For almost every workflow I run, I use snakemake. Snakemake is a workflow manager written by bioinformaticians for bioinformaticians. It has a lot of wonderful features (file tracking, cluster integration, reports, and integration with multiple languages), including support for conda environments. I use conda to specify all of the software I need for a rule, and conda takes care of building the environments for me. This makes my workflows more repeatable, and allows me to quickly switch between different systems (e.g. my campus compute cluster and NSF XSEDE’s Jetstream).

Here is an example of a simple Snakefile, as well as the accompanying conda environment.


rule tally_iris:
    output: "iris_tally.csv"
    conda: 'dplyr.yml'
    shell: '''
    Rscript -e "library(dplyr); library(readr); iris %>% group_by(Species) %>% tally() %>% write_csv('iris_tally.csv')"


   - conda-forge
   - bioconda
   - defaults
   - r-dplyr=0.8.3
   - r-readr=1.3.1

To execute this snakefile, I would run:

snakemake --use-conda

However, sometimes I run into a situation where the package or library I use in my workflow does not have a conda package associated with it. In this case, I used to install all of the dependencies (assuming they had conda packages) in a conda environment, and then install the package I was interested in a rule in snakemake. I would usually also make this installation script write out a text file so that I knew the rule had finished running.

No more! Luiz Irber recently showed me how to make a conda-forge recipe from a CRAN pacakge. I did this successfully with the optimr package, and couldn’t believe how streamlined the process is. I walk through the process below.

1. Build the recipe using conda_r_skeleton_helper

conda_r_skeleton_helper is a github repository that builds a properly formatted conda-forge recipe from an R CRAN package. With a user-created list of packages, it builds a recipe for each package in the list. It uses the documentation on CRAN to auto-populate recipe fields like dependencies and description, as well as others.

1a. Installing conda-build

conda_r_skeleton_helper requires conda-build, so I first installed it into its own conda environment.

conda create -n conda_build conda-build
conda activate conda_build

1b. Cloning conda_r_skeleton_helper

Next, I cloned the repository to my laptop.

git clone https://github.com/bgruening/conda_r_skeleton_helper.git

1c. Building the recipe

With conda_r_skeleton_helper on my laptop, I then followed the instructions on the README file and added the R CRAN packages I wanted to build a recipe for to the packages.txt file. I removed the packages that were already there.

In this case, I was building a recipe for optimr. My packages.txt file ended up looking like this:


With my packages of interest in the packages.txt file, I then ran the run script. I chose to run it in R, but it can be run in bash and python as well.

Rscript run.R

When this was finished running, I had a newly created folder called r-optimr. Inside it was three files, bld.bat, build.sh, meta.yaml.

I had successfully built a conda-forge recipe! As a last step, I added my github username to the maintainers section so that I can approve version bumps on the recipe. conda-forge has set up a bot to orchestrate these changes, but a maintainer still needs to click the merge button to propagate those changes. Because I made the recipe, I added myself so I can click the button.

2. Submit the recipe to conda-forge

With the recipe built, I now needed to submit it to conda-forge. I decided to orchestrate this process within GitHub instead of using git for no particular reason. To start the process, I first forked the conda-forge staged-recipes repository into my own github. Once there, I created a branch that I named r-optimr. I switched to that branch and changed into the recipes directory. I clicked upload, and uploaded my local r-optimr folder. Lastly, I started a pull request to merge my changes on my r-optimr branch to the conda-forge master branch. I followed the checklist that is in the PR template and clicked submit! My recipe passed all checks, so it was merged within a few hours of my posting it.

You can see my merged PR here, and the r-optimr conda-forge package here.

Thank you to Luiz Irber for teaching me this process, and for feedback on this post!