Deployment and updates

The fleet is deployed with colmena 🡕: a single command builds and applies the configuration on one or more hosts, remotely, from the admin workstation.

Apply a configuration

just apply <target> [action]    # alias : a

target = hostname, pattern ('*'), list (a,b) or colmena tag (@server).
action = switch (default), boot, test or build.

Command	Purpose
`just apply <target>`	Build + activate on the target(s)
`just apply-local`	Apply on the current machine (alias `al`)
`just apply-verbose <target>`	Same as `apply` in trace mode (alias `av`)

Deploy safely

Build confidence through action: each step is less risky than the next.

just apply <host> build      # downloads + compiles: 100% safe, nothing is activated
just apply <host> test       # activates without switching: no generation, no boot
just apply <host>            # switch: activates and creates a new generation

Progress from core to edge: deploy nodes in this order, to never cut off access to a node by the one preceding it.

Update

The system is pinned by flakes. Updating = refresh the inputs, then redeploy.

just update-flake     # updates dnf/ + root, commits the locks
just apply '*'        # deploys the update

Binary cache

The harmonia service acts as a signed binary cache for the fleet, and ncps relays it. Hosts thus retrieve already-built derivations instead of recompiling, which significantly speeds up deployments.