Laura Liparulo's blog

Tag: container

Docker commands – Getting started

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Posted inCONTAINERS

To run one of the Docker official image, you can simply use “docker run”:

$ docker run centos

The first time you run it, the image can´t be found and must be downloaded:

Once downloaded, the image is saved in the docker cache and can be reused if necessary.

If it´s an official image, you would only need to enter the image name only.

But it´s taken from a user´s repo the format is: <username>/<image>.

The 100% Free software linux image Trisquel, for example, is taken from the repository of a user called “kpengboy“.

In this case, even if you are logged in, you can´t run “docker run”. You need to pull it first:

$docker pull kpengboy/trisquelbash

To see the list of the images donwload so far, run:

$ docker images

If you also want to start a bash in the container, use “-it” for the interactive mode:

$ docker run -it kpengboy/trisquel

Then you can work with the bash shell:

As default, docker will download the latest version available, but you can additionally specify a version (called “tag”) you want to work with:

$ docker run redis:4.0

If you want to access a webapp or, for example, a database, you generally get an assigned url with a port number. But you can change the ports, by adding them as parameters.

For example, if you want to run mysql and access it at a different port than 3306, use the “-p” option to give <host>:<container-port>:

$ docker run  -p 52000:3307 mysql

To persist your data, even when the container is killed, you can mount a persistent volume with “-v”:

$ docker run -v /opt/data/mysql mysql

You can pass an environment variable to you container, which might help you to avoid modifying the image and achieve some strategic solution:

$ docker run -e BACKGROUND_COLOR simple-web-app

To see which containers are running:

$ docker ps

To see the stopped containers to

$ docker ps -a

If you want to get the details of a specific container:

$ docker inspect vibrant_chatelet

You can check the log by running:

$ docker logs vibrant_chatelet

You can start a container in background mode with the “-d” option:

$ docker -d kpengboy/trisquel

To remove a container (even if it´s running)

$ docker rm vibrant_chatelet

Or by containerID

$ docker rm 0d6d64f9053c

To remove the image you need to make sure that no container is running it first. You migh use “docker stop” or just remove it directly.

To remove an image you need:

$ docker rmi kpengboy/trisquel

Kubernetes – Running from a custom Docker image

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Posted inCONTAINERS , DOCKER , Kubernetes

As I am getting ready for CKA exam, I will show you how to run a pod on Kubernetes starting from the a Dockerfile.

Let´s say we want to create a Node.Js simple server, a simpe app.js file.

const http = require('http');
const os = require('os');

console.log("My node js server is starting...");

var handler = function(request, response) {
  console.log("Received request from " + request.connection.remoteAddress);
  response.writeHead(200);
  response.end("You've hit " + os.hostname() + "\n");
};

var www = http.createServer(handler);
www.listen(8080);

Once we have the app.js file, we can create a Dockerfile too:

FROM node:7
ADD app.js /app.js
ENTRYPOINT ["node", "app.js"]

Then we can build the image:

docker build -t node-js-server-image .

Once we have created the image, we need to login to Docker Hub with the “docker login” command, then tag and push our image:

$ docker login

$ docker tag node-js-server-image lauraliparulo/node-js-server-image

$ docker push lauraliparulo/node-js-server-image

Then you can use the image to create a kubernetes pod

$ kubectl run nodejs --image=lauraliparulo/node-js-server-image --port=8080

With “kubectl describe pod node-js” we can find the IP of the exposed pod:

Then we can check the content with “curl”:

Kubernetes – Logging

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Posted incloud , CONTAINERS , Kubernetes

The standard error (stderr) and output (stdout) are stored by Kubernetes for every container and can be visualized with the “kubectl logs” command.

Let´s consider for example a simple pod like:

apiVersion: v1
kind: Pod
metadata:
  name: now
spec:
  containers:
    - name: date-pod
      image: g1g1/py-kube:0.2
      command: ["/bin/bash", "-c", "while true; do sleep 20; date; done"]

If you run “kubectl logs now” you will see the date:

if you pod is a multicontainer, you need to specify which container do you want to inspect:

For example if you want to check the logs of a container called “background” in  a pod called “webapp”, using the “-c” option:

$ kubectl logs webapp -c background

If your pod is in a deployment:

$ kubectl logs deployment/flask

If you want to stream the log, add the “-f” option:

$ kubectl logs deployment/flask -f

You can as well redirect it in a file.. .also with “tee” for both screen and file:

$ kubectl logs now | tee log.txt

You can check the logs of the previous container with the “-p” options:

$ kubectl logs -p podname

You can also add the timestamp. For example:

$ k run text-pod --image=busybox --labels="tier=msg,review=none" --env VAR1=hello --env VAR2=world -o yaml > p.yaml --command -- sh -c "while true; do echo this is a logging text; sleep 2; done"

Then run:

$ kubectl logs text-pod --timestamps

Kubernetes – labels, selectors and annotations

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Posted incloud , CONTAINERS , Kubernetes

When you create a deployment or simply are new pod with Kubernetes, you are expected to add some metadata, like semantic information in form of labels or deployment annotations. That´s because the amount of pods you need to run might grow a lot and you need a way to search through them.

It´s a mechanism for organizing the dozens of resources you are going to have.

LABELS

Labels are key-value pairs used mainly for grouping and selecting purposes.

For instance, you can use them to add information about the environment, the team or area of responsibility involved, the version, etc.

labels are not the same as “selectors”, but you can use the “-l” options For both, if you want to  retrieve a set of resources:

$ kubectl get pods -l app=flask

You get:
Name: flask
Namespace: default
CreationTimestamp: Sat, 16 Sep 2017 08:31:00 -0700
labels: pod-template-hash=866287979
        run=flask
Annotations: deployment.kubernetes.io/revision=1
kubectl.kubernetes.io/last-applied-configuration={"apiVersion":"apps/v1beta1","kind":"deployment","metadata":{"annotations":{},"labels":{"run":"flask"},"name":"flask","namespace":"default"},"spec":{"t...
Selector: app=flask
Replicas: 1 desired | 1 updated | 1 total | 1 available | 0 unavailable
StrategyType: RollingUpdate
MinReadySeconds: 0
RollingUpdateStrategy: 25% max unavailable, 25% max surge
pod Template:
 labels: app=flask
 etc.
 


If you create a deployment using “kubectl run”, the level “run=flask” is added automatically.
the command assigns the keys run, pod-template-hash, and app For specific meanings.

To get the label values in the information view, use “–show-labels”.

$ kubectl get pods --show-lables

To query labeled pods:

$ kubectl get pods -L run,pod-template-hash
$ kubectl get po -l creation_method=manual
$ kubectl get po -l '!env'

Notice that also the “not” operator (!) can be used.

You can add a label to an existing pod:

$ kubectl label po kubia-manual creation_method=manual

Or you can overwrite an existing one:

$ kubectl label po kubia-manual-v2 env=debug --overwrite

Assign a label by searching two or possible values:

$ kubectl label pod -l "type in (worker,runner)" protected=true


SELECTORS

Labels can be used in selectors:

$ kubectl get deployments.app --selector nl=spook

For example, to find all the deployments that have the label “app” set to “nginx”:

$ kubectl get all --selector="app=nginx" -o wide

FIELD SELECTORS

all The fields you see in the yaml files can be used for querying with the “field-selector” options like:

$ kubectl get pods --field-selector status.phase=Running
$ kubectl get pods --field-selector metadata.namespace!=jupiter
$ kubectl get pods --field-selector=status.phase!=Running,spec.restartPolicy=Always

You can also use the metadata as environment variables with “fieldRef” in the manifest file:


    spec:
      containers:
      - image: nginx
        name: nginx
        env:
        - name: POD_NAME
          valueFrom:
            fieldRef:
                fieldPath: metadata.name 

ANNOTATIONS

Annotations are used to provide additional information related to an instance. They are intended as descriptions and are very useful when it comes to checking a rollout history.

For example:

$ kubectl annotate pod redis description="this is doc"

This will be added to the metadata of your yaml file.

To set an annotation for the deployment history:

$ kubectl annotate deployment flask kubernetes.io/change-cause='deploying image 0.1.1'
deployment "flask" annotated

Now, if we look at the history, you will see the following displayed:

kubectl rollout history deployment/flask
deployments "flask"
REVISION  CHANGE-CAUSE
1         <none>
2         deploying image 0.1.1

The second revision now has a “change-cause” entry.

It´s important to know that you annotate a group of resources that have the same labels, especially if you have a lot of pods:

$ kubectl annotate pod -l protected=true protected="do not delete this pod".

Arquillian testing with Maven in Eclipse: Deployment scenario issue (Glassfish embedded example)

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Posted injava , Programming , Software development , xml

To run a test with Arquillian using Maven you might consider embedded, local or remote containers. You can set them all in your pom.xml file and specify deployment profiles like the following:

 <profile>
			<id>arquillian-glassfish-embedded</id>
			<activation>
				<activeByDefault>true</activeByDefault>
			</activation>
			<dependencies>
				<dependency>
					<groupId>org.jboss.arquillian.container</groupId>
					<artifactId>arquillian-glassfish-embedded-3.1</artifactId>
					<version>1.0.0.CR4</version>
					<scope>test</scope>
				</dependency>
				<dependency>
					<groupId>org.glassfish.main.extras</groupId>
					<artifactId>glassfish-embedded-all</artifactId>
					<version>4.0</version>
					<scope>provided</scope>
				</dependency>

				<dependency>
					<groupId>org.glassfish.jersey.core</groupId>
					<artifactId>jersey-client</artifactId>
					<version>2.4.1</version>
					<scope>provided</scope>
				</dependency>

				<dependency>
					<groupId>org.glassfish.jersey.containers</groupId>
					<artifactId>jersey-container-servlet</artifactId>
					<version>2.4.1</version>
					<scope>provided</scope>
				</dependency>

			</dependencies>
		</profile>

The container must be configured in the arquillian.xml file. A simple one might look like this:

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<arquillian xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
   xmlns="http://jboss.org/schema/arquillian"
   xsi:schemaLocation="http://jboss.org/schema/arquillian http://jboss.org/schema/arquillian/arquillian_1_0.xsd">
   <!--  this is only needed if you want to override AS7  -->
   <!--  <defaultProtocol type="Servlet 3.0"/> -->
   <container qualifier="arquillian-glassfish-embedded">
   	<configuration>
   		<property name="bindHttpPort">9090</property>
   	</configuration>
   </container>
   <!-- 
   <container qualifier="tomcat">
   	<configuration>
   		<property name="user">tomcat</property>
   		<property name="pass">tomcat</property>
   	</configuration>
   </container>
    -->
</arquillian>

Setting the container in the pom.xml and the arquillian.xml files is not enough to run the test in Eclipse.
You would get the following error:

org.jboss.arquillian.container.test.impl.client.deployment.ValidationException: DeploymentScenario contains a target (_DEFAULT_) not matching any defined Container in the registry.
Please include at least 1 Deployable Container on your Classpath.
          at org.jboss.arquillian.container.test.impl.client.deployment.DeploymentGenerator.throwNoContainerFound(DeploymentGenerator.java:250)
          at org.jboss.arquillian.container.test.impl.client.deployment.DeploymentGenerator.throwTargetNotFoundValidationException(DeploymentGenerator.java:243)
          at org.jboss.arquillian.container.test.impl.client.deployment.DeploymentGenerator.validate(DeploymentGenerator.java:102)
          at org.jboss.arquillian.container.test.impl.client.deployment.DeploymentGenerator.generateDeployment(DeploymentGenerator.java:84)
          at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
          at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
          at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
          at java.lang.reflect.Method.invoke(Method.java:597)
          at org.jboss.arquillian.core.impl.ObserverImpl.invoke(ObserverImpl.java:94)
          at org.jboss.arquillian.core.impl.EventContextImpl.invokeObservers(EventContextImpl.java:99)
          at org.jboss.arquillian.core.impl.EventContextImpl.proceed(EventContextImpl.java:81)
          at org.jboss.arquillian.core.impl.ManagerImpl.fire(ManagerImpl.java:135)
          at org.jboss.arquillian.core.impl.ManagerImpl.fire(ManagerImpl.java:115)
          at org.jboss.arquillian.core.impl.EventImpl.fire(EventImpl.java:67)
…

To make the test run you need to set the active maven profiles in Eclipse. Simply right click on the project and select Properties>Maven and add “arquillian-glassfish-embedded” in the Active maven profiles textbox.

Liferay search container pagination problem when passing form parameter SOLVED

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Posted injava , Liferay , Programming , Software development

Hello, guys!
I’ve been struggling for a couple of days trying to make my seach container pagination works.
When you clicking on the next page and you need to use a form parameter value submitted to get the rows, you need to store it in the portlet preferences, otherwise you lose it in the page “refresh”.

I haven’t found a solution on the web so far, so I’m posting my code snippets… that WORKS lol:
but I’m using portlet preferences … check it out!

[b]action method in the controller:[/b]

		public void searchVolume(ActionRequest request, ActionResponse response)
			throws IOException, PortletException, PortalException,
			SystemException, NoSuchVolumeException {

		String volumeIdentifier = request.getParameter("volumeId");
		long volumeId = (long) Integer.parseInt(volumeIdentifier);
		long idVol = 0;

		boolean found = false;
		boolean emptyList = false;

		List volume = new ArrayList();
		volume = VolumeLocalServiceUtil.getAllVolumes();
		List caseArchive = new ArrayList();
		caseArchive = CaseArchiveLocalServiceUtil
				.getAllCasesbyVolumeId(volumeId);

		if (caseArchive.size() == 0) {
			emptyList = true;
		}

		for (Volume itemVolume : volume) {
			if (itemVolume.getVolumeId() == volumeId)
				found = true;
		}

		if (found && emptyList) {
			SessionMessages.add(request, "no-cases-found");
		} else if (found && !emptyList) {
			Volume vol = DBUtil.getVolumefromRequest(request);
			idVol = vol.getVolumeId();

			if (idVol == 1) {
				System.out.println("Volume id iniziale: " + volumeId);
				SessionErrors.add(request, "error-volume");
			} else if (SearchValidator.volumeNotNull(idVol) && !(idVol == 1))

			{
				System.out.println("Volume id action : " + vol.getVolumeId());

				response.setRenderParameter("volId", volumeIdentifier);
				System.out.println("search volume clicked");

				PortletPreferences prefs = request.getPreferences();
				String volumeIdent = request.getParameter("volumeId");
				if (volumeIdent != null) {
					prefs.setValue("volumeIdPref", volumeIdent);
					prefs.store();
				}

				VolumeLocalServiceUtil.clearService();

				SessionMessages.add(request, "search-volume");

			}
		} else
			SessionErrors.add(request, "error-volume");

		response.setRenderParameter("jspPage", viewDatabaseJSP);

	}

[b]JSP page[/b]:


	CaseArchiveLocalServiceUtil.clearCache();
	VolumeLocalServiceUtil.clearCache();

	//RoiLocalServiceUtil.clearCache();
	//ImageDBLocalServiceUtil.clearCache();
	//DicomLocalServiceUtil.clearCache();
	ImageTypeLocalServiceUtil.clearCache();

	List volumes = VolumeLocalServiceUtil.getAllVolumes();
	List cases = CaseArchiveLocalServiceUtil.getAllCases();
	Long volumeIdentifier = 1L;

	Collections.sort(volumes, new Comparator() {
		public int compare(Volume o1, Volume o2) {
			Volume p1 = (Volume) o1;
			Volume p2 = (Volume) o2;
			return p1.getVolumeName().compareToIgnoreCase(
					p2.getVolumeName());
		}
	});

	PortletURL portletURL = renderResponse.createRenderURL();

	portletURL.setParameter("jspPage", "/html/admin/viewDatabase.jsp");

	int selected = 0;
	String volSel = null;

	PortletPreferences prefs = renderRequest.getPreferences();
	String volumeId = (String) prefs.getValue("volumeIdPref", "1");
%>

	method="post">

		 1) {
						volumeIdentifier = (long) Integer.parseInt(volumeId);

					}

					List tempResults = DBUtil
							.getAllCasesOk(volumeIdentifier);

					results = ListUtil.subList(tempResults,
							searchContainer.getStart(),
							searchContainer.getEnd());

					total = tempResults.size();

					pageContext.setAttribute("results", results);
					pageContext.setAttribute("total", total);

					portletURL.setParameter("cur",
							searchContainer.getCurParam());
					System.out.println("Cur PRINT:" + searchContainer.getCur());
		%>

					href="" name='view Case' />

 <a href="<%=cancelURL%>">← Back to Menu</a>

In the example above, volumeId is the form action parameter (passed by the select option), while volumeIdPref is the portlet preferences parameter, which keeps the value while consulting the pages.
In the action method, that is invoked when submitting the form value, i’ve set a response parameter called volId which is used in the jsp to set the variable value when invoking the search-container result page “1”. The render parameter is null when visiting the other pages, but it can be retrieved by the portlet preferences value.

I hope this helps. Let me know if you have questions or suggestions.
Regards
Laura

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