ci: implement simple package cache

sync tarball of sources on S3 to use as a simple cache of these
packages so we don't have to download them from the internet
everytime.

We have to special case xtensa because of how the build dirs for
it work.

Signed-off-by: Kumar Gala <[email protected]>

Author: galak

.buildkite/download.yml

@@ -5,9 +5,10 @@ steps:
     command:
     - buildkite-agent artifact download crosstool.linux.x86_64.tar.bz2 .
     - tar xf crosstool.linux.x86_64.tar.bz2
+    - aws s3 sync s3://builds.zephyrproject.org/sdk/cache/ build/output/sources
     - export CT_ONLY_DOWNLOAD=y
     - ./go.sh arm
-    - buildkite-agent artifact upload "build/output/sources/*"
+    - aws s3 sync build/output/sources s3://builds.zephyrproject.org/sdk/cache/
     env:
       BUILDKITE_CLEAN_CHECKOUT: "true"
     plugins:

.buildkite/pipeline-template.yml

@@ -41,7 +41,16 @@ steps:
          16) TARGET="arc64";;
       esac
     - buildkite-agent artifact download crosstool.$OS.$MACHINE.tar.bz2 .
-    - buildkite-agent artifact download build/output/sources/* .
+    - >
+      case "$${TARGET}" in
+         xtensa_*)
+           TARGET_DIR="xtensa/$${TARGET#xtensa_}/"
+           aws s3 sync s3://builds.zephyrproject.org/sdk/cache/ build/output/$${TARGET_DIR}/sources
+           ;;
+         *)
+           aws s3 sync s3://builds.zephyrproject.org/sdk/cache/ build/output/sources
+           ;;
+      esac
     - tar xf crosstool.$OS.$MACHINE.tar.bz2
     - ./go.sh $${TARGET}
     - >