gridka-go-tutorial

gridka-go-tuto is a simple repository holding sources for the Go hands-on session of the GridKa School.

The slides are here.

Bootstrapping the work environment

Installing the Go toolchain

The Go hands-on session obviously needs a working Go toolchain.

There are 3 ways to achieve this:

• install Go via your favorite package manager (yum, apt-get, fink, ...)
• install Go via docker
• install Go manually.

The VMs crafted and made available to the GridKa students should already have Go installed:

$> ssh gks@gridka-vm

[gks@gridka-vm]$ cat /etc/redhat-release 
CentOS Linux release 7.2.1511 (Core) 

[gks@gridka-vm]$ go version
go version go1.6.3 linux/amd64

On other machines, installing and configuring Go can be achieved by following the instructions of the official Go installation page: https://golang.org/doc/install

Setting up the work environment

Like python and its $PYTHONPATH environment variable, Go uses $GOPATH to locate packages' source trees. You can choose whatever you like (obviously a directory under which you have read/write access, though.)

In the following, we'll assume you chose $HOME/go:

$ mkdir -p $HOME/go
$ export GOPATH=$HOME/go
$ export PATH=$GOPATH/bin:$PATH

Make sure the go tool is correctly setup:

$ go env
GOARCH="amd64"
GOBIN=""
GOCHAR="6"
GOEXE=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOOS="linux"
GOPATH="$HOME/go"
GORACE=""
GOROOT="/usr/lib/golang"
GOTOOLDIR="$HOME/go/pkg/tool/linux_amd64"
CC="gcc"
GOGCCFLAGS="-fPIC -m64 -pthread -fmessage-length=0"
CXX="g++"
CGO_ENABLED="1"

(on other platforms/architectures, the output might differ slightly. The important env.vars. are GOPATH and GOROOT.)

Testing go get

Now that the go tool is correctly setup, let's try to fetch some code. For this part, you'll need the following tools installed to actually retrieve the code from the repositories:

• git

Without further ado:

$ go get -u -v github.com/sbinet/gridka-go-tuto/cmd/gridka-hello
github.com/sbinet/gridka-go-tuto (download)

go get downloaded (cloned, in git speak) the whole github.com/sbinet/gridka-go-2017 repository (under $GOPATH/src) and compiled the gridka-hello command. As the compilation was successful, it also installed the gridka-hello command under $GOPATH/bin.

The gridka-hello command is now available from your shell:

$ gridka-hello
Hello GridKa!

$ gridka-hello you
Hello you!

Setting up your favorite editor

Extensive documentation on how to setup your editor (for code highlighting, code completion, ...) is available here:

https://github.com/golang/go/wiki/IDEsAndTextEditorPlugins

At the very least, you should try to install and setup goimports as explained here:

https://godoc.org/golang.org/x/tools/cmd/goimports

goimports provides automatic code formating as well as automated insertion/deletion of used/unused packages (in your import package statements.)

Documentation

The Go programming language is quite new (released in 2009) but ships already with quite a fair amount of documentation. Here are a few pointers:

• https://golang.org/doc/code.html
• https://tour.golang.org
• https://golang.org/doc/effective_go.html
• https://dave.cheney.net/resources-for-new-go-programmers
• https://gobyexample.com

For more advanced topics:

• https://talks.golang.org
• https://blog.golang.org
• https://groups.google.com/d/forum/golang-nuts (Go community forum)
• the internets. typical queries are go something or golang something