Skip setup if they want to get --help

[yosifkit]

This will allow users to see available flags with docker run -it --rm mysql --verbose --help.

[tianon]

@ltangvald what're your thoughts on this? Right now it falls over pretty hard if we use --help... (tries to initialize a database, etc)

Do you think there are other mysqld options we should add to the "bypass" list? (maybe start with this and keep our eyes open for more examples as we go?)

[ltangvald]

Maybe --print-defaults?

[ltangvald]

A concern is that this will quickly balloon out of control if we start adding checks for any options that cause the server to behave in a non-standard way. E.g. -? is a variant of --help and would also need to be included. Maybe better to either try to detect the failure early so the user doesn't have to wait for a timeout or have a specific, documented way of getting a readme-like output from the image?

[yosifkit]

It could get longer, yes, but I think there is a limited set that cause the server to not actually run that we should catch, rather than trying to detect that a failure is a success. We would otherwise have to detect them in two spots, one after trying to get DATADIR and skip the rest of the setup, and the other would be when we start the server in the background, which could've failed for other reasons.

The set I have found is: -'?'|--help|--print-defaults|-V|--version. The user will have to be aware that --print-defaults needs to be the first argument, but that is in the verbose help output and should not be something we need to explicitly test for.

[yosifkit]

@ltangvald, does this seem like a solid solution?

[ltangvald]

Gah, sorry. Yeah as long as we keep it limited it looks good :)

[tianon]

LGTM 👍