calicoctl node diags has unexplained 'exit status 1' in its output

[tmjd]

When running the command sudo calicoctl node diags the output includes exit status 1.

Expected Behavior

Whatever command is returning exit status 1 should be reported in the output or the message should be eliminated if it is an unimportant failure.

Current Behavior

This is the current output

Collecting diagnostics
Using temp dir: /tmp/calico458969731
Dumping netstat
Dumping routes (IPv4)
Dumping routes (IPv6)
Dumping interface info (IPv4)
Dumping interface info (IPv6)
Dumping iptables (IPv4)
Dumping iptables (IPv6)
Dumping ipsets
exit status 1
Dumping ipsets (container)
Copying journal for calico-node.service
Dumping felix stats
Copying Calico logs

Diags saved to /tmp/calico458969731/diags-20170522_193031.tar.gz
If required, you can upload the diagnostics bundle to a file sharing service 
such as transfer.sh using curl or similar.  For example:

    curl --upload-file /tmp/calico458969731/diags-20170522_193031.tar.gz https://transfer.sh//tmp/calico458969731/diags-20170522_193031.tar.gz

Steps to Reproduce (for bugs)

1. Setup kubernetes cluster in vagrant following http://docs.projectcalico.org/v2.2/getting-started/kubernetes/installation/vagrant/
2. Install calicoctl and make executable
3. Run sudo calicoctl node diags

Context

Your Environment

• Calico version v2.2 installed
  • Using the calicoctl versions from Calico v2.2, v2.1 and v2.0 all contained the exit status 1 line
• Kubernetes 1.6.2

[heschlie]

So it looks like it is cause by ipset list throwing an error:

ipset v6.20.1: Kernel and userspace incompatible: settype by userspace. with revision 1378325840 not supported

And when a command fails we just dump the Go error to stdout, which with exec.Command is what we see here, exit status 1. I feel like we have two good low hanging fruit:

1. Change the output to be something more like "Failed to run command: $command"
2. Show the actual error message (and probably command) in the output

I'm mostly just not sure how much noise we want to generate, @tmjd WDYT?

[tmjd]

I think 1 would work, just show the failed command. I'm thinking, then if they want to see more they can just run that command.