docker backend

test backend

The default testlab backend — disposable Linux containers from an image.

The docker backend is the testlab's default. Each test (or test group) gets a disposable container from the test's image. It is Linux-only.

Field	Value
backend value	"docker" (default)
image	a docker image ref, e.g. "debian:12"
requires	image must contain sleep and sh (distroless unsupported)
parallelism	--docker-jobs N (default min(cpu, 8))