Prevent selected Debian package from upgrading

An example situation we have had recently: Erlang Solutions have published a new version of esl-erlang package with the newest Erlang/OTP 20.0. This new major Erlang release contains a few incompatibilities with earlier versions and that is why we have had to hold this update in a system we have been building.

There is a simple way to temporarily prevent apt-get upgrade from upgrading the ‘esl-erlang’ package to the newest version – the only thing you need to do is to put this package on ‘hold’ with apt-mark hold els-erlang.

Later on you use apt-mark unhold esl-erlang to again allow debian package manager to upgrade this package.

Locked file system after restarting Docker service

During the system upgrade (apt-get upgrade) which updates also the docker-engine package, the docker service is restarted, which means stopping all containers.

Theoretically, containers created with the restart policy set to „always” should restart themselves automatically, but some time ago we had a problem with restarting one of such containers. The container was part of the multi-container application:

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