use caching for docker builds (#1340)

* try pulling for cached layers

* use cache-from and cache-to

* empty commit

* add readme

* use specific cache tags

* also cache from main

containers/build.sh

@@ -9,7 +9,9 @@ if [[ $3 == "--push" ]]; then
 fi
 
 echo -e "Building: $image_name"
-tags=(latest)
+tags=()
+cache_tag_base="buildcache"
+cache_tag="$cache_tag_base"
 if [[ -n $GITHUB_REF_NAME ]]; then
   # check if ref name is a version number
   if [[ $GITHUB_REF_NAME =~ ^v[0-9]+\.[0-9]+\.[0-9]+$ ]]; then
@@ -18,6 +20,7 @@ if [[ -n $GITHUB_REF_NAME ]]; then
     tags+=($major_version $minor_version)
   fi
   sanitized=$(echo $GITHUB_REF_NAME | sed 's/[^a-zA-Z0-9.-]\+/-/g')
+  cache_tag+="-${sanitized}"
   tags+=($sanitized)
 fi
 echo "Tags: ${tags[@]}"
@@ -38,7 +41,7 @@ fi
 DOCKER_REPOSITORY=$DOCKER_REGISTRY/$DOCKER_ORG/$DOCKER_IMAGE
 echo "Repo: $DOCKER_REPOSITORY"
 echo "Base dir: $DOCKER_BASE_DIR"
-#docker pull $DOCKER_REPOSITORY:main || true # try to get any cached layers
+
 args=""
 for tag in ${tags[@]}; do
   args+=" -t $DOCKER_REPOSITORY:$tag"
@@ -49,6 +52,9 @@ fi
 
 docker buildx build \
   $args \
+  --cache-to=type=registry,ref=$DOCKER_REPOSITORY:$cache_tag,mode=max \
+  --cache-from=type=registry,ref=$DOCKER_REPOSITORY:$cache_tag \
+  --cache-from=type=registry,ref=$DOCKER_REPOSITORY:$cache_tag_base-main \
   --platform linux/amd64,linux/arm64 \
   --provenance=false \
   -f $dir/Dockerfile $DOCKER_BASE_DIR