Update WORKSPACE

WORKSPACE

@@ -1,11 +1,6 @@
 register_toolchains("//:python_toolchain")
 
 load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive", "http_file")
-load(
-    "@bazel_tools//tools/build_defs/repo:http.bzl",
-    "http_archive",
-    "http_file",
-)
 load("@bazel_tools//tools/build_defs/repo:git.bzl", "git_repository")
 
 http_archive(

doc/build-the-builder.md

@@ -0,0 +1,75 @@
+# Build The KubeVirt CDI Builder Container
+
+## Native Build toolchain
+
+1. Install the [prerequisites](https://github.com/kubevirt/kubevirt/blob/main/docs/build-the-builder.md#prerequisites) as in the instructions for building the KubeVirt builder container.
+2. Also install `jq` if the docker build utility you use is `podman-buildah`.  
+3. Build the KubeVirt builder container if you haven't already
+
+
+## Environment Variables and defaults
+
+
+ | env variable | default | option or example |
+ | ------------ | ------- | -------- |
+ | BUILD_ARCH | amd64 | s390x aarch64 amd64 |
+ | DOCKER_PREFIX | quay.io/kubevirt | icr.io/kubevirt, docker.io/ibm, ... |
+ | QUAY_REPOSITORY | kubevirt-cdi-bazel-builder |  |
+ | UNTAGGED_BUILDER_IMAGE | quay.io/kubevirt/kubevirt-cdi-bazel-builder | ${DOCKER_PREFIX}/${QUAY_REPOSITORY} |
+ | BUILDER_TAG | <nothing> | s390xTest01 |
+
+Note: although `arm64` is equal to `aarch64` in CPU, this project only use `aarch64` in souce code.
+
+An example of setting these environment variables would be:
+```
+export BUILD_ARCH=s390x
+export DOCKER_PREFIX="icr.io/kubevirt"
+export QUAY_REPOSITORY=kubevirt-cdi-bazel-builder
+export UNTAGGED_BUILDER_IMAGE=${DOCKER_PREFIX}/${QUAY_REPOSITORY} 
+export BUILDER_TAG=s390xTest01
+```
+
+## Manual build of the builder container
+
+The point of this step is to build the CDI builder/helper container described in `hack/build/docker/builder/Dockerfile`. 
+
+```
+cd hack/build/docker/builder
+```
+
+The build can be conducted with either `podman-buildah` or `docker`.  
+
+### With Podman-buildah
+
+With podman-buildah the builder image can be built and pushed with:
+
+```
+buildah build --platform linux/${BUILD_ARCH} --manifest ${UNTAGGED_BUILDER_IMAGE}:${BUILDER_TAG} . 
+buildah manifest push --all ${UNTAGGED_BUILDER_IMAGE}:${BUILDER_TAG}  docker://${UNTAGGED_BUILDER_IMAGE}:${BUILDER_TAG}
+```
+and you can check the digest with: 
+```
+podman inspect $(podman images | grep ${UNTAGGED_BUILDER_IMAGE} | grep ${BUILDER_TAG} | awk '{ print $3 }') |  jq '.[]["Digest"]'
+```
+
+### With docker
+
+With docker, the builder image can be built and pushed with:
+
+```
+docker build --tag ${UNTAGGED_BUILDER_IMAGE}:${BUILDER_TAG} .
+```
+and you can check the digest with:
+```
+docker images --digests | grep ${UNTAGGED_BUILDER_IMAGE} | grep ${BUILDER_TA
+G} | awk '{ print $4 }'
+```
+
+## Make Target
+
+
+`make builder-push` both builds the KubeVirt CDI builder image and pushes it to the registry you specified in the environment variables (above); however the script only works when the following condition is false: 
+```
+git diff-index --quiet HEAD~1 hack/build/docker
+```
+since the make target to build the builder is only intended to run during a post-submit job where the PR has squashed the candidate into a single commit.