#Docker run image environment variables how to

They are imported into our application using tag inside the head section of index.html. We can write them into a file which can be served via Nginx (which also serves our React app). Then we can read environment variables from inside the container. The specific moment when it is still possible to inject environment variables happens when we start our container. This means it can only be configured during build time. During transpiling, Webpack process replaces all occurrences of process.env with a string value that was given. It canвЂ™t inject environment variables during content serving (like Next.js does). CRA by default doesnвЂ™t do server-side rendering. In reality, the object process does not exist inside the browser environment, itвЂ™s Node-specific. env files and REACT_APP prefixed environment variables which come straight from documentation? Even inside the source code, these are used as process.env just like we use environment variables inside Node.js. Whichever solution we use nowadays is nothing but a fake abstraction.Д«ut, then you might ask, what about. ? The problemДЇirst of all, it must be clear that there is no such thing as environment variables inside the browser environment.

So for anyone targeting dynamic environments or using orchestration systems, this approach is definitely something to consider.

But once setup is done, environment specific configurations and deployment will be way easier to handle. On first glance, this approach may seem to bring too small of a benefit for the extra work it requires for initial setup. We should be able to configure our React application using -e flag (environment variables) when using Docker run command. Our application should allow configuration within docker-compose file such as this: version: '3.2' The output should be a lightweight and performant container which serves our React application as static content, which we achieve by using Ngnix Alpine. It runs everywhere by being configurable during runtime. We want to be able to run our React application as a Docker container that is built once. Therefore no build per environment would be required. This means it enforces reconfiguration during runtime. LetвЂ™s use an approach which respects Twelve-Factor App methodology. There are many ways to configure your React application.

#Docker run image environment variables how to

By Krunoslav Banovac How to implement runtime environment variables with create-react-app, Docker, and Nginx