Add missing options for cache control

[priv-kweihmann]

As https://github.com/nexB/scancode-toolkit/blob/develop/src/scancode/cli.py#L1043 states, there is an open TODO for controlling the cache.
I'm using scancode in an environment where ~/.cache should NOT be used for storing any kind of artifacts.

Please add one of the following options

• disable caching in total (as stated by the linked TODO)
• option to specify the caching directory via CLI

[pombredanne]

Actually the cache can be controlled this way:

1. the license index cache is created as package data when using the release script, so that's not really cache per se, unless you are developing.
2. SCANCODE_CACHE is an environment variable that you can set to a dir and that's where cache will be written
3. SCANCODE_TEMP is an environment variable that you can set to a dir and that's where temp files will be written

This definitely should be better documented

[priv-kweihmann]

Thanks, I guess that should do it

[pombredanne]

@priv-kweihmann we could also expose this as command line options. Would you prefer this? that's an easy thing
BTW, unrelated, I will soon work on merging support for bitbake from https://github.com/nexB/scancode-toolkit/tree/1243_collect_data_from_yocto/bitbake_.bb thanks to your excellent library! 🙇

[pombredanne]

We need to document the cache env var in the doc BTW. So I am reopening this
See #2355 (comment)

[priv-kweihmann]

Always happy to help. And the dedicated environment vars are more than enough for me - just didn't wanted to override HOME for my use case, so I consider this here fixed. Any further CLI option could by handled as future enhancements

[krishna9358]

Is this issue still open ?

[priv-kweihmann]

@krishna9358 I think the ticket can be closed - problem was solved for me with the added documentation