Step-by-step playbooks for when things go sideways. Interactive checklists with copy-paste commands.
Troubleshoot Docker container networking failures. Covers DNS resolution, inter-container communication, network inspection, and firewall rules.
Diagnose DNS resolution failures on Linux systems and Kubernetes clusters. Covers resolver config, upstream DNS, systemd-resolved, CoreDNS, and DNSSEC issues.
Fix a certbot renewal that's stuck failing. Covers HTTP-01 + DNS-01 challenges, rate limits, webroot + authenticator mismatches, and getting the cert pushed to services that cached the old chain.