Simplify Nessie CLI arguments

[e-minguez]

For k8s & system mode

Right now to run Nessie against a k8s node this is needed:

podman run --rm --privileged \
  -v /etc/rancher/k3s/k3s.yaml:/etc/rancher/k3s/k3s.yaml:ro \
  -v /var/log/journal:/var/log/journal:ro \
  -v /run/systemd:/run/systemd:ro \
  -v /etc/machine-id:/etc/machine-id:ro \
  -v /tmp:/tmp \
  -e NESSIE_LOG_DIR="/tmp" \
  -e NESSIE_ZIP_DIR="/tmp" \
  registry.suse.com/edge/3.4/nessie:1.0.0

A few improvements would be:

• Use /kubeconfig by default, so users just need to set the volume as -v /path/to/my/kubeconfig:/kubeconfig:ro
• Use /output instead of /tmp to simplify things. Set a volume like -v /path/to/whatever:/output then make nessie to use that /output to create the folder structure needed there.

Then it should look like:

podman run --rm --privileged \
  -v /home/foo/.kube/config:/kubeconfig:ro \
  -v /var/log/journal:/var/log/journal:ro \
  -v /run/systemd:/run/systemd:ro \
  -v /etc/machine-id:/etc/machine-id:ro \
  -v /home/foo/tmp/whatever:/output \
  registry.suse.com/edge/3.4/nessie:1.0.0

For system mode
For system mode, right now this is needed:

podman run --rm --privileged \
  -v /var/log/journal:/var/log/journal:ro \
  -v /run/systemd:/run/systemd:ro \
  -v /etc/machine-id:/etc/machine-id:ro \
  -v /tmp:/tmp \
  -e NESSIE_LOG_DIR="/tmp" \
  -e NESSIE_ZIP_DIR="/tmp" \
  -e NESSIE_VERBOSE="1" \
  -e NESSIE_SKIP_POD_LOGS="true" \
  -e NESSIE_SKIP_K8S_CONFIGS="true" \
  -e NESSIE_SKIP_METRICS="true" \
  registry.suse.com/edge/3.4/nessie:1.0.0

Instead, if kubeconfig is not found, then just avoid the need to have so many flags:

podman run --rm --privileged \
  -v /var/log/journal:/var/log/journal:ro \
  -v /run/systemd:/run/systemd:ro \
  -v /etc/machine-id:/etc/machine-id:ro \
  -v /home/foo/tmp/whatever:/output \
  registry.suse.com/edge/3.4/nessie:1.0.0