- The build-time variables are passed as environment-context for command(s)
run as part of the RUN primitve. These variables are not persisted in environment of
intermediate and final images when passed as context for RUN. The build environment
is prepended to the intermediate continer's command string for aiding cache lookups.
It also helps with build traceability. But this also makes the feature less secure from
point of view of passing build time secrets.
- The build-time variables also get used to expand the symbols used in certain
Dockerfile primitves like ADD, COPY, USER etc, without an explicit prior definiton using a
ENV primitive. These variables get persisted in the intermediate and final images
whenever they are expanded.
- The build-time variables are only expanded or passed to the RUN primtive if they
are defined in Dockerfile using the ARG primitive or belong to list of built-in variables.
HTTP_PROXY, HTTPS_PROXY, http_proxy, https_proxy, FTP_PROXY and NO_PROXY are built-in
variables that needn't be explicitly defined in Dockerfile to use this feature.
Signed-off-by: Madhav Puri <madhav.puri@gmail.com>
- rewrite intro to Dockerfile reference usage section to remove
references to 'source repository'
- Closes#14714
- Fixes: #8648
- Updating with Seb's comments
Signed-off-by: Mary Anthony <mary@docker.com>
* Clarify the list of supported instructions.
* Clarify behavior of ONBUILD, based on comments by @SvenDowideit, @theJeztah in PR #14735.
* Reorder list of instructions in alphabetical order.
Signed-off-by: Charles Chan <charleswhchan@users.noreply.github.com>
The current documentation correctly states that dockerignore pattern
searches are non-recursive. However, the example given for Markdown
files seems to contradict this by saying that `*.md` will exclude *all*
Markdown files. This commit clarifies the situation by explicitly
specifying that `*.md` will only exclude files in the root directory of
the project.
Signed-off-by: Tim Wraight <tim.wraight@tangentlabs.co.uk>
Tweaking for Hugo
Updating the Dockerfile with new sed; fix broken link on Kitematic
Fixing image pull for Dockerfile
Removing docs targets
Signed-off-by: Mary Anthony <mary@docker.com>
Aidan Hobson Sayers