CD: Continuous Deployment

At this point, we are an organization that uses Continuous Integration and Continuous Delivery but, we can go one step farther and start using Continuous Deployment.

Now we work in a continuous delivery environment but we still need to push a button to deploy things into our production environments, not a big deal but still not moving as fast as we want. Deploying to production can be a risky and costly exercise that sometimes requires putting all development on hold. And, we are still dependent on a deployment cycle and the more commits we fit into a release the more risky it is and the more possibilities we have to introduce an error.

Continuos deployment tries to solve all these drawbacks by automatically shipping every change pushed to the main repository to production. We can obtain benefits like:

  • No one is required to drop their work to make a deployment because everything is automated.
  • Releases become smaller and easier to understand.
  • The feedback loop with our customers is faster: new features and improvements go straight to production when they are ready.


We are already applying continuous integration what means we have plenty of tests, they cover our functionality and guarantee that we are not introducing breaking changes but, are they good enough?

One of the things we need is that the quality of our test suite will determine the level of risk for our release, and our team will need to make automating testing a priority during development. This was important before but now, takes a new level of importance. This means implementing tests for every new feature, as well as adding tests for any regressions discovered after release.

Another thing we need is that fixing a broken build for the main branch should also be first on the list. Why? Because if we don not do that, changes are going to be accumulated and we are going to end up killing the benefits of our new continuous deployment environment.

We need to start using some kind of coverage tools. We can do a rough estimation of our coverage but this does not work. Just try it. If we do the rough estimation and after that use a coverage tool, we will be surprised. It is said that a good goal is to aim for 80% coverage but, there is a big but. Coverage must be meaningful it is not enough writing tests that go through every line of code, the tests need to challenge the code. The tests need to cover business cases, edge conditions and any possible problem we can think of. Code reviews help with this, in addition with helping to transfer knowledge. Our test suite is now the keeper of our production environment, we want to have the best and strongest keeper we can achieve.

Once our code has been deployed to production we need to monitor the situation, we need to check that everything is working as expected and we are serving our customers appropriately. And this monitoring needs to be real-time monitoring. There are some tools out there that can help us with this step. We do not just need to monitor our system is up and running, we need to monitor CPU, memory consumption, average request time… All the parameters we decide we need to keep our systems healthy and to receive alerts if something is off.

No matter how confident we are in our pre-deployment process and our monitoring capabilities, after every deployment we should have some kind of tests running. These test are smoke test, now they earn a lot of importance. We do not need to run anything big, just a  few simple tests loading some static pages and a few more that require to use all production services, micro services, 3rd parties, databases… Our smoke tests should be able to guarantee us that everything is working properly.

At this point, I am sure that some of you (I was doing it) are thinking, what happen with my QA team now? Fair question. Now, the QA team should be working closely with the product manager and the development team to define the risks associated with new improvements. They can help to define cases that need to be tested not just increasing coverage but increasing the quality coverage. They can work in automatization and, they can respond and define properly together with the development team possible bugs found into production.

If any of you readers is a project manager, delivery manager or similar, I am sure by now you are thinking, what about the release notes? There is not space for release notes unless we want to spam our clients. In a big continuous deployment environment we can release code hundreds or thousands of times per day. The advice here is to focus on key announcements for features or enhancements. If you fix a bug that it is particularly affecting one of your customers, just inform this customer. Everything else, you use one of the infinity number of management tools out there to handled changes like JIRA or Trello.

I can be a hard path to move from continuous delivery to continuous deployment. If the effort is worth it or not, it is a decision that the companies and teams need to take. The only advice here is start small and build up your continuous deployment knowledge and experience. If you have a new project, try to apply everything we have mention here, even you can start building your production infrastructure before you even code and push your changes after that. Once you have manage to use continuous deployment in one project, try to apply all the lessons learned to the rest of your projects, the existing ones or even the legacy ones if it is worth it.

CD: Continuous Deployment

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