Improving the image

[SnowMB]

Hey,

I ran into the issue, that I need letsencrypt like certificates for my mailserver, but traefik does not store them in the right format. I found your image and while it does the extracting job quite well, I needed a bit additional functionality.

So I hacked a little bit on the script myself and added / improved the following things:

• added proper command line arguments #3
  • -c --certs Certificate file to watch
  • -d --directory Output directory
• added --include and --exclude to either restrict the extraction to specific domains or ignore specific domains and take the rest (they are mutally exclusive) #2
• added a small delay (2s) between the event and the actual work, because watchdog would trigger 2-4 times in my tests
• changed the arguments so that only a single file is wachted instead of every *.json file in the folder. It can be changed through the command line argument -c or --certs
• added the python docker API to automatically restart any container that needs to be notified about the certificate change (can be toggled by command line argument -r --restart_container). It watches for the following label: com.github.DanielHuisman.traefik-certificate-extractor.restart_domain=<DOMAIN>. Multiple domains can be seperated by ,
• added test -dry-run option
• split export into normal, letsencrypt style (default) and demoted flat export to a command line option (--flat)
• included changes in the Readme

I'm by no means an experienced python programmer, so the code might look a bit messy.

Please use everything as you need. For testing purposes I added an own docker image at snowmb/traefik-certificate-extractor with a different label.

[DanielleHuisman]

Thansk for contributing to this repository! I'm currently on holiday, but I will take a look at this PR in a few days.

[callumgare]

@DanielHuisman @SnowMB Are these changes still been considered for upstreaming? I love the ability to be able to specify what domain should cause a container to restart :)