Docker Cookbook

9.1 Getting Detailed Information About a Container with docker inspect | 275

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If you prefer to use another Docker client such as 
docker-py
(see 
Recipe 4.10
), you
can also access the detailed information about containers and images by using stan‐
dard Python dictionary notation:
$ python
...
>>> from docker import Client
>>> c=Client(base_url="unix://var/run/docker.sock")
>>> c.inspect_container('kickass_babbage')['State']['Running']
True
>>> c.inspect_container('kickass_babbage')['NetworkSettings']['IPAddress']
u'172.17.0.3'
9.2 Obtaining Usage Statistics of a Running Container
Problem
You have a running container on one of your Docker hosts and would like to monitor
its resource usage (e.g., memory, CPU, network).
Solution
Use the 
docker stats
command. This new API endpoint was introduced on Febru‐
ary 10, 2015 and is accessible in Docker 1.5. The usage syntax is simple: you pass the
container name (or container ID) to it and receive a stream of statistics. Here you
start a Flask application container and run 
stats
on it:
$ docker run -d -p 5000:5000 runseb/flask
$ docker stats dreamy_mccarthy
CONTAINER CPU % MEM USAGE/LIMIT MEM % NET I/O
dreamy_mccarthy 0.03% 24.01 MiB/1.955 GiB 1.20% 648 B/648 B
Since you are receiving a stream, you will not press the Ctrl-C keys to kill the stream.
Discussion
Getting quick stats from the command line is useful for interactive debugging. How‐
ever, you will most likely want to collect all these statistics and aggregate them with a
log collector solution like 
Logstash
for futher visualization and analysis.
To prepare for such a monitoring framework, you can try to use the 
stats
API via
curl
, by issuing TCP requests to the Docker daemon. First you will need to configure
your local Docker daemon to listen on port 2375 over TCP. On Ubuntu systems,
edit 
/etc/default/docker
to include the following:
DOCKER_OPTS="-H tcp://127.0.0.1:2375"