I resolved my problem
I fist had
raph@raph-Lenovo-Yoga-2-13:~/go/src/github.com/mattermost/platform$ make
Starting docker containers
/bin/sh: 1: gofmt: not found
Building mattermost server
rm -Rf dist
/home/raph/work/bin/godep go clean -i ./...
make: /home/raph/work/bin/godep: Command not found
make: *** [build-server] Error 127
So I installed godep with
/home/raph/go/bin/go get github.com/tools/godep
which is equivalent to
$HOME/go/bin/go get github.com/tools/godep
and now mattermost compil
Thank you !