Labs

The layer everything else runs on — files, permissions, users, processes, systemd, logs, disks, and networking.

Assumes

Nothing — start here

Unlocks

Docker

• Find your way around a machine you have never seenAnswer the four questions you always ask on a new box — where am I, what is here, what is this thing, and how big is it.15mBeginner
• Read and search files without opening an editorUse less, head, tail and grep to answer questions about a 200MB log you must never load into memory.15mBeginner
• Create, copy, move and delete without regretThe four commands that change a filesystem, and the flags that stop them destroying something you needed.15mBeginner

Addresses, routes, DNS, and TLS — the vocabulary every cloud console assumes you already have.

Assumes

Nothing — start here

• Read a machine's network configurationAnswer the four questions every network problem starts with — what are my addresses, what is my route out, who is my resolver, and what is listening.25mBeginner
• Work out subnets and CIDR by handCalculate network, broadcast and usable range for a prefix, then size the VPC subnets you would actually deploy.30mBeginner
• Follow a name to an address, end to endTrace a lookup from the root servers down, read the record types that matter, and reproduce the classic "dig works but the app does not" bug.35mBeginner

Containers from first principles — build them, run them, network them, and debug them when they will not start.

Assumes

Linux Administration

• Run your first container and inspect itStart a container, get a shell inside it, and prove from the host that it is an ordinary process.20mBeginner
• Build a small image with a multi-stage DockerfileBuild the same Go service two ways and measure why the build toolchain should not ship to production.35mBeginner
• Wire two containers together on a network you definePut a service and a Postgres instance on a user-defined network, resolve one from the other by name, and watch what a volume survives.40mIntermediate