Author: Tracy M

Last Thursday, at the London PaaS User Group (LOPUG) meetup and heard the best type of technical talk: the kind that immediately inspires you to try out the technology you’ve just learnt about. Stev Witzel showed a demo of a mash-up of Cloud Foundry tools (BOSH) with Weave Scope, an open source tool for visualizing, managing and monitoring containers. In the demo, Weave Scope provided a very slick visualization of the individual components and apps running on the Cloud Foundry platform and instantly gave me a deeper comprehension of the complex system.

I was keen to try out Weave Scope so asked myself “Can I quickly and easily use WeaveScope to visualise the Docker containers in Eclipse Che?”

The answer was a resounding yes! First of all the Weave Works documentation is terrific (note to self: guides with Katacoda are my new gold standard for documentation). I found this  getting started article which I could adapt for my use-case. Given I already had Che installed & running on my Windows 10 laptop, installing & running Weave Scope was straightforward.

docker-machine ssh default
sudo wget -O /usr/local/bin/scope \
   https://github.com/weaveworks/scope/releases/download/latest_release/scope
sudo chmod a+x /usr/local/bin/scope
sudo scope launch

 

To my pure joy and delight, it JUST WORKED!!

In one browser I had Eclipse Che up and running, I created a few different workspaces

In a separate browser I had Weave Scope running.  As I created workspaces in Che, I would see them automagically appear in the scope tool.

Incidentally, when I first started working with Che it took me a while to understand each Eclipse Che workspace is a separate Docker container, but with this visualisation the understanding is immediate. Weave Scope is a great tool for those new to the technologies to quickly grasp some key concepts.

I love, love, love visual representations of systems; it’s a more natural way to quickly gain insights into a system, not to mention commit things to memory in the imagery part of my brain. Weave Scope let’s you monitor CPU usage:

You can also monitor memory usage as workspaces loaded up:

Plus it has a nice way to inspect containers, even attach or exec a shell on them:

In this case the system is relatively small and everything is running locally. However, I can easily see how it would be really useful to use Weave Scope when you want to troubleshoot Eclipse Che running in a production environment in the cloud by comparing it with a system running on a local development machine.

Weave Scope is open source, licensed under Apache-2.0.

Key Takeaways

Weave Scope is a great, slick, open source tool for visualizing & monitoring containers and is really super simple to get started with and use.

Eclipse Che, based on the ubiquitous Docker containers, allows leveraging of a whole world of awesome container-related technology, including the Weave Scope visualisation tool.

In Eclipse Che, stacks are runtime configurations for workspaces.  Eclipse Che 5.0 provides the ability to quickly create a new stack based on an existing Docker image. There are a few requirements, with the main one being that the image must include a bash shell (fortunately most already do). Additionally, Docker images used with Che must have a non-terminating CMD command so that the container doesn’t shut down immediately after loading. However, we can do this in Che without having to modify the Docker image.

This article outlines how you can create a new stack based on the docker/whalesay image, the Docker image many folks would have come across when going through the Docker tutorial.

Step 1: Create a new Runtime Stack

1. Install and launch Eclipse Che. (This article is based on 5.3.1)
2. In the left-hand menu, click on ‘Stacks’ then ‘Add Stack’
3. In the new stack page, fill in the ‘Name’ field e.g. Eclipse Che Whalesay 
4. For good measure, in the Tags section, delete the Java 1.8 tag and you can add in any preferred tags (press Enter after each tag to turn it blue).

From now your stack is available on the dashboard or stack list, but it doesn’t yet do anything impressive.

Step 2: Reference the Docker Image

1. To reference the Docker image, in the stack editor, first scroll down to the ‘Raw Configuration’ section and click ‘Show’. Find where it says ‘image’ and replace the existing entry with the docker/whalesay one. Click ‘Save’.
2. As the whalesay image normally shuts down after running, we need to make it so it keeps running. We can do this using Docker Compose syntax that is now supported in the stack editor. To do this we add the following command to the content.

   command: [tail, -f, /dev/null]

   
   Whitespace matters so check the recipe preview in the ‘Runtimes’ section to ensure it looks like correctly formatted Docker Compose syntax.  Although this is a bit hacky, it is great because it means we can reuse the docker image completely unchanged. 

Step 3: Add a Custom Command

Next we will create a command to allow us easily run the whalesay image within the browser IDE.

1. In the Commands section, click Add. Fill in the name and command fields. In this case we’ll simply make the command just say ‘boo’.
   • Name: cowsay
   • Command: cowsay boo

Step 4: Test the Stack

1. That’s it, now we can test it straightaway by clicking on the ‘Test’ button. A dialog will pop-up, click ‘Test Workspace’, no need to import any projects.
2. This should pull the whalesay image and launch up a workspace with it configured.
3. Click on the play icon next to the cowsay command and you should whalesay in the terminal saying boo!

Bonus Step: Use Macros

1. We can also use macros in commands, try editing the command to have the whale say the name of the selected file like this:
   • Name: cowsay
   • Command: cowsay ${explorer.current.file.name}

   A full list of macros can be found here: https://www.eclipse.org/che/docs/ide/commands/#macros

2. Then test the workspace again, this time including one or two example projects. Click on a file, then run the command. This time whalesay should say the name of any selected files. 

And that’s it, an unchanged Docker image easily integrated into a new runtime stack!

Over the last year or so there has been a reasonable amount of evolution of the best way to get Eclipse Che running on Windows. The latest set of instructions are reasonably straightforward though not a complete no-brainer. This post records my snapshot of the step-by-step install process for Eclipse Che 5.2.2 including Docker install, dead ends & false starts.

1. The aim is to set up a local install of pre-built Che on Windows 10 Home Edition. Starting point, scan documentation at https://www.eclipse.org/che/docs/setup/getting-started/
2. Install prerequisite Docker. Download & install ‘Docker for Windows’. Helpful error message redirects me to use Docker Toolbox. 
3. Download Docker Toolbox for Windows. Run installer. Requires 77.6M, and also wants to install Git.  The reason it needs to install a full source control system is merely down to the fact that the Git install comes with a nicely packaged bash & terminal implementation. Nevertheless I already have git installed so no need to here.
4. Install completes, use shortcut ‘Docker Quickstart Terminal’ doesn’t work as it can’t find bash.exe (The shortcut expects Git to be in a certain default location).
5. Update shortcut to point at my installed version of Git’s bash.exe (after another false start trying to use Git’s bash directly, fiddling with running things as Admin, etc).
6. Success & I can run docker run hello-world
7. Now to the actual Eclipse Che part, try default command line

   docker run -it eclipse/che start

   Not so hasty there, a helpful error message tells me I’m missing a mandatory parameter.

8. Add in missing parameter, try again

   docker run -it --rm -v /var/run/docker.sock:/var/run/docker.sock \
       eclipse/che start

   Get another useful message about needing to mount a directory to save data:

9.  Create a temporary directory and rerun the command specifying a data directory. Get a warning about data folder needing to be in %userprofile% (now you tell me). 
10. Make a different directory and run command again

    docker run -it --rm -v /var/run/docker.sock:/var/run/docker.sock \
        -v /c/Users/tracy/tmp:/data eclipse/che start

    Success!

11. Launch up browser, point at http://192.168.99.100:8080, Eclipse Che is up and running.