Explained: OAuth 2.0 Token Exchange

You're building a feature. A user calls your API, your API authenticates them, and then your service needs to call three downstream services to assemble the response. One of those services keeps an audit log — it records which user triggered each operation. So your team wires it up: when your API calls downstream, it forwards the user's token. Simple enough. Except the downstream service starts rejecting requests. The token your API hold… Read More

Architecture: How EC2 Works

You spin up an instance, SSH in, and it just works. You get a Linux prompt, a fixed amount of memory, network access, and a disk. Where that instance actually runs, what it shares with other instances, how your keystrokes travel from your laptop to that shell — all of it is invisible. That invisibility is the product. But understanding what is underneath it changes how you design for failure, choose instance types, tune networking, and debug the… Read More

Architecture: Kafka Active-Active with Confluent Bidirectional Cluster Linking

Your Confluent Cluster Linking DR setup is solid. Two clusters, one link, replication lag under five seconds. Then your platform team asks a reasonable question: the DR cluster is sitting idle, your producers in the secondary region are paying cross-regional latency on every write, and a failover still involves a manual promotion step. Can both clusters carry live traffic simultaneously? Can a regional outage become a non-event rather than an in… Read More