container-yocto-builder: add Yocto build container with systemd

Multi-layer OCI container image that can compile the Yocto Project.
Three layers: systemd-base, build-tools, yocto-extras. Features
CROPS-style dynamic user creation matching /workdir volume owner
UID/GID.

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

1 files changed, 48 insertions, 0 deletions

diff --git a/recipes-extended/builder-container-config/files/builder-entry.sh b/recipes-extended/builder-container-config/files/builder-entry.sh
new file mode 100644
index 00000000..a23d8dae
--- /dev/null
+++ b/recipes-extended/builder-container-config/files/builder-entry.sh
@@ -0,0 +1,48 @@
+#!/bin/bash
+# builder-entry.sh - Container entrypoint for Yocto builder
+# Creates a 'builder' user matching the /workdir owner's UID/GID,
+# then exec's /sbin/init (systemd).
+#
+# Usage:
+#   docker run --privileged -v /home/user/yocto:/workdir builder-image
+#   docker run --privileged -e BUILDER_UID=1000 -e BUILDER_GID=1000 builder-image
+
+WORKDIR="/workdir"
+DEFAULT_UID=1000
+DEFAULT_GID=1000
+
+# Determine UID/GID
+if [ -n "$BUILDER_UID" ] && [ -n "$BUILDER_GID" ]; then
+    TARGET_UID="$BUILDER_UID"
+    TARGET_GID="$BUILDER_GID"
+elif [ -d "$WORKDIR" ] && [ "$(stat -c %u "$WORKDIR")" != "0" ]; then
+    TARGET_UID=$(stat -c %u "$WORKDIR")
+    TARGET_GID=$(stat -c %g "$WORKDIR")
+else
+    TARGET_UID=$DEFAULT_UID
+    TARGET_GID=$DEFAULT_GID
+fi
+
+# Refuse UID/GID 0 (root)
+[ "$TARGET_UID" = "0" ] && TARGET_UID=$DEFAULT_UID
+[ "$TARGET_GID" = "0" ] && TARGET_GID=$DEFAULT_GID
+
+# Create group and user if they don't exist
+if ! getent group builder >/dev/null 2>&1; then
+    groupadd -g "$TARGET_GID" builder 2>/dev/null || groupadd builder
+fi
+if ! getent passwd builder >/dev/null 2>&1; then
+    useradd -m -u "$TARGET_UID" -g builder -s /bin/bash builder
+fi
+
+# Ensure /workdir is accessible
+[ -d "$WORKDIR" ] && chown builder:builder "$WORKDIR"
+
+# Grant passwordless sudo
+if [ -d /etc/sudoers.d ]; then
+    echo "builder ALL=(ALL) NOPASSWD: ALL" > /etc/sudoers.d/builder
+    chmod 0440 /etc/sudoers.d/builder
+fi
+
+# Hand off to systemd
+exec /sbin/init "$@"