Merge pull request #5816 from unclejack/docs_run_cache

docs: explain when RUN cache gets invalidated
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Sven Dowideit 2014-05-15 19:54:15 +10:00
commit 5dfe7c43d4
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@ -131,6 +131,16 @@ any point in an image's history, much like source control.
The *exec* form makes it possible to avoid shell string munging, and to `RUN`
commands using a base image that does not contain `/bin/sh`.
The cache for `RUN` instructions isn't invalidated automatically during the
next build. The cache for an instruction like `RUN apt-get dist-upgrade -y`
will be reused during the next build.
The cache for `RUN` instructions can be invalidated by using the `--no-cache`
flag, for example `docker build --no-cache`.
The first encountered `ADD` instruction will invalidate the cache for all
following instructions from the 'Dockerfile' if the contents of the context
have changed. This will also invalidate the cache for `RUN` instructions.
### Known Issues (RUN)
- [Issue 783](https://github.com/dotcloud/docker/issues/783) is about file