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  • The runbook link belongs in the alert

    An alert saying HighErrorRate on shop-web at three in the morning is a puzzle. The person receiving it may not have written the check, and the context lives…

  • fr is not a length and does not work in calc

    fr looks like a unit and behaves like a share of what is left after everything else has been laid out, which is why it cannot appear in…

  • Enqueue in the footer unless it must block

    The fifth argument to wp_enqueue_script() decides whether the tag goes in the head, where it blocks parsing, or before </body>, where it does not. The default is the…

  • async and await are native now

    Every current browser and Node 8 ship async functions, which means the transform is no longer the reason for a build step — although the build step is…

  • withoutOverlapping on a scheduled command

    A scheduled task that occasionally runs longer than its interval will be started again while the first is still going, which for an import means two processes writing…

  • A topic exchange is a routing decision you can change later

    Publishing directly to a queue name binds the producer to the consumer topology, so adding a second consumer means changing the publisher. A topic exchange puts a routing…

  • A circuit breaker has three states and people implement two

    Closed and open are obvious: pass through, or fail fast. The third state is what makes it a breaker rather than a switch — half-open lets exactly one…

  • A saga is a workflow with compensation, not a transaction

    A distributed transaction is not available, so the pattern is: do each step, and if a later one fails, run compensating actions to undo the earlier ones. Compensation…

  • proxy_pass with a variable forces DNS resolution per request

    nginx resolves an upstream hostname once at start-up and caches it forever, which breaks the moment a container is recreated with a new address. Using a variable changes…

  • An event-driven seam between two services

    The synchronous call between two services was the reason both were down. Publishing an event decouples their availability — and makes eventual consistency a business decision.