run_sdk_container: Fall back to tar ball download for SDK image

The nightly SDK image is not pushed to a registry but has to be
downloaded from the build server as tar ball.
Fall back to the tar ball import for a better user experience.
To reuse the ci logic it had to support the "docker" env variable.
The use of the pigz container is not always needed if the user has
pigz available.

ci-automation/ci-config.env

@@ -17,8 +17,10 @@ CONTAINER_REGISTRY="ghcr.io/flatcar-linux"
 
 GC_BUCKET="flatcar-linux"
 
+if ! command -v pigz > /dev/null; then
   # No PIGZ on Flatcar
   PIGZ="docker run --rm -i ghcr.io/flatcar-linux/pigz --fast"
+fi
 
 CI_GIT_AUTHOR="flatcar-ci"
 CI_GIT_EMAIL="infra+ci@flatcar-linux.org"

ci-automation/ci_automation_common.sh

@@ -8,6 +8,7 @@
 
 source ci-automation/ci-config.env
 : ${PIGZ:=pigz}
+: ${docker:=docker}
 
 function init_submodules() {
     git submodule init
@@ -136,7 +137,7 @@ function image_exists_locally() {
     local version="$2"
     local image="${name}:${version}"
 
-    local image_exists="$(docker images "${image}" \
+    local image_exists="$($docker images "${image}" \
                             --no-trunc --format '{{.Repository}}:{{.Tag}}')"
 
     [ "${image}" = "${image_exists}" ]
@@ -157,7 +158,7 @@ function docker_image_fullname() {
     local image="$1"
     local version="$2"
 
-    docker images --no-trunc --format '{{.Repository}}:{{.Tag}}' \
+    $docker images --no-trunc --format '{{.Repository}}:{{.Tag}}' \
         | grep -E "^(${CONTAINER_REGISTRY}/)*${image}:${version}$"
 }
 # --
@@ -169,7 +170,7 @@ function docker_image_to_buildcache() {
     # strip potential container registry prefix
     local tarball="$(basename "$image")-${version}.tar.gz"
 
-    docker save "${image}":"${version}" | $PIGZ -c > "${tarball}"
+    $docker save "${image}":"${version}" | $PIGZ -c > "${tarball}"
     copy_to_buildcache "containers/${version}" "${tarball}"
 }
 # --
@@ -179,7 +180,7 @@ function docker_commit_to_buildcache() {
     local image_name="$2"
     local image_version="$3"
 
-    docker commit "${container}" "${image_name}:${image_version}"
+    $docker commit "${container}" "${image_name}:${image_version}"
     docker_image_to_buildcache "${image_name}" "${image_version}"
 }
 # --
@@ -199,7 +200,7 @@ function docker_image_from_buildcache() {
         --retry-connrefused --retry-max-time 60 --connect-timeout 20 \
         --remote-name "${url}"
 
-    cat "${tgz}" | $PIGZ -d -c | docker load
+    cat "${tgz}" | $PIGZ -d -c | $docker load
 
     rm "${tgz}"
 }
@@ -213,10 +214,11 @@ function docker_image_from_registry_or_buildcache() {
         return
     fi
 
-    if docker pull "${CONTAINER_REGISTRY}/${image}:${version}" ; then
+    if $docker pull "${CONTAINER_REGISTRY}/${image}:${version}" ; then
         return
     fi
 
+    echo "Falling back to tar ball download..." >&2
     docker_image_from_buildcache "${image}" "${version}"
 }
 # --

run_sdk_container

@@ -4,7 +4,7 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
-set -eu
+set -euo pipefail
 
 cd $(dirname "$0")
 source sdk_lib/sdk_container_common.sh
@@ -104,6 +104,9 @@ if [ -z "$stat" ] ; then
 
     gpg_volumes=$(gnupg_ssh_gcloud_mount_opts)
 
+    source ci-automation/ci_automation_common.sh
+    docker_image_from_registry_or_buildcache "flatcar-sdk-${arch}" "${docker_sdk_vernum}"
+
     $docker create $tty -i \
        -v /dev:/dev \
        -v "$(pwd)/sdk_container:/mnt/host/source/" \