Mozilla, Telemetry

Conda is pretty great

Jan 13th, 2020

Lately the data engineering team has been looking into productionizing (i.e. running in Airflow) a bunch of models that the data science team has been producing. This often involves languages and environments that are a bit outside of our comfort zone — for example, the next version of Mission Control relies on the R-stan library to produce a model of expected crash behaviour as Firefox is released.

To make things as simple and deterministic as possible, we’ve been building up Docker containers to run/execute this code along with their dependencies, which makes things nice and reproducible. My initial thought was to use just the language-native toolchains to build up my container for the above project, but quickly found a number of problems:

  1. For local testing, Docker on Mac is slow: when doing a large number of statistical calculations (as above), you can count on your testing iterations taking 3 to 4 (or more) times longer.
  2. On initial setup, the default R packaging strategy is to have the user of a package like R-stan recompile from source. This can take forever if you have a long list of dependencies with C-compiled extensions (pretty much a given if you’re working in the data space): rebuilding my initial docker environment for missioncontrol-v2 took almost an hour. This isn’t just a problem for local development: it also makes continuous integration using a service like Circle or Travis expensive and painful.

I had been vaguely aware of Conda for a few years, but didn’t really understand its value proposition until I started working on the above project: why bother with a heavyweight package manager when you already have Docker to virtualize things? The answer is that it solves both of the above problems: for local development, you can get something more-or-less identical to what you’re running inside Docker with no performance penalty whatsoever. And for building the docker container itself, Conda’s package repository contains pre-compiled versions of all the dependencies you’d want to use for something like this (even somewhat esoteric libraries like R-stan are available on conda-forge), which brought my build cycle times down to less than 5 minutes.

tl;dr: If you have a bunch of R / python code you want to run in a reproducible manner, consider Conda.