MAC address conflict since v25 #47146
Description
Description
I understand that, unless --mac-address is specified when calling docker run that a MAC address will be generated on container start with the prefix 02:42:ac and then the last 3 components being the container's ipv4 address in hex notation.
Since v25.0.0 (using the official docker-ce Ubuntu package for 22.04) it seems that "docker start" retains the previous MAC address even when the IP is changed and that this can cause a MAC address conflict.
This behaviour does not occur on 24.x.
Reproduce
docker network create test-network
docker run -d --name server1 --network test-network httpd
docker stop server1
docker run -d --name server2 --network test-network httpd
docker start server1
Now if you “docker inspect” for server1 and server2 they will have the same MAC address but a different IP. Connectivity will be intermittent for both containers.
Expected behavior
Starting a container should assign a unique MAC address if no MAC address was specified when the container was created.
docker version
Client: Docker Engine - Community
Version: 25.0.0
API version: 1.44
Go version: go1.21.6
Git commit: e758fe5
Built: Thu Jan 18 17:09:49 2024
OS/Arch: linux/amd64
Context: default
Server: Docker Engine - Community
Engine:
Version: 25.0.0
API version: 1.44 (minimum version 1.24)
Go version: go1.21.6
Git commit: 615dfdf
Built: Thu Jan 18 17:09:49 2024
OS/Arch: linux/amd64
Experimental: false
containerd:
Version: 1.6.27
GitCommit: a1496014c916f9e62104b33d1bb5bd03b0858e59
runc:
Version: 1.1.11
GitCommit: v1.1.11-0-g4bccb38
docker-init:
Version: 0.19.0
GitCommit: de40ad0docker info
Client: Docker Engine - Community
Version: 25.0.0
API version: 1.44
Go version: go1.21.6
Git commit: e758fe5
Built: Thu Jan 18 17:09:49 2024
OS/Arch: linux/amd64
Context: default
Server: Docker Engine - Community
Engine:
Version: 25.0.0
API version: 1.44 (minimum version 1.24)
Go version: go1.21.6
Git commit: 615dfdf
Built: Thu Jan 18 17:09:49 2024
OS/Arch: linux/amd64
Experimental: false
containerd:
Version: 1.6.27
GitCommit: a1496014c916f9e62104b33d1bb5bd03b0858e59
runc:
Version: 1.1.11
GitCommit: v1.1.11-0-g4bccb38
docker-init:
Version: 0.19.0
GitCommit: de40ad0
root@containering:~# docker info
Client: Docker Engine - Community
Version: 25.0.0
Context: default
Debug Mode: false
Plugins:
buildx: Docker Buildx (Docker Inc.)
Version: v0.12.1
Path: /usr/libexec/docker/cli-plugins/docker-buildx
compose: Docker Compose (Docker Inc.)
Version: v2.24.1
Path: /usr/libexec/docker/cli-plugins/docker-compose
Server:
Containers: 2
Running: 0
Paused: 0
Stopped: 2
Images: 1
Server Version: 25.0.0
Storage Driver: overlay2
Backing Filesystem: extfs
Supports d_type: true
Using metacopy: false
Native Overlay Diff: true
userxattr: false
Logging Driver: json-file
Cgroup Driver: systemd
Cgroup Version: 2
Plugins:
Volume: local
Network: bridge host ipvlan macvlan null overlay
Log: awslogs fluentd gcplogs gelf journald json-file local splunk syslog
Swarm: inactive
Runtimes: io.containerd.runc.v2 runc
Default Runtime: runc
Init Binary: docker-init
containerd version: a1496014c916f9e62104b33d1bb5bd03b0858e59
runc version: v1.1.11-0-g4bccb38
init version: de40ad0
Security Options:
apparmor
seccomp
Profile: builtin
cgroupns
Kernel Version: 5.15.0-91-generic
Operating System: Ubuntu 22.04.3 LTS
OSType: linux
Architecture: x86_64
CPUs: 1
Total Memory: 1.918GiB
Name: containering
ID: 172a9933-7614-4ae1-a496-3f40c37b45c7
Docker Root Dir: /var/lib/docker
Debug Mode: false
Experimental: false
Insecure Registries:
127.0.0.0/8
Live Restore Enabled: falseAdditional Info
No response