LABELs split across mutliple lines in Dockerfile are handled incorrectly

[miabbott]

/kind bug

When building an image from a Dockerfile that has key=value pairs split across multiple lines of a single LABEL instruction, the resulting image has a mangled LABEL output.

This was observed on Fedora 28, using podman 0.7.2:

$ cat Dockerfile.multi 
FROM registry.fedoraproject.org/fedora:28
LABEL io.openshift.commit = "deadbeef" \
      io.openshift.version = "3.11"
ENTRYPOINT "/bin/bash"

$ sudo podman build -t quay.io/miabbott/podman-label-test:multi -f Dockerfile.multi
STEP 1: FROM registry.fedoraproject.org/fedora:28
STEP 2: LABEL io.openshift.commit = "deadbeef"       io.openshift.version = "3.11"
STEP 3: ENTRYPOINT "/bin/bash"
STEP 4: COMMIT containers-storage:[overlay@/var/lib/containers/storage+/var/run/containers/storage:overlay.override_kernel_check=true]quay.io/miabbott/podman-label-test:multi
Getting image source signatures
Skipping fetch of repeat blob sha256:4656e146fab7f95ad90808bab5aa27e0041f1fa2427597a68efc6fa66693689d
Skipping fetch of repeat blob sha256:4f4fb700ef54461cfa02571ae0db9a0dc1e0cdb5577484a6d75e68dc38e8acc1
Copying config sha256:2a84c16f3f8d0cead85069105deb6399e6d0d27a657b730d90e8e2abb8c71fa1
 733 B / 733 B [============================================================] 0s
Writing manifest to image destination
Storing signatures
--> 2a84c16f3f8d0cead85069105deb6399e6d0d27a657b730d90e8e2abb8c71fa1

$ sudo podman inspect quay.io/miabbott/podman-label-test:multi
[
    {
        "Id": "2a84c16f3f8d0cead85069105deb6399e6d0d27a657b730d90e8e2abb8c71fa1",
        "Digest": "sha256:d1c1fdaf1387d124cfdca4bd38b759c72177e2d72847c7f552b2bd7d383ddd5a",
        "RepoTags": [
            "quay.io/miabbott/podman-label-test:multi"
        ],
        "RepoDigests": [
            "quay.io/miabbott/podman-label-test@sha256:d1c1fdaf1387d124cfdca4bd38b759c72177e2d72847c7f552b2bd7d383ddd5a"                                                                                          
        ],
        "Parent": "",
        "Comment": "Created by Image Factory",
        "Created": "2018-07-24T14:12:44.280970058Z",
        "ContainerConfig": {
            "Env": [
                "DISTTAG=f28container",
                "FGC=f28",
                "PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin"
            ],
            "Entrypoint": [
                "/bin/sh",
                "-c",
                "\"/bin/bash\""
            ],
            "WorkingDir": "/",
            "Labels": {
                "io.openshift.commit": "= deadbeef       io.openshift.version = 3.11",
                "license": "MIT",
                "name": "fedora",
                "vendor": "Fedora Project",
                "version": "28"
            }
        },
        "Version": "",
        "Author": "",
        "Architecture": "amd64",
        "Os": "linux",
        "Size": 262873295,
        "VirtualSize": 262873295,
        "GraphDriver": {
            "Name": "overlay",
            "Data": {
                "LowerDir": "/var/lib/containers/storage/overlay/4656e146fab7f95ad90808bab5aa27e0041f1fa2427597a68efc6fa66693689d/diff",
                "MergedDir": "/var/lib/containers/storage/overlay/091bcce0127a47ee3e4342cbc6fe065b2a7f0787718ce7dab7e755031df09902/merged",
                "UpperDir": "/var/lib/containers/storage/overlay/091bcce0127a47ee3e4342cbc6fe065b2a7f0787718ce7dab7e755031df09902/diff",
                "WorkDir": "/var/lib/containers/storage/overlay/091bcce0127a47ee3e4342cbc6fe065b2a7f0787718ce7dab7e755031df09902/work"
            }
        },
        "RootFS": {
            "Type": "layers",
            "Layers": [
                "sha256:4656e146fab7f95ad90808bab5aa27e0041f1fa2427597a68efc6fa66693689d",
                "sha256:5f70bf18a086007016e948b04aed3b82103a36bea41755b6cddfaf10ace3c6ef"
            ]
        },
        "Labels": {
            "io.openshift.commit": "= deadbeef       io.openshift.version = 3.11",
            "license": "MIT",
            "name": "fedora",
            "vendor": "Fedora Project",
            "version": "28"
        },
        "Annotations": {},
        "ManifestType": "application/vnd.oci.image.manifest.v1+json",
        "User": ""
    }
]

If I change the Dockerfile to use a single LABEL instruction per key=value pair, it works correctly:

$ cat Dockerfile.single 
FROM registry.fedoraproject.org/fedora:28
LABEL io.openshift.commit = "deadbeef"
LABEL io.openshift.version = "3.11"
ENTRYPOINT "/bin/bash"

$ sudo podman build -t quay.io/miabbott/podman-label-test:single -f Dockerfile.single
STEP 1: FROM registry.fedoraproject.org/fedora:28
STEP 2: LABEL io.openshift.commit = "deadbeef"
STEP 3: LABEL io.openshift.version = "3.11"
STEP 4: ENTRYPOINT "/bin/bash"
STEP 5: COMMIT containers-storage:[overlay@/var/lib/containers/storage+/var/run/containers/storage:overlay.override_kernel_check=true]quay.io/miabbott/podman-label-test:single
Getting image source signatures
Skipping fetch of repeat blob sha256:4656e146fab7f95ad90808bab5aa27e0041f1fa2427597a68efc6fa66693689d
Skipping fetch of repeat blob sha256:4f4fb700ef54461cfa02571ae0db9a0dc1e0cdb5577484a6d75e68dc38e8acc1
Copying config sha256:b05f036107d096578f7ced852104d3a9506079f77cbc3c03cbcbc9b88d4d8f27
 729 B / 729 B [============================================================] 0s
Writing manifest to image destination
Storing signatures
--> b05f036107d096578f7ced852104d3a9506079f77cbc3c03cbcbc9b88d4d8f27

$ sudo podman inspect quay.io/miabbott/podman-label-test:single
[                  
    {
        "Id": "b05f036107d096578f7ced852104d3a9506079f77cbc3c03cbcbc9b88d4d8f27",
        "Digest": "sha256:bd815b2a4be9cf8157844cf28eb86b8757c3c533fff8a2134bcd2bb0296dafde",
        "RepoTags": [
            "quay.io/miabbott/podman-label-test:single"
        ],
        "RepoDigests": [
            "quay.io/miabbott/podman-label-test@sha256:bd815b2a4be9cf8157844cf28eb86b8757c3c533fff8a2134bcd2bb0296dafde"
        ],
        "Parent": "",
        "Comment": "Created by Image Factory",
        "Created": "2018-07-24T14:14:20.42654769Z",
        "ContainerConfig": {
            "Env": [
                "DISTTAG=f28container",
                "FGC=f28",
                "PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin"
            ],
            "Entrypoint": [
                "/bin/sh",
                "-c",
                "\"/bin/bash\""
            ],
            "WorkingDir": "/",
            "Labels": {
                "io.openshift.commit": "= deadbeef",
                "io.openshift.version": "= 3.11",
                "license": "MIT",
                "name": "fedora",
                "vendor": "Fedora Project",
                "version": "28"
            }
        },
        "Version": "",
        "Author": "",
        "Architecture": "amd64",
        "Os": "linux",
        "Size": 262873291,
        "VirtualSize": 262873291,
        "GraphDriver": {
            "Name": "overlay",
            "Data": {
                "LowerDir": "/var/lib/containers/storage/overlay/4656e146fab7f95ad90808bab5aa27e0041f1fa2427597a68efc6fa66693689d/diff",
                "MergedDir": "/var/lib/containers/storage/overlay/091bcce0127a47ee3e4342cbc6fe065b2a7f0787718ce7dab7e755031df09902/merged",
                "UpperDir": "/var/lib/containers/storage/overlay/091bcce0127a47ee3e4342cbc6fe065b2a7f0787718ce7dab7e755031df09902/diff",
                "WorkDir": "/var/lib/containers/storage/overlay/091bcce0127a47ee3e4342cbc6fe065b2a7f0787718ce7dab7e755031df09902/work"
            }
        },
        "RootFS": {
            "Type": "layers",
            "Layers": [
                "sha256:4656e146fab7f95ad90808bab5aa27e0041f1fa2427597a68efc6fa66693689d",
                "sha256:5f70bf18a086007016e948b04aed3b82103a36bea41755b6cddfaf10ace3c6ef"
            ]
        },
        "Labels": {
            "io.openshift.commit": "= deadbeef",
            "io.openshift.version": "= 3.11",
            "license": "MIT",
            "name": "fedora",
            "vendor": "Fedora Project",
            "version": "28"
        },
        "Annotations": {},
        "ManifestType": "application/vnd.oci.image.manifest.v1+json",
        "User": ""
    }
]

[mheon]

This looks like a Buildah bug, as we use Buildah for builds.
@miabbott Can you refile against https://github.com/projectatomic/buildah

[miabbott]

Ah, that makes sense. Moving over there - containers/buildah#879.