BUILD.bazel

genrule(
    name = "kubeconfig",
    stamp = True,
    outs = ["k3s.yaml"],
    cmd = """\
docker cp k3s:/etc/rancher/k3s/k3s.yaml $@
""",
    visibility = ["//visibility:public"],
)

workspace_status.sh

# Inject k3s container id in the workspace
k3s_id=$(docker ps -aqf "name=k3s")

echo "STABLE_K3S_CONTAINER_ID" "${k3s_id}"

k3s_id changes, and thus introduces stamp invalidation to the genrule, which is then re-executed.

I also have this handy rule, for quick stamp references in genrules/shell scripts:

genrule(
    name = "stamps_sh",
    outs = ["stamps.sh"],
    cmd = """sed -E 's/ +/=/' bazel-out/stable-status.txt > $@""",
    stamp = True,
    visibility = ["//visibility:public"],
)

Which is then used:

. $(location //:stamps_sh)
echo ${STABLE_SOME_KEY} > $@

@steeve can you share the build rules that can spin up a k3s cluster?