Previously, our team used Jenkins. However, since it's a shared deployment resource we don't have admin access. We tried GoCD as it's open source and we really like. We set up our deployment pipeline to run whenever codes are merged to master, run the unit test and revert back if it doesn't pass. Once it's deployed to the staging environment, we can simply do 1-click to deploy the appropriate version to production. We use this to deploy to an on-prem server and also AWS. Some deployment pipelines use custom Powershell script for.Net application, some others use Bash script to execute the docker push and cloud formation template to build elastic beanstalk.
RubyGems is a great packaging library primarily because of its verbose logging information and easy to navigate system architecture. We've dealt with artifactory systems in the past for Java and JavaScript, and RubyGems just makes it a lot easier to handle the packaging and deployment of our reusable libraries. We've noticed in the past that there are times where (if all 200+ teams) are releasing at a similar time that publishing the gems can lag, but that's fairly rare.
Pipeline-as-Code works really well. All our pipelines are defined in yml files, which are checked into SCM.
The ability to link multiple pipelines together is really cool. Later pipelines can declare a dependency to pick up the build artifacts of earlier ones.
Agents definition is really great. We can define multiple different kinds of environments to best suit our diverse build systems.
RubyGems has strong community support and finding issues to errors is as simple as searching for the error message you're receiving (but usually the error is clear enough without having to bother with that). Honestly, the framework is simple enough that support isn't needed much, but it has been helpful to us in the past when we have needed it.
GoCD is easier to setup, but harder to customize at runtime. There's no way to trigger a pipeline with custom parameters.
Jenkins is more flexible at runtime. You can define multiple user-provided parameters so when user needs to trigger a build, there's a form for him/her to input the parameters.
RubyGems is easier to use and to troubleshoot issues overall. Sometimes when troubleshooting in other systems errors are masked and it takes a trained eye or a lot of time searching through Google trying to find out what it really means. RubyGems is very verbose and allows for quick troubleshooting of any deployment problems.
Settings.xml need to be backed up periodically. It contains all the settings for your pipelines! We accidentally deleted before and we have to restore and re-create several missing pipelines
More straight forward use of API and allows filtering e.g., pull all pipelines triggered after this date
