What challenge are you facing?

Tons of issues are opened all the time because various funny characters cause breakage in various places (e.g. fly, web UI):

• Restrict use of "/" in job and resource names #2336
• Slash in job name only allows job to be run once. Ever. #1892
• Job names with + characters break links to builds page #3941
• Regression with resource names: forward slashes in name break webui in >4.2.2 #3787
• Concourse Web UI shows 404 when viewing a resource which name contains a slash #2211
• "%" percent character in pipeline or job name causes display issues #3724
• Pipeline names should be validated for "sensible" characters #1902
• ...probably like 10 others somewhere I can't find

We've never had any validation for these so folks have started to use all kinds of weird naming schemes which are difficult to support going forward, especially in contexts like fly where we often have our own notation in flags.

What would make this better?

We should just decide on allowable characters and perform validation at pipeline submission time.

If I were to start Concourse over I would have restricted everything to [a-z0-9-]+ and force everyone to use fairly simple job/pipeline names. I say a-z but I really mean alphabetical in whatever language the user speaks - I don't remember the regex notation for that.

I would even go as far as only allowing lowercase characters so we don't have to care about case-sensitivity, and allowing - but not _ so we don't end up with ideological wars.

The advantage of having such a strict set of allowable characters would be that everyone's Concourse feels the same. This also allows us to use notation more freely, e.g. / for pipeline hierarchies (#532).

Are there any use cases out there for certain special characters in job/pipeline names?

How many people have I made angry with my recklessly narrow definition of allowed characters?