feat: add custodian base image Dockerfile

Author: starpit

Diff for: deploy/custodian/Dockerfile

@@ -0,0 +1,9 @@
+FROM alpine/helm:3.11.3
+
+LABEL org.opencontainers.image.source https://github.com/project-codeflare/codeflare-cli
+
+RUN if [[ $(uname -m) = aarch64 ]]; then KUBECTL_ARCH=arm64; else KUBECTL_ARCH=amd64; fi; curl -LO "https://dl.k8s.io/release/$(curl -L -s https://dl.k8s.io/release/stable.txt)/bin/linux/$KUBECTL_ARCH/kubectl" && \
+        chmod a+rx kubectl && \
+        mv kubectl /usr/local/bin
+
+ENTRYPOINT bash

Diff for: deploy/custodian/README.md

@@ -0,0 +1,45 @@
+# Guide for building multi-arch docker images
+
+## Creating a `docker buildx` build config
+
+To build for both amd64 and aarch4 (e.g. for running on Apple
+Silicon), you can use `docker buildx`.
+
+First, you will need to create a buildx config, because the default
+one does not seem to work well for cross-platform builds. Here we name
+that config `multiarch`, but it can be named anything.
+
+We have found that using the `kubernetes` driver works better than the
+default `docker-container` driver.
+
+```shell
+docker buildx create --name multiarch --use --driver kubernetes --driver-opt=qemu.install=true
+```
+
+The `--use` part tells buildx to set this as the default builder.
+
+_Note_: We tell docker buildx to use qemu, so that the amd64 images
+can be built on an aarch64 host.
+
+_Warning_: If your KUBECONFIG env var is colon-separated, this is
+something that `docker buildx` apparently does not support. You will
+need to run any `docker buildx` commands with
+e.g. `KUBECONFIG=~/.kube/config`, i.e. pointing it to a single
+filepath.
+
+## Starting a build
+
+Now you should be able to build and push:
+
+```shell
+# whatever you need here, but note that the Dockerfiles
+# may need to change, as you update these image names and tags
+TAG=ghcr.io/project-codeflare/custodian:0.0.1
+
+# build for aarch64 (arm64/v8) and amd64
+PLATFORMS=linux/arm64/v8,linux/amd64
+
+# note here that we build and push in one step; for some reason,
+# buildx fails when only building
+docker buildx build --push --platforms $PLATFORMS --tag $TAG .
+```