Docker Cookbook

296 | Chapter 9: Monitoring Containers

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of these systems and the changes going on in the images, you might have to adjust the
docker run
commands shown previously to get a working system.
9.12 Gaining Visibility into Your Containers’ Layout with
Weave Scope
Problem
Building a distributed application based on a 
microservices architecture
leads to hun‐
dreds of (and potentially more) containers running in your data center. Visibility into
that application and all the containers that it’s made of is crucial and a key part of
your overall infrastructure.
Solution
Weave Scope from 
Weaveworks
 provides a simple yet powerful way of probing your
infrastructure and dynamically creating a map of all your containers. It gives you
multiple views—per container, per image, per host, and per application—allowing
you to group containers and drill down on their characteristics.
It is open source and available on 
GitHub
.
To facilitate testing, I prepared a Vagrant box, similar to many other recipes in this
book. Clone the repository with Git and launch the Vagrant box:
$ git clone https://github.com/how2dock/docbook.git
$ cd how2dock/ch09/weavescope
$ vagrant up
The Vagrant box installs the latest Docker version (i.e., 1.6.2 as of this writing) and
installs Docker Compose (see 
Recipe 7.1
). In the 
/vagrant
folder, you will find a 
com‐
pose
file that gives you a synthetic three-tiered application made of two load-
balancers, two application containers, and three database containers. This is a toy
application meant to illustrate Weave Scope. Once the VM has booted, 
ssh
into it, go
to the 
/vagrant
folder, and launch Compose and the Weave Scope script (i.e., 
scope
)
like so:
$ vagrant ssh
$ cd /vagrant
$ docker-compose up -d
$ ./scope launch
You will end up with eight containers running: seven for the tiered toy application
and one for Weave Scope. The toy application is accessible at 
http://
192.168.33.10:8001
 or 
http://192.168.33.10:8002
. Of course, the most interesting part
is the Weave Scope dashboard. Open your browser at 
http://192.168.33.10:4040
 and
you will see something similar to 
Figure 9-5
.