Kubernetes: BASH function to change namespace

So when working with a lot of different namespaces in Kubernetes and you only know the “oc project” command from OpenShift, you start to miss an easy way to change namespaces in Kubernetes.

The official documentation to switch namespaces proposes something like this:

$ kubectl config set-context $(kubectl config current-context) --namespace=<insert-namespace-name-here>

Not something that I want to type regularly. First I tried to create a BASH alias or something, which did not work. So I looked around for BASH functions. I found that Jon Whitcraft proposed a nice BASH function in a GitHub issue. I lightly modified this and placed this in my own .bashrc file:

function kubectlns() {
  ctx=`kubectl config current-context`
  ns=$1

  # verify that the namespace exists
  ns=`kubectl get namespace $1 --no-headers --output=go-template={{.metadata.name}} 2>/dev/null`
  if [ -z "${ns}" ]; then
    echo "Namespace (${1}) not found, using default"
    ns="default"
  fi

  kubectl config set-context ${ctx} --namespace="${ns}"
}

So to change your namespace, use something like this:

$ kubectlns simon
Context "kubernetes-admin@kubernetes" modified.

Nice and short.

Automating Database Startup and Shutdown on Red Hat

Well, I was quite busy before the holidays, but here is another post I just keep for my reference.

For each database, I believe it is important to automate database shutdown and database startup. This way, in case of an emergency, a systems administrator can start and stop database services without the need for a database administator. Oracle provides an excellent article on this topic, but the Oracle documentation is quite generic. So I hereby provide a step-by-step guide for Red Hat Linux.

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BASH: Wait for log entry

For a startup script, I needed to start JBoss and start another component as soon as the complete JBoss server was started. When you execute the “run.sh” script that comes with JBoss, it immediately exits and starts JBoss in the background (which is quite nice I think). Unfortunately, when I started the other component using this method, the additional program was unhappy, since JBoss was not ready yet. So I had to come up with a trick to delay the start of the additional program.

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BASH Setup in Solaris 10

Coming from Linux distributions where BASH is usually already set up and configured, I had to find my way around in a UNIX environment first. So here I present the files necessary for a proper installation of BASH under Solaris 10 (yes, I know Solaris 11 Express is out :)).

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