This PR introduces two new server configuration options, for providing a
custom .JS and .CSS file.
These can be used to show custom banner messages, add
environment-dependent signals, or simply a corporate logo.
### Motivation (what problem I try to solve)
I'm operating Woodpecker in multiple k8s clusters for different
environments.
When having multiple browser tabs open, I prefer strong indicators for
each environment.
E.g. a red "PROD" banner, or just a blue "QA" banner.
Also, we sometimes need to have the chance for maintenance, and instead
of broadcasting emails,
I prefer a banner message, stating something like: "Heads-up: there's a
planned downtime, next Friday, blabla...".
Also, I like to have the firm's logo visible, which makes Woodpecker
look more like an integral part of our platform.
### Implementation notes
* Two new config options are introduced ```WOODPECKER_CUSTOM_CSS_FILE```
and ```WOODPECKER_CUSTOM_JS_FILE```
* I've piggy-bagged the existing handler for assets, as it seemed to me
a minimally invasive approach
* the option along with an example is documented
* a simple unit test for the Gin-handler ensures some regression safety
* no extra dependencies are introduced
### Visual example
The documented example will look like this.
### Areas of uncertainty
This is my first contribution to Woodpecker and I tried my best to align
with your conventions.
That said, I found myself uncertain about these things and would be glad
about getting feedback.
* The handler tests are somewhat different than the other ones because I
wanted to keep them simple - I hope that still matches your coding
guidelines
* caching the page sometimes will let the browser not recognize changes
and a user must reload. I'm not fully into the details of how caching is
implemented and neither can judge if it's a real problem. Another pair
of eyes would be good.
