Add squash-all, fix squash option in build

[TomSweeneyRedHat]

Translate the podman build --squash command to podman build --layers=false which
has the same functionality as docker build --squash. Add a new option --squash-all
which will squash all layers into one. This will be translated to buildah bud --squash
for the buildah bud api.

Also allow only one option, squash, layers or squash--all to be used per build command.

Fixes: containers/buildah#1234

Signed-off-by: TomSweeneyRedHat tsweeney@redhat.com

[TomSweeneyRedHat]

I neglected to update the man page and bash completions, will tend to those once I get general consensus for this approach.

[openshift-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: TomSweeneyRedHat

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Details

Needs approval from an approver in each of these files:

• OWNERS [TomSweeneyRedHat]

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[TomSweeneyRedHat]

I've updated with @rhatdan's suggestion to have the squash-all option defined here rather than in buildahcli like the other options. I've also updated bash completions and the man pages. Assuming happy tests and LGTM's, this is good to go.

[TomSweeneyRedHat]

Testing:

# touch alpinetest.tgz # or better yet create a tgz file with a few files in it.

# cat ~/Dockerfile.squash-a
FROM busybox:latest
ADD alpinetest.tgz /data

# cat ~/Dockerfile.squash-b
FROM test-squash-a:latest
RUN rm -rf /data

# cat ~/Dockerfile.squash-c
FROM busybox:latest
ADD alpinetest.tgz /data
RUN rm -rf /data

# podman build -f ~/Dockerfile.squash-a -t test-squash-a:latest .
STEP 1: FROM busybox:latest
STEP 2: ADD alpinetest.tgz /data
--> Using cache c54637689450d9516e6f2e497bb78f663405d9b609882ec89f4b481e84395eba
STEP 3: COMMIT test-squash-a:latest
c54637689450d9516e6f2e497bb78f663405d9b609882ec89f4b481e84395eba

# podman build -f ~/Dockerfile.squash-b --squash -t test-squash-b:latest .
STEP 1: FROM test-squash-a:latest
STEP 2: RUN rm -rf /data
STEP 3: COMMIT test-squash-b:latest
Getting image source signatures
Copying blob 6c0ea40aef9d skipped: already exists
Copying blob 2f2b43ce2ffb skipped: already exists
Copying blob 2f27bd025155 done
Copying config bb31c226ee done
Writing manifest to image destination
Storing signatures
bb31c226ee4317cbecd41747500e58c92c2f00c13df4e591d20571974a8a9109

# podman build -f ~/Dockerfile.squash-c --squash -t test-squash-c:latest .
STEP 1: FROM busybox:latest
STEP 2: ADD alpinetest.tgz /data
STEP 3: RUN rm -rf /data
STEP 4: COMMIT test-squash-c:latest
Getting image source signatures
Copying blob 6c0ea40aef9d skipped: already exists
Copying blob cb21ed953734 done
Copying config 7ccbafc877 done
Writing manifest to image destination
Storing signatures
7ccbafc877f09c403f455918e97bca9bad7895719baf5e43177fbd555202768f

# podman build -f ~/Dockerfile.squash-c --squash-all -t test-squash-d:latest .
STEP 1: FROM busybox:latest
STEP 2: ADD alpinetest.tgz /data
STEP 3: RUN rm -rf /data
STEP 4: COMMIT test-squash-d:latest
Getting image source signatures
Copying blob 2e9938a66ae2 done
Copying config 968b309097 done
Writing manifest to image destination
Storing signatures
968b3090976361347cd9e40ee7e8d98c1cba9692524c94abce6d7f3101463c5a

# podman inspect --format "{{.RootFS.Layers}}" test-squash-a
[sha256:6c0ea40aef9d2795f922f4e8642f0cd9ffb9404e6f3214693a1fd45489f38b44 sha256:2f2b43ce2ffb410197ef7c43d96e132a1d12a24519f1fc0eb3598afd9c912ccd]

# podman inspect --format "{{.RootFS.Layers}}" test-squash-b
[sha256:6c0ea40aef9d2795f922f4e8642f0cd9ffb9404e6f3214693a1fd45489f38b44 sha256:2f2b43ce2ffb410197ef7c43d96e132a1d12a24519f1fc0eb3598afd9c912ccd sha256:5a47f575b5d22f740a0689eb1e72ba71fb1491e22a5740bef87023c64c7605e6]

# podman inspect --format "{{.RootFS.Layers}}" test-squash-c
[sha256:6c0ea40aef9d2795f922f4e8642f0cd9ffb9404e6f3214693a1fd45489f38b44 sha256:46f19664b40a2e34c2cab5d6ead1fefcba940c4bbda55ae742206cef82edebbd]

# podman inspect --format "{{.RootFS.Layers}}" test-squash-d
[sha256:c84a24cbfc61792badfacf0d6831d3ec5fa406f0a93cb0ad7b6e9b15bbb6ed54]

[rhatdan]

LGTM

[rh-atomic-bot]

☔ The latest upstream changes (presumably #4201) made this pull request unmergeable. Please resolve the merge conflicts.

[TomSweeneyRedHat]

Somethings wrong with the CI tests on this, they're all green...

[rhatdan]

@mheon @baude @giuseppe @vrothberg @QiWang19 PTAL

[vrothberg]

The changes LGTM but I'd love us to have some tests as we could regress (for whatever) reason in Podman while Buildah continues working. Simple tests could be to use the different flags and use podman-inspect to make sure we have the expected amount of layers (e.g., podman inspect f945ea07f224 -f "{{len .RootFS.Layers}}"). We also should test that invalid combinations of the flags yield errors.

[rhatdan]

/lgtm

[vrothberg]

Eeek. I didn't ack this PR. Without tests we are likely to silently regress. @TomSweeneyRedHat, mind opening another PR to add some tests?