Building a static flanneld binary on Ubuntu

I just spent some time trying to build flannel and since there were some nuances, I decided to list the instructions here.

1. Install build dependencies:

    sudo apt-get install linux-libc-dev golang gcc
   

2. Make Go directories:

    mkdir -p ~/go/src
    cd ~/go/src
    export GOPATH=~/go
   

3. Clone flannel:

    git clone https://github.com/coreos/flannel.git
   

4. Install Go dependencies:

    cd flannel
    go install
   

5. Since I wanted a statically linked binary, I edited the Makefile and updated the build instruction like this:

    dist/flanneld: $(shell find . -type f  -name '*.go')
        go build -o dist/flanneld \
           -ldflags '-extldflags "-static" -X github.com/coreos/flannel/version.Version=$(TAG)'
   

6. Now build the binary:

    make dist/flanneld
   

7. flanneld binary should now be created in the dist directory. You can strip it to make it smaller:

    strip dist/flanneld
   

One other problem I encountered was that you need at least 2GB of RAM for this. I was trying this in a VM with 1GB and I ran out of memory.