Operating environment

Node.js applications generally obtain environment variables through NODE_ENV to meet different needs in different environments. For example, in production environment, cache is turned on to optimize performance, while in development environment, all log switches are turned on to output detailed error messages, etc.

Specify the operating environment

Since NODE_ENV will be intercepted and injected by some toolkits in some cases, under Midway system, we will acquire the environment first according to the MIDWAY_SERVER_ENV, while NODE_ENV will acquire as the second priority.

We can specify it by adding environment variables at startup.

MIDWAY_SERVER_ENV=prod npm start // first priority
NODE_ENV=local npm start // second priority

In windows, you must use the cross-env module to achieve the same effect.

cross-env MIDWAY_SERVER_ENV=prod npm start // first priority
cross-env NODE_ENV=local npm start // second priority

Get the environment in the code

Midway provides the getEnv() method to obtain the environment for app objects. Midway handles different upper-level frameworks to ensure that the getEnv() method is available in different scenarios. .

import { Application } from '@midwayjs/koa';

// process.env.MIDWAY_SERVER_ENV=prod

@Provide()
export class UserService {

  @App()
  app: Application;

  async invoke() {
    console.log(this.app.getEnv()); // prod
  }
}

If neither the NODE_ENV nor the MIDWAY_SERVER_ENV is assigned, the return value of the method is prod by default.

info

Note that you cannot get the environment directly through NODE_ENV and MIDWAY_SERVER_ENV, both values may be empty, and Midway will not set it in reverse. To obtain the environment, please obtain the API method provided by other frameworks through app.getEnv().

Common environmental variable values

In general, each company has its own environmental variable values, and here are some common environmental variable values and their corresponding descriptions.

Value	Description
local	Local development environment
dev/daily/development	Daily development environment
pre/prepub	Pre-production environment
prod/production	Production environment
test/unittest	Unit test environment
benchmark	Performance test environment

Dependent on the acquisition environment from the injection container

In the process of dependent injection container initialization, Midway initializes a EnvironmentService service to parse the environment by default and maintains the service object throughout the life cycle.

For more information, see Environment Services.