In an effort to make layer content 'stable' between import
and export from two different graph drivers, we must resolve
an issue where AUFS produces metadata files in its layers
which other drivers explicitly ignore when importing.
The issue presents itself like this:
- Generate a layer using AUFS
- On commit of that container, the new stored layer contains
AUFS metadata files/dirs. The stored layer content has some
tarsum value: '1234567'
- `docker save` that image to a USB drive and `docker load`
into another docker engine instance which uses another
graph driver, say 'btrfs'
- On load, this graph driver explicitly ignores any AUFS metadata
that it encounters. The stored layer content now has some
different tarsum value: 'abcdefg'.
The only (apparent) useful aufs metadata to keep are the psuedo link
files located at `/.wh..wh.plink/`. Thes files hold information at the
RW layer about hard linked files between this layer and another layer.
The other graph drivers make sure to copy up these psuedo linked files
but I've tested out a few different situations and it seems that this
is unnecessary (In my test, AUFS already copies up the other hard linked
files to the RW layer).
This changeset adds explicit exclusion of the AUFS metadata files and
directories (NOTE: not the whiteout files!) on commit of a container
using the AUFS storage driver.
Also included is a change to the archive package. It now explicitly
ignores the root directory from being included in the resulting tar archive
for 2 reasons: 1) it's unnecessary. 2) It's another difference between
what other graph drivers produce when exporting a layer to a tar archive.
Docker-DCO-1.1-Signed-off-by: Josh Hawn <josh.hawn@docker.com> (github: jlhawn)
Upstream-commit: 0d97e082c3b849a6901992e653b8963e8ef10f54
Component: engine
This backend uses the overlayfs union filesystem for containers
plus hard link file sharing for images.
Each container/image can have a "root" subdirectory which is a plain
filesystem hierarchy, or they can use overlayfs.
If they use overlayfs there is a "upper" directory and a "lower-id"
file, as well as "merged" and "work" directories. The "upper"
directory has the upper layer of the overlay, and "lower-id" contains
the id of the parent whose "root" directory shall be used as the lower
layer in the overlay. The overlay itself is mounted in the "merged"
directory, and the "work" dir is needed for overlayfs to work.
When a overlay layer is created there are two cases, either the
parent has a "root" dir, then we start out with a empty "upper"
directory overlaid on the parents root. This is typically the
case with the init layer of a container which is based on an image.
If there is no "root" in the parent, we inherit the lower-id from
the parent and start by making a copy if the parents "upper" dir.
This is typically the case for a container layer which copies
its parent -init upper layer.
Additionally we also have a custom implementation of ApplyLayer
which makes a recursive copy of the parent "root" layer using
hardlinks to share file data, and then applies the layer on top
of that. This means all chile images share file (but not directory)
data with the parent.
Docker-DCO-1.1-Signed-off-by: Alexander Larsson <alexl@redhat.com> (github: alexlarsson)
Upstream-commit: 453552c8384929d8ae04dcf1c6954435c0111da0
Component: engine
The vfs storage driver currently shells out to the `cp` binary on the host
system to perform an 'archive' copy of the base image to a new directory.
The archive option preserves the modified time of the files which are created
but there was an issue where it was unable to preserve the modified time of
copied symbolic links on some host systems with an outdated version of `cp`.
This change no longer relies on the host system implementation and instead
utilizes the `CopyWithTar` function found in `pkg/archive` which is used
to copy from source to destination directory using a Tar archive, which
should correctly preserve file attributes.
Docker-DCO-1.1-Signed-off-by: Josh Hawn <josh.hawn@docker.com> (github: jlhawn)
Upstream-commit: b6db23cffe942b8d94c80d1e9b3f1f6fca87d139
Component: engine
This will allow us to use a common Git prefix check for both api/clients/commands.go and
builder/job.go. Previous prefix check in build from Git (in builder/jobs.go) ignored valid prefixes such as "git@", "http://" or "https://".
Signed-off-by: Lakshan Perera <lakshan@laktek.com>
Upstream-commit: d3ac9ea98e872fee808693c736bc5a465d6426e2
Component: engine
builder: some small fixups + fix a bug where empty entrypoints would not override inheritance.
Upstream-commit: c681bea0620d24e9df370147a13a98f94bc66ee0
Component: engine
