GoCD circuit breaker / readiness check script.

gocd-readiness-check.rb

#!/usr/bin/env ruby

# Copyright (c) 2016 Matt Greensmith and Cozy Services Ltd.
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#
### GoCD circuit breaker / readiness check script.
###
### Should be configured as a downstream pipeline for all pipelines in PIPELINE_GROUP.
### When run, checks to see whether there are any pipelines currently building from the
### upstream group, and whether there are labels for upstream builds that are newer than
### the build that triggered this build. Fails if there are in-progress builds or if there
### is a build that will trigger this pipeline is the future.

require 'go_api_client'

PIPELINE_GROUP = 'my-upstream-pipelines'
GOCD_SERVER_HOST = 'my.ci.server.tld'
GOCD_SERVER_PORT = 80

failed = false

client = GoApiClient::Client.new(host:GOCD_SERVER_HOST, port: GOCD_SERVER_PORT)
pipelines = client.api(:config).pipelines(group_name: PIPELINE_GROUP)

building = []
last_build_label = {}
pipelines.each do |p|
  building << p unless client.api(:cctray).projects(:pipeline_name => p.name, :activity => 'Building').empty?
  last_build_label[p.name] = client.api(:cctray).projects(:pipeline_name => p.name)[0].last_build_label rescue nil
end

unless building.empty?
  building.each do |p|
    puts "#{p.name} is building"
  end
  failed = true
end

pipelines.each do |p|
  # p.name looks like some-upstream-job
  # env var looks like GO_DEPENDENCY_LABEL_SOME_UPSTREAM_JOB=6
  env_var_name = "GO_DEPENDENCY_LABEL_#{p.name.upcase.gsub(/-/,  '_')}"

  current_build_label = ENV[env_var_name]
  if current_build_label == last_build_label[p.name]
    puts "#{p.name} build label #{current_build_label} triggered me, it is the newest build"
  else
    puts "#{p.name} build label #{current_build_label} triggered me, but newer label #{last_build_label[p.name]} exists"
    failed = true
  end
end

if failed
  puts "Not ready to deploy."
  exit 1
end

puts 'Ready to deploy!'