A few days ago, a devops engineer posted on r/devops:
"MCP servers just showed up in our infrastructure and I genuinely have no idea how to secure them, anyone been through this?"
Filesystem access, shell permissions, database connectors - all callable by agents without human approval. At the time I'm writing this, the thread has 76 upvotes and 39 comments from fellow engineers improvising solutions: "separate by blast radius," "don't mix list_files and execute_shell in one server," "three security surfaces, not one."
They're all describing the same thing: the patterns they are rediscovering have been formalized in Domain-Driven Design (DDD), by Eric Evans.
In his book, Eric introduced concepts like Bounded Contexts and Anti-Corruption Layers, which gave us the vocabulary we've been using for system boundaries ever since. They helped us survive the microservices transition, and they apply directly to the architectural problems AI systems are creating right now.
