Choose languages for your environment¶
You can define many different languages in your configuration files. This page describes how to use some of the more common ones.
Python¶
Your environment will have Python (and specified dependencies) installed when you use one of the following configuration files:
requirements.txt
environment.yml
Note that by default, the environment will have Python 3 installed.
Specifying a version of Python¶
To specify a specific version of Python, you have two options:
Use
runtime.txt
. Include a line that specifies the Python version in this file. This line takes the following form:python=X.X
For example,:
python=2.7
Use
environment.yml
. The Anaconda distribution also lets you define the Python environment withinenvironment.yml
. To do so, addpython=X.X
to your dependencies section, like so:name: python 2.7 dependencies: - python=2.7 - numpy
The R Language¶
To ensure that R is installed, you must specify a version of R in a runtime.txt
file. This takes the following form:
r-YYYY-MM-DD
The date corresponds to the state of the MRAN repository at this day. Make sure
that you choose a day with the desired version of your packages. For example,
to use the MRAN repository on January 1st, 2018, add this line to runtime.txt
:
r-2018-01-01
Note that to install specific packages with the R environment, you should
use the install.R
configuration file.
Julia¶
To build an environment with Julia, include a configuration file called
REQUIRE
. Each line of this file should include a package that you wish
to have installed with Julia. For example, the following contents of REQURE
would install the PyPlot
package with your Julia environment.:
PyPlot
Languages not covered here¶
If a language is not “officially” supported by a build pack, it can often be
installed with a postBuild
script. This will run arbitrary bash
commands,
and can be used to download / install a language.
Using multiple languages at once¶
It may also be possible to combine multiple languages in a single environment. The details on how to accomplish this with all possible combinations are outside the scope of this guide. However we recommend that you take a look at the Multi-Language Demo repository for some inspiration.