Israel Perales ripper2hl

Podman with docker-compose on MacOS.

Podman an alternative to Docker Desktop on MacOS

Getting podman installed and started is super easy.
Just use brew to install it.

> brew install podman

Now since podman uses a VM just like the Docker Client on MacOS we need to initialize that and start it.

Various ways to restart pods

Restart deployment

The most gracefull way is to trigger a restart for the deployment. In this case, a pod will only be terminated once the new pod is ready. It will slowly replace all pods one after the other.

kubectl rollout restart deployment <deployment-name>

Restart pods in a statefulset

What do the resource requests and limits mean in OpenShift and how might they effect your Java application?

Java resource management

To the extent it is implementation specific the discussion below is based on the OpenJDK HotSpot runtime.

Threads

The JVM maps threads in Java to OS threads 1:1 , i.e., there are no "green threads" in Java like there are in some other virtual machines, for example BEAM, the Erlang virtual machine.

A thread in the JVM can be in one of the following states:

thread_new: a new thread in the process of being initialized

oc scale --replicas=0 $(oc get dc -o name | xargs) -n

Disabling GNOME Tracker and Other Info

GNOME's tracker is a CPU and privacy hog. There's a pretty good case as to why it's neither useful nor necessary here: http://lduros.net/posts/tracker-sucks-thanks-tracker/

After discovering it chowing 2 cores, I decided to go about disabling it.

Directories

	---
	apiVersion: v1
	kind: PersistentVolumeClaim
	metadata:
	name: microcks-pvc
	labels:
	app: microcks
	spec:
	resources:
	requests:

	/******** Step 1 ********************
	********* File Imports *************/
	import com.amazonaws.services.transcribe.AmazonTranscribe;
	import com.amazonaws.services.transcribe.AmazonTranscribeClientBuilder;
	import com.amazonaws.services.transcribe.model.DeleteTranscriptionJobRequest;
	import com.amazonaws.services.transcribe.model.GetTranscriptionJobRequest;
	import com.amazonaws.services.transcribe.model.GetTranscriptionJobResult;
	import com.amazonaws.services.transcribe.model.LanguageCode;
	import com.amazonaws.services.transcribe.model.Media;
	import com.amazonaws.services.transcribe.model.StartTranscriptionJobRequest;

	[Unit]
	Description=SonarQube service
	After=syslog.target network.target

	[Service]
	Type=forking

	ExecStart=/opt/sonarqube/bin/linux-x86-64/sonar.sh start
	ExecStop=/opt/sonarqube/bin/linux-x86-64/sonar.sh stop

	https://access.redhat.com/solutions/2178611


	### How to Force a pod to schedule to a specific node using nodeSelector in OCP

	Pods get scheduled to nodes based on the node labels. NodeSelector will get set either for the cluster, project, or pod to determine which node or group of nodes the pod will be scheduled to.

	The easiest way to test and ensure a pod is scheduled to a node is by setting it at the project level. This can only be done by cluster-admins or users with elevated privileges.

	# oc adm project <NAME> --node-selector='foo=bar'

	import org.hibernate.jpa.HibernatePersistenceProvider;
	import org.springframework.context.annotation.Configuration;

	import javax.annotation.PostConstruct;
	import javax.persistence.spi.PersistenceProvider;
	import javax.persistence.spi.PersistenceProviderResolver;
	import javax.persistence.spi.PersistenceProviderResolverHolder;
	import java.util.Collections;
	import java.util.List;