The file .dockerignore is a type of file that can be placed in the user’s project and used with the ignore files and directories during docker build, with the aim of preventing these from being copied to the Docker image by mistake.
In addition to this, the .dockerignore file has the ability to specify the list of elements that you need to skip during the build process. This also helps to reduce the size of the image and accelerate the generation of these Dockers (they are not sent to the context).
Advantages of .dockerignore
The dockerignore files feature is its ability to ignore folders and files during the creation of a Docker image. This function translates into a beneficial element when the user works with environments in which many tasks and constant activities are carried out, because allows the reduction of the size of the images on the platform.
This reduction in the size of the images is of great importance, since it implies a reduction of costs allocated to paying for storage carried out by the company or technological project. Also, smaller image size contributes to the deployment processes of different applications and services at scale.
Another advantage of the .dockerignore file is that it can help reduce the attack plane of Docker images, which avoids exposing important files like keys in the final image of the build context. Therefore, this file is responsible for ignoring this information by mentioning it within the files to be omitted dockerignore dockerfile . This means that the .dockerignore file contributes to the reduction of strange or suspicious elements inside the images Docker, which is ideal when dealing with files with sensitive content, such as passwords or confidential data.
In addition to this, the docker ignore file It is used for the purpose of invalidating the cache. This is because, usually, instructions are used that copy all folders and files within a compilation context (build) on the Docker container platform. However, this process can result in new intermediate image layers being generated, so at times when changes are made to the dockerfile continuously, .dockerignore is responsible for creating different invalidations to that cache, which avoids the waste of resources and valuable elements for the user’s project.
What is the next step?
In this article you have been able to delve deeper into what the .dockerignore file is, as well as what its main characteristics are and the advantages of its implementation. Now, don’t hesitate to go one step further and Keep learning about this and other Docker tools, its containers, images and more, through our DevOps & Cloud Computing Full Stack Bootcamp. Thanks to this bootcamp, in just 6 months you will be able to master everything you need to become an expert in the sector and stand out from your competition. Sign up now and continue your training process now!