Add¶

Destination address must not be relative. Something like ~/dev will not copy anything to the folder.
Docker requires root escalation in order to execute an image, that creates some problem with files creation. The copied file is in root usr group and cannot be removed.

cannot actually delete files in a previous layer¶

https://pythonspeed.com/articles/docker-build-secrets/ \ NOTE: Deleting a file does not actually remove it from the image, because Docker uses layer caching: all previous layers are still present in the image. That means the secret ends up in one of the image's layers, even if you delete it in a later layer.

https://www.educative.io/answers/how-to-remove-directories-and-files-in-another-layer-using-docker Solutions:

use WORKDIR
use VOLUME
use multistage build

multistage build: copy install and then delete the copied files¶

https://rabbithole.wwwdotorg.org/2021/03/02/1-avoiding-docker-add-copy-layers.html

Docker buildkit added a --mount option to the RUN statement. must set export DOCKER_BUILDKIT=1. The first stage image will not be included.

# syntax=docker/dockerfile:1.2
FROM ubuntu:20.04 AS downloader
ADD https://server.com/foo.deb /downloads

FROM ubuntu:20.04
RUN --mount=type=bind,from=downloader,source=/downloads,target=/downloads dpkg -i /downloads/*.deb

In this case, the layers in the first stage will be dropped after the second stage run. So the conda package files will not be preserved in the final image.

ADD failed: Forbidden path outside the build context¶

This error occurs because the path you're trying to add with the ADD instruction is located outside the Docker build context. Docker restricts file operations to within the build context directory for security reasons.

To resolve this issue, we need to copy the folder to the build contect directory.

copy content of folder x into folder y¶

https://stackoverflow.com/questions/26504846/copy-directory-to-another-directory-using-add-command

ADD x /home/user/y/

copy folder x to folder y¶

ADD x /home/user/y/x