2016-11-11 TOMMY TYNJÄ
This article is a continuation on my previous article on how to release software with quality and confidence.
When the big e-commerce holidays such as Black Friday, Cyber Monday and Christmas are looming around the corner, many companies are gearing up to make sure their systems are stable and able to handle the expected increase in traffic.
What many organizations do is introducing a full code freeze for the holiday season, where no new code changes or features are allowed to be released to the production systems during this period of the year. Another approach is to only allow updates to the production environment during a few hours during office hours. These approaches might sound logical but are in reality anti-patterns that neither reduces risk nor ensures stability.
What you’re doing when you stop deploying software is interrupting the pace of the development teams. The team’s feedback loop breaks and the ways of workings are forced to deviate from the standard process, which leads to decreased productivity.
When your normal process allows deploying software on a regular basis in an automated and streamlined fashion, it becomes just as natural as breathing. When you stop deploying your software, it’s like holding your breath. This is what happens to your development process. When you finally turn on the floodgates after the holiday season, the risk for bugs and deployment failures are much more likely to occur. As more changes are stacked up, the bigger the risk of unwanted consequences for each deployment. Changes might also be rushed, with less quality to be able to make it into production in time before a freeze. Keeping track of what changes are pending release becomes more challenging.
Keeping your systems stable with exceptional uptime should be a priority throughout the whole year, not only during holiday season. The ways of working for the development teams and IT organization should embrace this mindset and expectations of quality. Proper planning can go a long way to reduce risk. It might not make sense to push through a big refactoring of the source code during the busiest time of the year.
A key component for allowing a continuous flow of evolving software throughout the entire year is organizational maturity regarding monitoring, logging and planning. It should be possible to monitor, preferably visualised on big screens in the office, how the systems are behaving and functioning in real-time. Both technical and business metrics should be metered and alarm thresholds configured accordingly based on these metrics.
Deployment strategies are also of importance. When deploying a new version of a system, it should always be cheap to rollback to a previous version. This should be automated and possible to do by clicking just one button. Then, if there is a concern after deploying a new version, discovered by closely monitoring the available metrics, it is easy to revert to a previously known good version. Canary releasing is also a strategy where possible issues can be discovered before rolling out new code changes for all users. Canary releasing allows you to route a specific amount of traffic to specific version of the software and thus being able to compare metrics, outcomes and possible errors between the different versions.
When the holiday season begins, keep calm and keep breathing.