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Issue #14433

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Try to improve the cache behavior for `ADD` and `COPY` commands.

Signed-off-by: Charles Chan <charleswhchan@users.noreply.github.com>
This commit is contained in:
Charles Chan 2015-07-17 21:20:06 -07:00
parent a0a0b8499e
commit 08d5424c04
1 changed files with 6 additions and 6 deletions
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12
docs/articles/dockerfile_best-practices.md
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@ -105,12 +105,12 @@ not, the cache is invalidated.
of the child images is sufficient. However, certain instructions require
a little more examination and explanation.
* In the case of the `ADD` and `COPY` instructions, the contents of the file(s)
being put into the image are examined. Specifically, a checksum is done
of the file(s) and then that checksum is used during the cache lookup.
If anything has changed in the file(s), including its metadata,
then the cache is invalidated. The last-modified and last-accessed times of the
file(s) are not considered in these checksums.
* For the `ADD` and `COPY` instructions, the contents of the file(s)
in the image are examined and a checksum is calculated for each file.
The last-modified and last-accessed times of the file(s) are not considered in
these checksums. During the cache lookup, the checksum is compared against the
checksum in the existing images. If anything has changed in the file(s), such
as the contents and metadata, then the cache is invalidated.
* Aside from the `ADD` and `COPY` commands cache checking will not look at the
files in the container to determine a cache match. For example, when processing