From 5a3180065b0c63c5c1116efbbe67f5c07ca194e3 Mon Sep 17 00:00:00 2001
From: Tugdual Saunier <tugdual.saunier@gmail.com>
Date: Sun, 16 Apr 2023 16:52:02 -0400
Subject: [PATCH] Build the Docker driver for arm64

**What this PR does / why we need it**:
Add ARM64 build and release of the Docker driver in Drone pipeline

**Which issue(s) this PR fixes**:
Fixes #5682

**Special notes for your reviewer**:
I would have loved to have a unified x64 and arm64 build but apparently Docker drivers does not support multi arch images.
So instead I went with tweaking the build steps to allow cross building the image for ARM64 and added the instructions to do so in `drone.yml`.

**Checklist**
- [x] Reviewed the [`CONTRIBUTING.md`](https://github.com/grafana/loki/blob/main/CONTRIBUTING.md) guide (**required**)
- [x] Documentation added
- [ ] Tests updated
- [ ] Changes that require user attention or interaction to upgrade are documented in `docs/sources/upgrading/_index.md`
---
 .drone/drone.jsonnet                           |  1 +
 Makefile                                       |  7 ++++++-
 clients/cmd/docker-driver/Dockerfile           | 18 ++++++++++++++----
 docs/sources/send-data/docker-driver/_index.md |  3 +++
 4 files changed, 24 insertions(+), 5 deletions(-)

diff --git a/.drone/drone.jsonnet b/.drone/drone.jsonnet
index 718f0a84aa886..5c8e154960f93 100644
--- a/.drone/drone.jsonnet
+++ b/.drone/drone.jsonnet
@@ -628,6 +628,7 @@ local build_image_tag = '0.33.2';
         commands: [
           'git fetch origin --tags',
           'make docker-driver-push',
+          'make docker-driver-push PLUGIN_ARCH=-arm64',
         ],
         volumes: [
           {
diff --git a/Makefile b/Makefile
index cadce23fe2624..463caf5f6be09 100644
--- a/Makefile
+++ b/Makefile
@@ -458,13 +458,18 @@ endif
 LOKI_DOCKER_DRIVER ?= "grafana/loki-docker-driver"
 PLUGIN_TAG ?= $(IMAGE_TAG)
 PLUGIN_ARCH ?=
+PLUGIN_BUILD_ARGS ?=
+ifeq ("$(PLUGIN_ARCH)", "-arm64")
+	PLUGIN_BUILD_ARGS = --build-arg GOARCH=arm64
+endif
 
 # build-rootfs
 # builds the plugin rootfs
 define build-rootfs
 	rm -rf clients/cmd/docker-driver/rootfs || true
 	mkdir clients/cmd/docker-driver/rootfs
-	docker build --build-arg $(BUILD_IMAGE) -t rootfsimage -f clients/cmd/docker-driver/Dockerfile .
+
+	docker build $(PLUGIN_BUILD_ARGS) --build-arg $(BUILD_IMAGE) -t rootfsimage -f clients/cmd/docker-driver/Dockerfile .
 
 	ID=$$(docker create rootfsimage true) && \
 	(docker export $$ID | tar -x -C clients/cmd/docker-driver/rootfs) && \
diff --git a/clients/cmd/docker-driver/Dockerfile b/clients/cmd/docker-driver/Dockerfile
index 88f6b47fe2623..fc429182e4855 100644
--- a/clients/cmd/docker-driver/Dockerfile
+++ b/clients/cmd/docker-driver/Dockerfile
@@ -1,16 +1,26 @@
+
 ARG BUILD_IMAGE=grafana/loki-build-image:0.33.4
+ARG GOARCH=amd64
 # Directories in this file are referenced from the root of the project not this folder
 # This file is intended to be called from the root like so:
-# docker build -t grafana/loki -f cmd/loki/Dockerfile .
+# docker build -t grafana/loki-docker-driver -f clients/cmd/docker-driver/Dockerfile .
 
-# TODO: add cross-platform support
 FROM $BUILD_IMAGE as build
 COPY . /src/loki
 WORKDIR /src/loki
 RUN make clean && make BUILD_IN_CONTAINER=false clients/cmd/docker-driver/docker-driver
 
-FROM alpine:3.18.5
-RUN apk add --update --no-cache ca-certificates tzdata
+FROM alpine:3.18.5 as temp
+
+RUN apk add --update --no-cache --arch=${GOARCH} ca-certificates tzdata
+
+FROM --platform=linux/${GOARCH} alpine:3.18.5
+
+COPY --from=temp /etc/ca-certificates.conf /etc/ca-certificates.conf
+COPY --from=temp /usr/share/ca-certificates /usr/share/ca-certificates
+COPY --from=temp /usr/share/zoneinfo /usr/share/zoneinfo
+
 COPY --from=build /src/loki/clients/cmd/docker-driver/docker-driver /bin/docker-driver
+
 WORKDIR /bin/
 ENTRYPOINT [ "/bin/docker-driver" ]
diff --git a/docs/sources/send-data/docker-driver/_index.md b/docs/sources/send-data/docker-driver/_index.md
index f262829d58fd7..bc290fd9a3ff3 100644
--- a/docs/sources/send-data/docker-driver/_index.md
+++ b/docs/sources/send-data/docker-driver/_index.md
@@ -31,6 +31,9 @@ Run the following command to install the plugin, updating the release version if
 ```bash
 docker plugin install grafana/loki-docker-driver:2.9.2 --alias loki --grant-all-permissions
 ```
+{{% admonition type="note" %}}
+Add `-arm64` to the image tag for AMR64 hosts.
+{{% /admonition %}}
 
 To check installed plugins, use the `docker plugin ls` command. 
 Plugins that have started successfully are listed as enabled: