Original, source-backed articles about running small systems, static sites, HTTP, DNS, TLS, and operations.
Posts are original articles written for this site. Each one is script-free, source-backed, and tied to the same operational reality the rest of the site records: how a small, static, publicly served system is built, secured, and kept honest.
Small commits tell a coherent story
A useful commit answers one question about the behavior of a repository. It includes the implementation, the checks that establish that behavior, and documentation needed to use it. Smallness means a bounded reason for change, rather than a target number of lines. An inclusive shipping threshold might require edits to both a function and its regression test while leaving an unrelated draft outside the commit.
...
CORS preflight checks a browser request before it is sent
A CORS preflight asks whether a browser may send a particular cross-origin request. It describes the requesting origin, intended method, and relevant header names. The browser evaluates the reply before sending that request, unless a valid preflight cache entry already grants permission. CORS also governs whether JavaScript can read the actual response. These are related checks, but neither replaces application authentication or authorization.
...
WATCH protects Redis read-modify-write decisions
MULTI/EXEC prevents another client’s commands from interleaving while the queued commands execute. That alone does not protect a value read earlier in the application. If two buyers read the same stock count and later write their own calculated value, wrapping each SET in a transaction can still lose an update.
...
Cardinality is a metric budget
A metric costs more than its short name suggests. Prometheus identifies a time series by its metric name and complete label set. A new observed label combination creates a different series, which must be ingested, indexed, retained, and queried. Cardinality budgeting asks which distinctions are worth paying for and whether their number stays bounded as the service grows.
...
A Postgres index lives to answer a query
An index is valuable because it changes the work needed by a real query. Counting indexed columns is not a useful success measure. A narrow B-tree that finds one customer’s newest three orders can outperform a wider structure that cannot supply the needed ordering, while a query reading almost every row may correctly ignore both. Evaluate access, ordering, and result volume together.
...
Set file limits in the process that starts the workload
A shell’s ulimit builtin changes resource limits for that shell and the processes it subsequently starts. For file descriptors, RLIMIT_NOFILE has a current soft value and a hard ceiling. Understanding where those values are inherited is essential when a terminal reports a generous limit but an independently managed service still fails to open files or accept connections.
...
Dashboards summarize; they do not magnify
A useful dashboard helps a reader decide what to inspect next. It reduces a large collection of measurements into a small set of questions: are users succeeding, where is the impact, and is capacity becoming constrained? Reduction must preserve important differences. A green global percentage can conceal a failing region, and a blank panel can mean missing telemetry rather than a quiet, healthy service.
...
A rota needs continuous coverage and a load review
A rota can distribute responsibility, but equal shift counts do not guarantee equal burden. Review nighttime pages, incident effort, recovery time, and reliable backup alongside the schedule.
A job that is shared On-call work is a job that belongs to a team, not to one hero. A rotation turns ‘whoever was last awake’ into a defined roster and a schedule, so responsibility is explicit and no one is assumed to carry the whole queue indefinitely. The schedule itself — a weekly handoff, a backup/secondary on-call, a follow-the-sun structure across sites — is how you keep the obligation sustainable without letting it turn into a possession. Don’t let the urgency of tonight’s page decide who owns tomorrow; the rotation decides on purpose, ahead of time.
...
