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.
Exit status is a compact report of what went wrong
An exit status is a small value that a shell uses to decide what runs next. Zero means success for shell control flow; a nonzero status takes the failure branch. That does not give every number a universal application meaning. A search with no matches, invalid input, and an unavailable server may deserve different handling even though all can produce nonzero results. Read the command’s contract before deciding what to retry or ignore.
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Error budgets are a real budget
An error budget makes a reliability agreement usable during planning. Product and operations choose an objective, measure failures against it, and agree what changes when the allowance is exhausted. The number supports that agreement; it does not predict whether tomorrow’s deployment will cause an incident. Shipping a release creates risk, while observed bad events consume the measured budget.
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INSERT ... ON CONFLICT turns a race into one statement
INSERT … ON CONFLICT lets PostgreSQL resolve an insert collision inside the statement that performs the write. It replaces a fragile “check whether the key exists, then insert” sequence with an explicit conflict policy backed by an eligible index or constraint. It does not turn every insertion error into a successful update or define the application’s merge policy for you.
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Referrer-Policy chooses how much source URL to send
The HTTP Referer request header can tell a destination which page initiated a request. Its historical spelling differs from Referrer-Policy, the policy that controls how much source information the browser supplies. Depending on that policy and the destination, the value may include the source path and query, contain only the source origin, or be omitted. Sending the full URL to every external destination is not the modern default.
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Related images share layers; running containers keep separate changes
An image describes an ordered filesystem assembled from immutable layer changesets, together with configuration such as its default command. Related images can reference the same base layers while adding different application files. A running container gets its own writable layer above that image. Distinguishing those three things explains how image reuse saves work without making every container’s runtime edits visible to its neighbors.
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A sorted set keeps members ordered by score
A Redis sorted set stores unique byte-string members, each associated with a numeric score. Scores determine order; they need not be unique. This supports leaderboards and time-based indexes, but it does not make score values into automatic expiration deadlines. Model membership, ranking, and cleanup as distinct operations with explicit boundaries.
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HTTP/3 separates stream delivery, not all recovery
HTTP/3 carries HTTP over QUIC instead of TCP. QUIC offers independently ordered streams, so a missing range in one stream need not prevent delivery of already received data on another. This removes a particular transport ordering dependency. It does not give each request a separate congestion controller, loss detector, or guaranteed completion time.
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EXPLAIN estimates need execution context
EXPLAIN describes the plan PostgreSQL intends to execute. EXPLAIN ANALYZE executes that plan and adds measurements. Comparing them is useful only after interpreting what each number counts. An apparent mismatch can reflect stale estimates, repeated execution, or a parent that stopped requesting rows. Matching cardinalities strengthen one part of the model; they do not prove the chosen plan is the fastest possible plan.
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