K6_SYSTEM_TAGS is returning an error when set

[markjmeier]

When executing a test with the K6_SYSTEM_TAGS Env variable an error is returned. e.g.:

export 
K6_SYSTEM_TAGS=proto,subproto,status,method,url,name,group,check,error,tls_version,vu,iter

returns

ERRO[0001] envconfig.Process: assigning K6_SYSTEM_TAGS to SystemTags: 
converting 
'proto,subproto,status,method,url,name,group,check,error,tls_version,vu,iter' 
to type lib.TagSet. details: invalid map item: "proto"

The flag --system-tags does NOT produce this error and works as expected.

[na--]

I think this happens because envconfig tries to work with the underlying map that's currently used to track the enabled system tags. To fix that we probably have to implement the TextUnmarshaler interface for the type: https://github.com/kelseyhightower/envconfig#supported-struct-field-types

The biggest issue with fixing this is that both parts of the equation would soon change - we'd probably have to replace envconfig pretty soon (because of #671 and a few other issues), and we also probably should change the underlying type used to track the enabled system tags (#755)... So we'll either do a quick fix that would soon be overwritten or fix this as part of one of the aforementioned issues.

[cuonglm]

@na-- This issue seems to be fixed.

[na--]

Hmm unfortunately, the error seems to have disappeared at some point, but instead of being fixed, I think it's just not triggered, since the current k6 doesn't seem to read the K6_SYSTEM_TAGS variable at all. Running K6_SYSTEM_TAGS=proto,status k6 run -o json script.js with k6 v0.24.0 or v0.25.0 doesn't produce the error, but it also doesn't change the used system tags, while k6 v0.23.1 produces the error reported above...

[na--]

Ah, actually, my mistake. It seems like @mstoykov partially fixed this here in the datadog/statsd pull request, but it was masked because of the CLI option handling bug, which you recently fixed. So @cuonglm, you are completely right, this is now fixed - it's working perfectly on master and it's soon going to be released in v0.25.1.