Fix broken list parsing in cli arguments --tags and --experiments

[lox]

Currently, buildkite-agent start --tags "a=1,b=2" sets a single tag of a=1,b=2. This is a shortcoming of the upstream urfave.cli library (see urfave/cli#62) which expects --tags "a=1" --tags "a=2".

This adds a normalization for --tags and --experiments that makes them behave as expected.

[keithpitt]

Oh, I assume it's fine with --tags "foo=bang,bar,bing"

[keithpitt]

(Where you specifically want foo to be a comma separated list..)

[lox]

Nope! Won't work!

[lox]

Wouldn't work in config either.

[keithpitt]

As in, it has never worked? Or, it won't work with the current changes?

I know that some customers use this syntax for things like:

--tags "supports=ruby1.9.3,mysql,node-1.2.3"

[keithpitt]

(Actually, I can't remember if before cli used to expand them into multiple values...)

[lox]

Yeah, it's really perplexed me too. I'm pretty sure the example you just gave would have worked via the cli argument (because no splitting occurred), but failed via a config key.

[lox]

See

agent/cliconfig/loader.go

Line 220 in 22864f1

value = strings.Split(configFileValue, ",")

[lox]

I have no idea how to fix this with the current config syntax, beyond possibly suggesting people can escape commas? We'd need to add support for that.

[keithpitt]

Just chatted with @lox in real life, we've never supported commas in tag values before, so it's fine to ship as-is!