Defining Our First Custom Image

Build image

The process of generating an image from a Dockerfile is called building an image. We do that with the docker build command, which has the following format:

$ docker build [options] path/to/build/directory 

If we are in the directory containing our Dockerfile and project file, we can use the following command:

$ docker build . 

To name the image, we use -t option:

docker build -t [image_name] .

We will use the following command to build an image. You can see how it works by clicking the Run button.

docker build -t railsapp .

Try to press the Run button periodically as the terminal can get disconnected.