With more and more teams getting ready with practices like continuous deployment and DevOps, there are lot of questions about the best practices regarding application deployment. I've been working with projects and setting up continuous delivery and automated deployments as part of the work. Below are some of the practices that I follow for application deployments.
There is a lot of focus on automation nowadays and a lot of tools and information is available to automate the manual actions in the deployment process. Almost every deployment automation tools allows complete customization and extensibility to make use of scripting languages that are used to carry out OS specific tasks. This makes it very easy to use these tools in the process even though you have a specific task to perform that is not available out-of-the-box in the tool that you are using. For .NET applications you can use PowerShell for example to do almost anything on windows environments.
Build once, deploy it many times
For avoiding situations like, "it works in the Test environment but not in Production". you need to use the same binaries that were installed and tested on lower environments when deploying to higher environments. For automated deployments to go risk free, we need to have the confidence that we are deploying the same package that was tested and approved from a lower environment. If you are planning to recompile the code base every time a deployment is happening, there are lot of hidden changes and troubles coming along with that process, which makes the deployments unstable.
Maintain a repository for the build artifacts
Things can sometimes go wrong and sometimes its needed to roll-back to a known-working version. Having an artifact repository for your packages not only will help you in using the same version on every environment, but also to locate old versions of an application without having to build them again. Also its a stable version that was working before!!!
Change configuration variables at deployment time not at build time
One of the common challenges with applications which migrate through the usual lifecycle of environments such as development, test and production is getting the configuration context right. Some of the most common examples are connection strings, trace modes etc. There are multiple ways to handle this problem with one of them being making use of configuration file transformations as part of the build process. This can introduce the same risk as rebuilding binaries for each environment. It’s a good practice to make use of the deployment tool to apply environment specific configuration changes during deployment time to the applications. This will allow you to be flexible with the latest changes in the environments.
Don’t customize the deployment process or steps based on environments
It’s always good to treat your deployment process the same across environments. This helps you to create more reliable and predictable deployments across environments. A lot can go wrong when you try to make adjustments in the deployment process based on environments. Let’s keep it simple J