seedling: Generic arm64 isos (#1291)

🌱 Generate arm64 generic isos

 - Use latest osbuilder tools image as it contains fixes for arm64 isos
 - Add a small job to build an iso as part of the image arm workflow
 - Rework /boot/vmlinuz linking so it works on x86 and arm64

This also adds an iso-remote target for earthfile that allows to build
an iso from a remote rootfs in the shape of a docker artifact. This
allows for easy reproduce of isos based on existing artifacts instead of
having to rebuild the whole thing. You point to the artifact and it
spits an iso really fast. Also works with arm64 artifacts so we can
easily build a local arm64 iso for testing for pushed artifacts.

This PR makes it so generation of isos for arm64 works.

Signed-off-by: Itxaka <itxakaserrano@gmail.com>

Earthfile

@@ -2,7 +2,8 @@ VERSION 0.6
 FROM alpine
 ARG VARIANT=core # core, lite, framework
 ARG FLAVOR=opensuse-leap
-ARG IMAGE=quay.io/kairos/${VARIANT}-${FLAVOR}:latest
+ARG BASE_URL=quay.io/kairos
+ARG IMAGE=${BASE_URL}/${VARIANT}-${FLAVOR}:latest
 ARG ISO_NAME=kairos-${VARIANT}-${FLAVOR}
 # renovate: datasource=docker depName=quay.io/luet/base
 ARG LUET_VERSION=0.34.0
@@ -353,7 +354,6 @@ base-image:
         # no dracut on those flavors, do nothing
     ELSE
         # Regenerate initrd if necessary
-        RUN --no-cache kernel=$(ls /boot/vmlinuz-* | head -n1) && ln -sf "${kernel#/boot/}" /boot/vmlinuz
         RUN --no-cache kernel=$(ls /lib/modules | head -n1) && dracut -f "/boot/initrd-${kernel}" "${kernel}" && ln -sf "initrd-${kernel}" /boot/initrd
         RUN --no-cache kernel=$(ls /lib/modules | head -n1) && depmod -a "${kernel}"
     END
@@ -363,15 +363,23 @@ base-image:
         RUN rm -rf /boot/initramfs-*
     END
 
+    # Set /boot/vmlinuz pointing to our kernel so elemental-cli can use it
+    # https://github.com/kairos-io/elemental-cli/blob/23ca64435fedb9f521c95e798d2c98d2714c53bd/pkg/elemental/elemental.go#L553
     IF [ ! -e "/boot/vmlinuz" ]
         # If it's an ARM flavor, we want a symlink here from zImage/Image
-        IF [ -e "/boot/Image" ]
+        # Check that its not a symlink already or grub will fail!
+        IF [ -e "/boot/Image" ] && [ ! -L "/boot/Image" ]
             RUN ln -sf Image /boot/vmlinuz
         ELSE IF [ -e "/boot/zImage" ]
-            RUN ln -sf zImage /boot/vmlinuz
+            IF  [ ! -L "/boot/zImage" ]
+                RUN ln -sf zImage /boot/vmlinuz
+            ELSE
+                RUN kernel=$(ls /boot/zImage-* | head -n1) && if [ -e "$kernel" ]; then ln -sf "${kernel#/boot/}" /boot/vmlinuz; fi
+            END
         ELSE
-            RUN kernel=$(ls /lib/modules | head -n1) && \
-             ln -sf "${kernel#/boot/}" /boot/vmlinuz
+            # Debian has vmlinuz-VERSION
+            RUN kernel=$(ls /boot/vmlinuz-* | head -n1) && if [ -e "$kernel" ]; then ln -sf "${kernel#/boot/}" /boot/vmlinuz; fi
+            RUN kernel=$(ls /boot/Image-* | head -n1) && if [ -e "$kernel" ]; then ln -sf "${kernel#/boot/}" /boot/vmlinuz; fi
         END
     END
 
@@ -419,6 +427,23 @@ iso:
     SAVE ARTIFACT /build/$ISO_NAME.iso kairos.iso AS LOCAL build/$ISO_NAME.iso
     SAVE ARTIFACT /build/$ISO_NAME.iso.sha256 kairos.iso.sha256 AS LOCAL build/$ISO_NAME.iso.sha256
 
+# This target builds an iso using a remote docker image as rootfs instead of building the whole rootfs
+# This should be really fast as it uses an existing image. This requires a pushed image from the +image target
+# defaults to use the $IMAGE name (so ttl.sh/core-opensuse-leap:latest)
+# you can override either the full thing by setting --IMG=docker:REPO/IMAGE:TAG
+# or by --IMAGE=REPO/IMAGE:TAG
+iso-remote:
+    ARG OSBUILDER_IMAGE
+    ARG ISO_NAME=${OS_ID}
+    ARG IMG=docker:$IMAGE
+    ARG overlay=overlay/files-iso
+    FROM $OSBUILDER_IMAGE
+    WORKDIR /build
+    COPY . ./
+    RUN /entrypoint.sh --name $ISO_NAME --debug build-iso --squash-no-compression --date=false $IMG --overlay-iso /build/${overlay} --output /build/
+    SAVE ARTIFACT /build/$ISO_NAME.iso kairos.iso AS LOCAL build/$ISO_NAME.iso
+    SAVE ARTIFACT /build/$ISO_NAME.iso.sha256 kairos.iso.sha256 AS LOCAL build/$ISO_NAME.iso.sha256
+
 netboot:
    ARG OSBUILDER_IMAGE
    FROM $OSBUILDER_IMAGE