The docker R package provides access to the docker API to programmatically control a docker engine from R. The docker engine could be running either locally or remotely. The docker package uses the reticulate R package to invoke the Python SDK for docker. Using the Python SDK allows the docker package to have a very minimal foot-print and yet allow complete docker API access. The package has been tested against docker engine running on Linux and Microsoft Windows and should also work under MacOS.
Controlling a docker engine from withing R can be useful for …
Release version
install.packages('docker')OR development version
if(!require(devtools)) {
install.packages("devtools")
}
devtools::install_github('user001vk/docker')Before you can use this package you need to have Python 2.x (>=2.7) or Python 3.x (>=3.4) with the docker Python module which provides Python SDK for docker. A simple way to do this is using a virtual environment. virtualenvwrapper makes setting up Python modules quite painless.
Once you have installed Python and setup virtualenvwrapper you need to create a new virtual environment and install the docker Python module in it.
mkvirtualenv --python=/usr/bin/python3 docker
workon docker
pip install docker
# Test the SDK againsts a locally running docker
# You should have a locally running docker engine for this.
python -c 'import docker; print(docker.from_env().version())'You should see something like below, provided you had a locally running docker engine.
{'Os': 'linux', 'Arch': 'amd64', 'KernelVersion': '4.10.0-24-generic', 'GitCommit': '02c1d87',
'Version': '17.06.0-ce', 'BuildTime': '2017-06-23T21:19:04.990631145+00:00',
'MinAPIVersion': '1.12', 'GoVersion': 'go1.8.3', 'ApiVersion': '1.30'}Here we provide a simple getting started example. We start the alpine docker image which is a small Linux image.We run a command to output “Hello World!” from within the started docker container and access it on the R side.
# This is a hint to the reticulate package to find a
# python environment with the "docker" python module available.
reticulate::use_virtualenv("docker")
library(docker)
client <- docker$from_env()
s <- client$containers$run("alpine", 'echo -n "Hello World!"', remove=TRUE)
print(s$decode("UTF-8"))[1] Hello World!
Below is more of a real-world example where we start a redis container and interact with it using the rredis package, and subsequently tear it down.
reticulate::py_discover_config("docker")
library(docker)
library(rredis)
docker_client <- docker$from_env()
docker_client$ping()
redis_instance <- docker_client$containers$run(
'redis', name='redis', detach=TRUE, ports=list('6379/tcp'='6379'))
redis_instance$status
redisConnect(host='127.0.0.1', port=6379, nodelay=TRUE)
redisSet('docker-test', rnorm(20))
redisGet('docker-test')
redis_instance$stop()
redis_instance$remove()And here’s how it looks when run.
> reticulate::py_discover_config("docker")
python: /home/user001/.virtualenvs/docker/bin/python
libpython: /usr/lib/python3.5/config-3.5m-x86_64-linux-gnu/libpython3.5.so
pythonhome: /usr:/usr
virtualenv: /home/user001/.virtualenvs/docker/bin/activate_this.py
version: 3.5.2 (default, Nov 17 2016, 17:05:23) [GCC 5.4.0 20160609]
numpy: /home/user001/.virtualenvs/docker/lib/python3.5/site-packages/numpy
numpy_version: 1.13.1
docker: /home/user001/.virtualenvs/docker/lib/python3.5/site-packages/docker
python versions found:
/home/user001/.virtualenvs/docker/bin/python
/usr/bin/python
/usr/bin/python3
> library(docker)
> library(rredis)
> docker_client <- docker$from_env()
> docker_client$ping()
[1] TRUE
> redis_instance <- docker_client$containers$run(
'redis', name='redis', detach=TRUE, ports=list('6379/tcp'='6379'))
> redis_instance$status
[1] "created"
> Sys.sleep(5) # Wait for the container to start the service.
> redisConnect(host='127.0.0.1', port=6379, nodelay=TRUE)
> redisSet('docker-test', rnorm(20))
[1] "OK"
> redisGet('docker-test')
[1] 1.01545119 0.08353996 0.71668645 -0.34256345 -0.09871241 0.24834106
[7] 0.28802550 0.02321578 -1.62448884 -1.31099073 0.54530365 1.29799034
[13] 0.80973704 0.30018833 -0.72609402 -0.47678730 -0.79877246 1.08857741
[19] -1.92010832 1.61439356
> redis_instance$stop()
> redis_instance$remove()The reticulate::py_discover_config("docker") call is used to ensure that reticulate was able to find a Python environment with the docker Python module installed.
You can call every API supported by the Python SDK using reticulate. Please consult the documents for the SDK and the reticulate R package in the links given above.