Using your Synology Diskstation as a SOHO git Server

Yes, you should use GitHub for your public and private repos (IMHO), but if you just need a small office solution with a few machines and / or users and already have a Diskstation (RAID config and backup recommended) why not install a git server locally.

Install the git server as described in the Synology guide. Create users in DSM that match your workstation users and are assigned to the group Users. In git server DSM manager assign those users to git. Then use the following steps to create repos on the server (guide assumes diskstation is your dns name of the Synology):

ssh admin@diskstation
cd /volume1/Repos # that folder needs to be created within volume manager

git init --bare --shared MyRepo.git

The option bare makes the repo a server representation of a git repository without a working directory and share makes the repo read/write enabled for all Users group members.

On your workstations you can than use the git ssh protocol to clone the created empty repos:

# if your local user and diskstation user match, clone as:
git clone ssh://diskstation/volume1/Repos/MyRepo.git

# if your local user and disk station user do not match, clone as:
git clone ssh://your-user@diskstation/volume1/Repos/MyRepo.git

If you want to push your existing local git repos to the newly created diskstation counterparts use:

cd MyRepo
git remote add origin ssh://diskstation/volume1/Repos/MyRepo.git
git push --set-upstream origin master

After the set-upstream option you can omit it for further pushes.

You can save yourself from typing passwords and increase security by using ssh keys (copy your public key to the diskstation).

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Kubernetes & Kops: Make Your Own Encrypted Debian AMI

Kops is the most popular solution to install Kubernetes on AWS in a highly-available way. Debian is the preferred Linux distro for kops, which is somewhat annoying if you see that CoreOS is the preferred container Linux.

Moreover, the Debian AMI for kops is custom build, not only the OS itself, but also the kernel. AMIs are marked public, so you can easily reuse them. As soon as you want to encrypt your images, you will need access to the underlying snapshot that is not public at the moment.

You may instantiate an EC2 instance, encrypt the snapshot or you can use kube-deploy to make yourself your own image the same way that kops does.

Clone the kube-deploy repo, configure your aws credential and run the following steps in the kube-deploy folder:

./hack/ # comment out the imagebuilder call in this file

# be careful not to overwrite your key at id_rsa!
ssh-keygen -t rsa -b 2048 -f $(pwd)/.ssh/id_rsa -C "${USER}@${HOSTNAME}" -N ""

aws ec2 import-key-pair  --key-name "id_rsa" --public-key-material file:///$(pwd)/.ssh/

docker run --rm -ti -v "$PWD":/usr/local/go/src/ -w /usr/local/go/src/ -v $HOME/.aws:/root/.aws:ro -v $HOME/.ssh:/root/.ssh:ro golang:1.8 bash

In the container that is starting run:


export AWS_REGION=$(aws configure get region)

imagebuilder --config=aws.yaml --replicate=false

Wait and proceed with AMIs with Encrypted Snapshots

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Kubernetes: Make Pods Run on Your Master Nodes

Some pods you might want to run on your master nodes, too. This may be because they are exporting master node metrics or even to save resources: say you want many instances of a specific pod. In that case (and given you are on Kubernetes >= 1.7) you can use tolerations to override NoSchedule taints. Add this to your pod’s spec:

  - effect: NoSchedule

You may even want your pods to run only on master nodes. Then add this node selector key to your pod spec:

nodeSelector: ""

But be aware that masters may not be able to communicate to nodes, due to your setup (security groups etc).

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Kubernetes: How to Make Your Node a Master

Under some circumstances Kubernetes is forgetting its master nodes (kops version < 1.8.0 and canal). If this happens, your masters will get scheduled full of pods. If this is the case the following command might help you: kubectl taint master1.compute.internal

This command seems to be buggy at times, complaining about wrong characters in the string. If that’s the case then try this nice patch:

kubectl patch node master1.compute.internal -p '{"spec":{"taints":[{"effect":"NoSchedule","key":""}]}}'

After you have correctly set the taints with above command, you can terminate workload pods and they will get restarted on non-masters.

BTW, if you do not take the measures above, not only will pods get scheduled on your masters which might get problematic, but in addition any differences between your master and node will catch you cold. E.g. you might open a security group on your nodes but not on your master. If a pod get scheduled to run on the master it will not able to communicate as desired.

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Kubernetes: How to Delete all Taints from a Node

kubectl patch node node1.compute.internal -p '{"spec":{"taints":[]}}'

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Lost Web Passwords After Migrating to New Mac

After migrating to a new Mac, I found out that a ton of my web site passwords were gone or were out of date (I haven’t been using iCloud passwords or any other password app). The Migration Assistant seems to have problems under certain conditions. While I haven’t completely figured out the underlying issue, the only viable solutions were to either copy passwords to a new key chain or to use iCloud passwords temporarily or permanently.

On newer MacOSes password storage focuses on iCloud that is complemented with a local cache and local system passwords. You can find the password cache in key chain files and folders in ~/Library/Keychains. If you deactivate iCloud password use, the cache will be referred to as “Local Items” (if you decide to keep it). Every Mac gets its own UUID folder so if the migration succeeded you will find your old Mac’s folder and a new one for you new Mac. Now even with the files present on the drive the passwords were still missing. Copying those files around won’t help.

After investing a bit of time I decided to activate iCloud on my old Mac and then my on new Mac. The files are synced online and then to the new Mac (sure enough, during the experimentation phase this syncing deleted at least one of my very new passwords…). Since this did the trick, I am now even considering keeping iCloud passwords active and thus simplifying my future migration processes.

If you don’t want to store passwords on the iCloud servers permanently, just deactivate iCloud passwords on ALL devices (not that easy if you use a ton ;). Actually, Apple is suggesting that there is a way to completely skip password storage in the iCloud by not creating a Cloud Security Code. I haven’t tried this and am even unsure if this still works in Sierra.

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Pricing Strategies for a Fairer Trade

Today I opened a milk carton that was printed with a thank you, because by buying this brand of milk we are supporting dairy hill farmers. Germany is the home some of the hardest discounters (and other retailers) who, acting in the interest of the consumer, use their economies of scale to dictate the purchasing cost for food and other goods. This process has lowered the retail prices in Germany to the lowest in the EU. However, it also jeopardizes farmers and other producers.

What if there is a better way for pricing?

First I would like to look at the reasons why consumers push for such low prices and then propose an alternative pricing model. While retailers act in the interest of consumers to lower the cost of goods, they also want to maximize their return. So the price of the goods gets an additional level of complexity. Competing retailers advertise their prices and consumers can compare the offers. Commodities such as milk are not differentiated, so the comparison is easy. Rational consumers decide for the cheaper offer, since they need to maximize the utility of their income.

However, I think that there is a second interest that the consumer is after, at least me. Since there is a considerable retail margin on top of the goods, it is this we are trying to optimize away. Retailers have long lost their personality and their knowledge but still try to earn the same margin. For example, I know more about the BMW I am pursuing or the camera than my dealers do. All the information is available on the internet and as a buyer I am more interested in the product than the dealer. With all the price transparency would you buy more at a more expensive retailer if the there is zero benefit to it?

In addition, I think that consumers want to support the producers of goods, some of my colleagues are also supportive of retailers (much more so than me).

New pricing model

Discounters that often offer only one type of a commodity, should provide two prices for that good. One that is calculated hard as it is today and one that is a few cents more expensive. That additional margin transparently and to 100% is cashed out directly to the producer of the good. Without even ending on the profit and loss account of the retailer. Technology should make this easy to implement.

One could extend this strategy to other products and retailers, too.

A consumer can then decide if they want or if they can support the producer directly without in any way supporting the retailer (other than purchasing at the store). This would increase fairness to the producers. By having two prices for a single product, the consumer can themselves decide (not through the proxy of the discounter) if the prices are too high. It would still be good for the retailer who would provide the offer, initially differentiating themselves from the competition and later still provide that solid margin for the base good.

It is also fair to the consumer, since not all are equal. Wealthy consumers could easily afford the higher prices, while the poorer could pay the lower prices, knowing that the pricing model is supporting the producers. Both could decide to do the opposite if they so wish. This model would directly show the interest of the consumer to the producer without being proxied through the retailer.

Why not just buy that milk brand described in the introduction? How fair is that? Who gets the margin? Is it fair to the consumer? Where can I get that brand? Transparency, fairness, availability are all reasons to not use that model, if the proposed strategy is implemented.

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List of Application Dependencies

Docker and containers in general are revolutionising the way we think about application development and operations. As a new packaging technology I think it perfectly defines the interface between an application and the host it will be running on. In order to better understand why this is so, I have looked at this interface and how it captures application dependencies and what it leaves out. Because many different packaging technologies have been used. Here’s a historic list of those that I have ever been using:

  • C64 BASIC source code (actually it is byte code but can be seen as equivalent)
  • C64 6502 machine code
  • Atari ST executable plus RSC file
  • Unix shell source code
  • Unix executable plus libs plus conf
  • NextStep application package in a tar
  • Windows installer package with executables, registry, libs, files, services (a nightmare)
  • Linux RPMs and other packaging formats
  • Java JAR, EAR, WAR
  • Virtual machine
  • Docker containers
  • Unikernels

By looking specifically at the dependencies that applications in these packaging formats need to consider I came up with this list:

  • Hardware
  • Hypervisor
  • Operating system
  • Runtime environment (interpreter, middleware, …)
  • Libraries
  • Filesystem structure, size and specific files
  • Registry and other application configuration
  • System services
  • Networking
  • Other application components
  • Other enterprise services
  • Internet / external services
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How to Get Proficient in New Technologies

Breakthrough innovations are changing IT at ever faster speeds. New tools, languages, libraries, virtualisation technologies, workflows appear and get adopted in shorter times. A perfect example of this is Docker.

Keeping pace in that kind of environment affords a structured methodology. Here is what I do when preparing for a new thing, keeping in mind that no matter how cool it is, I will probably be far away from using it at my current paid projects.

  • Read a lot on sites such as InfoQ, where practitioners report.
  • Go to general DevOps conferences such as QCon, Velocity or watch in Youtube.
  • Key people will start to emerge from what you read and hear. Follow their publications and talks.
  • Pick a topic that matches your preferences and that will keep you focused over the next months and hopefully years.
  • Try it out, start with a small startup scenario, prototype it. Ask for help.
  • Drop it if it is shitty.
  • Energy and passion will be key to your success.
  • Tweet and blog about key observations.
  • Use gist for your code snippets and include them on your blog.
  • Create your own cheatsheet.
  • Organise your thoughts by keeping a list of findings, questions, conflicts, quotes, competition, etc.
  • Eat your own dog food by using the new thing for your own mini projects.
  • Build yourself a lab environment. With vagrant and docker this is nowadays easier than ever.
  • If its open source, understand the code, understand the process. If you have the time and energy, get involved.
  • If its closed source, scan the ecosystem for open stuff.
  • Make one conceptual slide per day.
  • Prepare a slide deck for your colleagues at work. Start with Why, show just enough concept then do a demo. Proceed with more breadth.
  • Try to earn some money by giving training on the topic.
  • Speak at conferences, people like practical advice and distrust marketing.
  • Connect with likeminded people. Give more than you take.
  • Make the world a better place.
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Ops as a competitive differentiator?

Operational aspects of software systems are often treated as second class citizens. The point is that e.g. availability is expected to be a given. FRs (functional requirements) are a differentiator and NFRs (non-functional requirements) are not. So why should anyone focus on NFRs?

In a world of mobile and sharing economy NFRs are becoming a necessity for the consumer (enterprise IT guys need to understand the difference between an internal customer and a consumer). However, due to complexity, internal structure and ignorance some enterprises who are creating those new products won’t get Ops right.

The consumer will find itself in a world of imperfection. Focus on Ops will lead to differentiation and therefore competitive advantage. Or at least ineffective Ops might devastate the unprepared!

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