My personal Go environment setup

How many go version do you have installed?

The default upstream location for the binary is: /usr/local/go. But in SUSE it is: /usr/bin/go. This is a symlink created via update-alternatives.

# update-alternatives --list go
/usr/lib64/go/1.10/bin/go
/usr/lib64/go/1.8/bin/go
/usr/lib64/go/1.9/bin/go

I want to keep only the 1.10 so I will remove the others:

# zypper rm $(rpm -qf /usr/lib64/go/1.8/bin/go) $(rpm -qf /usr/lib64/go/1.9/bin/go)

To verify, try update-alternatives once more. There should be only one version:

# update-alternatives --list go
/usr/lib64/go/1.10/bin/go

The full should look like this:

# update-alternatives --display go
go - auto mode
  link best version is /usr/lib64/go/1.10/bin/go
  link currently points to /usr/lib64/go/1.10/bin/go
  link go is /usr/bin/go
  slave go.gdb is /etc/gdbinit.d/go.gdb
  slave go.sh is /etc/profile.d/go.sh
  slave gofmt is /usr/bin/gofmt
/usr/lib64/go/1.10/bin/go - priority 30
  slave go.gdb: /usr/lib64/go/1.10/bin/gdbinit.d/go.gdb
  slave go.sh: /usr/lib64/go/1.10/bin/profile.d/go.sh
  slave gofmt: /usr/lib64/go/1.10/bin/gofmt

This automatically created the following env vars:

# env | grep GO
GOPATH=/usr/share/go/1.10/contrib
GOROOT=/usr/lib64/go/1.10
GOBIN=/usr/bin
GOOS=linux
GOARCH=amd6

Setup the Go variables

Change .bashrc to know what is going on:

# Go stuff
# Where is the go binary
export GOROOT=/usr/lib64/go/1.10
export PATH=$PATH:$GOROOT/bin

# Libraries with executables
export GOPATH=/home/tux/golib
export PATH=$PATH:$GOPATH/bin

Now source the .bashrc to take changes into effect.

source .bashrc

This might create a problem if you update to a new-er version of go. As a result you better lock that package.

So next time you update your system, go will not be updated.

# zypper addlock go
Specified lock has been successfully added.

To verify this, try to dup and see that go pkg stays locked:

# zypper dup
Warning: You are about to do a distribution upgrade with all enabled repositories. Make sure these repositories are compatible before you continue. See 'man zypper' for more information about this command.
Loading repository data...
Reading installed packages...
Computing distribution upgrade...

The following item is locked and will not be changed by any action:
 Installed:
  go

Nothing to do.

Set a compound GOPATH for 3rd party libs and personal ones

Let us add a library for auto-completion:

$ go get github.com/nsf/gocode

Now check at the GOPATH folder:

$ ls -l ~/golib/
total 0
drwxr-xr-x 1 tux users 12 Sep 11 16:23 bin
drwxr-xr-x 1 tux users 20 Sep 11 16:16 src

$ ls -l golib/bin/
total 11044
-rwxr-xr-x 1 tux users 11305958 Sep 11 16:23 gocode

$ ls -l golib/src/github.com/nsf/
total 0
drwxr-xr-x 1 tux users 798 Sep 11 16:23 gocode

Apart from the 3rd party libraries, you might want to create your own when you are developing an app. For this, you can create a second place that points to GOPATH. Open your .bashrc and add:

export GOPATH=$GOPATH:/home/tux/code

Then source it and check again:

$ source .bashrc 
$ env | grep GOPATH
GOPATH=/home/tux/golib:/home/tux/code

So if I remove now the gocode binary…

$ cd golib; rm -rf *
$ ls -lah
total 0
drwxr-xr-x 1 tux users    0 Sep 11 16:35 ./
drwxr-xr-x 1 tux users 2418 Sep 11 16:32 ../

Now download it again:

$ go get github.com/nsf/gocode

Now, let’s see the two locations of GOPATH:

# First
$ ls -l golib/
total 0
drwxr-xr-x 1 tux users 12 Sep 11 16:36 bin
drwxr-xr-x 1 tux users 20 Sep 11 16:36 src

# Second
$ ls -l code/
total 

So the 3rd party lib, stored only at the golib folder. The second one, does not have it. This is fine, because the second one will be used only by our own libs – not 3rd party ones.

Setup your Workspace

To have a workspace for Go, you need to have an expected structure. This workspace is the location where GOPATH is going to look for this specific tree structure.

$ cd code; ls

We have nothing so far. Let’s create the necessarry folders:

So, let’s create those:

$ mkdir -p code/{bin,pkg,src}

$ ls -l code/
total 0
drwxr-xr-x 1 tux users 0 Sep 11 16:53 bin
drwxr-xr-x 1 tux users 0 Sep 11 16:53 pkg
drwxr-xr-x 1 tux users 0 Sep 11 16:53 src

Setup Microsoft VS

To setup:

sudo rpm --import https://packages.microsoft.com/keys/microsoft.asc
sudo sh -c 'echo -e "[code]\nname=Visual Studio Code\nbaseurl=https://packages.microsoft.com/yumrepos/vscode\nenabled=1\ntype=rpm-md\ngpgcheck=1\ngpgkey=https://packages.microsoft.com/keys/microsoft.asc" > /etc/zypp/repos.d/vscode.repo'
sudo zypper ref
sudo zypper install code

Learn more about it: https://code.visualstudio.com/docs/getstarted/introvideos

More information related to setup: https://code.visualstudio.com/docs/setup/linux

At first I’ve got the following error:

The "go-outline" command is not available. Use "go get-v github.com/ramya-rao-a/go-outoline" to install
Click "install all".

What VS code did, was to install 10 tools at /home/tux/golib:/home/tux/code/bin. This is what whappens behind the scenes:

$ go get -u -v github.com/nsf/gocode
$ go get -u -v golang.org/x/tools/cmd/godoc
$ go get -u -v github.com/ramya-rao-a/go-outline
$ go get -u -v github.com/acroca/go-symbols
$ go get -u -v golang.org/x/tools/cmd/guru
$ go get -u -v golang.org/x/tools/cmd/gorename
$ go get -u -v github.com/rogpeppe/godef
$ go get -u -v github.com/uudashr/gopkgs/cmd/gopkgs
$ go get -u -v github.com/derekparker/delve/cmd/dlv
$ go get -u -v github.com/sqs/goreturns
$ go get -u -v github.com/golang/lint/golint

What can I import?

The official go packages (e.g. fmt) are located under src folder of your GOROOT:

$ cd $GOROOT/src; ls
archive  bytes     container  database  errors  fmt   html   internal  math  os      reflect  sort     sync     text     unsafe
bufio    cmd       context    debug     expvar  go    image  io        mime  path    regexp   strconv  syscall  time     vendor
builtin  compress  crypto     encoding  flag    hash  index  log       net   plugin  runtime  strings  testing  unicode

The 3rd party ones are located at:

$ ls -l ~/golib/src/
total 0
drwxr-xr-x 1 tux users 130 Sep 11 17:32 github.com
drwxr-xr-x 1 tux users   2 Sep 11 17:27 golang.org

My personal packages under development can be found at:

$ ls -l ~/code/src/
total 0
drwxr-xr-x 1 tux users 16 Sep 11 17:18 github.com

Hello world in Go and VS

Go to the workspace and create the following folder structure:

$ cd ~/code
$ mkdir -p github.com/drpaneas/firstapp

At the VS code, create the following Main.go:

package main

import "fmt"

func main() {
	fmt.Println("Hello Go!")
}

Go run (compile) in VS Code

Open terminal inside VSCode type: ctrl+backtick and compile it: go run src/github.com/drpaneas/firstapp/Main.go

Go build in VS Code

Go build is different from compilation. It expects to find specific stuff at specific directories. It takes takes the actual package path. It tries to find the package into the following:

        /usr/lib64/go/1.10/src/whater_you_put (from $GOROOT)
        /home/tux/golib/src/whatever_you_put (from $GOPATH)
        /home/tux/code/src/whatever_you_put

That means, the correct build command would be:

$ go build github.com/drpaneas/firstapp/

Notice that while building I am not using src in the path and I also don’t put Main.go at the end. You can run this command not matter in whatever directory you are into. This compiles a package into an executable, so you can pass it to others and run it like ./firstapp.

Go install in VS Code

The other tools, is go install. This is expected to be pointing to a package that has an entry point and it’s going to install that into your bin folder. So, once again you have to use the package address and not the folder path.

$ go install github.com/drpaneas/firstapp

This creates a binary into my bin folder:

$ ls -l ~/code/bin/
total 1968
-rwxr-xr-x 1 tux users 2011612 Sep 12 11:13 firstapp

Happy coding :) Panos

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