Lately I’ve been looking at some tools to make it easier to package containerized applications as lightweight virtual machines, to get the best of both worlds: the developer experience of a Dockerfile with the added protection of a hypervisor. Terex tlb 840 operators manual.

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As part of this process, I’ve been digging into Juniper’s containerized routing stack called cRPD, and trying to get that into a virtual form factor, so that I can effectively have a Linux router that happens to use the Junos routing stack. I’ve worked out an approach for doing this that could, in theory, extend to all kinds of other software, including other disaggregated routing stacks, such as Free-Range Routing.

Using Linuxkit Generated Iso In Docker For Mac Linuxkit is a new project presented by Docker during the DockerCon 2017. If we look at the description of the project on: A secure, portable and lean operating system built for containers I am feeling already exited. I wanna create a docker image from an ISO file. And I meet the same question like this iso to docker file. I did same operations with him, and I know it's wrong now. Now what i have is: an ISO file. My own ISO file, based on ubuntu but it's not ubuntu. A computer, running ubuntu on it.

NOTE - you need access to download the cRPD software from Juniper if you wish to follow the instructions in this post, and at the time of this writing, there is no free trial for cRPD. However, a lot of us at Juniper are actively working on getting cRPD into your hands more easily, so stay tuned!

This post is written for folks like me who are looking to define their own modular, and automated OS build. As a result, this requires some advance knowledge of concepts pertaining to Linux and Docker. You’ll need a few things set up in advance:

Docker
A linux-based host OS (I’m using Ubuntu)
A hypervisor (these instructions are for QEMU)
Git

What is cRPD? What is LinuxKit?

cRPD takes some of the best parts of Junos (RPD, MGD), disaggregates and packages them in a lightweight container image.

Because it’s so stripped down, it is not designed/able to function as a full-blown operating system, or manage network interfaces, as we’re accustomed to being able to do with a typical Junos device - it’s just a routing stack with a management process. This means that in order to turn it into a real routing element, we need to run it on an existing OS, like Linux.

Linuxkit is “a toolkit for building custom minimal, immutable Linux distributions”. It allows you to build your own lightweight Linux distribution using containers. It uses a YAML-based specification where you can specify the components that go into your distribution, like the kernel, init systems, and the userspace processes you wish to deploy inside - all running as containers, but with the added layer of true virtual isolation.

For our purposes, this is a match made in heaven - pairing the powerful, mature routing stack and management daemon/CLI of cRPD with the automated, modular, and lightweight Linux distribution built with LinuxKit, we get the best of both worlds.

Building Our Custom cRPD Image

Before we get to building our own Linux distribution, we need to make some modifications to the Docker image we get with cRPD. Out of the box, cRPD is designed to be minimal, meaning there are a number of options that are not enabled or configured by default. To get things like SSH and NETCONF working, we’ll actually build our own custom Docker image that takes the base image we’ll download from the Juniper website, and adds the relevant configurations to make it useful for our purposes.

I created the crpd-linuxkit repo with all of the files we’ll be using forthis build, so start off by cloning that repository:

Next, follow the cRPD installation instructions (and specifically the section titled Download the cRPD Software ) to download a .tgz file containing the crpd image. This is a tarball that Docker will recognize and allow you to import into your local Docker image cache. Continue only once you see your image in the output of docker image ls | grep crpd.

We’re going to build a custom Docker image that uses this cRPD image as its base, so we can add things like a proper SSH configuration. This Dockerfile uses crpd:latest as its base image reference, which doesn’t yet exist. The following command will look up the ID of the image we just imported, and re-tag it as crpd:latest so we can use it in our custom build:

If you take a peek at the files in the repository, you’ll notice with have a few things that will go into our customDocker image:

Dockerfile - copies our modified configuration files into the container image, and also sets up authentication options
launch.sh - a launch script which is executed when the container starts, to copy our configuration files into the correct location, and also start relevant services like the ssh service.
sshd_config - this is our modified SSH configuration, which includes a very important step of pointing the NETCONF subsystem to the appropriate path. This way, NETCONF requests will go straight to cRPD.

This walkthrough won’t go into much more detail on the files here, as well as the other files in the repository, so if you see something you don’t understand, cat its contents and read it for youself! I added comments where I could.

These are all tied together with the Dockerfile, so you should be able to run the below to build everything:

To be clear, our ultimate goal is to run cRPD inside a virtual machine that we create with LinuxKit, but why don’t we take a second to marvel at the fact that we now have a container image that runs the Junos routing stack! Let’s start an instance of it to play around with real quick for funsies:

We can interactively enter the Junos CLI with:

This should start looking a lot more familiar:

However, it’s not without its oddities - for instance, there is no show interfaces terse command!

Keep in mind, this is just the Junos routing stack and management daemon. It has no control over the network interfaces themselves, that’s still firmly in control of the underlying operating system, which in this case is my laptop since I’m running this natively in docker.

We can view things like the routing status for network interfaces, as that’s relevant to what cRPD is designed to do:

This is just the beginning. If you’re new to cRPD and just want to play with it instead of setting it up, one of the reasons I’ve been working on this is building a reproducible image for the NRE Labs curriculum. Follow along there or on Twitter, as I’m hoping to be able to publish something like this in the next few months.

Let’s exit and delete our cRPD container. From now on, we’ll be running cRPD inside a LinuxKit virtual machine.

Building the Router VM Image with LinuxKit

Okay, so we have our cRPD container image, but again, it’s not designed to function as a full-blown operating system. To actually pass traffic, we will use this container image as an “app” to be deployed in a brand-new Linux distribution that LinuxKit will create for us. The end-result is that we have a Linux-based VM that runs Junos software.

At the time of this writing, LinuxKit’s latest release is v0.7. Since I’m running on Linux, I’ll grab the precompiled binary for my platform, and pop it into /usr/local/bin:

LinuxKit comes with a linuxkit run command, but I already have existing scripts for running VMs the way I want, soI just want a virtual hard drive image to be generated that I can just execute myself.

Take a look at the contents of crpd.yml, as the entire manifest for defining this virtual machine, including picking a Linux kernel version,