docker inspect <image> returning wrong information (docker v1.8.3)

[pommetjehorlepiep]

Description of problem:
I noticed when doing a docker inspect on a Docker Image that the "Image" information returned is incorrect. Although docker images shows a Repository (test) and Tag (1), docker inspect returns "" for "Image"

When image has a Parent, the "Image" field shows the Repository/Tag of the Parent image.

docker version:
Client:
Version: 1.8.3
API version: 1.20
Go version: go1.4.2
Git commit: f4bf5c7
Built: Mon Oct 12 05:27:08 UTC 2015
OS/Arch: linux/amd64

Server:
Version: 1.8.3
API version: 1.20
Go version: go1.4.2
Git commit: f4bf5c7
Built: Mon Oct 12 05:27:08 UTC 2015
OS/Arch: linux/amd64

docker info:
Containers: 25
Images: 92
Storage Driver: aufs
Root Dir: /var/lib/docker/aufs
Backing Filesystem: extfs
Dirs: 142
Dirperm1 Supported: true
Execution Driver: native-0.2
Logging Driver: json-file
Kernel Version: 3.16.0-4-amd64
Operating System: Debian GNU/Linux 8 (jessie)
CPUs: 4
Total Memory: 15.7 GiB
Name: raven
ID: 32ES:J7WZ:HDAY:OUQH:HGNW:XTPM:ERLW:L3U6:B6RE:KOP2:LGST:7XDH

uname -a:

Linux raven 3.16.0-4-amd64 #1 SMP Debian 3.16.7-ckt11-1+deb8u5 (2015-10-09) x86_64 GNU/Linux

Environment details (AWS, VirtualBox, physical, etc.):
physical

How reproducible:
Just run docker inspect on a Docker image which has a Repository & Tag set.

Steps to Reproduce:

1. Just run docker inspect on a Docker image which has a Repository & Tag set.

Actual Results:
For following image I expect "Image" to return "test:1" instead of just ""...:

docker images | grep d8ec
REPOSITORY TAG IMAGE ID CREATED VIRTUAL SIZE
test 1 db8ec01b1f1db About an hour ago 167.5 MB

docker inspect db8ec01b1f1db
[

{
    "Id": "d8ec01b1f1dbb6442bfa4206c951ccb3614f2135eb66b3305e802d7d9486234b",
    "Parent": "",
    "Comment": "Imported from -",
    "Created": "2015-11-07T01:29:22.550951754Z",
    "Container": "",
    "ContainerConfig": {
        "Hostname": "",
        "Domainname": "",
        "User": "",
        "AttachStdin": false,
        "AttachStdout": false,
        "AttachStderr": false,
        "Tty": false,
        "OpenStdin": false,
        "StdinOnce": false,
        "Env": null,
        "Cmd": null,
        **"Image": ""**,
        "Volumes": null,
        "WorkingDir": "",
        "Entrypoint": null,
        "OnBuild": null,
        "Labels": null
    },
    "DockerVersion": "1.8.3",
    "Author": "",
    "Config": {
        "Hostname": "",
        "Domainname": "",
        "User": "",
        "AttachStdin": false,
        "AttachStdout": false,
        "AttachStderr": false,
        "Tty": false,
        "OpenStdin": false,
        "StdinOnce": false,
        "Env": null,
        "Cmd": null,
        "Image": "",
        "Volumes": null,
        "WorkingDir": "",
        "Entrypoint": null,
        "OnBuild": null,
        "Labels": null
    },
    "Architecture": "amd64",
    "Os": "linux",
    "Size": 167510717,
    "VirtualSize": 167510717,
    "GraphDriver": {
        "Name": "aufs",
        "Data": null
    }
}

Expected Results:
"Image", "test:1" instead of "Image", ""

Additional info:
It seems that if image has a Parent, the "Image" field actually displays the Repository/Tag info or the Parent Image...

[phemmer]

This is expected behavior.
The ContainerConfig of an image is the container the image was generated from. In the case of your image, it wasn't generated from a container, but from running docker import.

[pommetjehorlepiep]

OK....so take a look at this then...

I ran test:1 and did a docker commit creating image with repo:tag test2:
ContainerConfig.Image is then correctly saying "test:1".
But what about Config.Image?? Isn't that in this case supposed to show "test:2"?
Or do I got it all wrong here?

docker images
REPOSITORY TAG IMAGE ID CREATED VIRTUAL SIZE
test 2 236d97cf0087 4 seconds ago 167.5 MB
test 1 d8ec01b1f1db 3 hours ago 167.5 MB

docker inspect 236d97cf0087
[

{
    "Id": "236d97cf008708800a1245b9b8731515a20b35ebbe4986a35f8d9f2d445aba39",
    "Parent": "d8ec01b1f1dbb6442bfa4206c951ccb3614f2135eb66b3305e802d7d9486234b",
    "Comment": "",
    "Created": "2015-11-07T05:28:52.184635318Z",
    "Container": "0f4db38481e9341a1b80e4bef3b35d6284d53daa1485358de27f68e6163bb131",
    "ContainerConfig": {
        "Hostname": "0f4db38481e9",
        "Domainname": "",
        "User": "",
        "AttachStdin": true,
        "AttachStdout": true,
        "AttachStderr": true,
        "Tty": true,
        "OpenStdin": true,
        "StdinOnce": true,
        "Env": null,
        "Cmd": [
            "/bin/bash"
        ],
        "Image": "test:1",
        "Volumes": null,
        "WorkingDir": "",
        "Entrypoint": null,
        "OnBuild": null,
        "Labels": {}
    },
    "DockerVersion": "1.8.3",
    "Author": "",
    "Config": {
        "Hostname": "",
        "Domainname": "",
        "User": "",
        "AttachStdin": false,
        "AttachStdout": false,
        "AttachStderr": false,
        "Tty": false,
        "OpenStdin": false,
        "StdinOnce": false,
        "Env": null,
        "Cmd": [
            "/bin/bash"
        ],
        "Image": "",
        "Volumes": null,
        "WorkingDir": "",
        "Entrypoint": null,
        "OnBuild": null,
        "Labels": null
    },
    "Architecture": "amd64",
    "Os": "linux",
    "Size": 532,
    "VirtualSize": 167511249,
    "GraphDriver": {
        "Name": "aufs",
        "Data": null
    }
}
]

[pommetjehorlepiep]

Or is the Config section only populated for containers and not for images?

[thaJeztah]

• Documentation was improved in api: improve documentation of ContainerConfig type #43461, but we may consider removing the ContainerConfig from the API response if it wasn't used (i.e., when BuildKit was used to produce the image)