let parent ENV and child ARG have the same name #34494
Description
Description
I have a parent Dockerfile:
FROM debian
ARG IMAGE_NAME
ENV IMAGE_NAME=$IMAGE_NAMEand a child Dockerfile:
FROM parent
ARG IMAGE_NAME
ENV IMAGE_NAME=$IMAGE_NAME
RUN echo $IMAGE_NAMEI build with:
docker build --build-arg IMAGE_NAME=parent -t parent -f Dockerfile.parent .
docker build --build-arg IMAGE_NAME=child -t child -f Dockerfile.child .Steps to reproduce the issue:
- Use files shown before and build
Describe the results you received:
The RUN command in the second container outputs parent, because the ARG IMAGE_NAME is ignored, since it exists as an ENV in the parent file.
Describe the results you expected:
Changing the name of ARG in the second container resolves this problem, but is this a bug or a feature? I would suspect ARG IMAGE_NAME to overload $IMAGE_NAME at least for the scope of the child Dockerfile.
Additional information you deem important (e.g. issue happens only occasionally):
Output of docker version:
Client:
Version: 17.06.0-ce
API version: 1.30
Go version: go1.8.3
Git commit: 02c1d87
Built: Fri Jun 23 21:23:31 2017
OS/Arch: linux/amd64
Server:
Version: 17.06.0-ce
API version: 1.30 (minimum version 1.12)
Go version: go1.8.3
Git commit: 02c1d87
Built: Fri Jun 23 21:19:04 2017
OS/Arch: linux/amd64
Experimental: false
Output of docker info:
Containers: 0
Running: 0
Paused: 0
Stopped: 0
Images: 69
Server Version: 17.06.0-ce
Storage Driver: aufs
Root Dir: /var/lib/docker/aufs
Backing Filesystem: extfs
Dirs: 46
Dirperm1 Supported: true
Logging Driver: json-file
Cgroup Driver: cgroupfs
Plugins:
Volume: local
Network: bridge host macvlan null overlay
Log: awslogs fluentd gcplogs gelf journald json-file logentries splunk syslog
Swarm: inactive
Runtimes: runc
Default Runtime: runc
Init Binary: docker-init
containerd version: cfb82a876ecc11b5ca0977d1733adbe58599088a
runc version: 2d41c047c83e09a6d61d464906feb2a2f3c52aa4
init version: 949e6fa
Security Options:
apparmor
seccomp
Profile: default
Kernel Version: 4.4.0-89-generic
Operating System: Ubuntu 16.04.3 LTS
OSType: linux
Architecture: x86_64
CPUs: 8
Total Memory: 31.25GiB
Name: precision
ID: Q2ND:NM4A:LDKO:MW5R:4MJA:2ERU:MC67:ZZUY:D66G:PBFA:23O3:YCOC
Docker Root Dir: /var/lib/docker
Debug Mode (client): false
Debug Mode (server): false
Registry: https://index.docker.io/v1/
Experimental: false
Insecure Registries:
127.0.0.0/8
Live Restore Enabled: false
WARNING: No swap limit support
Additional environment details (AWS, VirtualBox, physical, etc.):