Configuring containers

More often than not, we need to provide some configuration to the application running inside a container. The configuration is often used to allow one and the same container to run in very different environments, such as in development, test, staging, or production environments. 

In Linux, configuration values are often provided via environment variables. 

We have learned that an application running inside a container is completely shielded from its host environment. Thus, the environment variables that we see on the host are different from the ones that we see from within a container.

Let's prove that by first looking at what is defined on our host:

1. Use this command:

$ export

On my macOS, I see something like this (shortened):

...
COLORFGBG '7;0'
COLORTERM truecolor
HOME /Users/gabriel
ITERM_PROFILE Default
ITERM_SESSION_ID w0t1p0...