A technical engineer's blog: real problems, real fixes, real numbers. Backend, databases, infra, incident post-mortems, security, AI-native workflows.
A host that answers on no port while the kernel keeps logging is not failing memory. In OpenZFS before 2.4.4 and 2.3.9, zfs_fillpage() computes io_len = i_size - io_off in unsigned types: race an mmap read against an in-place truncate and the length underflows, so dmu_read() zero-fills physical memory far past the page. Fixed on 21 August 2026 in 2.4.4 and 2.3.9 — but not in 2.2.11, released the same minute.
With replication slots enabled, hot_standby_feedback moves the bloat risk onto the primary; raising max_standby_streaming_delay feeds the HAProxy check that ejects the replica. Two hundred cancelled queries and thirty-odd replica ejections looked like one problem, but barely one in twenty lined up.
A relay with more than two years of uptime failed nearly every Gmail delivery because SPF, DKIM and forward-confirmed reverse DNS were broken independently. The root cause of the DKIM half was one word: tables mounted as refile: instead of file:, which makes OpenDKIM drop the key lookup and sign nothing without logging a line.
Treat a disk that fails on writes as read-only: stream pg_dump over SSH to the target, pull EOL images from the registry instead of rebuilding them, and anchor rsync excludes with a leading slash. Notes from moving a Docker app of some fifteen services with a PostgreSQL database on the order of ten gigabytes.
PHP, Laravel, GraphQL, domain modeling, server-side architecture. Notes from mature monoliths and greenfields.
PostgreSQL, ClickHouse, MySQL. Migrations, optimization under load, incident post-mortems, escaping rules, common traps in mixed stacks.
Ansible, Terraform, Proxmox, libvirt/KVM, Docker, LXC, edge proxies, network, DNS. Bare metal, no clouds.
Post-mortems with the full diagnosis: hypotheses, ruled-out theories, root cause, real numbers. How systems actually break.
CrowdSec, SSH, TLS, secrets, hardening. Replacing ritual defense with something you can actually verify.
Claude Code, MCP, agent memory, skill conventions, workflows. Building software with an AI partner, as a process.
iOS, SwiftUI, Apollo GraphQL. Live client-server integrations, server-driven UI, debugging the network layer.