serverless-ruby-package
Teaches the serverless framework how to package ruby services and their gem dependencies.
By default, serverless
will package all files in your ruby service project.
That includes test files, node_modules
, readmes, etc. You don't need any of
those files to execute your function - they just increase the size of the package
and slow down updates. In most cases, it also won't include any rubygems that
your function depends on, so the function will not work once it is deployed.
This plugin solves those problems in a couple ways. First, it excludes all
files by default, forcing you to whitelist the files needed by your function
(using the package/includes
key in serverless.yml
). Second, it automatically
packages the gems from your default bundler group -- skipping gems from
any custom groups, like development
or test
. Sometimes gems themselves will
install their own test files - those will also be excluded from the package.
It also handles cross-compiling any gems with native extensions. For example, if you are developing your service on macOS, any gems with native extensions will be compiled locally for macOS. But to deploy to a provider like AWS Lambda, the gems need to be compiled for linux. The plugin will automatically detect this situation and build the extensions for linux using a local docker container. You only need to have docker installed with the daemon running.
Usage
The plugin will make it easier to work with rubygems in your serverless project, but it requires your project to follow some conventions:
- Add the plugin
npm install --save-dev serverless-ruby-package
Add the plugin to your serverless.yml
file:
plugins:
- serverless-ruby-package
- You must use bundler in standalone mode, with the path
vendor/bundle
:
bundle install --standalone --path vendor/bundle
- Add the following lines to the top of your service handler file:
load "vendor/bundle/bundler/setup.rb"
- The plugin will force the
serverless
packaging step to exclude all files by default. You need to explicitly add your service handler file toserverless.yml
:
package:
include:
- handler.rb
(optional) If your service is implemented across multiple ruby files, it is
recommended that you keep your handler file in the root, and the rest of the
files in a lib/
directory. You can make them available to your handler by
adding the following line to the top of your handler:
# handler.rb
load "vendor/bundle/bundler/setup.rb"
$LOAD_PATH.unshift(File.expand_path("lib", __dir__))
You will also need to edit your serverless.yml
package
settings to include
those files:
package:
include:
- handler.rb
- lib/**
Verify
Build your package to confirm it is being built as expected:
serverless package
Note - if you have gems with native extensions, and are not developing on linux, make sure have docker installed and running. The first time you package may take a really long time as the docker image is downloaded. Future packaging will be much faster.
That will create the package that is uploaded during a serverless deploy
, but
keep it around so you can examine it. You can use the following command to verify
it only includes the files you expect:
unzip -l .serverless/<servicename>.zip
Configuration
By default, if any gems have native extensions, they will be compiled for the AWS Lambda Linux using Docker.
You can override the default behavior by adding to your serverless.yml
file:
custom:
rubyPackage:
alwaysCrossCompileExtensions: false
You can also override this behavior using environment variable. If you set the
environment variable, it will have precedence over the serverless.yml
file:
CROSS_COMPILE_EXTENSIONS=false serverless package
Development
To work on this plugin, you should first run the following in your local directory:
./dev_setup.sh # configures the demo service project needed by the tests
yarn test # run the automated test suite
./integration-test.sh # run serverless package on the demo project and observe the results
Troubleshooting the demo_service
-
Make sure the version of bundler specified in the demo_service Gemfile.lock is compatible with the version installed in the
amazon/aws-lambda-ruby:3.2
image. -
Make sure you can invoke the function n in the docker image:
./invoke-service.sh
Releasing a new version
-
Commit a description of the changes in CHANGELOG.md
-
Run
yarn publish
. It will prompt for the new version number, and npm credentials. It will create a new commit and tag with the version number changes. Make sure to push them.