Add environment variables for configuration

[fin-ger]

Hi,

first of all, thank you for this awesome project!

I added a bunch of environment variables which can set defaults for many of the values visible in the web-interface. This makes it easier to automatically deploy wireguard-ui e.g. with Ansible, K8S, etc. with a predefined configuration. This also includes the option to control the defaults entered in the New Client dialog, which helps reducing errors where e.g. a CIDR of 0.0.0.0/0 is not suitable as only a number of subnets should be routed to the WireGuard server.

I welcome any suggestions to my changes and would be happy to see this merged upstream.

#99 would be fixed by this.

[fin-ger]

I rebased and added environment variables for ForwardMark and EndpointAddress.

[ngoduykhanh]

LGTM. Thanks for your contribution @fin-ger

[olegStreejak]

Hello. Trying to set it up under FreeBSD, latest available binary
Wireguard UI
App Version : v0.3.7
Git Commit : ad4ca4d9bb344236a2793fee54ec24cf07d6cd8c
Git Ref : refs/tags/v0.3.7
Build Time : 05-14-2022 16:51:29
Git Repo : https://github.com/ngoduykhanh/wireguard-ui
Authentication : true
Bind address : 192.168.0.1:5000
Email from : noreply@to.me
Email from name : WireGuard UI
⇨ http server started on 192.168.0.1:5000
started by daemon, set its env so that
$ procstat environment 3799
PID COMM ENVIRONMENT
3799 wireguard-ui WGUI_DEFAULT_CLIENT_ALLOWED_IPS="10.0.1.0/24,192.168.0.0/24"

but if I press + New Client button, there's always the default 0.0.0.0/0

Why?

p.s.: tried only one CIDК net, tried WGUI_DEFAULT_CLIENT_EXTRA_ALLOWED_IPS - all in vain

[fin-ger]

This feature is currently only available on the latest git master. It has not been released, yet.

[olegStreejak]

Thank you for reply!