workflows: upload os images on build

.github/workflows/os.yml

@@ -3,9 +3,11 @@ on:
   push:
     paths:
     - "os/**"
+    - "hack/os/**"
   pull_request:
     paths:
     - "os/**"
+    - "hack/os/**"
 jobs:
   build:
     name: build
@@ -16,3 +18,9 @@ jobs:
     - run: ./hack/os/build.sh
       env:
         KRATA_KERNEL_BUILD_JOBS: "5"
+    - uses: actions/upload-artifact@v4
+      with:
+        name: krata-os-x86_64
+        path: "target/os/krata.qcow2"
+        compression-level: 0
+  

hack/os/build.sh

@@ -16,14 +16,18 @@ docker run --rm --privileged -v "${PWD}:/mnt" -it alpine:latest "/mnt/os/interna
 sudo chown "${USER}:${GROUP}" "${TARGET_OS_DIR}/rootfs.tgz"
 sudo modprobe nbd
 
-NBD_DEVICE="$(find /dev -maxdepth 2 -name 'nbd[0-9]*' | while read -r DEVICE
+next_nbd_device() {
+  find /dev -maxdepth 2 -name 'nbd[0-9]*' | while read -r DEVICE
   do
     if [ "$(sudo blockdev --getsize64 "${DEVICE}")" = "0" ]
     then
       echo "${DEVICE}"
       break
     fi
-done)"
+  done
+}
+
+NBD_DEVICE="$(next_nbd_device)"
 
 if [ -z "${NBD_DEVICE}" ]
 then