Tuning embedded etcd

[nikkictl]

An operator may find it beneficial to configure embedded etcd's storage size QuotaBackendBytes and max request size MaxRequestBytes.

sensu-go/backend/etcd/etcd.go

Lines 161 to 162 in 66b0502

	// Default to 4G etcd size. TODO: make this configurable.
	cfg.QuotaBackendBytes = int64(4 * 1024 * 1024 * 1024)

These values can be loaded as backend flags and config file arguments.

Related to #2641

Expected Behavior

The following command would configure embedded etcd's variables accordingly.

sensu-backend start --etcd-max-request-bytes $((1.5 * 1024 * 1024)) --etcd-quota-backend-bytes $((4 * 1024 * 1024 * 1024))

Current Behavior

There is no way to configure embedded etcd's variables with sensu, however using external etcd would probably allow you to do so.

Possible Solution

Provide config arguments. #2641 solves a similar issue.

Steps to Reproduce (for bugs)

N/A

Context

This would allow us to empower operators to tune embedded etcd. Developers may need to better understand the implications of allowing operators to tune embedded etcd rather than using default (and suggested) values.

Your Environment

N/A

[ghost]

I would also like to be able to tweak things like the heartbeat interval and election timeouts.
Some way to add additional configuration options to etcd would be great.

[palourde]

Closed by #2968