Creating a minimal WildFly Docker image

The default way of creating an image with Docker is to extend an image by using the FROM call in the Dockerfile. But this is not the only way to do this. You can easily create a base image by using only the yum command.

WildFly 8.0.0.Final was recently released and is now available in Fedora 20 updates-testing repository. Let’s create an image that could be used to test this release but make it as minimal as it could be. The application server does have a lot of dependencies, so do not expect a 100 MB image. It’ll be closer to 1 GB.

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Assigning IP addresses to Docker containers via DHCP

In my last blog post I explained how to run a Docker installation across multiple hosts. In the comments I was asked if it would be possible to use a DHCP server to assign IPs to the containers. I thought immediately — why not? In fact, assigning IPs using DHCP is a nice way to overcome the IP assignment issue I talked about before.

The set up is pretty similar to my earlier work.

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Connecting Docker containers on multiple hosts

In my previous blog post I talked about running the Fedora Cloud images on a local KVM with libvirt. This was not a standalone task, but rather the preparation for this blog post: running Docker containers on multiple hosts attached to the same network.

I was asked in the comments on my WildFly cluster based on Docker blog post if it would be possible to run a cluster on multiple hosts. I found a very nice tutorial written by Franck Besnard. I’ve decided to set up a similar environment on my own to see how/if it works.

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Running Fedora Cloud images on KVM

Inspired by Matt’s blog post I’ve decided to make something that is similar but better fits my use case. I plan to do some clustering and routing testing and therefore I need to have similar VMs running side-by-side. These images will be short-lived and I would like to automate as many things I can.

Additionally, I found out that the images shipped by Fedora require some changes to work well in my case, for example the default 2GB disk is too small.

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Wrong battery estimate in Fedora on Lenovo ThinkPad 430s

I had a power mangement issue when running Fedora 19 (and later 20) on my Lenovo ThinkPad 430s. When the battery was low - the laptop just powered off itself, without a clean shutdown or even warning me. As you may guess - this wasn’t something I very happy about.

I discovered that it happens when the battery is still at 15%. The system reported at that time still about 40 min of available time.

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