- AWS – Elastic Beanstalk, and Whether to Use It in 2026
Beanstalk still works and still deploys a web app in one command, and it is still the fastest path from a zip file to a URL with a load balancer in front. What it actually creates on your behalf, `.ebextensions` and where the abstraction leaks, the deployment policies and which ones can serve two versions at once — and an honest comparison against ECS Fargate and App Runner before you commit.
- MongoDB – Atomicity and Transactions
Single-document atomicity covers more than you would think. What multi-document transactions cost, and when you genuinely need one.
- AWS – SNS: Fan-out, Filtering and SQS Subscriptions
SNS pushes, SQS pulls, and the useful thing is putting them together: one topic, several queues, each consumer at its own pace. Topics and subscriptions, the confirmation handshake an HTTP endpoint has to complete, message filtering so a consumer is not woken for events it ignores, and the raw message delivery setting that stops your payload arriving wrapped in an envelope you did not ask for.
- MongoDB – $lookup, $unwind and $facet
Joining collections in an aggregation, flattening arrays, running several pipelines at once — and the strict type match that makes a join return nothing.
- AWS – SES: Sending Email That Arrives
Getting SES to send is easy; getting the mail delivered is the work. Verifying a domain, and the three DNS records — SPF, DKIM, DMARC — that decide whether you land in an inbox or a spam folder. The sandbox and what leaving it requires, the reputation metrics AWS will suspend you over, and handling bounces and complaints through SNS instead of discovering them when your sending is paused.