
+
+    for (const [key, value] of Object.entries(envVariables)) {
+      for (let index = 0; index < this.options.prefixes.length; index++) {
+        const prefix = this.options.prefixes[index];
+        prefixedEnvVariables[`${prefix}${key}`] = value;
+      }
+    }
+
+    return prefixedEnvVariables;
+  }
+
+  /**
+   * Get list of empty values
+   * @param {Object} envVariables - Environment variables
+   * @returns {Array} - List of empty values
+   */
+  getEmptyValues(envVariables) {
+    const emptyValues = [];
+
+    for (const [key, value] of Object.entries(envVariables)) {
+      if (value === "") {
+        emptyValues.push(key);
+      }
+    }
+
+    return emptyValues;
+  }
+
   /**
    * Webpack apply hook
    * @param {Compiler} compiler - Webpack compiler
@@ -131,9 +160,23 @@ class DotenvWebpackPlugin {
 
           const filteredEnvVariables = this.filterVariables(envVariables);
 
+          const emptyValues = this.getEmptyValues(filteredEnvVariables);
+
+          if (!this.options.allowEmptyValues && emptyValues.length > 0) {
+            const logger = compiler.getInfrastructureLogger("DotenvWebpackPlugin");
+            logger.error(
+              `Environment variables cannot have an empty value. The following variables are empty: ${emptyValues.join(
+                ", ",
+              )}`,
+            );
+            return;
+          }
+
+          const prefixedEnvVariables = this.assignPrefixes(filteredEnvVariables);
+
           // expand environment vars
           const expandedEnvVariables = dotenvExpand.expand({
-            parsed: filteredEnvVariables,
+            parsed: prefixedEnvVariables,
             // don't write to process.env
             ignoreProcessEnv: true,
           }).parsed;

packages/dotenv-webpack-plugin/src/options.json

@@ -12,15 +12,19 @@
       }
     },
     "prefixes": {
-      "description": "The prefixes to use for the environment variables",
+      "description": "The prefixes to prepend to the environment variables",
       "type": "array",
       "items": {
         "type": "string"
       }
     },
     "envVarPrefix": {
-      "description": "The prefix to use for the environment variables",
+      "description": "The prefix to filter environment variables by",
       "type": "string"
+    },
+    "allowEmptyValues": {
+      "description": "Whether to allow empty values for environment variables",
+      "type": "boolean"
     }
   }
 }

packages/dotenv-webpack-plugin/src/types.d.ts

@@ -1,5 +1,6 @@
 export type Config = {
-  envFiles: string[];
-  prefixes: string[];
-  envVarPrefix: string;
+  envFiles?: string[];
+  prefixes?: string[];
+  envVarPrefix?: string;
+  allowEmptyValues?: boolean;
 };

test/build/dotenv-webpack-plugin/allow-empty-values/.env

@@ -0,0 +1,2 @@
+PUBLIC_VARIABLE=
+PUBLIC_VARIABLE2=

test/build/dotenv-webpack-plugin/allow-empty-values/src/index.js

@@ -0,0 +1 @@
+console.log("Hello from index.js");

test/build/dotenv-webpack-plugin/allow-empty-values/webpack.config.js

@@ -0,0 +1,15 @@
+const { join } = require("path");
+const DotenvWebpackPlugin = require("../../../../packages/dotenv-webpack-plugin/src");
+
+module.exports = {
+  entry: "./src/index.js",
+  mode: "production",
+  output: {
+    path: join(__dirname, "dist"),
+  },
+  plugins: [
+    new DotenvWebpackPlugin({
+      allowEmptyValues: true,
+    }),
+  ],
+};

test/build/dotenv-webpack-plugin/dotenv-webpack-plugin.test.js

@@ -285,4 +285,20 @@ describe("dotenv-webpack-plugin", () => {
 
     expect(stderr).toContain("Could not read ./env.custom");
   });
+
+  it("throws an error if empty value is passed for an environment variable", async () => {
+    const testDir = join(__dirname, "validates-empty-value");
+    const { stderr } = await run(testDir);
+
+    expect(stderr).toContain(
+      "Environment variables cannot have an empty value. The following variables are empty: PUBLIC_VARIABLE, PUBLIC_VARIABLE2",
+    );
+  });
+
+  it("does not throw an error if empty value is passed for an environment variable and allowEmptyValues is set to true", async () => {
+    const testDir = join(__dirname, "allow-empty-values");
+    const { exitCode, stderr, stdout } = await run(testDir);
+
+    assertNoErrors(exitCode, stderr, stdout, testDir);
+  });
 });

test/build/dotenv-webpack-plugin/validates-empty-value/.env

@@ -0,0 +1,2 @@
+PUBLIC_VARIABLE=
+PUBLIC_VARIABLE2=

test/build/dotenv-webpack-plugin/validates-empty-value/src/index.js

@@ -0,0 +1 @@
+console.log("Hello from index.js");

test/build/dotenv-webpack-plugin/validates-empty-value/webpack.config.js

@@ -0,0 +1,11 @@
+const { join } = require("path");
+const DotenvWebpackPlugin = require("../../../../packages/dotenv-webpack-plugin/src");
+
+module.exports = {
+  entry: "./src/index.js",
+  mode: "production",
+  output: {
+    path: join(__dirname, "dist"),
+  },
+  plugins: [new DotenvWebpackPlugin()],
+};