Building conda packages with conda skeleton

Overview
Who is this for?
Before you start
Building a simple package with conda skeleton pypi
Optional---Building for a different Python version
Optional---Converting conda package for other platforms
Optional---Uploading packages to Anaconda.org
Troubleshooting a sample issue
More information

Overview 

This tutorial describes how to quickly build a conda package for a Python module that is already available on PyPI.

In the first procedure, building a simple package, you build a package that can be installed in any conda environment of the same Python version as your root environment. The remaining optional procedures describe how to build packages for other Python versions and other architectures, as well as how to upload packages to your Anaconda.org account.

Note

You may consider using Docker to run the tutorial.

Who is this for?

This tutorial is for Windows, macOS, and Linux users who wish to build a conda package from a PyPI package. No prior knowledge of conda-build or conda recipes is required.

Before you start 

Before you start, check the Prerequisites.

Building a simple package with conda skeleton pypi 

The conda skeleton command picks up the PyPI package metadata and prepares the conda-build recipe. The final step is to build the package itself and install it into your conda environment.

It is easy to build a skeleton recipe for any Python package that is hosted on PyPI, the official third-party software repository for the Python programming language.

In this section you are going to use conda skeleton to generate a conda recipe, which informs conda-build about where the source files are located and how to build and install the package.

You'll be working with a package named Click that is hosted on PyPI. Click is a tool for exposing Python functions to create command line interfaces.

First, in your user home directory, run the conda skeleton command:

conda skeleton pypi click

The two arguments to conda skeleton are the hosting location, in this case pypi, and the name of the package.

This creates a directory named click and creates one skeleton file in that directory: meta.yaml. Many other files can be added there as necessary, such as build.sh and bld.bat, test scripts, or anything else you need to build your software. For simple, pure-Python recipes, these extra files are unnecessary and the build/script section in the meta.yaml is sufficient. Use the ls command on macOS or Linux or the dir command on Windows to verify that this file has been created. The meta.yaml file has been populated with information from the PyPI metadata and in many cases will not need to be edited.

Files in the folder with meta.yaml are collectively referred to as the "conda-build recipe":

meta.yaml---Contains all the metadata in the recipe. Only the package name and package version sections are required---everything else is optional.
bld.bat---Windows commands to build the package.
build.sh---macOS and Linux commands to build the package.

Now that you have the conda-build recipe ready, you can use conda-build to create the package:

conda-build click

When conda-build is finished, it displays the exact path and filename of the conda package. See Troubleshooting a sample issue if the conda-build command fails.

Windows example file path:

C:\Users\jsmith\miniconda\conda-bld\win-64\click-7.0-py37_0.tar.bz2

macOS example file path:

/Users/jsmith/miniconda/conda-bld/osx-64/click-7.0-py37_0.tar.bz2

Linux example file path:

/home/jsmith/miniconda/conda-bld/linux-64/click-7.0-py37_0.tar.bz2

Note

Your path and filename will vary depending on your installation and operating system. Save the path and filename information for the next step.

Now you can install your newly built package in your conda environment by using the use-local flag:

conda install --use-local click

Notice that Click is coming from the local conda-build channel.

(click) 0561:~ jsmith$ conda list
# packages in environment at /Users/Jsmith/miniconda/envs/click:
# Name                    Version                   Build  Channel
ca-certificates           2019.1.23                     0
certifi                   2019.3.9                 py37_0
click                     7.0                      py37_0    local

Now verify that Click installed successfully:

conda list

Scroll through the list until you find Click.

At this point you now have a conda package for Click that can be installed in any conda environment of the same Python version as your root environment. The remaining optional sections show you how to make packages for other Python versions and other architectures and how to upload them to your Anaconda.org account.

Optional---Building for a different Python version 

By default, conda-build creates packages for the version of Python installed in the root environment. To build packages for other versions of Python, you use the --python flag followed by a version. For example, to explicitly build a version of the Click package for Python 2.7, use:

conda-build --python 2.7 click

Notice that the file printed at the end of the conda-build output has changed to reflect the requested version of Python. conda install will look in the package directory for the file that matches your current Python version.

Windows example file path:

C:\Users\jsmith\Miniconda\conda-bld\win-64\click-7.0-py27_0.tar.bz2

macOS example file path:

/Users/jsmith/miniconda/conda-bld/osx-64/click-7.0-py27_0.tar.bz2

Linux example file path:

/home/jsmith/miniconda/conda-bld/linux-64/click-7.0-py27_0.tar.bz2

Note

Your path and filename will vary depending on your installation and operating system. Save the path and filename information for the next task.

Optional---Converting conda package for other platforms 

Now that you have built a package for your current platform with conda-build, you can convert it for use on other platforms with the conda convert command. This works only for pure Python packages where there is no compiled code. Conda convert does nothing to change compiled code, it only adapts file paths to take advantage of the fact that Python scripts are mostly platform independent. Conda convert accepts a platform specifier from this and a platform specifier from this list:

osx-64.
linux-32.
linux-64.
win-32.
win-64.
all.

In the output directory, 1 folder will be created for each of the 1 or more platforms you chose and each folder will contain a .tar.bz2 package file for that platform.

Windows:

conda convert -f --platform all C:\Users\jsmith\miniconda\conda-bld\win-64\click-7.0-py37_0.tar.bz2
-o outputdir\

macOS and Linux:

conda convert --platform all /home/jsmith/miniconda/conda-bld/linux-64/click-7.0-py37_0.tar.bz2
-o outputdir/

Note

Change your path and filename to the exact path and filename you saved in Optional---Building for a different Python version.

To use these packages, you need to transfer them to other computers and place them in the correct conda-bld/$ARCH directory for the platform, where $ARCH can be osx-64, linux-32, linux-64, win-32, or win-64.

A simpler way is to upload all of the bz2 files to Anaconda.org as described in the next task.

If you find yourself needing to use conda convert, you might instead prefer to change your recipe to make your package a "noarch" package. Noarch packages run anywhere and do not require conda convert. Some of the ecosystem tools don't yet support noarch packages but, for the most part, noarch packages are a better way to go.

Optional---Uploading packages to Anaconda.org 

Anaconda.org is a repository for public or private packages. Uploading to Anaconda.org allows you to easily install your package in any environment with just the conda install command, rather than manually copying or moving the tarball file from one location to another. You can choose to make your files public or private. For more information about Anaconda.org, see the Anaconda.org documentation.

Create a free Anaconda.org account and record your new Anaconda.org username and password.
Run conda install anaconda-client and enter your Anaconda.org username and password.
Log into your Anaconda.org account from your terminal with the command anaconda login.

Now you can upload the new local packages to Anaconda.org.

Windows:

anaconda upload C:\Users\jsmith\miniconda\conda-bld\win-64\click-7.0-py37_0.tar.bz2

macOS and Linux:

anaconda upload /home/jsmith/miniconda/conda-bld/linux-64/click-7.0-py37_0.tar.bz2

Note

Change your path and filename to the exact path and filename you saved in Optional---Building for a different Python version. Your path and filename will vary depending on your installation and operating system.

If you created packages for multiple versions of Python or used conda convert to make packages for each supported architecture, you must use the anaconda upload command to upload each one. It is considered best practice to create packages for Python versions 2.7, 3.4, and 3.5 along with all of the architectures.

Tip

If you want to always automatically upload a successful build to Anaconda.org, run: conda config --set anaconda_upload yes

You can log out of your Anaconda.org account with the command:

anaconda logout

Troubleshooting a sample issue 

Conda-build may produce the error message "Build Package missing."

To explore this error:

Create a conda skeleton package for skyfield. The conda skeleton command is:
```
conda skeleton pypi skyfield
```
This command creates the skyfield conda-build recipe.

Run conda-build skyfield and observe that it fails with the following output:

Removing old build environment
Removing old work directory
BUILD START: skyfield-0.8-py35_0
Using Anaconda Cloud api site https://api.anaconda.org
Fetching package metadata: ......
Solving package specifications: .
Error:  Package missing in current osx-64 channels:
  - sgp4 >=1.4

In this example, the conda recipe requires sgp4 for the skyfield package. The skyfield recipe was created by conda skeleton. This error means that conda could not find the sgp4 package and install it.

Since many PyPI packages depend on other PyPI packages to build or run, the solution is sometimes as simple as using conda skeleton to create a conda recipe for the missing package and then building it:

conda skeleton sgp4
conda build sgp4

You may also try using the --recursive flag with conda skeleton, but this makes conda recipes for all required packages, even those that are already available to conda install.

More information 

For more options, see the full conda skeleton command documentation.