Tracks

1.1 First steps From system basics and command input to navigation, files, text, and pipelines. 15 stages

2.1 Users, permissions, and processes From file permissions and accounts to sudo, groups and processes. 13 stages 2.2 Packages, services, and logs From packages and systemd services to your own unit, the journal, schedules and log rotation. 13 stages

3.1 Networking From addresses and routes to ports, filtering, DNS, SSH, multi-host connectivity and packets in tcpdump. 15 stages 3.2 Storage From space diagnosis and mounting, through preparing a new disk and a RAID 1 mirror, to logical volumes and data recovery. 12 stages 3.3 Bash: text processing and scripts Searching and editing text with grep, sed and awk, your own scripts with arguments and checks, exit codes and scheduled runs with a log and a lock. 9 stages

4.2 Web stack Sites and reverse proxy on nginx, certificates and HTTPS, PostgreSQL access and restoring from a dump — up to a site and a database on two machines. 9 stages 4.3 Server security What a server exposes and what it keeps running after an update, password policy and fail2ban, a service with least privilege, AppArmor and auditd — up to getting a new server ready for publication. 10 stages 4.4 Containers: Docker and compose Image and container, ports, environment and restart, your own Dockerfile, volumes, container networking and a compose stack, memory limits and the user inside a container. 11 stages 4.1 Inside the system: resources, kernel, processes Load average and the CPU, memory and the OOM killer, process limits and kernel parameters, disk load, strace and /proc, kernel messages, the system boot and emergency mode, time synchronisation — up to triaging a slow server. 13 stages 4.5 Automation: Git and Ansible Configuration under git: who changed what, how to get the working version back and update a server from a repository; Ansible: inventory, ad-hoc commands, an idempotent playbook, roles, variable precedence and secrets in a vault — up to configuring a second machine from the first. 8 stages 4.6 Observability: metrics, alerts, logs Machine and application metrics in Prometheus and PromQL queries; alert rules and notification delivery through Alertmanager; logs from several machines on one collector and investigating with logs — up to watching a second machine from the first. 9 stages

5.1 SRE practices: SLOs, incidents, redundancy Availability and latency from a log, SLOs and error budgets; the first minutes of an incident by a runbook, rolling back a release and a blameless postmortem; a load balancer with health checks and a keepalived floating address — up to an on-call shift on two machines. 8 stages