Admin guideBuilds

Runner images

The per-language container images isolated mode runs workloads in, and the version sets they declare.

In isolated mode each workload runs in a runner image — one per language family, never per framework or per app.

RUNNER_IMAGE_PYTHON=ghcr.io/example/toft-runner-python:1
RUNNER_IMAGE_NODE=ghcr.io/example/toft-runner-node:1
RUNNER_IMAGE_GO=ghcr.io/example/toft-runner-go:1
RUNNER_IMAGE_R=ghcr.io/example/toft-runner-r:1
RUNNER_IMAGE_STATIC=ghcr.io/example/toft-runner-static:1

An app whose family has no image is refused at start, naming the family. The Runner images row on Admin → System checks warns for a missing image and for one tagged latest or untagged.

Declaring the versions an image carries

RUNNER_PYTHON_VERSION=3.15,3.14,3.13
RUNNER_NODE_VERSION=24,22,20
RUNNER_R_VERSION=4.6,4.5,4.4

Rule	Effect
First entry is the default	Same as the platform’s probe
Every entry is required	At bootstrap the runner checks its image for each series and refuses to start a workload if one is missing
A malformed entry voids the whole list	Never silently shortened
Platform and runner images carry the same set	An R library is restored on the platform and loaded in the pod; a mismatch fails at `dyn.load`

There is no RUNNER_GO_VERSION: Go builds a binary. See language versions.

Tags and upgrades

Never tag latest; a moving tag changes what runs at an unplanned restart.
To add a series: rebuild the image, push a new tag, change the variable.
RUNNER_VERSION is the runner contract version the platform expects. It is configuration, for the window when the two halves of an upgrade are out of step.

The static runner

Static apps and rendered documents are served by a subcommand of the platform binary; RUNNER_IMAGE_STATIC is a thin image around it. Shared mode runs the same subcommand.