We recently upgraded many of our services to Rails 5.2 which installs
bootsnap to make start-up faster. However,
bootsnap depends on caching data to the local file system and our production containers run with read-only file systems for security. So I decided to remove
bootsnap in production:
# Gemfile #... group :development, :test do gem 'bootsnap', '~>; 1.3' end #... # config/boot.rb #... require "bundler/setup" # Set up gems listed in the Gemfile. begin require "bootsnap/setup" # Speed up boot time by caching expensive operations. rescue LoadError # bootsnap is an optional dependency, so if we don't have it it's fine # Do not load in production because file system (where cache would be written) is read-only nil end
The code above makes two changes:
- It only loads
:testenvironments. When production images are created we exclude those environments from the bundle.
- It fails gracefully if
These changes were mostly based on a change that GitLab did to accomplish the same thing (although for different reasons). There was discussion on the
bootsnap issues about disabling it in production but the solution was much more convoluted. This is a nice simple change.
I’m not yet convinced that we should even be running
bootsnap. It’s stated purpose is to “Boot large Ruby/Rails apps faster”, but we try to keep services small. In one service I found the following differences:
real 0m2.094s user 0m1.743s sys 0m0.353s
real 0m5.124s user 0m3.590s sys 0m1.527s
So while it does save 3 seconds I am not sure that makes that much of a difference to our daily life for development or testing.