Dynamically generate flags passed to etcd binary

[serathius]

Part of #16673 to randomize etcd configuration we need to expand coverage of flags that can be provided in e2e tests. Instead of manually transforming embed.Config struct fields, we can use flagset to automatically generate flags.

[serathius]

cc @ahrtr

[ahrtr]

Suggested change

	var value string
	if value != "false" && value != "0" {
	value = f.Value.String()
	}
	values[f.Name] = value
	value := f.Value.String()
	if value != "" && value != "false" && value != "0" {
	values[f.Name] = value
	}

[serathius]

I think the result is different, but I will double check if there impact on the list of flags generated.

[serathius]

ok, makes sense.

[serathius]

Needed to revert. The code change makes a difference for flags with default value true, that is set to false during the test.

[serathius]

If I have time I will add a unit test for this.

[ahrtr]

I don't think you understand my comment. I am talking about a simple golang syntax problem (although not a big problem): you are checking a variable value which is always ""

[serathius]

And I responded, that after I applied you change the test started to consistently fail and it needs further investigation.

[serathius]

With #16747 I have confirmed that your change breaks logic:

--- FAIL: TestEtcdServerProcessConfig (0.00s)
    --- FAIL: TestEtcdServerProcessConfig/StrictReconfigCheck (0.00s)
        cluster_test.go:214: diff:   []string{
                ... // 11 identical elements
                "/tmp/fake/member-0",
                "--initial-cluster-token=new",
            +   "--strict-reconfig-check=false",
              }
FAIL
FAIL    go.etcd.io/etcd/tests/v3/framework/e2e  0.051s
FAIL

[ahrtr]

Please forget my original suggested change. Instead, change

		var value string
		if value != "false" && value != "0" {
			value = f.Value.String()
		}

to

value := f.Value.String()

[serathius]

Changed updated it. PTAL. Now with unit test it should be clear what was the problem.

[ahrtr]

LGTM

Nice simplification & refactoring! thx

[serathius]

Flake

[jmhbnz]

LGTM - Nice work.

#16707 (comment)

[ahrtr]

#16707 (comment)

action needed:

• fix the simple golang programming problem (always checking a variable which is always "") as I mentioned.
• resolve related test failure

[serathius]

Created the PR with tests #16707

[serathius]

ping @ahrtr