Docker on Windows tips & tricks

Just some tips & tricks on Docker on Windows I documented for myself.

Location of Docker daemon logs

The Docker daemon logs can be found in the following location.

C:\ProgramData\Docker

By default C:\ProgramData is hidden in Explorer, you need to make it visible in the options (File -> Change folder and search options, select tab View, select the option ‘Show hidden files, folders and drives’ under ‘Hidden files and folders’).

Change folder and search options

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Validating a json file from the command line in Linux

Today I needed to validate a json file on one of my servers. It turns out there is a simple nodejs program or actually a linter to do this with.

Just execute the following line and you are in business.

sudo npm install jsonlint -g

This assumes nodejs is already installed. If not, execute the following line.
sudo apt-get install -y nodejs npm

To validate a json file run the following command.

jsonlint -qc settings.analyzer.json

When running the program the first time I ran into the problem that the json file contains comments. Yes, I know this is not in line with the spec, but it is damn handy for understanding the file. So I needed to strip the comments to valiate the file. After googeling around a bit I found an awk command to do just this. Try the following command.

awk '{sub(/\/.*$/,"")}1' settings.analyzer.json > settings.analyzer.json

Now run jsonlint again and it should work.

P.s. I know the title of this post says Linux, but jsonlint will also work under any other system that nodejs runs on.

Hope this saves someone some time.

Adding two factor authentication to KeePass & KeePass2Android

Time to beef up security. Like everyone I have a large number of online accounts. They are generally secured with username and password. I use KeePass to generate unique passwords and keep track of them. There have been a lot of hacks lately. So I wanted to make my most important accounts more secure. More and more online services are adding two factor authentication, e.g. Google, Dropbox. Two factor authentication adds an additional layer of security.
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Error compiling Scalatra project

Seriously? Unsupported major.minor version 51.0 when compiling a Scalatra project? The complete error is “Caused by: java.lang.UnsupportedClassVersionError: org/eclipse/jetty/server/Handler : Unsupported major.minor version 51.0”. After some Googling I found the following statement “You are using different JDK versions to compile and run the application”. No way, that is not possible. Continue reading

Installing Scalatra on Windows

Scalatra is a micro framework for Scala. Installation does not seem to be as straight forward as adding Scalatra to the dependencies of build.sbt. It requires a number of other tools to work: Conscript and giter8. Conscript is a tool for installing and updating Scala code. giter8, which depends on conscript, allows you to check out project templates directly from Github. It’s the recommended way to generate Scalatra project skeletons. These are quick installation instructions for Scalatra on Windows. Continue reading