A Dockerfile contains all the commands you can call on a command line to assemble an image. Docker build can build images by reading the instructions from a Dockerfile. The creation of the Dockerfile is manual, and it’s challenging to remember attributes/objects. Roost, which does everything through policies and standard templates, makes it extremely easy to create these Dockerfiles with its unique Drag n Drop feature.
Roost recommends multi-stage docker builds. A multi-stage build drastically reduces the final image’s size; the final container doesn’t have various layers involved. The result is no extra binaries in your deployed container. These stages can run in parallel, which will cut down docker build time.
Multi-stage dockerfile could be pretty complex, and they may need a good template approach. Roost offers an easy way to create Dockerfile and minimize errors.
Using Roost Desktop Development Environment, we can drag and drop the instructions from Palette to Canvas. Let’s drag four instructions [COPY, FROM, RUN, WORKDIR] to Canvas. We can see a preview by clicking the Show Preview button, which is updated live.
We can fill in values/instructions by clicking on its node. We can define the Dockerfile flow by connecting instructions through edges in desired order [FROM => WORKDIR => COPY => RUN].
Finally, let’s save the file by clicking on Generate Dockerfile button. We can also upload an existing Dockerfile and reverse engineer it.
Roost also provides some commonly used Dockerfile templates. You can select a required template and edit its fields as per your need.