Sensu Go Ruby Runtime Assets

This project provides Sensu Go Assets containing portable Ruby runtimes (for various platforms), based on the excellent ruby-install project by postmodern. In practice, this Ruby runtime asset should allow Ruby-based scripts (e.g. Sensu Community plugins) to be packaged as separate assets containing Ruby scripts and any corresponding gem dependencies. In this way, a single shared Ruby runtime may be delivered to systems running the new Sensu Go Agent via the new Sensu's new Asset framework (i.e. avoiding solutions that would require a Ruby runtime to be redundantly packaged with every ruby-based plugin).

This same project may be used to build Sensu Assets for Ruby-based plugins via bundler or other similar tools. We'll share more information on building Ruby-based assets with third-party gem depdencies using Bundler soon; in the interim, please review the instructions below for more information on how to get started with this project.

Platform Coverage:

Currently this repository only supports a subset of Linux distribution by making use of Docker containers to build and test. If you would like extend the coverage, please take a look at the Github Action integration and associated build scripts. We're happy to take pull requests that extending the platform coverage. Here's the current platform matrix that we are testing for as of the 0.1 release:

Asset Platform	Tested Operating Systems Docker Images
alpine (based on alpine:3.8)	Alpine(3, 3.8, latest)
centos7 (based on centos:7)	Centos(7,8), Debian(8, 9, 10), Ubuntu(14.04, 16.04, 18.04, 20.04)
centos8 (based on centos:8)	Centos(8), Debian(10), Ubuntu(20.04)
debian (based on debian:9)	Debian(8, 9, 10), Ubuntu(14.04, 16.04, 18.04, 20.04), Centos(7,8)
amnz1 (based on amazonlinux:1)	Debian(8, 9, 10), Ubuntu(14.04, 16.04, 18.04, 20.04), Centos(7,8)
amnz2 (based on amazonlinux:2)	Debian(10), Ubuntu(18.04, 20.04), Centos(8)

OpenSSL Cert Dir

Please note that when using the ruby runtime asset built on a target OS that is different from the build platform, you may need to explicitly set the SSL_CERT_DIR environment variable to match the target OS filesystem. Example: CentOS configures it libssl libraries to look for certs by default in /etc/pki/tls/certs and Debian/Ubuntu use /usr/lib/ssl/certs. The CentOS runtime asset when used on a Debian system would require the use of SSL_CERT_DIR override in the check command to correctly set the cert path to /usr/lib/ssl/certs

Instructions

Please note the following instructions:

1. Use a Docker container to install ruby-install, build a Ruby, and generate a local_build Sensu Go Asset.

   $ docker build --build-arg "RUBY_VERSION=2.4.4" -t sensu-ruby-runtime:2.4.4-alpine -f Dockerfile.alpine .
   $ docker build --build-arg "RUBY_VERSION=2.4.4" -t sensu-ruby-runtime:2.4.4-debian -f Dockerfile.debian .
   

2. Extract your new sensu-ruby asset, and get the SHA-512 hash for your Sensu asset!

   $ mkdir assets
   $ docker run -v "$PWD/assets:/assets" sensu-ruby-runtime:2.4.4-debian cp /assets/sensu-ruby-runtime_2.4.4_debian_linux_amd64.tar.gz /assets/
   $ shasum -a 512 assets/sensu-ruby-runtime_2.4.4_debian_linux_amd64.tar.gz
   

3. Put that asset somewhere that your Sensu agent can fetch it. Perhaps add it to the Bonsai asset index!

4. Create an asset resource in Sensu Go.

   First, create a configuration file called sensu-ruby-runtime-2.4.4-debian.json with the following contents:

   {
     "type": "Asset",
     "api_version": "core/v2",
     "metadata": {
       "name": "sensu-ruby-runtime-2.4.4-debian",
       "namespace": "default",
       "labels": {},
       "annotations": {}
     },
     "spec": {
       "url": "http://your-asset-server-here/assets/sensu-ruby-runtime-2.4.4-debian.tar.gz",
       "sha512": "4f926bf4328fbad2b9cac873d117f771914f4b837c9c85584c38ccf55a3ef3c2e8d154812246e5dda4a87450576b2c58ad9ab40c9e2edc31b288d066b195b21b",
       "filters": [
         "entity.system.os == 'linux'",
         "entity.system.arch == 'amd64'",
         "entity.system.platform == 'debian'"
       ]
     }
   }
   

   Then create the asset via:

   $ sensuctl create -f sensu-ruby-runtime-2.4.4-debian.json
   

5. Create a second asset containing a Ruby script.

   To run a simple test using the Ruby runtime asset, create another asset called helloworld-v0.1.tar.gz with a simple ruby script at bin/helloworld.rb; e.g.:

   #!/usr/bin/env ruby
   
   require "date"
   
   puts "Hello world! The time is now #{Time.now()}"

   NOTE: this is a simple "hello world" example, but it shows that we have support for basic stlib gems!

   Compress this file into a g-zipped tarball and register this asset with Sensu, and then you're all ready to run some tests!

6. Create a check resource in Sensu 2.0.

   First, create a configuration file called helloworld.json with the following contents:

   {
     "type": "CheckConfig",
     "api_version": "core/v2",
     "metadata": {
       "name": "helloworld",
       "namespace": "default",
       "labels": {},
       "annotations": {}
     },
     "spec": {
       "command": "helloworld.rb",
       "runtime_assets": ["sensu-ruby-runtime-2.4.4-debian", "helloworld-v0.1"],
       "publish": true,
       "interval": 10,
       "subscriptions": ["docker"]
     }
   }
   

   Then create the asset via:

   $ sensuctl create -f helloworld.json
   

   At this point, the sensu-backend should begin publishing your check request. Any sensu-agent member of the "docker" subscription should receive the request, fetch the Ruby runtime and helloworld assets, unpack them, and successfully execute the helloworld.rb command by resolving the Ruby shebang (#!/usr/bin/env ruby) to the Ruby runtime on the Sensu agent $PATH.:wq