feat(devtool): pull latest test artifacts

Instead of using fixed artifact path for a current FC version
pull latest artifacts from S3. This way we can update them
independently while keeping old versions around.

Signed-off-by: Egor Lazarchuk <yegorlz@amazon.co.uk>

Author: ShadowCurse

tools/devtool

@@ -133,6 +133,14 @@ TARGET_PREFIX="$(uname -m)-unknown-linux-"
 # Container path to directory where we store built CI artifacts.
 CTR_CI_ARTIFACTS_PATH="${CTR_FC_ROOT_DIR}/resources/$(uname -m)"
 
+DEFAULT_ARTIFACTS_S3_BUCKET=s3://spec.ccfc.min/firecracker-ci
+
+# Query default S3 bucket with artifacts and return the most recient path
+get_newest_s3_artifacts() {
+  echo $(aws s3 ls $DEFAULT_ARTIFACTS_S3_BUCKET/ --no-sign-request | grep "PRE" | sort -k2 | tail -1 | awk -v bucket="$DEFAULT_ARTIFACTS_S3_BUCKET" '{print bucket "/" $2}')
+}
+
+
 # Check if Docker is available and exit if it's not.
 # Upon returning from this call, the caller can be certain Docker is available.
 #
@@ -571,9 +579,8 @@ ensure_ci_artifacts() {
     fi
 
     # Fetch all the artifacts so they are local
-    say "Fetching CI artifacts from S3"
-    FC_VERSION=$(cmd_sh "cd src/firecracker/src; cargo pkgid | cut -d# -f2 | cut -d. -f1-2")
-    S3_URL=s3://spec.ccfc.min/firecracker-ci/v$FC_VERSION/$(uname -m)
+    S3_URL=$(get_newest_s3_artifacts)/$(uname -m)
+    say "Fetching CI artifacts from S3: " $S3_URL
     ARTIFACTS=$MICROVM_IMAGES_DIR/$(uname -m)
     if [ ! -d "$ARTIFACTS" ]; then
         mkdir -pv $ARTIFACTS