podman: ERROR: table `nat' is incompatible, use 'nft' tool.

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

/kind bug

Description

I use nftables; when starting a container I get:

ERRO[0000] Error adding network: failed to list chains: running [/usr/sbin/iptables -t nat -S --wait]: exit status 1: iptables v1.8.2 (nf_tables): table `nat' is incompatible, use 'nft' tool.

ERRO[0000] Error while adding pod to CNI network "podman": failed to list chains: running [/usr/sbin/iptables -t nat -S --wait]: exit status 1: iptables v1.8.2 (nf_tables): table `nat' is incompatible, use 'nft' tool.

Error: error configuring network namespace for container 51f6adbaed7d674fb4b48d501eb7ce0605d09e003ac09f6588b98dea7230ca9f: failed to list chains: running [/usr/sbin/iptables -t nat -S --wait]: exit status 1: iptables v1.8.2 (nf_tables): table `nat' is incompatible, use 'nft' tool.

Steps to reproduce the issue:

1. Create network configuration:

cat >/etc/cni/net.d/podman.conflist <<EOF
{
  "cniVersion": "0.4.0",
  "name": "podman",
  "plugins": [
    {
      "type": "bridge",
      "bridge": "cni-podman0",
      "isGateway": true,
      "ipMasq": true,
      "ipam": {
        "type": "host-local",
        "routes": [
          {
            "dst": "0.0.0.0/0"
          }
        ],
        "ranges": [
          [
            {
              "subnet": "192.168.124.0/24",
              "gateway": "192.168.124.1"
            }
          ]
        ]
      }
    },
    {
      "type": "portmap",
      "capabilities": {
        "portMappings": true
      }
    },
    {
      "type": "firewall",
      "backend": "nftables"
    }
  ]
}
EOF

1. Pull fedora image and start a container:

podman pull fedora:latest
podman run -it fedora bash

Describe the results you received:

ERRO[0000] Error adding network: failed to list chains: running [/usr/sbin/iptables -t nat -S --wait]: exit status 1: iptables v1.8.2 (nf_tables): table `nat' is incompatible, use 'nft' tool.

ERRO[0000] Error while adding pod to CNI network "podman": failed to list chains: running [/usr/sbin/iptables -t nat -S --wait]: exit status 1: iptables v1.8.2 (nf_tables): table `nat' is incompatible, use 'nft' tool.

Error: error configuring network namespace for container 51f6adbaed7d674fb4b48d501eb7ce0605d09e003ac09f6588b98dea7230ca9f: failed to list chains: running [/usr/sbin/iptables -t nat -S --wait]: exit status 1: iptables v1.8.2 (nf_tables): table `nat' is incompatible, use 'nft' tool.

Describe the results you expected:

No errors.

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

Output of podman version:

podman version 1.6.4

Output of podman info --debug:

debug:
  compiler: gc
  git commit: ""
  go version: go1.12.12
  podman version: 1.6.4
host:
  BuildahVersion: 1.12.0-dev
  CgroupVersion: v1
  Conmon:
    package: conmon-2.0.6-1.module+el8.1.1+5259+bcdd613a.x86_64
    path: /usr/bin/conmon
    version: 'conmon version 2.0.6, commit: 6ffbb2ec70dbe5ba56e4bfde946fb04f19dd8bbf'
  Distribution:
    distribution: '"rhel"'
    version: "8.1"
  MemFree: 483997450240
  MemTotal: 540217061376
  OCIRuntime:
    name: runc
    package: runc-1.0.0-64.rc9.module+el8.1.1+5259+bcdd613a.x86_64
    path: /usr/bin/runc
    version: 'runc version spec: 1.0.1-dev'
  SwapFree: 10737414144
  SwapTotal: 10737414144
  arch: amd64
  cpus: 64
  eventlogger: journald
  kernel: 4.18.0-147.5.1.el8_1.x86_64
  os: linux
  rootless: false
  uptime: 662h 43m 16.45s (Approximately 27.58 days)
registries:
  blocked: null
  insecure: null
  search:
  - registry.redhat.io
  - registry.access.redhat.com
  - quay.io
  - docker.io
store:
  ConfigFile: /etc/containers/storage.conf
  ContainerStore:
    number: 4
  GraphDriverName: overlay
  GraphOptions: {}
  GraphRoot: /var/lib/containers/storage
  GraphStatus:
    Backing Filesystem: xfs
    Native Overlay Diff: "true"
    Supports d_type: "true"
    Using metacopy: "false"
  ImageStore:
    number: 2
  RunRoot: /var/run/containers/storage
  VolumePath: /var/lib/containers/storage/volumes

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

podman-1.6.4-2.module+el8.1.1+5363+bf8ff1af.x86_64

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

Physical.