A Dockerfile is where you write the instructions to build a Docker image

Yes, it was right, but nowadays Dockerfiles are not specific to Docker. Dockerfiles also work with Buildah & Podman (and there might be other ones in the future) and they have generalized the naming: “Containerfile.”

We comment out the failed line, and the Dockerfile now looks like this:

Some options (you will have to use your own judgment, based on your use case)

When you have one layer that downloads a large temporary file and you delete it in another layer, that has the result of leaving the file in the first layer, where it gets sent over the network and stored on disk, even when it's not visible inside your container. Changing permissions on a file also results in the file being copied to the current layer with the new permissions, doubling the disk space and network bandwidth for that file.

making sure the longest RUN command come first and in their own layer (again to be cached), instead of being chained with other RUN commands: if one of those fail, the long command will have to be re-executed. If that long command is isolated in its own (Dockerfile line)/layer, it will be cached.