What if your Kubernetes cluster simply refused to run unsigned images? I spent some time experimenting with enforcing image provenance in a small Kubernetes setup using MicroK8s. The idea was simple: Only container images with valid cryptographic signatures are allowed to run in the cluster. For this I used: GitLab CI/CD (build + signing pipeline) Cosign / Sigstore (image signing) Kyverno (admissi
Most teams I have worked with have one auth test in their suite. It looks like this: test('valid token verifies', () => { const token = signSync({ sub: 'user-1', aud: 'api://backend' }, secret); const result = verify(token, options); expect(result.valid).toBe(true); }); That test is fine. It is also a smoke test, not a regression suite. It catches the case where verification is completely b
The on-call alert at 02:14 said auth_5xx_rate spiked from 0.01 to 31.4. Not a deploy window. Not a traffic spike. Just thirty-one percent of authenticated requests failing for ~four minutes, then back to baseline. The cause was a JWKS rotation on the issuer side. New keys came in. Old keys went out. Caches in our service didn't refresh fast enough. Tokens signed with the new key were rejected beca
Imagine you run a bustling coffee shop. In the beginning, you take orders, make the coffee, and serve pastries all by yourself. It works perfectly when you have a handful of customers. But as the crowd grows, you become the single point of failure. If you are stuck making a complex latte, the simple drip coffee line grinds to a halt. In software engineering, this "one-person shop" represents a mon
ID generation looks like a small backend decision. In many systems, we simply add an id column, make it the primary key, and move on. But once the table grows, this decision can affect database performance, indexing, pagination, debugging, and how easily the system scales across services. The common choices are: UUIDv4 UUIDv7 Snowflake ID Each one solves the uniqueness problem, but they behave dif
Java LLD: Designing a High-Concurrency Elevator System Designing an elevator system is a classic "Machine Coding" round favorite because it tests concurrency, state management, and algorithmic efficiency simultaneously. At companies like Apple or Amazon, interviewers aren't just looking for a working loop; they are looking for thread safety and optimal scheduling. Using a simple Queue<Integer>
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