As you could have imagined, CI is the phase in which your application gets built, tested, and packaged (whatever the package format is—web application, binary, container, and so on). The de facto standard tool for this phase is Jenkins.

The first CD stands for continuous delivery, and is the phase where your final artifact gets delivered to an environment. Continuous means that your artifact gets delivered, that is, promoted, from environment to environment until the preproduction environment, or at least at the last environment before production, which then needs a manual promotion— typically a manager approval for deploying to production.

Again, Jenkins helps out in this phase, as it can directly promote the application from environment to environment by relying on pipelines.

The last CD stands for continuous deployment, and it is exactly the same as continuous delivery, except for the fact that the artifact, once built, gets promoted from the first stage environment to production directly in an automated way.

Which one to choose depends on which one is right for your organization.

However, there are four golden rules for the deployment process:

•  Build the final artifact only once: What needs to be deployed from environment to environment must be exactly the same thing. To achieve such goals easily, OpenShift relies on Jenkins.
• Keep deployment the same: Always deploy in the same manner for each environment. Less configuration, better automation, less risk.
•  Test, test, and test: Testing is essential for CI and CD. Testing must be part of the deployment process.
•  Similar environments: Environments should differ only in terms of available resources. All software stack layers should be the same to minimize any differences that could eventually impact the stability and misconfiguration of your system. Clean and safe. Here as well, container technology is a godsend.

In the following sections, we will look at different ways to deploy an application for different purposes.