caddy-git: App running by plugin crashed & not restart

Hi! Application runned by Git add-on goes down after several hours & don’t restart.

This is error log of application (created by caddy) 13/Jan/2016:19:57:22 +0300 [ERROR 502 /] unreachable backend

This is few strings from caddy.log

[GIN-debug] Listening and serving HTTP on :9000
[GIN-debug] [ERROR] listen tcp :9000: bind: address already in use

This is Caddyfile

mimozaflowers.ru, www.mimozaflowers.ru {
        root /root/gocode/src/github.com/pavlik/mimozaflowers
        gzip
        log /var/log/mimoza_access.log

        errors {
                log /var/log/mimoza_error.log
                #404 404.html # Not Found
        }

        git {
                path ./
                repo https://github.com/pavlik/mimozaflowers
                hook /webhook secret
                then go install
                then_long /root/gocode/bin/mimozaflowers
        }

        proxy / localhost:9000
}

This is my app https://github.com/pavlik/mimozaflowers/blob/master/server.go

I would appreciate if you help to understand what is the reason off app shutdown…