How to specify environment via `ng build` in Angular 6 app

Question

In Angular 5, we could generate build for different environments using

ng build --prod --env=uat 

After migration to Angular 6 the above command throws error

Unknown option: '--env' 

Answer 1

One needs to use the configuration option

ng build --prod --configuration=uat 

or

ng build --prod -c uat 

More information here

Also for ng serve same option as answered here

Answer 2

I have tested in an Angular 6 Project.

ng build --prod --configuration=uat doesn't seem to work as it only picks uat configuration when you run this command and ignores --prod flag and doesn't apply any optimization such as aot, minification and upglification etc.

Running ng build --prod --configuration=uat has the effect as same as only running ng build --configuration=uat. In order to apply any other configuration options we need to add them explicitly in the uat build options in angular.json

"configurations": {         "production": {           "fileReplacements": [             {               "replace": "src/environments/environment.ts",               "with": "src/environments/environment.prod.ts"             }           ],           "optimization": true,           "outputHashing": "all",           "sourceMap": false,           "extractCss": true,           "namedChunks": false,           "aot": true,           "extractLicenses": true,           "vendorChunk": false,           "buildOptimizer": true         },         "uat": {           "fileReplacements": [             {               "replace": "src/environments/environment.ts",               "with": "src/environments/environment.test.ts"             }           ],           "optimization": true,           "outputHashing": "all",           "sourceMap": false,           "extractCss": true,           "namedChunks": false,           "aot": true,           "extractLicenses": true,           "vendorChunk": false,           "buildOptimizer": true         }       }     }