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8bf0466 Mar 20, 2018
@ilackarms @ilevine @phenixrizen @leecalcote @jlaceda @ingve @d2r
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Getting Started

In this tutorial we'll be:

  1. installing UniK
  2. writing a simple HTTP Daemon in Go
  3. compiling to a unikernel and launching an instance on Virtualbox

Installing UniK


Ensure that each of the following are installed

Install, configure, and launch UniK

  1. Install UniK
$ git clone
$ cd unik
$ make binary

note: make will take quite a few minutes the first time it runs. the UniK Makefile is pulling all of the Docker images that bundle UniK's dependencies.

Then, place the unik executable in your $PATH to make running UniK commands easier:

$ mv _build/unik /usr/local/bin/
  1. Configure a Host-Only Network on Virtualbox
  • Open Virtualbox
  • Open Preferences > Network > Host-only Networks
  • Click the green add button on the right side of the UI
  • Record the name of the new Host-Only adapter (e.g. "vboxnet0"). You will need this in your UniK configuration
  • Ensure that the Virtualbox DHCP Server is Enabled for this Host-Only Network:
    • With the Host-Only Network selected, Click the edit button (screwdriver image)
    • In the Adapter tab, note the IPv4 address and netmask of the adapter.
    • In the DHCP Server tab, check the Enable Server box
    • Set Server Address an IP on the same subnet as the Adapter IP. For example, if the adapter IP is, make set the DHCP server IP as 192.168.100.X, where X is a number between 2-254.
    • Set Server Mask to the netmask you just noted
    • Set Upper / Lower Address Bound to a range of IPs on the same subnet. We recommend using the range X-254 where X is one higher than the IP you used for the DHCP server itself. E.g., if your DHCP server is, you can set the lower and upper bounds to and, respectively.
  1. Configure UniK daemon
  • UniK configuration files are stored in $HOME/.unik. Create this directory, if it is not present:
$mkdir $HOME/.unik
  • Using a text editor, create and save the following to $HOME/.unik/daemon-config.yaml:
    - name: my-vbox
      adapter_type: host_only
      adapter_name: NEW_HOST_ONLY_ADAPTER

replacing NEW_HOST_ONLY_ADAPTER with the name of the network adapter you created.

  1. Launch UniK and automatically deploy the Virtualbox Instance Listener
  • Open a new terminal window/tab. This terminal will be where we leave the UniK daemon running.
  • cd to the _build directory created by make
  • run unik daemon --debug (the --debug flag is optional, if you want to see more verbose output)
  • UniK will compile and deploy its own 30 MB unikernel. This unikernel is the Unik Instance Listener. The Instance Listener uses udp broadcast to detect (the IP address) and bootstrap instances running on Virtualbox.
  • After this is finished, UniK is running and ready to accept commands.
  • Open a new terminal window and type unik target --host localhost to set the CLI target to the your local machine.

Write a Go HTTP server

  1. Open a new terminal window, but leave the window with the daemon running. This window will be used for running UniK CLI commands.

  2. Create a file httpd.go using a text editor. Copy and paste the following code in that file:

package main

import (

func main() {
    http.HandleFunc("/", handler)
    http.ListenAndServe(":8080", nil)

func handler(w http.ResponseWriter, r *http.Request) {
    fmt.Fprintf(w, "my first unikernel!")
  1. Try running this code with go run httpd.go. Visit http://localhost:8080/ to see that the server is running.
  2. We need to create a dummy Godeps file. This is necessary to tell the Go compiler how Go projects and their dependencies are structured. Fortunately, with this example, our project has no dependencies, and we can just fill out a simple Godeps file without installing godep. Note: for Go projects with imported dependencies, and nested packages, you will need to install Godeps and run GO15VENDOREXPERIMENT=1 godep save ./... in your project. See Compiling Go Apps with UniK for more information.
  • To create the dummy Godeps file, create a folder named Godeps in the same directory as httpd.go. Inside, create a file named Godeps.json and paste the following inside:
	"ImportPath": "my_httpd",
	"GoVersion": "go1.6",
	"GodepVersion": "v63",
	"Packages": [
	"Deps": [
			"ImportPath": "",
			"Rev": "f8cc0dd435de36377eac060c93481cc9f3ae9688"
  • For the purposes of this example, that matters here is my_httpd. It instructs the go compiler that the project should be installed from $GOPATH/src/my_httpd.
  1. Great! Now we're ready to compile this code to a unikernel.

Compile an image and run on Virtualbox

  1. run the following command from the directory where your httpd.go is located:
unik build --name myImage --path ./ --base rump --language go --provider virtualbox

This command will instruct UniK to compile the sources found in the working directory (./) using the rump-go-virtualbox compiler. 2. You can watch the output of the build command in the terminal window running the daemon. 3. When build finishes, the resulting disk image will reside at $HOME/.unik/virtualbox/images/myImage/boot.vmdk 4. Run an instance of this image with

unik run --instanceName myInstance --imageName myImage
  1. When the instance finishes launching, let's check its IP and see that it is running our application.
  2. Run unik instances. The instance IP Address should be listed.
  3. Direct your browser to http://instance-ip:8080 and see that your instance is running!
  4. To clean up your image and the instance you created
unik rmi --force --image myImage