Cannot execute microstack.ovn-trace

[Mark Beierl]

I've tried many combinations of quotes, escapes, etc, and it seems there is no method to invoke ovn-trace. The following error is displayed:

Example command:
  sudo microstack.ovn-trace cluster 'inport == "lp11" && eth.src == 00:01:02:03:04:05 && eth.dst == ff:ff:ff:ff:ff:ff'

Output:
  ovn-trace: exactly two non-option arguments are required (use --help for help)

[Paul Goins (vultaire)]

I've confirmed this. For BootStack team training purposes, I'm trying to walk through the OVN OpenStack tutorial [1] using Microstack as the underlying openstack environment.

In the tutorial, there's a command:

  ovn-trace n1 'inport == "ap"'

Converting for microstack w/o aliases, that becomes:

  sudo microstack.ovn-trace n1 'inport == "ap"

And... I get the exact same issue as the original author.

[1] https://docs.ovn.org/en/latest/tutorials/ovn-openstack.html

[Billy Olsen (billy-olsen)]

I confirm - this is due to the way that wrappers are used to run the commands. Note, the ovn-chassis snap moves away from using the wrappers to execute commands as they get in the way.

A hacky work around for the time being, would be to try executing these commands using the snap shell, e.g. "sudo snap run --shell microstack.ovn-trace"

This drops you into an interactive shell where you can exec ovn-trace directly and passing the arguments through. You will likely need to have some environment variables set that the wrappers attempt to do. (see https://github.com/ubuntu-ovn-eng/snap-ovn-chassis/blob/main/snap/snapcraft.yaml#L26 as an example of the env variables set in the ovn-chassis snap).

[Paul Goins (vultaire)]

I'm not 100% sure if there might be other dependencies, but based upon the link from Billy, I could get an ovn-trace command working via the snap shell simply by running "export OVN_RUNDIR=$SNAP_COMMON/run/ovn" prior to running ovn-trace.