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 grafana#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
- [ ] `CHANGELOG.md` updated
- [ ] Changes that require user attention or interaction to upgrade are documented in `docs/sources/upgrading/_index.md`

.drone/drone.jsonnet

@@ -918,6 +918,7 @@ local manifest_ecr(apps, archs) = pipeline('manifest-ecr') {
         },
         commands: [
           'make docker-driver-push',
+          'make docker-driver-push PLUGIN_ARCH=-arm64',
         ],
         volumes: [
           {

CHANGELOG.md

@@ -17,6 +17,7 @@
 * [10380](https://github.com/grafana/loki/pull/10380) **shantanualsi** Remove `experimental.ruler.enable-api` in favour of `ruler.enable-api`
 * [10395](https://github.com/grafana/loki/pull/10395/) **shantanualshi** Remove deprecated `split_queries_by_interval` and `forward_headers_list` configuration options in the `query_range` section
 * [10456](https://github.com/grafana/loki/pull/10456) **dannykopping** Add `loki_distributor_ingester_append_timeouts_total` metric, remove `loki_distributor_ingester_append_failures_total` metric
+* [9247](https://github.com/grafana/loki/pull/9247) **tucksaun**: Build the Docker driver for arm64
 
 ##### Fixes
 

Makefile

@@ -421,13 +421,18 @@ endif
 LOKI_DOCKER_DRIVER ?= "grafana/loki-docker-driver"
 PLUGIN_TAG ?= $(IMAGE_TAG)
 PLUGIN_ARCH ?=
+ifeq ("$(PLUGIN_ARCH)", "-arm64")
+	PLUGIN_BUILD_ARGS = --build-arg GOARCH=arm64
+else
+	PLUGIN_BUILD_ARGS = 
+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 -t rootfsimage -f clients/cmd/docker-driver/Dockerfile .
+	docker build $(PLUGIN_BUILD_ARGS) -t rootfsimage -f clients/cmd/docker-driver/Dockerfile .
 
 	ID=$$(docker create rootfsimage true) && \
 	(docker export $$ID | tar -x -C clients/cmd/docker-driver/rootfs) && \

clients/cmd/docker-driver/Dockerfile

@@ -1,16 +1,25 @@
 ARG BUILD_IMAGE=grafana/loki-build-image:0.29.3
+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:3.16.7
-RUN apk add --update --no-cache ca-certificates tzdata
+FROM alpine:3.16.7 as temp
+
+RUN apk add --update --no-cache --arch=${GOARCH} ca-certificates tzdata
+
+FROM --platform=linux/${GOARCH} alpine:3.16.7
+
+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" ]

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:2.8.2 --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: