The newly launched Mingle SaaS offering runs entirely on the AWS cloud. As discussed in our earlier blog on Layering the Cloud, because there is no existing system that we have to modify or integrate with, we've got the freedom to design the architecture from scratch. This has led us to rethink the role of environments in our development and deployment process.
What’s wrong with the traditional approach to environments?
In traditional data-center-based applications there are usually a small, fixed number of environments into which the application is deployed. For example there might be the production environment, a staging environment where candidate builds are deployed before they go into production, a test environment where new work is verified and a development environment where developers can run new code as part of a full system.
The availability and nature of these environments is strongly constrained by the availability of hardware and infrastructural systems for them to run on. We would like all our environments to be as similar to production as possible, but physical hardware and traditional infrastructural systems like databases are expensive and slow to provision.
In practice this means that there is a sliding scale of realism in the environments as you go from development to production. Development environments tend to be smaller than production (load-balanced applications may have only a single server when there are a dozen in production), they often use alternatives for some components (they may have a different database server) and they frequently share components (fileservers, databases, monitoring systems) when these are dedicated in production. Similar differences exist for test and even staging environments; although of course the hope is that they can be more realistic the closer they are to production.
This variation between environments causes several problems. The most obvious problem is that some bugs are found further down the pipeline, rather than being identified by developers as they are working on the code; this increases the cost of fixing the bugs. Another problem is that supporting the variation in environments increases the complexity of the code. And, more subtly, we end up making decisions that don't cause outright bugs but which cause our architectures not to be optimized for the real deployment environment, because developers are divorced from the reality of running the system in that environment.
The inevitable restriction on the number of environments also causes problems. Availability of environments is yet another dependency to be juggled, which can cause delays or influence us to miss out testing that we would like to do. And maintenance of the environments, cleaning up after running stress tests for example, also takes time.
How have we approached environments in the cloud?
We have found that building a system that runs entirely on the cloud has enabled us to reconsider our use of environments and ensure that we don't fall foul of any of these problems.
Stay tuned for our next blog where we discuss the principles we used; such as ad-hoc environments, shared-nothing environments and cookie-cutter environments to optimize our use of environments in the cloud.