Building Blocks of Docker: Understanding Images

Docker images are templates containing code and libraries for creating containers, simplifying environment setup. A Dockerfile, a file without an extension, defines the image. The Dockerfile's instructions create layers within the image. Each line in the Dockerfile constitutes a separate layer. The first layer typically specifies a base image, like a specific operating system or runtime environment. Subsequent layers add functionalities, such as setting working directories, copying files, and executing commands. The `docker build` command creates the image from the Dockerfile. The final layer specifies the command executed when the container is run. Layers are stacked, enabling efficient image management and updates. This layered approach enhances efficiency by only rebuilding changed layers. The created image can then be used to generate containers.