gin 
gin is a simple command line utility for live-reloading Go web applications.
Just run gin in your app directory and your web app will be served with
gin as a proxy. gin will automatically recompile your code when it
detects a change. Your app will be restarted the next time it receives an
HTTP request.
gin adheres to the "silence is golden" principle, so it will only complain
if there was a compiler error or if you succesfully compile after an error.
Installation
Assuming you have a working Go environment and GOPATH/bin is in your
PATH, gin is a breeze to install:
go install github.com/codegangsta/gin@latestThen verify that gin was installed correctly:
gin helpBasic usage
gin run main.goOptions
--laddr value, -l value listening address for the proxy server
--port value, -p value port for the proxy server (default: 3000)
--appPort value, -a value port for the Go web server (default: 3001)
--bin value, -b value name of generated binary file (default: "gin-bin")
--path value, -t value Path to watch files from (default: ".")
--build value, -d value Path to build files from (defaults to same value as --path)
--excludeDir value, -x value Relative directories to exclude
--immediate, -i run the server immediately after it's built
--all reloads whenever any file changes, as opposed to reloading only on .go file change
--godep, -g use godep when building
--buildArgs value Additional go build arguments
--certFile value TLS Certificate
--keyFile value TLS Certificate Key
--logPrefix value Setup custom log prefix
--notifications enable desktop notifications
--help, -h show help
--version, -v print the version
Supporting Gin in Your Web app
gin assumes that your web app binds itself to the PORT environment
variable so it can properly proxy requests to your app. Web frameworks
like Martini do this out of
the box.
Using flags?
When you normally start your server with flags
if you want to override any of them when running gin we suggest you
instead use github.com/namsral/flag
as explained in this post
If you want to still use the standard flag package but support environment variables, you might want to try github.com/peak6/envflag.