no default dns plugin when creating rootless network

[trusch]

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

/kind bug

Description

When I create a new network in as non-root, the dns plugin is not added, even when explicitly setting --disable-dns=false.
Besides that, I'm super happy about rootless networking :)

Steps to reproduce the issue:

1. podman network create --disable-dns=false foo

2. cat ~/.config/cni/net.d/foo.conflist | grep dnsname

Describe the results you received:
There is no DNS plugin configured, I need to add it manually

Describe the results you expected:
The DNS plugin should be automatically added (perhaps when dnsmasq binary is found?!)

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

Output of podman version:

Version:      2.1.1
API Version:  2.0.0
Go Version:   go1.15.2
Git Commit:   9f6d6ba0b314d86521b66183c9ce48eaa2da1de2
Built:        Sat Sep 26 17:50:37 2020
OS/Arch:      linux/amd64

Output of podman info --debug:

host:
  arch: amd64
  buildahVersion: 1.16.1
  cgroupManager: cgroupfs
  cgroupVersion: v1
  conmon:
    package: Unknown
    path: /usr/bin/conmon
    version: 'conmon version 2.0.21, commit: 35a2fa83022e56e18af7e6a865ba5d7165fa2a4a'
  cpus: 8
  distribution:
    distribution: arch
    version: unknown
  eventLogger: journald
  hostname: beast
  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: 5.8.14-arch1-1
  linkmode: dynamic
  memFree: 292761600
  memTotal: 33390354432
  ociRuntime:
    name: runc
    package: Unknown
    path: /usr/bin/runc
    version: |-
      runc version 1.0.0-rc92
      commit: ff819c7e9184c13b7c2607fe6c30ae19403a7aff
      spec: 1.0.2-dev
  os: linux
  remoteSocket:
    exists: true
    path: /run/user/1000/podman/podman.sock
  rootless: true
  slirp4netns:
    executable: /usr/bin/slirp4netns
    package: Unknown
    version: |-
      slirp4netns version 1.1.4
      commit: b66ffa8e262507e37fca689822d23430f3357fe8
      libslirp: 4.3.1
      SLIRP_CONFIG_VERSION_MAX: 3
  swapFree: 0
  swapTotal: 0
  uptime: 40h 50m 7.36s (Approximately 1.67 days)
registries:
  search:
  - docker.io
  - registry.fedoraproject.org
  - quay.io
  - registry.access.redhat.com
  - registry.centos.org
store:
  configFile: /home/tino/.config/containers/storage.conf
  containerStore:
    number: 33
    paused: 0
    running: 21
    stopped: 12
  graphDriverName: overlay
  graphOptions:
    overlay.mount_program:
      Executable: /usr/bin/fuse-overlayfs
      Package: Unknown
      Version: |-
        fusermount3 version: 3.10.0
        fuse-overlayfs: version 1.1.0
        FUSE library version 3.10.0
        using FUSE kernel interface version 7.31
  graphRoot: /home/tino/.local/share/containers/storage
  graphStatus:
    Backing Filesystem: extfs
    Native Overlay Diff: "false"
    Supports d_type: "true"
    Using metacopy: "false"
  imageStore:
    number: 230
  runRoot: /run/user/1000/containers
  volumePath: /home/tino/.local/share/containers/storage/volumes
version:
  APIVersion: 2.0.0
  Built: 1601135437
  BuiltTime: Sat Sep 26 17:50:37 2020
  GitCommit: 9f6d6ba0b314d86521b66183c9ce48eaa2da1de2
  GoVersion: go1.15.2
  OsArch: linux/amd64
  Version: 2.1.1

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

pacman -Q podman
podman 2.1.1-1

Have you tested with the latest version of Podman and have you checked the Podman Troubleshooting Guide?

Yes

Additional environment details (AWS, VirtualBox, physical, etc.):
Local laptop

[Luap99]

The dnsname plugin is only added to the config if the plugin is installed.

For rootless this check make no sense since we use a cni-infra container for networking which always has the plugin.