containers.no_hosts is not considered by podman system service

[reda-alaoui]

Is this a BUG REPORT or FEATURE REQUEST? (leave only one on its own line)

/kind bug

Description

I use Jetbrains IntelliJ to connect to the Docker api. I don't have control on the way IntelliJ communicates with Docker.
All I can do is point IntelliJ to podman unix socket.

I want podman to behave like Docker regarding /etc/hosts entries management. Docker does not copy host /etc/hosts entries to the container /etc/hosts. I thought I would use https://docs.podman.io/en/latest/markdown/podman-run.1.html#no-hosts.

But containers.no_hosts=true is not considered when running containers via the REST api (works otherwise).

Steps to reproduce the issue:

1. Add the following to ~/.config/containers/containers.conf :

[containers]
no_hosts=true

2. Start a container via the REST api

Describe the results you received:

The container /etc/hosts contains entries coming from the host /etc/hosts.

Describe the results you expected:

I don't expect the host /etc/hosts entries to be copied to the container.

Additional information you deem important (e.g. issue happens only occasionally):

Since podman does not exhibit the same behaviour as Docker, maybe there is also an additional bug about a wrong default to consider here.

Output of podman version:

Version:      3.4.2
API Version:  3.4.2
Go Version:   go1.16.6
Built:        Thu Jan  1 01:00:00 1970
OS/Arch:      linux/amd64

Output of podman info --debug:

host:
  arch: amd64
  buildahVersion: 1.23.1
  cgroupControllers: []
  cgroupManager: cgroupfs
  cgroupVersion: v1
  conmon:
    package: 'conmon: /usr/libexec/podman/conmon'
    path: /usr/libexec/podman/conmon
    version: 'conmon version 2.0.30, commit: '
  cpus: 16
  distribution:
    codename: focal
    distribution: ubuntu
    version: "20.04"
  eventLogger: journald
  hostname: rhousni
  idMappings:
    gidmap:
    - container_id: 0
      host_id: 1000
      size: 1
    - container_id: 1
      host_id: 100000
      size: 65536
    uidmap:
    - container_id: 0
      host_id: 1000
      size: 1
    - container_id: 1
      host_id: 100000
      size: 65536
  kernel: 5.13.0-37-generic
  linkmode: dynamic
  logDriver: journald
  memFree: 39771643904
  memTotal: 67288952832
  ociRuntime:
    name: crun
    package: 'crun: /usr/bin/crun'
    path: /usr/bin/crun
    version: |-
      crun version UNKNOWN
      commit: ea1fe3938eefa14eb707f1d22adff4db670645d6
      spec: 1.0.0
      +SYSTEMD +SELINUX +APPARMOR +CAP +SECCOMP +EBPF +CRIU +YAJL
  os: linux
  remoteSocket:
    path: /run/user/1000/podman/podman.sock
  security:
    apparmorEnabled: false
    capabilities: CAP_CHOWN,CAP_DAC_OVERRIDE,CAP_FOWNER,CAP_FSETID,CAP_KILL,CAP_NET_BIND_SERVICE,CAP_SETFCAP,CAP_SETGID,CAP_SETPCAP,CAP_SETUID,CAP_SYS_CHROOT
    rootless: true
    seccompEnabled: true
    seccompProfilePath: /usr/share/containers/seccomp.json
    selinuxEnabled: false
  serviceIsRemote: false
  slirp4netns:
    executable: /usr/bin/slirp4netns
    package: 'slirp4netns: /usr/bin/slirp4netns'
    version: |-
      slirp4netns version 1.1.8
      commit: unknown
      libslirp: 4.3.1-git
      SLIRP_CONFIG_VERSION_MAX: 3
      libseccomp: 2.4.3
  swapFree: 1023406080
  swapTotal: 1023406080
  uptime: 3h 43m 1.36s (Approximately 0.12 days)
plugins:
  log:
  - k8s-file
  - none
  - journald
  network:
  - bridge
  - macvlan
  volume:
  - local
registries:
  search:
  - docker.io
  - quay.io
store:
  configFile: /home/rhousni/.config/containers/storage.conf
  containerStore:
    number: 5
    paused: 0
    running: 0
    stopped: 5
  graphDriverName: overlay
  graphOptions: {}
  graphRoot: /home/rhousni/.local/share/containers/storage
  graphStatus:
    Backing Filesystem: extfs
    Native Overlay Diff: "true"
    Supports d_type: "true"
    Using metacopy: "false"
  imageStore:
    number: 34
  runRoot: /run/user/1000/containers
  volumePath: /home/rhousni/.local/share/containers/storage/volumes
version:
  APIVersion: 3.4.2
  Built: 0
  BuiltTime: Thu Jan  1 01:00:00 1970
  GitCommit: ""
  GoVersion: go1.16.6
  OsArch: linux/amd64
  Version: 3.4.2

Package info (e.g. output of rpm -q podman or apt list podman):

Listing... Done
podman/unknown,now 100:3.4.2-1 amd64 [installed]
podman/unknown 100:3.4.2-1 arm64
podman/unknown 100:3.4.2-1 armhf
podman/unknown 100:3.4.2-1 s390

Have you tested with the latest version of Podman and have you checked the Podman Troubleshooting Guide? (https://github.com/containers/podman/blob/main/troubleshooting.md)

Yes

[white-gecko]

I can reproduce this issue with podman version 4.0.2.

MWE:

1. Compare to the output of podman run/docker run

$ podman run --rm -it ubuntu /bin/bash -c "cat /etc/hosts"
127.0.0.1   localhost localhost.localdomain localhost4 localhost4.localdomain4
::1         localhost localhost.localdomain localhost6 localhost6.localdomain6

… further content of my hosts /etc/hosts …

# used by slirp4netns
10.0.2.100	1e8e2a4e38fb adoring_napier
192.168.1.110	host.containers.internal

2. configure in containers.conf

$ cat ~/.config/containers/containers.conf
[containers]
no_hosts=true

3. Start socket

$ systemctl --user start podman.socket

4. Create a docker-compose.yml:

version: "3"

services:
  ubuntu:
    image: "ubuntu"
    command: cat /etc/hosts

5. Compare to the output of podman run/docker run

$ podman run --rm -it ubuntu /bin/bash -c "cat /etc/hosts"
$ docker run --rm -it ubuntu /bin/bash -c "cat /etc/hosts"

(The output is empty, as it should be)

6. run docker-compose

$ export DOCKER_HOST=unix:///run/user/$UID/podman/podman.sock
$ docker-compose up                                          
Creating network "podman-hosts-mwe_default" with the default driver
Creating podman-hosts-mwe_ubuntu_1 ... done
Attaching to podman-hosts-mwe_ubuntu_1
ubuntu_1  | 127.0.0.1   localhost localhost.localdomain localhost4 localhost4.localdomain4
ubuntu_1  | ::1         localhost localhost.localdomain localhost6 localhost6.localdomain6
ubuntu_1  | 
ubuntu_1  | … further content of my hosts /etc/hosts …
ubuntu_1  | 
ubuntu_1  | 10.89.1.2	b7d7626ce0af podman-hosts-mwe_ubuntu_1
ubuntu_1  | 10.89.1.1 host.containers.internal
podman-hosts-mwe_ubuntu_1 exited with code 0

The output still contains the hosts /etc/hosts, which it should not.

[rhatdan]

@Luap99 has been working on this.