Liveness and readiness probes tell Kubernetes whether a pod is running and ready to do some work. An enterprise application can probe the status of an application via HTTP. If no HTTP endpoint is exposed Kubernetes can also probe by executing commands.
WildFly ships with the useful jboss-cli.sh. This CLI retrieves information about the server and deployment states as follows:
$> ./jboss-cli.sh --connect --commands="ls" [...] process-type=Server product-name=WildFly Full product-version=11.0.0.Final [...] server-state=running suspend-state=RUNNING uuid=c52658a9-ca39-4548-9879-162cd6e14d93
We can combine a shell command to check for running servers:
./jboss-cli.sh --connect --commands=ls | grep "server-state=running"
A similar commands gives us the deployed applications:
$> ./jboss-cli.sh --connect --commands="ls deployment" hello.war
We compose a shell command again to check whether our applications has been deployed successfully:
./jboss-cli.sh --connect --commands="ls deployment" | grep "hello.war"
Now let’s insert these commands into the YAML descriptor:
...
containers:
- name: hello-joker
image: docker.example.com/hello:1
imagePullPolicy: IfNotPresent
livenessProbe:
exec:
command:
- /bin/sh
- -c
- /opt/jboss/wildfly/bin/jboss-cli.sh --connect --commands=ls | grep 'server-state=running'
readinessProbe:
exec:
command:
- /bin/sh
- -c
- /opt/jboss/wildfly/bin/jboss-cli.sh --connect --commands='ls deployment' | grep 'hello.war'
...If your application emits status or “ping” resources, the easier way is to probe the pod via HTTP as shown in this post.
Happy application probing!
Found the post useful? Subscribe to my newsletter for more free content, tips and tricks on IT & Java:
Success! Now check your email to confirm your subscription.
| Published on Java Code Geeks with permission by Sebastian Daschner, partner at our JCG program. See the original article here: WildFly Kubernetes exec probes Opinions expressed by Java Code Geeks contributors are their own. |
