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Which is a benefit of using multistage builds with Docker?
With multi-stage builds, you use multiple FROM statements in your Dockerfile. Each FROM instruction can use a different base, and each of them begins a new stage of the build. You can selectively copy artifacts from one stage to another, leaving behind everything you don’t want in the final image.
How is Packer different from Docker?
Docker is a system for building, distributing and running Docker containers. Containers can be run on Linux and Windows. Packer is an automated build system to manage the creation of images for containers and virtual machines. It outputs an image that you can then take and run on the platform you require.
Why we have to create your own Docker image?
Creating your own Docker images can go a long way to deploying more secure containers. Jack Wallen shows you how with just a few quick commands. Without those images, it would be a challenge to develop any applications to be deployed as services.
What happens during Docker build?
The docker build command builds Docker images from a Dockerfile and a “context”. A build’s context is the set of files located in the specified PATH or URL . The build process can refer to any of the files in the context. For example, your build can use a COPY instruction to reference a file in the context.
What is from scratch in Docker?
FROM scratch You can use Docker’s reserved, minimal image, scratch , as a starting point for building containers. Using the scratch “image” signals to the build process that you want the next command in the Dockerfile to be the first filesystem layer in your image.
Can a packer be used to build a docker image?
The docker Packer builder builds Docker images using Docker. The builder starts a Docker container, runs provisioners within this container, then exports the container for reuse or commits the image. Packer builds Docker containers without the use of Dockerfiles.
Can a docker image be converted to a HCl file?
Since HCL is still very fresh within Packer, its still not possible to use an automated tool to convert json files (where you have plenty of samples to learn from) to .pkr.hcl files. So, lets check a json example of how to build a docker image within packer.
Which is an example of instructions in Docker builders?
Example of instructions are CMD, ENTRYPOINT, ENV, and EXPOSE. Example: [ “USER ubuntu”, “WORKDIR /app”, “EXPOSE 8080” ] container_dir (string) – The directory inside container to mount temp directory from host server for work file provisioner. This defaults to c:/packer-files on windows and /packer-files on other systems.
Can you use Packer 1.5 HCL2 with HCl?
Since Packer 1.5 HCL2 is supported, and even though its still in beta, and some features are still missing, for those used to HCL writing hashicorp modules, it beats json previous templating. In this post we will use Packer with HCL to create two docker images, one alpine based and one debian based, that will run nginx.