Slides from Docker Los Angeles meetup on 4/18/2018. Most of us have used Docker to ship application code from a laptop or a continuous integration system to a production server. But why stop there? In this talk, we will discuss some little known and less commonly understood ways to use Docker to increase portability of everything else. For example, Docker can be used as a portable apt repository to install packages on any server, not only in a container. Another example is to use Docker (and LinuxKit) as a way to distribute Docker images when a registry isn’t available. *About the Speaker:* Dex Horthy, is a Core Engineer at Replicated. He has spent the last year designing and writing production grade enterprise software for the Replicated platform, including container orchestration runtimes and custom integrations into the Kubernetes and Docker APIs.

2. @dexhorthy
@dexhorthy

10. FROM busybox:latest
VOLUMES [“/config”]
ADD . /shippedConfig
CMD cp /shippedConfig/* /config/
{...}
.
├── Dockerfile
└── my.cnf

11. $ docker run --name config test/config:dev
{...}
$ docker run --volumes-from config busybox
/bin/sh -c “cat /config/my.cnf”
busybox

21. FROM ubuntu:16.04
RUN apt-get update
RUN apt-get -y install curl apt-transport-https
RUN mkdir -p /packages
# ...snip
COPY ./kubernetes.list /etc/apt/sources.list.d/kubernetes.list
RUN apt-get update
RUN apt-get install --download-only -y
kubeadm kubelet kubectl kubernetes-cni
-oDebug::NoLocking=1 -o=dir::cache=/packages/

22. FROM ubuntu:16.04
RUN apt-get update
RUN apt-get -y install curl apt-transport-https
RUN mkdir -p /packages
# ...snip
COPY ./kubernetes.list /etc/apt/sources.list.d/kubernetes.list
RUN apt-get update
RUN apt-get install --download-only -y
kubeadm kubelet kubectl kubernetes-cni
-oDebug::NoLocking=1 -o=dir::cache=/packages/

23. FROM ubuntu:16.04
RUN apt-get update
RUN apt-get -y install curl apt-transport-https
RUN mkdir -p /packages
# ...snip
COPY ./kubernetes.list /etc/apt/sources.list.d/kubernetes.list
RUN apt-get update
RUN apt-get install --download-only -y
kubeadm kubelet kubectl kubernetes-cni
-oDebug::NoLocking=1 -o=dir::cache=/packages/

24. FROM ubuntu:16.04
RUN apt-get update
RUN apt-get -y install curl apt-transport-https
RUN mkdir -p /packages
# ...snip
COPY ./kubernetes.list /etc/apt/sources.list.d/kubernetes.list
RUN apt-get update
RUN apt-get install --download-only -y
kubeadm kubelet kubectl
kubernetes-cni
-oDebug::NoLocking=1 -o=dir::cache=/packages/

25. FROM ubuntu:16.04
RUN apt-get update
RUN apt-get -y install curl apt-transport-https
RUN mkdir -p /packages
# ...snip
COPY ./kubernetes.list /etc/apt/sources.list.d/kubernetes.list
RUN apt-get update
RUN apt-get install --download-only -y
kubeadm kubelet kubectl kubernetes-cni
-oDebug::NoLocking=1 -o=dir::cache=/packages/

26. FROM ubuntu:16.04
RUN apt-get update
RUN apt-get -y install curl apt-transport-https
RUN mkdir -p /packages
# ...snip
COPY ./kubernetes.list /etc/apt/sources.list.d/kubernetes.list
RUN apt-get update
RUN apt-get install --download-only -y
kubeadm kubelet kubectl kubernetes-cni
-oDebug::NoLocking=1 -o=dir::cache=/packages/

27. FROM ubuntu:16.04
RUN apt-get update
RUN apt-get -y install curl apt-transport-https
RUN mkdir -p /packages
# ...snip
COPY ./kubernetes.list /etc/apt/sources.list.d/kubernetes.list
RUN apt-get update
RUN apt-get install --download-only -y
kubeadm kubelet kubectl kubernetes-cni
-oDebug::NoLocking=1 -o=dir::cache=/packages/
FROM busybox:latest
COPY --from=0 /packages /packages
CMD cp -r /packages/* /out/

28. $ docker run -v ${PWD}:/out
gcr.io/replicated-equip/k8s-packages:ubuntu-1604-v1.9.3
$ sudo dpkg -i archives/*.deb
$ ls -l archives
total 57304
-rw-r--r-- 1 root root 79416 Apr 17 14:12 ebtables_2.0.10.4-3.4ubuntu2_amd64.deb
-rw-r--r-- 1 root root 97500 Apr 17 14:12 ethtool_1%3a4.5-1_amd64.deb
-rw-r--r-- 1 root root 522092 Apr 17 14:12 iproute2_4.3.0-1ubuntu3.16.04.3_amd64.deb
-rw-r--r-- 1 root root 265782 Apr 17 14:12 iptables_1.6.0-2ubuntu3_amd64.deb
-rw-r--r-- 1 root root 88648 Apr 17 14:12 kmod_22-1ubuntu5_amd64.deb
-rw-r--r-- 1 root root 20091708 Apr 17 14:12 kubeadm_1.9.3-00_amd64.deb
-rw-r--r-- 1 root root 10539730 Apr 17 14:12 kubectl_1.9.3-00_amd64.deb
-rw-r--r-- 1 root root 20454776 Apr 17 14:12 kubelet_1.9.3-00_amd64.deb
-rw-r--r-- 1 root root 5909628 Apr 17 14:12 kubernetes-cni_0.6.0-00_amd64.deb
-rw-r--r-- 1 root root 24248 Apr 17 14:12 libatm1_1%3a2.5.1-1.5_amd64.deb
-rw-r--r-- 1 root root 27230 Apr 17 14:12 libxtables11_1.6.0-2ubuntu3_amd64.deb
drwx------ 2 root root 4096 Apr 17 14:12 partial
-rw-r--r-- 1 root root 321050 Apr 17 14:12 socat_1.7.3.1-1_amd64.deb
-rw-r--r-- 1 root root 22988 Apr 17 14:12 tcpd_7.6.q-25_amd64.deb

31. linuxit

33. linuxkit pkg build

34. kube-dns
kube-proxy
etcd
kube-apiserver
...
docker save
docker save
docker save
docker save
docker save
k8s-images
kube-dns.tar
kube-proxy.tar
etcd.tar
kube-apiserver.tar
...

35. gcr.io/google_containers/kube-proxy-amd64:v1.9.3@sha256:19277373ca983423c3ff82dbb14f079a2f37b84926a4c569375314fa39a4ee96
gcr.io/google_containers/k8s-dns-sidecar-amd64:1.14.7@sha256:f80f5f9328107dc516d67f7b70054354b9367d31d4946a3bffd3383d83d7efe8
gcr.io/google_containers/k8s-dns-kube-dns-amd64:1.14.7@sha256:f5bddc71efe905f4e4b96f3ca346414be6d733610c1525b98fff808f93966680
gcr.io/google_containers/k8s-dns-dnsmasq-nanny-amd64:1.14.7@sha256:6cfb9f9c2756979013dbd3074e852c2d8ac99652570c5d17d152e0c0eb3321d6
gcr.io/google_containers/pause-amd64:3.0@sha256:163ac025575b775d1c0f9bf0bdd0f086883171eb475b5068e7defa4ca9e76516
weaveworks/weave-kube:2.2.0@sha256:a3f69d589e0b27b95070526e70de176811a3d2c6d9f07cc40c38c5fa7c026ff5
weaveworks/weave-npc:2.2.0@sha256:1d85c63e8b4cd433363d5527fdae263069d118308521490a9ea2d4b00b484a5e
brndnmtthws/nginx-echo-headers:latest@sha256:32dc6a6f408e8315622ee9fb8b4a6342d88df7d912f2075bb52929a16b33585a
gcr.io/google_containers/kube-apiserver-amd64:v1.9.3@sha256:a5382344aa373a90bc87d3baa4eda5402507e8df5b8bfbbad392c4fff715f043
gcr.io/google_containers/kube-controller-manager-amd64:v1.9.3@sha256:3ac295ae3e78af5c9f88164ae95097c2d7af03caddf067cb35599769d0b7251e
gcr.io/google_containers/kube-scheduler-amd64:v1.9.3@sha256:2c17e637c8e4f9202300bd5fc26bc98a7099f49559ca0a8921cf692ffd4a1675
gcr.io/google_containers/etcd-amd64:3.1.11@sha256:54889c08665d241e321ca5ce976b2df0f766794b698d53faf6b7dacb95316680

36. gcr.io/google_containers/kube-proxy-amd64:v1.9.3
@sha256:19277373ca983423c3ff82dbb14f079a2f37b84926a
4c569375314fa39a4ee96

37. FROM linuxkit/alpine:cba395fbc278daee841106801aba1e1bd7e0f2f7 AS build
RUN mkdir -p /out/etc/apk && cp -r /etc/apk/* /out/etc/apk/
RUN apk add --no-cache --initdb -p /out
alpine-baselayout
busybox
# Remove apk residuals. We have a read-only rootfs, so apk is of no use.
RUN rm -rf /out/etc/apk /out/lib/apk /out/var/cache
FROM scratch
WORKDIR /
COPY --from=build /out /
COPY --from=docker:17.06.0-ce /usr/local/bin/docker /usr/local/bin/docker
COPY dl/*.tar /images/
ENTRYPOINT [ "/bin/sh", "-c" ]
CMD [ "for image in /images/*.tar ; do docker image load -i $image && rm -f $image ; done" ]

38. FROM scratch
WORKDIR /
COPY --from=build /out /
COPY --from=docker:17.06.0-ce /usr/local/bin/docker /usr/local/bin/docker
COPY dl/*.tar /images/
ENTRYPOINT [ "/bin/sh", "-c" ]
CMD [ "for image in /images/*.tar ; do docker image load -i $image && rm -f $image ; done" ]

39. FROM scratch
WORKDIR /
COPY --from=build /out /
COPY --from=docker:17.06.0-ce /usr/local/bin/docker /usr/local/bin/docker
COPY dl/*.tar /images/
ENTRYPOINT [ "/bin/sh", "-c" ]
CMD [ "for image in /images/*.tar ; do docker image load -i $image && rm -f $image ; done" ]

40. kube-dns
kube-proxy
etcd
kube-apiserver
...
docker load
docker load
docker load
docker load
docker load
k8s-images
kube-dns.tar
kube-proxy.tar
etcd.tar
kube-apiserver.tar
...

41. $ docker run -v /var/run/docker.sock:/var/run/docker.sock
gcr.io/replicated-equip/k8s-containers:v1.9.3
$ docker images
gcr.io/google_containers/kube-apiserver-amd64 v1.9.3 360d55f91cbf
gcr.io/google_containers/kube-controller-manager-amd64 v1.9.3 83dbda6ee810
gcr.io/google_containers/kube-proxy-amd64 latest 35fdc6da5fd8
gcr.io/google_containers/kube-proxy-amd64 v1.9.3 35fdc6da5fd8
gcr.io/google_containers/kube-scheduler-amd64 v1.9.3 d3534b539b76
weaveworks/weave-npc 2.2.0 765b48853ac0
weaveworks/weave-kube 2.2.0 222ab9e78a83
gcr.io/google_containers/etcd-amd64 3.1.11 59d36f27cceb
gcr.io/google_containers/k8s-dns-sidecar-amd64 1.14.7 db76ee297b85
gcr.io/google_containers/k8s-dns-kube-dns-amd64 1.14.7 5d049a8c4eec
gcr.io/google_containers/k8s-dns-dnsmasq-nanny-amd64 1.14.7 5feec37454f4
gcr.io/google_containers/pause-amd64 3.0 99e59f495ffa