conf/distro: add build profile configuration fragments

Add includable configuration fragments that replace manual
DISTRO_FEATURES, CONTAINER_PROFILE, and related settings in
local.conf. Fragments are organized as a base + composable deltas:

- meta-virt-host.conf: base for all virtualization work
  (virtualization, systemd, seccomp, vmsep, vcontainer, BBMULTICONFIG)
- container-host-{docker,podman,containerd,k3s,k3s-node}.conf:
  container engine profiles setting CONTAINER_PROFILE and
  profile-specific DISTRO_FEATURES
- xen-host.conf: Xen hypervisor support (xen, vxn distro features,
  xen-image-minimal packages)
- meta-virt-dev.conf: QEMU development settings (IMAGE_FSTYPES,
  QB_MEM, debug image features)
- container-registry.conf: local dev registry defaults
  (insecure localhost:5000)

Profiles are pure deltas and do not auto-include the base to avoid
BitBake duplicate inclusion warnings. Users include meta-virt-host.conf
first, then add profile fragments. The BUILD_PROFILE variable enables
single-line profile switching.

Usage in local.conf:

  require conf/distro/include/meta-virt-host.conf
  BUILD_PROFILE ?= "podman"
  require conf/distro/include/container-host-${BUILD_PROFILE}.conf

Tested with podman, docker, and xen builds.

Signed-off-by: Bruce Ashfield <bruce.ashfield@gmail.com>

9 files changed, 174 insertions, 0 deletions

diff --git a/conf/distro/include/container-host-containerd.conf b/conf/distro/include/container-host-containerd.conf
new file mode 100644
index 00000000..c4a68845
--- /dev/null
+++ b/conf/distro/include/container-host-containerd.conf
@@ -0,0 +1,14 @@
+# Container host configuration fragment: Containerd
+#
+# Include from local.conf to set up a containerd-based container host.
+# Requires meta-virt-host.conf to be included first:
+#
+#   require conf/distro/include/meta-virt-host.conf
+#   require conf/distro/include/container-host-containerd.conf
+#   MACHINE = "qemux86-64"
+#   bitbake container-image-host
+#
+# Sets CONTAINER_PROFILE and the DISTRO_FEATURES required by
+# container-image-host with the containerd engine stack.
+
+CONTAINER_PROFILE = "containerd"
diff --git a/conf/distro/include/container-host-docker.conf b/conf/distro/include/container-host-docker.conf
new file mode 100644
index 00000000..5bf29359
--- /dev/null
+++ b/conf/distro/include/container-host-docker.conf
@@ -0,0 +1,14 @@
+# Container host configuration fragment: Docker
+#
+# Include from local.conf to set up a Docker-based container host.
+# Requires meta-virt-host.conf to be included first:
+#
+#   require conf/distro/include/meta-virt-host.conf
+#   require conf/distro/include/container-host-docker.conf
+#   MACHINE = "qemux86-64"
+#   bitbake container-image-host
+#
+# Sets CONTAINER_PROFILE and the DISTRO_FEATURES required by
+# container-image-host with the Docker engine stack.
+
+CONTAINER_PROFILE = "docker"
diff --git a/conf/distro/include/container-host-k3s-node.conf b/conf/distro/include/container-host-k3s-node.conf
new file mode 100644
index 00000000..75580d71
--- /dev/null
+++ b/conf/distro/include/container-host-k3s-node.conf
@@ -0,0 +1,18 @@
+# Container host configuration fragment: K3s agent node
+#
+# Include from local.conf to set up a K3s agent (worker) node.
+# Requires meta-virt-host.conf to be included first:
+#
+#   require conf/distro/include/meta-virt-host.conf
+#   require conf/distro/include/container-host-k3s-node.conf
+#   MACHINE = "qemux86-64"
+#   bitbake container-image-host
+#
+# Sets CONTAINER_PROFILE and the DISTRO_FEATURES required by
+# container-image-host with K3s agent-only orchestration. The
+# k3s-node profile bundles the k3s agent, embedded containerd,
+# and CNI plugins. The node joins an existing k3s server cluster.
+
+CONTAINER_PROFILE = "k3s-node"
+
+DISTRO_FEATURES:append = " k3s"
diff --git a/conf/distro/include/container-host-k3s.conf b/conf/distro/include/container-host-k3s.conf
new file mode 100644
index 00000000..6e3733b1
--- /dev/null
+++ b/conf/distro/include/container-host-k3s.conf
@@ -0,0 +1,17 @@
+# Container host configuration fragment: K3s server
+#
+# Include from local.conf to set up a K3s server (control plane + agent).
+# Requires meta-virt-host.conf to be included first:
+#
+#   require conf/distro/include/meta-virt-host.conf
+#   require conf/distro/include/container-host-k3s.conf
+#   MACHINE = "qemux86-64"
+#   bitbake container-image-host
+#
+# Sets CONTAINER_PROFILE and the DISTRO_FEATURES required by
+# container-image-host with K3s orchestration. The k3s-host profile
+# bundles the k3s server, embedded containerd, and CNI plugins.
+
+CONTAINER_PROFILE = "k3s-host"
+
+DISTRO_FEATURES:append = " k3s"
diff --git a/conf/distro/include/container-host-podman.conf b/conf/distro/include/container-host-podman.conf
new file mode 100644
index 00000000..7190e32b
--- /dev/null
+++ b/conf/distro/include/container-host-podman.conf
@@ -0,0 +1,17 @@
+# Container host configuration fragment: Podman
+#
+# Include from local.conf to set up a Podman-based container host.
+# Requires meta-virt-host.conf to be included first:
+#
+#   require conf/distro/include/meta-virt-host.conf
+#   require conf/distro/include/container-host-podman.conf
+#   MACHINE = "qemux86-64"
+#   bitbake container-image-host
+#
+# Sets CONTAINER_PROFILE and the DISTRO_FEATURES required by
+# container-image-host with the Podman engine stack.
+# Includes ipv6 which is required by the podman packagegroup.
+
+CONTAINER_PROFILE = "podman"
+
+DISTRO_FEATURES:append = " ipv6"
diff --git a/conf/distro/include/container-registry.conf b/conf/distro/include/container-registry.conf
new file mode 100644
index 00000000..357e7913
--- /dev/null
+++ b/conf/distro/include/container-registry.conf
@@ -0,0 +1,29 @@
+# Container registry configuration fragment
+#
+# Include from local.conf to enable a local development registry:
+#
+#   require conf/distro/include/container-registry.conf
+#
+# Defaults to an insecure (HTTP) registry at localhost:5000 with
+# namespace "yocto". Override any variable after the require line.
+#
+# This fragment enables the container-registry IMAGE_FEATURES, which
+# installs registry configuration into the target rootfs (daemon.json
+# for Docker, registries.conf.d/ for Podman/containerd).
+#
+# For a secure (TLS + authentication) registry, override these after
+# the require:
+#
+#   CONTAINER_REGISTRY_URL = "registry.example.com:5000"
+#   CONTAINER_REGISTRY_SECURE = "1"
+#   CONTAINER_REGISTRY_USERNAME = "myuser"
+#   # Optional: enable htpasswd authentication
+#   CONTAINER_REGISTRY_AUTH = "1"
+#   # Optional: custom namespace
+#   CONTAINER_REGISTRY_NAMESPACE = "myproject"
+
+CONTAINER_REGISTRY_URL ?= "localhost:5000"
+CONTAINER_REGISTRY_NAMESPACE ?= "yocto"
+CONTAINER_REGISTRY_INSECURE ?= "1"
+
+IMAGE_FEATURES:append = " container-registry"
diff --git a/conf/distro/include/meta-virt-dev.conf b/conf/distro/include/meta-virt-dev.conf
new file mode 100644
index 00000000..06dcbb95
--- /dev/null
+++ b/conf/distro/include/meta-virt-dev.conf
@@ -0,0 +1,28 @@
+# QEMU development and testing settings
+#
+# Include from local.conf when developing and testing with runqemu:
+#
+#   require conf/distro/include/meta-virt-dev.conf
+#
+# This is separate from the build profiles (container-host-*, xen-host-*)
+# and provides settings that only matter for QEMU-based development:
+# image format, memory, debug features, etc.
+#
+# Typical local.conf for QEMU-based k3s development:
+#
+#   require conf/distro/include/meta-virt-host.conf
+#   BUILD_PROFILE ?= "k3s"
+#   require conf/distro/include/container-host-${BUILD_PROFILE}.conf
+#   require conf/distro/include/meta-virt-dev.conf
+#   MACHINE = "qemux86-64"
+
+# Use raw ext4 for runqemu boot/test cycles.
+# Snapshot formats (qcow2) don't work well with repeated boots.
+IMAGE_FSTYPES = "ext4"
+
+# Xen QEMU settings: Dom0 memory cap and total VM memory
+QB_XEN_CMDLINE_EXTRA ?= "dom0_mem=512M"
+QB_MEM ?= "-m 1024"
+
+# Debug-friendly image features
+EXTRA_IMAGE_FEATURES ?= "allow-empty-password empty-root-password allow-root-login post-install-logging"
diff --git a/conf/distro/include/meta-virt-host.conf b/conf/distro/include/meta-virt-host.conf
new file mode 100644
index 00000000..99d5271e
--- /dev/null
+++ b/conf/distro/include/meta-virt-host.conf
@@ -0,0 +1,20 @@
+# Base virtualization host configuration fragment
+#
+# Common DISTRO_FEATURES for any virtualization work: containers, Xen,
+# k3s, or custom/mixed configurations.
+#
+# Use standalone for custom builds:
+#
+#   require conf/distro/include/meta-virt-host.conf
+#   MACHINE = "qemux86-64"
+#
+# Or let a specific profile (container-host-*, xen-host-*) inherit it.
+
+DISTRO_FEATURES:append = " virtualization systemd seccomp vmsep vcontainer"
+
+# Container runtime provider — the unified runc recipe provides both
+# runc-docker and runc-opencontainers via RPROVIDES
+PREFERRED_PROVIDER_virtual/runc ?= "runc"
+
+# Multiconfig for cross-arch vruntime builds (vdkr/vpdmn blobs)
+BBMULTICONFIG ?= "vruntime-aarch64 vruntime-x86-64"
diff --git a/conf/distro/include/xen-host.conf b/conf/distro/include/xen-host.conf
new file mode 100644
index 00000000..0d21cc63
--- /dev/null
+++ b/conf/distro/include/xen-host.conf
@@ -0,0 +1,17 @@
+# Xen host configuration fragment
+#
+# Include from local.conf for Xen Dom0 development and testing.
+# Requires meta-virt-host.conf to be included first:
+#
+#   require conf/distro/include/meta-virt-host.conf
+#   require conf/distro/include/xen-host.conf
+#   MACHINE = "qemux86-64"
+#   bitbake xen-image-minimal
+#
+# Enables Xen hypervisor support, vxn (Docker CLI for Xen), and containerd
+# for the OCI runtime path.
+
+DISTRO_FEATURES:append = " xen vxn"
+
+# Xen Dom0 image packages: vxn, containerd
+IMAGE_INSTALL:append:pn-xen-image-minimal = " vxn containerd-opencontainers"