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.
Webhooks push events instead of polling
A webhook lets a provider notify a registered receiver when something changes. It reverses who initiates the HTTP request, but that alone does not guarantee delivery, immediacy, ordering, or exactly-once processing. The operational contract comes from the provider and the receiver’s handling of acknowledgment and state.
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Redis append-only log trades speed for durability
An append-only file records Redis mutations for recovery, but choosing AOF is not the same as promising that no acknowledged write can ever disappear. Durability depends on the fsync policy, effective configuration, storage behavior, and which failure you mean. Start with a recovery objective rather than the reassuring word “log.”
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Shell parameter expansion rewrites values
Parameter expansion derives a value from a shell parameter before a command receives its arguments. It can provide a default, reject missing configuration, or remove part of a string without launching another process. This is expansion during execution, not an instruction to evaluate every variable when the script is first parsed: a function reads the current value when it runs.
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.gitignore controls untracked paths
Git ignore rules influence which untracked paths ordinary discovery and add operations consider. They are useful for generated files, editor state, and local configuration. They do not create an access-control boundary, remove a file already in the index, or erase earlier commits. Treat the ignore file as a project convention with observable matching rules, not as a guarantee that a sensitive file cannot enter history.
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Btrfs snapshots are copy-on-write, not copies
A btrfs snapshot is not a copy of anything. btrfs subvolume snapshot creates a new subvolume whose root points at the same extent tree as the source, so every extent the two share is referenced twice and stored once. Creation is a metadata operation measured in milliseconds whether the subvolume holds a gigabyte or ten terabytes.
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A page fault is not always a storage read
A page fault means the processor could not complete an access using the current mapping or permissions. It is not synonymous with a storage read, and some faults represent invalid accesses rather than recoverable demand paging. Linux’s minor and major counters distinguish whether handling required page-in I/O. Interpret those counters alongside the mapping type and workload; neither is a direct measurement of all application storage traffic.
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An LRU cache evicts the least recently used entry
LRU chooses a victim by recency, not by popularity, age, or business importance. When a bounded cache needs space, an exact least-recently-used policy removes the entry whose last qualifying access occurred longest ago. That rule can exploit temporal locality, but it neither guarantees useful hits nor keeps cached data fresh.
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Least connections measures occupied connections, not every kind of load
Least-connections balancing chooses a peer using active connection counts, with the implementation’s weighting and tie rules. In nginx, least_conn accounts for server weights and uses weighted round robin among equally suitable peers. This can help when requests occupy connections for different durations. It is still a connection-based measurement, not direct knowledge of CPU, memory pressure, queued jobs, or database contention.
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