An web application itself should be stateless and has the ability to set its own according to the runtime environment.
# Configure Runtime Environment
Egg has two ways to configure runtime environment:
config/envfile, usually we use the build tools to generate this file, the content of this file is just the env value, such as
EGG_SERVER_ENVenvironment variable to configure.
The second way will be more commonly used, defining the runtime environment via
EGG_SERVER_ENV when you start the application is more convenient, for example, use the code below to start the application in the production environment.
EGG_SERVER_ENV=prod npm start
# Access to the runtime environment in Application
Egg provides a variable
app.config.env to represent the current runtime environment of application.
# Configurations of runtime environment
Different running environment corresponds to different configurations, read Configuration of Config in detail.
# Difference from NODE_ENV
Lots of Node.js applications use
NODE_ENV to distinguish the runtime environment, but
EGG_SERVER_ENV distinguishes the environments much more specific. Generally speaking, there are local environment, test environment, production environment during the application development. In addition to the local development environment and the test environment, other environments are collectively referred to as the Server Environment and their
NODE_ENV should be set to
production. What's more, npm will use this variable and will not install the devDependencies when you deploy applications, so
production should also be applied.
Default mapping of
NODE_ENV (will generate
NODE_ENV setting if
EGG_SERVER_ENV is not specified)
|local||local development environment|
|test||unittest||unit test environment|
EGG_SERVER_ENV will be set to prod when
NODE_ENV is set as
EGG_SERVER_ENV is not specified.
# Customize environment
In normal development process, it's not limit to these environments mentioned above. So you can customize environment for your development process.
For example, if you want to add SIT (System integration testing) to development process, you can set
sit (also recommend to set
NODE_ENV = production), the framework will load
config/config.sit.js when launching, and the runtime environment
app.config.env will be
# Difference from Koa
We are using
app.env to distinguish the environments in Koa, and the default value for
process.env.NODE_ENV. But in Egg (and frameworks base on Egg), we put all the configurations in
app.config, so we should use
app.config.env to distinguish the environments,
app.env is no longer used.