Angular 6 Environment Configuration: Best Practices and Options

• Angular applications often have different configurations for development, staging, and production environments.
• Environment variables store settings specific to each environment (e.g., API URLs, logging levels).
• This approach keeps sensitive information out of your codebase and allows for easy configuration changes.

Steps to Set Environment Variables in Angular 6:

1. Generate Environment Files (if not already present):

   • Use the Angular CLI command: ng generate environments
   • This creates a src/environments directory with two files:
     • environment.ts: Default configuration (usually for production)
     • environment.prod.ts: Optional production-specific configuration

2. Create Additional Environment Files (Optional):

3. Define Environment Variables:

   • In each environment file, define variables using the export const environment = { ... }; syntax.
   • Example (in environment.ts):

   export const environment = {
     production: false,
     apiUrl: 'http://localhost:3000/api',
     logging: false
   };
   

4. Configure angular.json:

   • Open the angular.json file in your project's root directory.
   • Locate the "configurations" section under the "build" and optionally "serve" targets.
   • Add entries for each environment configuration you created.
   • The key is the environment name, and the value is an object with a "fileReplacements" property.
   • The "fileReplacements" property specifies a source file to be replaced with its environment-specific counterpart during build or serve.
   • Example (angular.json excerpt):

"configurations": { "production": { "...": "...", "fileReplacements": [ { "replace": "src/environments/environment.ts", "with": "src/environments/environment.prod.ts" } ] }, "staging": { "...": "...", "fileReplacements": [ { "replace": "src/environments/environment.ts", "with": "src/environments/environment.staging.ts" } ] } }

5. **Use Environment Variables in Your Code:**
- Import the `environment` object from `environments/environment` (or the specific environment file) into your components or services.
- Access environment variables using dot notation (e.g., `environment.apiUrl`).

```typescript
import { Component } from '@angular/core';
import { environment } from 'src/environments/environment';

@Component({
  selector: 'app-my-component',
  templateUrl: './my-component.component.html',
  styleUrls: ['./my-component.component.css']
})
export class MyComponent {
  apiUrl = environment.apiUrl;

  constructor() {}

  makeApiCall() {
    // Use this.apiUrl to make API calls based on the environment
  }
}

Using ng serve with Specific Environments:

• Example (to run with the staging environment):

  ng serve --configuration=staging
  

Key Points:

• This approach keeps environment-specific configurations separate from your main codebase.
• You can easily switch between environments for development, staging, and production.
• Consider using a more advanced environment variable management solution for complex projects.

• Create the environment.ts file (if it doesn't exist) in the src/environments directory:

// src/environments/environment.ts
export const environment = {
  production: false,
  apiUrl: 'http://localhost:3000/api', // Default API URL
  logging: false
};

• Create an additional environment file, for example environment.staging.ts, with environment-specific settings:

// src/environments/environment.staging.ts
export const environment = {
  production: false,
  apiUrl: 'https://staging.your-api.com/api', // Staging API URL
  logging: true // Enable logging for staging
};

angular.json Configuration:

"configurations": {
  "production": {
    "...": "...",
    "fileReplacements": [
      {
        "replace": "src/environments/environment.ts",
        "with": "src/environments/environment.prod.ts"
      }
    ]
  },
  "staging": {
    "...": "...",
    "fileReplacements": [
      {
        "replace": "src/environments/environment.ts",
        "with": "src/environments/environment.staging.ts"
      }
    ]
  }
}

Using Environment Variables in a Component:

• Create a component (e.g., app.component.ts):

// src/app/app.component.ts
import { Component } from '@angular/core';
import { environment } from 'src/environments/environment';

@Component({
  selector: 'app-root',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.css']
})
export class AppComponent {
  apiUrl = environment.apiUrl;

  constructor() {}
}

• Run ng serve with the --configuration flag to specify the environment:

  ng serve --configuration=staging // Starts development server with staging environment
  

• This method involves directly injecting environment variables at runtime.
• It's not ideal for most cases due to security concerns (environment variables might be exposed) and tight coupling to the deployment environment.
• However, it can be helpful in specific scenarios like local development with custom configurations.

Steps:

1. Set Environment Variables:
2. Access Variables in Code:

Example:

import { Component } from '@angular/core';

@Component({
  selector: 'app-my-component',
  templateUrl: './my-component.component.html',
  styleUrls: ['./my-component.component.css']
})
export class MyComponent {
  apiUrl = process.env.API_URL; // Assuming an environment variable named API_URL exists

  constructor() {}

  makeApiCall() {
    // Use this.apiUrl to make API calls
  }
}

Important Considerations:

• Security: This method exposes environment variables in your code, so be cautious with sensitive data.
• Management: Manually setting and managing variables can be cumbersome for complex projects.

Third-Party Environment Variable Libraries:

• Consider using libraries like dotenv or ngx-environment for more advanced environment variable management.
• These libraries provide features like loading environment variables from files or using different configurations based on the deployment environment.

Pros and Cons:

• Pros:
  • Offer more advanced features for managing environment variables.
  • Can improve security by keeping sensitive data out of code.
• Cons:
  • Introduce additional dependencies to your project.
  • May require learning new library APIs.

Choosing the Right Method:

• The recommended approach using Angular CLI's environment files strikes a good balance between simplicity and security for most Angular projects.
• Consider manual injection only for local development or specific testing scenarios.
• Third-party libraries are worth exploring for complex projects with advanced environment management needs.