When building the Dockerfiles for development, those images are mainly used to
create a reproducible build-environment. The source code is bind-mounted into
the image at runtime; there is no need to create an image with the actual
source code, and copying the source code into the image would lead to a new
image being created for each code-change (possibly leading up to many "dangling"
images for previous code-changes).
However, when building (and using) the development images in CI, bind-mounting
is not an option, because the daemon is running remotely.
To make this work, the circle-ci script patched the Dockerfiles when CI is run;
adding a `COPY` to the respective Dockerfiles.
Patching Dockerfiles is not really a "best practice" and, even though the source
code does not and up in the image, the source would still be _sent_ to the daemon
for each build (unless BuildKit is used).
This patch updates the makefiles, circle-ci script, and Dockerfiles;
- When building the Dockerfiles locally, pipe the Dockerfile through stdin.
Doing so, prevents the build-context from being sent to the daemon. This speeds
up the build, and doesn't fill up the Docker "temp" directory with content that's
not used
- Now that no content is sent, add the COPY instructions to the Dockerfiles, and
remove the code in the circle-ci script to "live patch" the Dockerfiles.
Before this patch is applied (with cache):
```
$ time make -f docker.Makefile build_shell_validate_image
docker build -t docker-cli-shell-validate -f ./dockerfiles/Dockerfile.shellcheck .
Sending build context to Docker daemon 41MB
Step 1/2 : FROM debian:stretch-slim
...
Successfully built 81e14e8ad856
Successfully tagged docker-cli-shell-validate:latest
2.75 real 0.45 user 0.56 sys
```
After this patch is applied (with cache)::
```
$ time make -f docker.Makefile build_shell_validate_image
cat ./dockerfiles/Dockerfile.shellcheck | docker build -t docker-cli-shell-validate -
Sending build context to Docker daemon 2.048kB
Step 1/2 : FROM debian:stretch-slim
...
Successfully built 81e14e8ad856
Successfully tagged docker-cli-shell-validate:latest
0.33 real 0.07 user 0.08 sys
```
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
Sebastiaan van Stijn
Daniel Nephin
Jean-Pierre Huynh