Dockerfile VOLUME instruction leads to incorrect image metadata

[augusto-sb]

Hello, if the VOLUME instruction is an array of single quotes or non quoted paths paths it leads to incorrect image metadata and later i cant mount a volume in the resultant path.

To reproduce i did a Dockerfile:

FROM docker.io/alpine:3.18.3
VOLUME /path1 /path2
VOLUME [/path3,/path4]
VOLUME ["/path5","/path6"]
VOLUME ['/path7','/path8']
the 2nd and 4rd VOLUME instructions didnt work as expected

commands:

docker build -t test .
docker run --rm -ti test sh
/ # tree /[
/[
├── path3,
│ └── path4]
└── path7,
└── path8]

docker image inspect test

...
"Volumes": {
"/path1": {},
"/path2": {},
"/path5": {},
"/path6": {},
"[/path3,/path4]": {},
"[/path7,/path8]": {}
},
...

the two latest i think are errors because the volumes should start with ###'/'

Expected behavior
i think the behaviour should be an error during the build, i know the array should be a valid JSON array so should only work with double quotes.

docker version
Client: Docker Engine - Community
Version: 24.0.5

[thaJeztah]

• Originally reported in Dockerfile: error in image with VOLUME instruction moby#46399
• related: Enhancement: print warnings when falling back from JSON to "shell" syntax (and other warnings) #1952

[tonistiigi]

the two latest i think are errors because the volumes should start with ###'/'

Where is this defined?

Note that this isn't the same as -v in docker run.