Don't allow Tetragon instance to run when there is another one running

[inliquid]

Is there an existing issue for this?

• I have searched the existing issues

Is your feature request related to a problem?

This is a follow up of discussion with @kkourt and @tixxdz. Currently Tetragon should be run as the single instance on a node (kernel). Otherwise its behavior can be unpredictable: instances can interfere on eBPF programs and/or maps, both on startup an cleanup. Tetragon writes an error to logfile if it sees another instance already up and running, but we would like to prevent it from starting. There is real-world case, our customer said they would like to "experiment" with Tetragon on a node while there is already an instance which protects this node. These experiments may lead to errors and they can break protection they have.

Describe the feature you would like

Tetragon should not start if it sees there is another instance already up and running. Error message should say that the reason for that, is possible unpredictable behavior because of the interference between instances.

Describe your proposed solution

No response

Code of Conduct

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[inliquid]

I will implement it and prepare PR.

[kkourt]

@inliquid thanks, I've assigned the issue to you.