project planning · application architecture


In my recent client engagement, I foresaw that serverless architecture was a perfect fit. The idea of adopting serverless architecture, though, didn’t fly to our client well due to the fear of vendor lock-in. It was an interesting time for retailers as staying in AWS might mean that Amazon, as another retail business, will be given a competitive advantage. Given the idea of not supporting a competitor, my client was interested to ensure that the solution chosen by us is fully portable to other cloud vendors.

From a technical perspective, ensuring that we have the ability to move our system from one platform to another is definitely desirable. With the advent of containerization, why would one be interested to be locked in a specific platform? A high lock-in cost is not something that we would like to show back to the business when we have decided to move another platform. We, therefore, need to make sure that the migration cost is as low as possible when this scenario happens. If I’m about to make a simple formula for lock-in cost with our current understanding, it would look like this:

Lock-in cost = Migration cost (?)

This formula is correct when we are looking at it only from a technical perspective. A business perspective, however, should not be overlooked. Remember that the technical solutions we deliver are always designed to solve business problems. Most of the times the business get a benefit when a particular technology is adopted. One of the significant benefits is a faster time to market. Faster time to market can be formulated into opportunity gain:

Lock-in cost = Migration cost - Opportunity gain

Opportunity gain is very difficult to measure because you are dealing with an unknown unknown. Migration cost can be analyzed and reasoned. Opportunity gain, in contrast, is not as easy to analyze. You can theorize and analyze how to migrate from one platform to another, but how would you calculate the gain of seizing your competitors’ market opportunity? By looking at your decision-making process from a holistic view, combining both the technical and business perspective, the lock-in decision you are taking might result in a profit.

Let’s have a look into an example of building an event-driven architecture. You will need to choose a distributed messaging system in the architecture. If you are already chosen AWS as your platform, you would have the option of vendor-specific services like Kinesis. These services are fully managed and you can get it running in no time, hence giving you an opportunity gain. In comparison with a vendor-agnostic system like Kafka, these vendor-specific services will incur a higher migration cost. Setting up your own distributed messaging system, however, will take more time to harden and for it to be made production ready, especially when you are not experienced in building such platform yet. Instead of looking at your decision from just migration cost, focus on how you can reduce the migration cost by making your system more adaptable. Especially in this example of using a cloud, this is a similar reason on why we recommend to avoid the practice of generic cloud usage.


Thanks to Chris Ford, Matt Newman, Luciano Ramalho, Tobias Vogel, Zhamak Dehghani, Kitson Kelly, and Peter Gillard-Moss for their inputs.

Special thanks to Martin Fowler for his support, suggestions, and time spent with the content and help with publishing.

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