kernels: Add support for creating ubuntu kernel packages

This only covers the 4.x Ubuntu kernels and for now does
not include the headers to build modules against.

Signed-off-by: Rolf Neugebauer <rolf.neugebauer@docker.com>

scripts/kernels/ubuntu.sh

@@ -0,0 +1,34 @@
+#! /bin/sh
+
+REPO="linuxkit/kernel-ubuntu"
+BASE_URL=http://mirrors.kernel.org/ubuntu/pool/main/l/linux/
+
+ARCH=amd64
+LINKS=$(curl -s ${BASE_URL}/ | sed -n 's/.*href="\([^"]*\).*/\1/p')
+# Just get names for 4.x kernels
+KERNELS=$(echo $LINKS | \
+    grep -o "linux-image-4\.[0-9]\+\.[0-9]\+-[0-9]\+-generic_[^ ]\+${ARCH}\.deb")
+
+for KERN_DEB in $KERNELS; do
+    VERSION=$(echo $KERN_DEB | \
+        grep -o "[0-9]\+\.[0-9]\+\.[0-9]\+-[0-9]\+" | head -1)
+
+    echo "$VERSION -> $KERN_DEB"
+    DOCKER_CONTENT_TRUST=1 docker pull ${REPO}:${VERSION} && continue
+
+    EXTRA_DEB=$(echo $LINKS | \
+        grep -o "linux-image-extra-${VERSION}-generic_[^ ]\+${ARCH}\.deb")
+
+    # Don't pull in the headers. This is mostly for testing
+    # HDR_DEB=$(echo $LINKS | \
+    #     grep -o "linux-headers-${VERSION}_[^ ]\+_all\.deb")
+    # HDR_ARCH_DEB=$(echo $LINKS | \
+    #     grep -o "linux-headers-${VERSION}-generic_[^ ]\+_${ARCH}\.deb")
+
+    URLS="${BASE_URL}/${KERN_DEB} ${BASE_URL}/${EXTRA_DEB} ${BASE_URL}/${HDR_DEB} ${BASE_URL}/${HDR_ARCH_DEB}"
+
+    # Doesn't exist build and push
+    docker build -t ${REPO}:${VERSION} -f Dockerfile.deb --no-cache \
+           --build-arg DEB_URLS="${URLS}" . &&
+        DOCKER_CONTENT_TRUST=1 docker push ${REPO}:${VERSION})
+done