From c9ead45731719ee51fce008ca47aa14ccc29bc66 Mon Sep 17 00:00:00 2001
From: Rolf Neugebauer <rolf.neugebauer@docker.com>
Date: Thu, 31 Aug 2017 17:04:25 +0100
Subject: [PATCH 1/3] kernel: Add Dockerfile to compile the ZFS kernel module

Note this is not the latest ZFS version but the version matched
by the current alpine zfs utilities.

Signed-off-by: Rolf Neugebauer <rolf.neugebauer@docker.com>
---
 kernel/Dockerfile.zfs | 59 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 59 insertions(+)
 create mode 100644 kernel/Dockerfile.zfs

diff --git a/kernel/Dockerfile.zfs b/kernel/Dockerfile.zfs
new file mode 100644
index 000000000..4bc34e619
--- /dev/null
+++ b/kernel/Dockerfile.zfs
@@ -0,0 +1,59 @@
+ARG IMAGE
+FROM ${IMAGE} AS ksrc
+FROM linuxkit/alpine:349a817bdd6b293ca623ab97acf5377ccdeac7d2 AS build
+RUN apk add \
+    attr-dev \
+    autoconf \
+    automake \
+    build-base \
+    file \
+    git \
+    libtirpc-dev \ 
+    libtool \
+    util-linux-dev \
+    zlib-dev
+
+COPY --from=ksrc /kernel-dev.tar /
+RUN tar xf kernel-dev.tar
+
+# Also extract the kernel modules
+COPY --from=ksrc /kernel.tar /
+RUN tar xf kernel.tar
+
+# Note: ZFS and SPL commits must match. It's unclear how much the user
+# space tools must match the kernel module version. The current zfs
+# package on Alpine is 0.6.5.9. We pick 0.6.5.10 because it has
+# support for 4.12 based kernels.
+ENV VERSION=0.6.5.10
+
+ENV SPL_REPO=https://github.com/zfsonlinux/spl.git
+ENV SPL_COMMIT=spl-${VERSION}
+RUN git clone ${SPL_REPO} && \
+    cd spl && \
+    git checkout ${SPL_COMMIT}
+
+ENV ZFS_REPO=https://github.com/zfsonlinux/zfs.git
+ENV ZFS_COMMIT=zfs-${VERSION}
+RUN git clone ${ZFS_REPO} && \
+    cd zfs && \
+    git checkout ${ZFS_COMMIT}
+
+WORKDIR /spl
+RUN ./autogen.sh && \
+    ./configure && \
+    cd module && \
+    make && \
+    make install
+
+WORKDIR /zfs
+RUN ./autogen.sh && \
+    ./configure --with-spl=/spl && \
+    cd module && \
+    make -j "$(getconf _NPROCESSORS_ONLN)" && \
+    make install
+
+FROM scratch
+ENTRYPOINT []
+CMD []
+WORKDIR /
+COPY --from=build /lib/modules/ /lib/modules/

From 8d45a96f34da115c25b33a18f25d1b2dbc35f98e Mon Sep 17 00:00:00 2001
From: Rolf Neugebauer <rolf.neugebauer@docker.com>
Date: Thu, 31 Aug 2017 17:09:49 +0100
Subject: [PATCH 2/3] kernel: Add zfs kmod build to the kernel build

This adds building the zfs-kmod package to the kernel build.
The zfs-kmod packages contains the matching ZFS kernel modules
for a given kernel in /lib/modules/$(uname -r)/extra.

The zfs-kmod package also contains the standard kernel modules
and depmod is run over them so that modprobe works

The zfs-kmod package is not build by default due to unclarity
about licenses. Users will have to build it themselves.

Signed-off-by: Rolf Neugebauer <rolf.neugebauer@docker.com>
---
 kernel/Makefile | 25 ++++++++++++++++++++++++-
 1 file changed, 24 insertions(+), 1 deletion(-)

diff --git a/kernel/Makefile b/kernel/Makefile
index 25ca0fcdf..0da485528 100644
--- a/kernel/Makefile
+++ b/kernel/Makefile
@@ -16,6 +16,7 @@
 ORG?=linuxkit
 IMAGE:=kernel
 IMAGE_PERF:=kernel-perf
+IMAGE_ZFS:=zfs-kmod
 
 # You can specify an extra options for the Makefile. This will:
 # - append a kernel_config$(EXTRA) to the kernel config for your kernel/arch
@@ -118,11 +119,13 @@ push: push_$(2)$(3)
 show-tags: show-tag_$(2)$(3)
 fetch: sources/linux-$(1).tar.xz
 
-ifneq ($(2), 4.4.x)
 # 'docker build' with the FROM image supplied as --build-arg
 # *and* with DOCKER_CONTENT_TRUST=1 currently does not work
 # (https://github.com/moby/moby/issues/34199). So, we pull the image
 # with DCT and then build with DOCKER_CONTENT_TRUST explicitly set to 0.
+
+ifneq ($(2), 4.4.x)
+# perf does not build out of the box for 4.4.x and 4.4.x is not that relevant anymore to work on a fix
 build_perf_$(2)$(3): build_$(2)$(3)
 	docker pull $(ORG)/$(IMAGE_PERF):$(1)$(3)-$(TAG)$(SUFFIX) || \
 		(docker pull $(ORG)/$(IMAGE):$(1)$(3)-$(TAG)$(SUFFIX) && \
@@ -143,6 +146,26 @@ build: build_perf_$(2)$(3)
 push: push_perf_$(2)$(3)
 endif
 
+ifneq ($(3), -dbg)
+# ZFS does not compile against -dbg kernels because CONFIG_DEBUG_LOCK_ALLOC
+# is incompatible with CDDL, apparently (this is ./configure check)
+build_zfs_$(2)$(3): build_$(2)$(3)
+	docker pull $(ORG)/$(IMAGE_ZFS):$(1)$(3)-$(TAG)$(SUFFIX) || \
+		(docker pull $(ORG)/$(IMAGE):$(1)$(3)-$(TAG)$(SUFFIX) && \
+		 DOCKER_CONTENT_TRUST=0 docker build -f Dockerfile.zfs \
+			--build-arg IMAGE=$(ORG)/$(IMAGE):$(1)$(3)-$(TAG)$(SUFFIX) \
+			--no-cache $(LABEL) -t $(ORG)/$(IMAGE_ZFS):$(1)$(3)-$(TAG)$(SUFFIX) .)
+
+push_zfs_$(2)$(3): build_zfs_$(2)$(3)
+	@if [ x"$(DIRTY)" != x ]; then echo "Your repository is not clean. Will not push image"; exit 1; fi
+	docker pull $(ORG)/$(IMAGE_ZFS):$(1)$(3)-$(TAG)$(SUFFIX) || \
+		(docker push $(ORG)/$(IMAGE_ZFS):$(1)$(3)-$(TAG)$(SUFFIX) && \
+		 docker tag $(ORG)/$(IMAGE_ZFS):$(1)$(3)-$(TAG)$(SUFFIX) $(ORG)/$(IMAGE_ZFS):$(1)$(3)$(SUFFIX) && \
+		 docker push $(ORG)/$(IMAGE_ZFS):$(1)$(3)$(SUFFIX) && \
+		 $(PUSH_MANIFEST) $(ORG)/$(IMAGE_ZFS):$(1)$(3)-$(TAG) $(DOCKER_CONTENT_TRUST) && \
+		 $(PUSH_MANIFEST) $(ORG)/$(IMAGE_ZFS):$(1)$(3) $(DOCKER_CONTENT_TRUST))
+endif
+
 endef
 
 #

From 5865a1aff36aa925d23afa19a3132818dac316b7 Mon Sep 17 00:00:00 2001
From: Rolf Neugebauer <rolf.neugebauer@docker.com>
Date: Wed, 6 Sep 2017 15:44:41 +0100
Subject: [PATCH 3/3] doc: Add some notes on ZFS

Signed-off-by: Rolf Neugebauer <rolf.neugebauer@docker.com>
---
 docs/kernels.md | 36 ++++++++++++++++++++++++++++++++++++
 1 file changed, 36 insertions(+)

diff --git a/docs/kernels.md b/docs/kernels.md
index 2daa65c65..139967e46 100644
--- a/docs/kernels.md
+++ b/docs/kernels.md
@@ -307,3 +307,39 @@ nsenter -m/proc/1/ns/mnt ash
 
 Alternatively, you can add the `kernel-perf` package as stage in a
 multi-stage build to add it to a custom package.
+
+
+## ZFS
+
+The kernel build Makefile has support for building the ZFS kernel
+modules. Note, the modules are currently not distributed as standard
+LinuxKit packages and if you wish to use them you have to compile them
+yourself:
+
+```sh
+cd kernel
+make ORG=<foo> NOTRUST=1 push_zfs_4.9.x # or different kernel version
+```
+
+will build and push a `zfs-kmod-4.9.<version>` image to Docker Hub
+under the `ORG` specified. This package contains the all the standard
+kernel modules from the kernel specified plus the `spl` and `zfs`
+kernel modules, with `depmod` run over them, so they can be
+`modprobe`ed. To use the modules do something like this in your YAML
+file:
+
+```
+kernel:
+  image: linuxkit/kernel:4.9.47
+  cmdline: "console=tty0 console=ttyS0 console=ttyAMA0"
+init:
+  - <foo>/zfs-kmod:4.9.47
+  ...
+```
+
+Then, you also need to make sure the Alpine `zfs` utilities are
+available in the container where your want to run `zfs` commands. The
+Alpine `zfs` utilities are available in `linuxkit/alpine` and the
+version of the kernel module should match the version of the
+tools. The container where you run the `zfs` tools might also need
+`CAP_SYS_MODULE` to be able to load the kernel modules.