Tag Archives: docker

Ubuntu Core – Atomicity rough on the edges

View of a Harbour Terminal before Containers existed

Before the invention of containers, docker was a much more manual job. And that’s what I’m looking for my Raspberry Pi.

I’ve been recently trying to play with Ubuntu Core on my 2nd Raspberry Pi 2. I like the concept of a minimalist host with atomic updates and the possibility to run my services inside containers. In addition, snap looks like an interesting package system (and more than that). But this setup does not fit my use cases, it is perfect for repeatable testing and safe environment for deployment. However I need a system that is stable and safe, but which I can tinker with (modify a specific configuration or kernel in order to optimise its use or detect new devices) and which grow organically (depending on my free time).

Introduction to Ubuntu Core

So Ubuntu Core (or the Project Atomic) do appeal to me but they are too restrictive for my use cases. I need more freedom. Anyway, for those of you who could be interested in these projects here is a quick review of these systems with respect to day-to-day use as I’m not going to explain the philosophy of Core/Atomic neither of snap/atomic technologies.

Both Ubuntu Core (armhf variant) and CentOS Atomic Host (x86_64 variant) felt a bit rough and despite carrying the respective name Ubuntu and CentOS I had to reconsider how I am used to administer such boxes. A basic concept is that you install a core (or minimalist) OS and you cannot pretty much change it (most parts are read only), but it should have everything to run containers. For Atomic Host, there is no way to install additional packages, you need to add every other bit of software as a container. The big difference with Ubuntu Core is that you have snaps which allows to extend the core OS without having to install and configure containers manually. A snap package – once installed – feels more or less like if you just installed a deb package. But there is a big difference, they are like little containers or sandboxed process(es) already neatly packaged so they feel like a normal command, but a lot is going on behind the scene. Here is an example, I’ve installed `htop` on my Raspberry Pi 2, now I get two distinct results if I run it with a standard user or with the super user rights, a behaviour uncommon on a standard Linux installation:

Standard User Super user

Snap htop - standard user

Snap htop – Standard User

Snap htop - super user (via sudo) - see complete list of processes

Snap htop – Super User (via sudo)

As it is visible in the case of htop, by default when I run it, htop shows only processes where the owner is myself. This is not bad but it is different from traditional Linux distribution and so you need to get the habit to do `sudo htop` to see all processes, but take care you then run htop as super user, and htop allows you to kill processes, so be careful.

However, on Raspberry Pi (and probably other ARMv7 (aka armhf) platforms) there is a very limited amount of snap packages available yet. It is probably changing fast, but if you run today Ubuntu Core 16 you can’t install much snaps and need to rely on Docker containers for adding extra applications to the base system (more on that later, including its current limitations).

Basic system configuration absent

Let’s get back to the beginning and I mean by that right after the installation of Ubuntu Core upon first boot. I still had my keyboard and screen attached to it (and you need it in order to login with your Launchpad SSO login to create the first user). After the first boot, I was not offered the possibility to change the keyboard layout (I do not have a US layout) but at least on Ubuntu Core one can change it afterwards by editing the file `/etc/default/keyboard`, this feat is not possible on Atomic Host. Anyway, not such a big issue as I’m using my Raspberry Pi mostly (if not alway) via SSH then it does not matter anymore. Staying on the localization topic, both systems do not allow changing the locale (language, regional preferences, etc.). On Atomic Host it is set to US with the “peculiar” time and date format ;-) no offense! Similar fate on Ubuntu Core but they are using the C locale (which sadly for me also uses the US date/time format). Although I would anyway stick to the English language, I don’t like the regional choice and I don’t like the lack of choices here.

So let’s move back to an SSH connection, at least the keyboard layout is no longer an issue. But here comes the next one ;-) whenever I use SSH, the first thing I do is launch a new tmux session or attach to an existing one. I’m open to other solutions, so if the host only has screen or byobu, I’m also fine. However, Ubuntu Core for ARMv7 does not ship by default with any of them, nor are they any existing snap package. So there is no simple way (out of compiling from source and creating a snap package) to have safe SSH session.


Normally thanks to container technology, it is possible to install more or less everything I would need and with some clever alias it would seem much like a snap installation. So I just wanted to create a Dockerfile which reference Alpine Linux and install tmux and build the container using Docker. Not possible with Ubuntu Core and the Docker snap. According to the Docker snap information, I should be creating a folder under `$HOME/apps/docker/1.6.xxx` (eventhough Docker 1.11.2 was installed, weird), but it does NOT work. The AppArmor profile installed with Docker snap denies it. I’ve tried many different folders to no avail. This is not a misconfiguration of Ubuntu Core but rather one of the Docker snap packager, but the end result is that as a user Ubuntu Core on armhf is barely usable (lack of too many essential tool, no snap and cannot easily use Docker).

Other rough edges with Docker are that your default user does not belong to the Docker group, so you need to sudo every single Docker command. There is also no way to add yourself to the Docker group (as the group is defined in the standard file `/etc/group` which is on a read-only filesystem). Your default user is also not a real traditional user, it is an “extra user” (did not know this subtlety before this) so there are a bunch of things that are not compatible with it like you cannot launch a container to run as yourself (docker run -u $(whoami) ...) as you are not a standard user (no entry in `/etc/passwd`), you are an extra users (see in `/var/lib/extrausers/passwd`), but at least it would be possible to do it specifying your user ID (e.g. 1000)! This is all logic but “rough”. A corollary to the previous statements is that you cannot run Docker in user namespaces mode (unprivileged Docker container) as you cannot add yourself to the Docker group.

At least the Docker snap includes Docker Compose, that is cool. On Atomic Host, Docker is installed but not Docker Compose. As the file system is also read-only there is good way to install Docker Compose in a central place, it should be run within a container. At least on Atomic Host, it is very easy (as on standard Linux OS) to create Dockerfile and build them. So these limitations (of not having Docker Compose and some other tools) can be overcome with some efforts.

Final Try

My next steps was to download some scripts and tools. However both curl and wget are absent of the base installation. Even git is not available as a snap or on the core installation. There is no way to build a Dockerfile, so in the end to have tmux, curl, git, etc. I had to create a lxd container running Ubuntu just to get a normal OS (or from my laptop, I could download the scripts and via scp pushing them to Ubuntu Core). But then I simply prefer to run Ubuntu Server or Raspbian on my Raspberry Pi.

For me I’ve lost too much time on this already. Ubuntu Core seems nice I really like the principles and approach, but it is definitively missing too many basic tools, too rough for my taste and available free time.


I will install Ubuntu Server or CentOS 7 for armhf on my second Raspberry Pi 2. Ubuntu Core is perhaps still a bit too young (maybe it is specific to the armhf platform) and requires too much work for my needs. At least this experience made me understand that I don’t want a lock down and safe box, but I need flexibility.

Picture credits: Public Domain. The picture is part of the State Library of South Australia collection (see original B 4433 photo).

Getting docker-compose on Raspberry Pi (ARM) the easy way

I really like docker-compose, it has a simple language (YaML) to describe how to build and run a container, so you do not have to remember (or count on your history availability) the long `docker build ...` and `docker run ...` commands (and many others).

However, docker-compose is not (yet) available for Raspberry Pi or any other ARM architecture.

Our Hypriot friends have done a great job and do provide a binary version of it on their repositories. But I usually do not like to add 3rd party repositories and I finded the list of changes (patches) longer than I expected.

So I forked the official Docker Compose repository and did a few minimalistic changes in order to get a built of docker-compose for Raspberry Pi. I have created a Pull Request in the hope that it might get accepted and that ARMv7 be officially built. But while waiting for the review process to be triggered, here is how to do it for yourself.

Download the Project

As pre-requisite you need to have `git` (sudo apt-get install git) and `docker` (see my previous article) already installed on your platform.

Then get a copy of the project on your local Raspberry Pi.

$ git clone https://github.com/docker/compose.git
$ git checkout release

Now apply the following patch:

$ cd compose
$ cp -i Dockerfile Dockerfile.armhf
$ sed -i -e 's/^FROM debian\:/FROM armhf\/debian:/' Dockerfile.armhf
$ sed -i -e 's/x86_64/armel/g' Dockerfile.armhf

Build and install docker-compose

To build the docker-compose binary, the procedure is rather simple. First you need to build the docker image which will be used to set-up the build environment. Second and last you need to run the container which will build docker-compose. At the end the binary will be available under the `dist` subfolder.

$ docker build -t docker-compose:armhf -f Dockerfile.armhf .
$ docker run --rm --entrypoint="script/build/linux-entrypoint" -v $(pwd)/dist:/code/dist -v $(pwd)/.git:/code/.git "docker-compose:armhf"

After several minutes you will get a binary file which you can then install on your system:

$ ls -l dist/
total 6816
-rwxr-xr-x 1 pi pi 6976500 Feb  8 11:41 docker-compose-Linux-armv7l
$ sudo cp dist/docker-compose-Linux-armv7l /usr/local/bin/docker-compose
$ sudo chown root:root /usr/local/bin/docker-compose
$ sudo chmod 0755 /usr/local/bin/docker-compose
$ docker-compose version
docker-compose version 1.11.0-rc1, build daed6db
docker-py version: 2.0.2
CPython version: 2.7.13
OpenSSL version: OpenSSL 1.0.1t  3 May 2016

Goodies: Install docker-compose bash autocompletion

Docker Compose provides autocompletion for bash. Installing it is as simple as doing:

$ sudo curl -L https://raw.githubusercontent.com/docker/compose/$(docker-compose version --short)/contrib/completion/bash/docker-compose -o /etc/bash_completion.d/docker-compose


If you might wonder why I stated “the easy way” in my title, well if you want to master Docker, you ought to consider the above easy :-)

Of course in our field of work nothing is as simple as a mouse click, especially when you need to create something that is not (until today) provided out of the box. If you want real easy and are using a Debian-based Linux OS, then just use the repository provided by Hypriot. If you’re not using Debian, you might want to consider the above described approach.

GPL https://commons.wikimedia.org/wiki/File:Sablier-temps-icone-5376-128.png

A Time Server in a Container – Part 1

To learn Docker in details I decided to use it to run a local time server using ntpd from the ntp.org project.

I have used an incremental approach where I started with an easy setup and then increased the challenges either to improve the time server or to better understand Docker.

Getting Started

So why ntpd and not <put your favourite time server>

I know ntpd for having configured it many times in the past 10 years. So I wanted to start with it first to quickly get time synchronisation working.

Which platform?

I have a Raspberry Pi (abbreviated RPi from now on) which serves as DHCP server and local forwarding and caching of DNS queries for my LAN. It had early support for Docker back in October when I started my experiment which added a bit of spice to it.

Getting Docker on a Raspberry Pi

There are many ways to get Docker running on your RPi. You could get the Hypriot OS Linux distribution which has everything setup nicely for running Docker containers. You can compile Docker on your platform of choice (which I had to do to squash a few early adopters’ bugs). You can install a tarball containing the binaries for your platform. But if running Raspbian Jessie – like I was – you can today just include Docker’s own repository and install a binary version using apt-get. Make sure your Kernel is recent (Docker requires 3.10 at least, but if you have a properly updated Raspbian it should be running 4.4 at the time of writing).

You can follow Docker’s installation guide for Debian, but by default it will install you the x86_64 Docker repository. As hinted in the documentation, for other architecture you need to use the [arch=...] clause. In addition, Docker provides a specific variant of the package for Raspbian. So for Raspbian Jessie, use the following entry for your docker.list file:

deb [arch=armhf] https://apt.dockerproject.org/repo raspbian-jessie main

Continue to follow the Docker guide, including how to set up non-root access to a specific user.

Creating a Docker image for ntpd

Create a specific folder somewhere on your Raspberry Pi storage (e.g. mkdir -p ~/projects/docker/ntpd) and create a file Dockerfile.armhf (I use the extension .armhf so I can have distinct Dockerfiles for each platform I use) with the following content:

FROM armhf/ubuntu:16.04
RUN apt-get update \
    && apt-get install -y --no-install-recommends ntp \
    && apt-get clean -q \
    && rm -Rf /var/lib/apt/lists/*
ENTRYPOINT ["/usr/sbin/ntpd"]

Note: This file as well as newer version of it and instructions to build and run the container are available on my GitHub ntp container project. In the rest of this blog post, I’m only going to detailed how I approach running the container and solve problems.

The first line state that the base image for the container will be Ubuntu 16.04 (the specific variant for RPi architecture). The second until the fifth lines are commands we execute on top of the base image, basically it updates the packages list to install the latest version of ntpd with the smallest dependencies, and it removes any cached or temporary files. So we minimise the size of the image on disk. Finally the last line, is the command that will be executed by Docker when instructed to run the container. I have used the term ENTRYPOINT because it allows me – while experimenting – to change the list of parameters I send to ntpd when I create the container and run it. This gives me flexibility with testing different parameters.

I picked up Ubuntu as the base image because it has sane default for the ntpd configuration file. It will use the NTP Pool project and the configuration is secured by default. Note that other base images could have also worked and have also sane default. I could have used Alpine Linux base image, it is really compact and lightweight, would have been perfect for a small platform like a Raspberry Pi, but it does not provide the ntpd packages from the NTP project which I wanted to start with. It only supports OpenNTPD (which does not support leap seconds, so it was a no go for me) and Chrony (which could be a good alternative but as I mentioned before I wanted to first experiment with Docker not learn yet another NTP application).

Let’s build the container image (I named the image “article/armhf/ntpd” and tagged it with the current date, but just name it like you want):

$ docker build -f Dockerfile.armhf -t article/armhf/ntpd:20170106.1 .

Running the NTP container

We are now going to spawn an instance of the container image in foreground to see what is going on and to notice any error:

$ docker run --rm -it article/armhf/ntpd:20170106.1 -n
 6 Jan 14:03:30 ntpd[1]: ntpd 4.2.8p4@1.3265-o Wed Oct  5 12:38:30 UTC 2016 (1): Starting
 6 Jan 14:03:30 ntpd[1]: Command line: /usr/sbin/ntpd -n
 6 Jan 14:03:30 ntpd[1]: Cannot set RLIMIT_MEMLOCK: Operation not permitted
 6 Jan 14:03:30 ntpd[1]: proto: precision = 1.198 usec (-20)
 6 Jan 14:03:30 ntpd[1]: Listen and drop on 1 v4wildcard
 6 Jan 14:03:30 ntpd[1]: Listen normally on 2 lo
 6 Jan 14:03:30 ntpd[1]: Listen normally on 3 eth0
 6 Jan 14:03:30 ntpd[1]: Listen normally on 4 lo [::1]:123
 6 Jan 14:03:30 ntpd[1]: Listening on routing socket on fd #21 for interface updates
 6 Jan 14:03:30 ntpd[1]: start_kern_loop: ntp_loopfilter.c line 1126: ntp_adjtime: Operation not permitted
 6 Jan 14:03:30 ntpd[1]: set_freq: ntp_loopfilter.c line 1089: ntp_adjtime: Operation not permitted
 6 Jan 14:03:31 ntpd[1]: Soliciting pool server
 6 Jan 14:03:32 ntpd[1]: Soliciting pool server
 6 Jan 14:03:32 ntpd[1]: adj_systime: Operation not permitted
 6 Jan 14:03:32 ntpd[1]: Soliciting pool server
 6 Jan 14:03:33 ntpd[1]: Soliciting pool server
 6 Jan 14:03:33 ntpd[1]: Soliciting pool server
 6 Jan 14:03:34 ntpd[1]: Soliciting pool server
 6 Jan 14:03:34 ntpd[1]: Soliciting pool server
^C 6 Jan 14:03:40 ntpd[1]: ntpd exiting on signal 2 (Interrupt)

We have a few errors (Operation not permitted) which I have highlighted above, one is about RLIMIT_MEMLOCK (this is about resetting the limit of the maximum locked-in-memory address space, ntpd uses it to forbid its main process from swapping to limit jitter) and the other ones are about ntp_adjtime and adj_systime (both are used by ntpd to interface with the Kernel and adjust the system time).

By default ntpd is running as root user, so it should have enough privilege for these operations. In addition, even though Docker supports running unprivileged containers (i.-e. the root user inside the container is mapped to a normal user on the host, this is based on user namespaces (see namespaces(7)), this is not the default Docker configuration, so my root user inside the container is the root user outside the container (and if Docker would be configured to use user namespace, they are not compiled in the Raspberry Pi foundation Kernel. So it is at the moment not possible to use that feature on a Raspberry Pi without some extra efforts, but I will details this in a future article).

In order to implement basic privilege limitations of container, Docker can use various security feature of the Linux Kernel to limit the container accessing certain sensible Kernel calls, the most notable ones are Linux Capabilities (since Docker 1.2), Linux SECCOMP filtering (since Docker 1.10, but better use Docker 1.12+ as pervious default SECCOMP profiles were in conflict with the Linux Capabilities management of Docker. In addition, the Raspbian Kernel (version 4.4 as of writing) has not the built-in support for SECCOMP filtering, so this functionality is not usable on Raspberry Pi, unless you compile your own Kernel) and Linux MAC (like SELinux or AppArmor, but none of them are available on Raspberry Pi without recompiling your own Kernel and installing the user space tools). So Docker on Raspberry Pi can only use Linux Capabilities as security feature.

By default Docker provides each container with a reasonable set of capabilities (see Docker documentation on capabilities). If you check both documentation (the Linux Capability manual and the Docker runtime privileges doc), you will find out that basically our container is missing the CAP_SYS_RESOURCE and CAP_SYS_TIME capabilities. Now there are 2 ways to add them, most online guide would tell you that when you run into “operations denied” errors, just add the --privilege flag to the docker run command line and it will be fixed, that’s the first way and it’s the wrong approach (sure it works, but it is like deactivating SELinux because you are not allowed to perform an operation). The other way is to add the missing capabilities to the container. This can be done by using the --cap-add flag. That’s what I’m going to show now:

$ docker run --rm -it --cap-add SYS_RESOURCE --cap-add SYS_TIME article/armhf/ntpd:20170106.1 -n
 7 Jan 11:19:24 ntpd[1]: ntpd 4.2.8p4@1.3265-o Wed Oct  5 12:38:30 UTC 2016 (1): Starting
 7 Jan 11:19:24 ntpd[1]: Command line: /usr/sbin/ntpd -n
 7 Jan 11:19:24 ntpd[1]: proto: precision = 1.823 usec (-19)
 7 Jan 11:19:24 ntpd[1]: Listen and drop on 0 v6wildcard [::]:123
 7 Jan 11:19:24 ntpd[1]: Listen and drop on 1 v4wildcard
 7 Jan 11:19:24 ntpd[1]: Listen normally on 2 lo
 7 Jan 11:19:24 ntpd[1]: Listen normally on 3 eth0
 7 Jan 11:19:24 ntpd[1]: Listen normally on 4 lo [::1]:123
 7 Jan 11:19:24 ntpd[1]: Listening on routing socket on fd #21 for interface updates
 7 Jan 11:19:25 ntpd[1]: Soliciting pool server
 7 Jan 11:19:26 ntpd[1]: Soliciting pool server
 7 Jan 11:19:26 ntpd[1]: Soliciting pool server
 7 Jan 11:19:27 ntpd[1]: Soliciting pool server
 7 Jan 11:19:27 ntpd[1]: Soliciting pool server
 7 Jan 11:19:27 ntpd[1]: Listen normally on 7 eth0 [fe80::42:acff:fe11:2%6]:123
 7 Jan 11:19:27 ntpd[1]: new interface(s) found: waking up resolver
 7 Jan 11:19:27 ntpd[1]: Soliciting pool server
 7 Jan 11:19:28 ntpd[1]: Soliciting pool server
 7 Jan 11:19:28 ntpd[1]: Soliciting pool server
 7 Jan 11:19:28 ntpd[1]: Soliciting pool server
 7 Jan 11:19:28 ntpd[1]: Soliciting pool server
^C  7 Jan 11:22:40 ntpd[1]: ntpd exiting on signal 2 (Interrupt)

To make sure this is working, first verify that you do not have any time synchronisation service running: $ sudo systemctl stop systemd-timesyncd ntp.

Then change the system time by shifting it by 5 seconds: $ sudo date -s "5 seconds".

Check that your system clock is now off by 5 seconds:

$ ntpdate -q time1.google.com
server, stratum 2, offset -5.002284, delay 0.14117
18 Jan 11:27:55 ntpdate[5217]: step time server offset -5.002284 sec

Start the container in the background this time: $ docker run --name ntpd --detach --restart always --cap-add SYS_RESOURCE --cap-add SYS_TIME article/armhf/ntpd:20170106.1 -g -n

Wait a few seconds and query again the network time using the above ntpdate command. The offset should now be below 5 seconds and probably close to 0 second.

You have now a ntp service running inside a container and synchronising your system clock using Internet time servers from the NTP pool project. If you want to stop the experiment here and restore your system, you need to stop the container ($ docker stop ntpd) and block it from restarting at next boot ($ docker update --restart=no ntpd) and perhaps reboot so that you reactivate the default time synchronisation service.

But if you want to keep experimenting or let the container do its job of time synchronisation, you should make sure to deactivate any other time synchronisation mechanisms to avoid conflicts if you want to keep your NTP container running:

$ sudo timedatectl set-ntp false 
$ sudo systemctl disable ntp chronyd
$ sudo systemctl mask systemd-timesyncd
$ sudo systemctl stop systemd-timesyncd ntp chronyd

Foreword about Time and NTP on a Raspberry Pi

The Raspberry Pi (at the time of writing this applies to all models) has no real time clock (RTC) module on its board. A RTC is a small oscillator (e.g. quartz, like in your electronic wristwatch) plus some electronic to keep track of time and a battery (or equivalent). Those RTCs help a system keep track of time when there are off and in the early phases of boot. On a standard desktop or laptop computer the motherboard has an RTC. Many oscillators are not particularly accurate (low quality) with non-stable frequencies which can depend on external factors such as room temperature. It is possible to add a RTC module to the Raspberry Pi (I will have a detailed article on that soon), but without RTC you need a network connection in order for the RPi to know the current time.

On Linux, the kernel manage 2 clocks, the hardware clock (which is based on the RTC) and the system clock (which is the clock used by the system to query/set the time, this clock is ticking using a clocksource such as a CPU/SoC timer, Kernel jiffies, etc.). On boot, the current time is read from the hardware clock and is used to initialise the system clock. The system clock is then driven by the ticks from the selected clocksource and the time read at boot from the hardware clock. Usually, on shutdown, many Linux distribution are configured to store the system clock in the hardware clock.

The Raspberry Pi has maybe no hardware clock but it has a clock source (current clocksource on Raspberry Pi 2, other models may differ):

[    0.000000] arm_arch_timer: Architected cp15 timer(s) running at 19.20MHz (phys).
[    0.000000] clocksource: arch_sys_counter: mask: 0xffffffffffffff max_cycles: 0x46d987e47, max_idle_ns: 440795202767 ns
[    0.000010] sched_clock: 56 bits at 19MHz, resolution 52ns, wraps every 4398046511078ns
[    0.000032] Switching to timer-based delay loop, resolution 52ns

So if the time is set on boot, the OS can keep track of the time even if disconnected and as long as it is up and running. Systemd 213 introduced a new service systemd-timesyncd which is a SNTP client implementation, so it is able to query a network time server and set the OS system time based on the response. This service has an extra feature for systems without RTCs, it saves the system time on disk on shutdown. So when your Raspberry Pi reboot, it can use the stored time to initialise its system time while waiting for more accurate time once the network is ready. Sure during the early boot process the system time might be off by a couple of seconds but it is better than nothing.

As for NTP, it is adjusting the system time based on responses from network time servers or when offline based on the clock drift NTP has been calculating for the current clock source. This means that if you run NTP, it is good to let it run at least 24hours so it can accurately measure the clock source drift and then it can compensate it during network disconnection periods. In addition, NTP will regularly sync back the system time to the hardware time to correct the RTC clock. In up coming articles, we will see how we can add a RTC to our Raspberry Pi and how to overcome the challenges of allowing RTC access to NTP inside the container and increasing the clock accuracy. In addition, we will see how we can become an NTP network time server for the local LAN.

What did we learn about Docker

First, we practiced the basics of building a container (the Dockerfile syntax and docker build ... command), running a container in foreground or background mode (docker run ...) and controlling the running container (docker stop ... and docker update ...). I did not yet elaborate much on the capabilities of these commands offer but it is my intention that we will discover them further as we progress we the experiment.

Second, we learned about some of Docker security measures (like Linux capabilities) and limitations of the current Raspberry Pi platform (like no SECCOMP filtering or AppArmor or user namespace), and we also learned how to extend a container permission by adding new capabilities.

Next to learn will be how to provide access to specific devices (such as an RTC), how to do simple monitoring (checking the container is running, its resource usage and logs), how to increase its security (dropping unnecessary capabilities, using the other security measures). With this quest we will learn a lot on the Raspberry Pi as well, we will add an RTC module, we will compile our own Kernels in order to add new security functions and improve the OS jitter, etc.


September 19, 2016

I’ve been busy in the past months and did not update much this  site. However, here are a few hints about some upcoming articles:

  • Install and run Docker on Raspberry Pi
  • Run ntpd to provide time to your local network (Docker), I will talk about the pros and cons of running that on a Raspberry Pi.
  • Run dnsmasq to provide a DHCP and DNS resolver on your local network (Docker)
  • This website is now using TLS so that the URL has changed to HTTPS. The certificate authority is Let’s Encrypt which my hosting provider is offering easily.
  • I have a few more unfinished articles which might still take some time to complete, topics are ranging from: LXC advance usage and tips&tricks, LXD first usage, Linux SSH key management, SSD caching on Linux, FreeBSD/Arch Linux on Raspberry Pi 2.
  • Last but not least, I ought to announce why I’ve been so busy in the past months (and years). I will give some hints soon.