Now we know how to download & run docker images. Now let's see how can we build them.
There are typically two ways to build a docker image.
First is to run a Docker container as we’ve done in hello world example, and later make changes into it & commit our changes using
docker commit command. The Commit saves your changes to the new image layer.
The second way to build a docker is using the
DockerFile is referred to as the blueprint or recipe book of the docker image. For instance node has
package.json, PHP has
composer.json, similarly for managing third party tools in our project, we use
DockerFile which manages the step by step guidelines for those tools.
DockerFile is a simple text file & contains build steps for your application. Each actionable step in the
DockerFile becomes a separate layer in docker image.
Which method to use for building?
Well, in real world, Docker Commit has a very little place and isn’t really a popular choice. On the other hand,
DockerFile is superior & you should go for it too.
Digging in the Docker Image
Docker images consists of layers. Each layer composed of self-contained files & the docker image is the result of one or more layers.