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@@ -26,3 +26,12 @@ IPS
 eBay
 Aliexpress
 retrosix
+ARM32
+ARM64
+ARMv8
+Cloud-Init
+EC2
+OpenSuse
+x86
+systemd
+Golang

content/posts/run-arm32-docker-daemon-on-arm64-servers/index.md

@@ -0,0 +1,173 @@
+---
+title: "Run an ARM32 Docker daemon on ARM64 servers"
+date: 2020-09-24T10:30:00+02:00
+authors:
+  - robert-kaussow
+tags:
+  - Automation
+  - Container
+  - Sysadmin
+resources:
+  - name: feature
+    src: "images/feature.jpg"
+    params:
+      anchor: Center
+      credits: >
+        [Yannick Pipke](https://unsplash.com/@joker2000) on
+        [Unsplash](https://unsplash.com/s/photos/cpu)
+---
+
+In the last days I worked on a suitable setup for a [Drone CI](https://drone.io/) server to support multi-arch builds. While the setup for common x86 Drone runners is easy, working with setups for ARM, especially ARM32, is a bit tricky. The easiest way would be to have native servers of the respective architecture available. However, it's difficult to find hosting offers for ARM at all - for ARM32 this seems almost impossible. I decided to use Amazon EC2 ARM64 servers, they are relatively cheap and can also be used as a private customer.
+
+<!--more-->
+
+But how do you turn an ARM64 server into an ARM32 server? Basic requirement is an ARMv8 CPU. This type supports (in most cases) both `AArch32` and `AArch64`. The first step is to enable multi-arch support on your operating system. I use Ubuntu 18.10 for this setup:
+
+```Shell
+dpkg --add-architecture armhf
+```
+
+Then add the Docker CE repository for ARM32 and install the packages:
+
+<!-- prettier-ignore-start -->
+<!-- markdownlint-disable -->
+<!-- spellchecker-disable -->
+{{< highlight bash "linenos=table" >}}
+# add GPG key
+curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo apt-key add -
+
+# add repos
+add-apt-repository \
+   "deb [arch=armhf] https://download.docker.com/linux/ubuntu \
+   $RELEASE \
+   stable
+
+# install
+apt-get update
+apt-get install docker-ce:armhf
+{{< /highlight >}}
+<!-- spellchecker-enable -->
+<!-- markdownlint-restore -->
+<!-- prettier-ignore-end -->
+
+To use the right architecture within Docker containers you still have to force the Docker daemon into ARM32 mode. This can be accomplished by two systemd overwrites:
+
+<!-- prettier-ignore-start -->
+<!-- markdownlint-disable -->
+<!-- spellchecker-disable -->
+{{< highlight bash "linenos=table" >}}
+# overwrite docker.service
+# /etc/systemd/system/docker.service.d/override.conf
+[Service]
+ExecStart=
+ExecStart=/usr/bin/setarch linux32 -B /usr/bin/dockerd -H fd:// --containerd=/run/containerd/containerd.sock
+
+# overwrite containerd.service
+# /etc/systemd/system/containerd.service.d/override.conf
+[Service]
+ExecStart=
+ExecStart=/usr/bin/setarch linux32 -B /usr/bin/containerd
+{{< /highlight >}}
+<!-- spellchecker-enable -->
+<!-- markdownlint-restore -->
+<!-- prettier-ignore-end -->
+
+That's it. Don't forget to reload and restart the systemd daemon:
+
+```Shell
+systemctl, daemon reload
+systemctl, restart, docker
+```
+
+What you get is a Docker daemon that runs in ARM32 mode. This can be used for example to start a Golang container and build apps without cross-compile.
+
+<!-- prettier-ignore-start -->
+<!-- markdownlint-disable -->
+<!-- spellchecker-disable -->
+{{< highlight bash "linenos=table" >}}
+root@ip-10-0-225-151:~# docker version
+Client: Docker Engine - Community
+ Version:           19.03.13
+ API version:       1.40
+ Go version:        go1.13.15
+ Git commit:        4484c46
+ Built:             Wed Sep 16 17:07:23 2020
+ OS/Arch:           linux/arm
+ Experimental:      false
+
+Server: Docker Engine - Community
+ Engine:
+  Version:          19.03.13
+  API version:      1.40 (minimum version 1.12)
+  Go version:       go1.13.15
+  Git commit:       4484c46
+  Built:            Wed Sep 16 17:01:08 2020
+  OS/Arch:          linux/arm
+  Experimental:     false
+ containerd:
+  Version:          1.3.7
+  GitCommit:        8fba4e9a7d01810a393d5d25a3621dc101981175
+ runc:
+  Version:          1.0.0-rc10
+  GitCommit:        dc9208a3303feef5b3839f4323d9beb36df0a9dd
+ docker-init:
+  Version:          0.18.0
+  GitCommit:        fec3683
+root@ip-10-0-225-151:~# docker run alpine uname -a
+Linux dbad5ddeb5ea 5.3.0-1035-aws #37-Ubuntu SMP Sun Sep 6 01:17:41 UTC 2020 armv8l Linux
+{{< /highlight >}}
+<!-- spellchecker-enable -->
+<!-- markdownlint-restore -->
+<!-- prettier-ignore-end -->
+
+Just a word of warning. I'm not a hardware specialist and there might be some situations where this setup does not work. Furthermore it seems that some operating systems have problems to recognize `armv8l` as ARM32 architecture. For OpenSuse as an example I had to force `zypper` into `armv7hl` mode to get it working. After this step building ARM32 OpenSuse Docker images also works for me.
+
+```Shell
+sed -i 's/# arch = s390/arch = armv7hl/g' /etc/zypp/zypp.conf
+```
+
+If you want to give it a try, I've prepared a minimal Cloud-Init configuration:
+
+<!-- prettier-ignore-start -->
+<!-- markdownlint-disable -->
+<!-- spellchecker-disable -->
+{{< highlight yaml "linenos=table" >}}
+#cloud-config
+
+apt_reboot_if_required: false
+package_update: true
+package_upgrade: true
+
+bootcmd:
+  - [ dpkg, --add-architecture, armhf  ]
+
+apt:
+  sources:
+    docker.list:
+      source: deb [arch=armhf] https://download.docker.com/linux/ubuntu $RELEASE stable
+      keyid: 0EBFCD88
+
+packages:
+  - 'docker-ce:armhf'
+
+write_files:
+  - path: /etc/systemd/system/docker.service.d/override.conf
+    content: |
+      [Service]
+      ExecStart=
+      ExecStart=/usr/bin/setarch linux32 -B /usr/bin/dockerd -H fd:// --containerd=/run/containerd/containerd.sock
+
+  - path: /etc/systemd/system/containerd.service.d/override.conf
+    content: |
+      [Service]
+      ExecStart=
+      ExecStart=/usr/bin/setarch linux32 -B /usr/bin/containerd
+
+runcmd:
+  - [ systemctl, daemon-reload ]
+  - [ systemctl, restart, docker ]
+
+{{< /highlight >}}
+<!-- spellchecker-enable -->
+<!-- markdownlint-restore -->
+<!-- prettier-ignore-end -->