Add kubernetes template for standalone deployment

.dockerignore

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-**/target/
 **/*.log
 **/*.jar
 **/*.war

kubernetes-dbless/README.md

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+# JQM Kubernetes DB-less ("Standalone") deployment
+
+This is the official Kubernetes DB-less setup for JQM (Job Queue Manager). It contains a deployment script and related
+documentation.
+
+In this document, "node" refers to a replicated instance, containing a JQM Engine, JQM Webservice, and HSQLDB
+in-memory database.
+
+## Limitations
+
+JQM is originally designed to work with a central database aggregating jobs for active engines. Removing this central
+database is not the intended use for it, and as such, some limitations are required to make it work in this way.
+
+- The Kubernetes deployment is expected to use the `jqm-standalone` docker image, a variant of the Linux image with
+  standalone-specific parameters enabled.
+
+- Each individual node still requires a local database to function. For now, only in-memory HSQLDB is supported.
+
+- Each individual node requires a unique IPv4 address. This IPv4 will be used by the node to assign job IDs. A node may
+  only enqueue up to 1 million jobs, after that threshold, behavior is undefined and may lead to malfunctions, so the
+  node should be restarted to clear its database. The `1789` port of each node needs to be exposed to other nodes.
+
+- Each individual node hosts its own instance of the JQM REST API. When making requests to the JQM API, whether to
+  enqueue a new job or control an existing job, the request should go through a simple load balancer. There is no
+  additional logic to pick a "better suited" node for enqueue requests.
+
+- Each individual node is completely unaware of other nodes. When queried for a job that does not belong to it, it
+  guesses the corresponding IPv4 and forwards the request. No information about the state of other nodes is saved, it
+  is up to the user to decide when a node is considered offline to avoid making unnecessary requests.
+
+## Testing for developpers
+
+Microk8s is recommended.
+
+This guide will help you install it and properly alias `kubectl` for ease of use:
+https://kubernetes.io/blog/2019/11/26/running-kubernetes-locally-on-linux-with-microk8s/
+
+Run the following script at the root of the repository:
+
+```bash
+# Stop existing kube configs
+kubectl delete service jqm-standalone-lb-service
+kubectl delete deployment jqm-standalone-deployment
+
+# Package the application
+cd ./jqm-all
+/snap/intellij-idea-ultimate/510/plugins/maven/lib/maven3/bin/mvn clean install -DskipTests || exit 1
+cd ..
+
+# Build the image
+docker build --no-cache -t enioka/jqm-standalone -f ./kubernetes-dbless/docker/Dockerfile . || exit 1
+
+# Import the image into Microk8s, otherwise it will try to pull from dockerio
+docker save -o ./jqm-standalone.tar enioka/jqm-standalone || exit 1
+microk8s ctr image import jqm-standalone.tar || exit 1
+rm jqm-standalone.tar
+
+# Load the deployment configuration
+kubectl apply -f ./kubernetes-dbless/deployment.yml
+
+# Load the loadbalancer configuration
+kubectl apply -f ./kubernetes-dbless/service.yml
+
+# Wait for boot
+sleep 10
+
+# Verify the state of your kubernetes configuration
+kubectl get deployments
+kubectl get pods
+
+# If any pod is in a "READY: 0/1" state:
+# Get an overview with
+#kubectl describe pod '<Pod id from the "kubectl get pods" command>'
+# Get more detailed logs with
+#kubectl logs -p -c jqm-standalone-deployment '<Pod id from the "kubectl get pods" command>'
+```

kubernetes-dbless/deployment.yml

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+apiVersion: apps/v1
+kind: Deployment
+metadata:
+    name: jqm-standalone-deployment
+    labels:
+        app: jqm-standalone
+spec:
+    replicas: 1
+    selector:
+        matchLabels:
+            app: jqm-standalone
+    template:
+        metadata:
+            labels:
+                app: jqm-standalone
+        spec:
+            containers:
+                - name: jqm-standalone-deployment
+                  image: enioka/jqm-standalone
+                  imagePullPolicy: IfNotPresent
+                  ports:
+                      - containerPort: 1789
+                  livenessProbe:
+                      httpGet:
+                          path: /ws/simple/localnode/health
+                          port: 1789
+                      initialDelaySeconds: 15
+                      periodSeconds: 15
+                  readinessProbe:
+                      httpGet:
+                          path: /ws/simple/localnode/health
+                          port: 1789
+                      initialDelaySeconds: 5
+                      periodSeconds: 10

kubernetes-dbless/docker/Dockerfile

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+FROM maven:3-eclipse-temurin-21 as installer
+
+ARG MVN_SETTINGS=" "
+ARG SKIP_TESTS=true
+
+WORKDIR /jqm-all
+
+RUN apt update && apt install unzip
+
+#COPY ./docker/windows/nexus/settings.xml ./jqm-all ./  # FIXME: settings needed ?
+COPY ./jqm-all ./
+
+RUN --mount=type=cache,target=/root/.m2/repository mvn install -DskipTests=${SKIP_TESTS} ${MVN_SETTINGS}
+RUN mkdir /jqm
+RUN unzip ./jqm-service/target/jqm*.zip -d /tmp/
+RUN mv /tmp/jqm*/ /tmp/jqm/
+
+COPY ./kubernetes-dbless/docker/node.sh /tmp/jqm/bin/
+COPY ./kubernetes-dbless/docker/selfConfig.standalone.xml /tmp/jqm/
+
+
+
+FROM azul/zulu-openjdk-alpine:21
+
+COPY --from=installer /tmp/jqm/ /jqm/
+RUN apk add curl
+
+ENV JAVA_OPTS="-Xms128m -Xmx512m -XX:MaxMetaspaceSize=128m" \
+    JQM_ROOT="/jqm" \
+    JQM_NODE_NAME="ContainerNode" \
+    JQM_NODE_WS_INTERFACE="0.0.0.0" \
+    #JQM_CREATE_NODE_TEMPLATE=TEMPLATE_WEB \
+    JQM_INIT_MODE=SINGLE \
+    JQM_POOL_CONNSTR="jdbc:hsqldb:file:db/jqmdatabase;shutdown=true;hsqldb.write_delay=false" \
+    JQM_POOL_USER="sa" \
+    JQM_POOL_PASSWORD="" \
+    JQM_POOL_DRIVER="org.hsqldb.jdbcDriver" \
+    JQM_POOL_VALIDATION_QUERY="SELECT 1 FROM INFORMATION_SCHEMA.SYSTEM_USERS" \
+    JQM_POOL_INIT_SQL=\
+    JQM_POOL_MAX=10 \
+    JQM_HEALTHCHECK_URL="http://localhost:1789/ws/simple/localnode/health"
+
+EXPOSE 1789 1790 1791
+VOLUME /jqm/hotdeploy/ \
+    /jqm/ext/drivers/
+
+WORKDIR /jqm
+
+# Import initial config
+RUN java -jar jqm.jar Update-Schema ; java -jar jqm.jar Import-ClusterConfiguration -f selfConfig.standalone.xml ; java -jar jqm.jar Import-JobDef -f ./jobs/jqm-demo ; rm -f .\logs\* ; chmod 700 /jqm/bin/*.sh ;
+
+# Run node on startup
+ENTRYPOINT /jqm/bin/node.sh
+
+# Healthcheck is equivalent to calling Node.AllPollersPolling
+# Kubernetes already has probes
+#HEALTHCHECK --interval=30s --start-period=91s --retries=2 --timeout=10s CMD curl --connect-timeout 2 -q --http1.1 -4 -s -S  ${JQM_HEALTHCHECK_URL}
+STOPSIGNAL SIGINT

kubernetes-dbless/docker/node.sh

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+#!/bin/sh
+
+###############################################################################
+## Startup script for Linux docker deployments.
+###############################################################################
+
+
+# set resource file from env variables
+if [ ! "x${JQM_POOL_INIT_SQL}" = "x" ]
+then
+    export JQM_POOL_INIT_SQL="initSQL=\"${JQM_POOL_INIT_SQL}\""
+fi
+
+echo "<resource
+    name='jdbc/jqm'
+    auth='Container'
+    type='javax.sql.DataSource'
+    factory='org.apache.tomcat.jdbc.pool.DataSourceFactory'
+    testWhileIdle='true'
+    testOnBorrow='false'
+    testOnReturn='true'
+    validationQuery=\"${JQM_POOL_VALIDATION_QUERY}\"
+    ${JQM_POOL_INIT_SQL}
+    logValidationErrors='true'
+    validationInterval='1000'
+    timeBetweenEvictionRunsMillis='60000'
+    maxActive='${JQM_POOL_MAX}'
+    minIdle='2'
+    maxIdle='5'
+    maxWait='30000'
+    initialSize='5'
+    removeAbandonedTimeout='3600'
+    removeAbandoned='true'
+    logAbandoned='true'
+    minEvictableIdleTimeMillis='60000'
+    jmxEnabled='true'
+    username='${JQM_POOL_USER}'
+    password='${JQM_POOL_PASSWORD}'
+    driverClassName='${JQM_POOL_DRIVER}'
+    url='${JQM_POOL_CONNSTR}'
+    connectionProperties='v\$session.program=JQM;'
+    singleton='true'
+/>" > ${JQM_ROOT}/conf/resources.xml
+
+# helper for swarm deployment - use local host name for node name.
+if [ "${JQM_NODE_NAME}" = "_localhost_" ]
+then
+    export JQM_NODE_NAME=$(hostname)
+fi
+if [ "${JQM_NODE_WS_INTERFACE}" = "_localhost_" ]
+then
+    export JQM_NODE_WS_INTERFACE=$(hostname)
+fi
+
+if [ "${JQM_INIT_MODE}" = "SINGLE" ]
+then
+    echo "### Checking configuration in database for node ${JQM_NODE_NAME} - Single mode."
+    if [ ! -f /jqm/db/${JQM_NODE_NAME} ]
+    then
+        echo "#### Node does not exist (as seen by the container). Single node mode."
+
+        echo "### Updating database schema"
+        java -jar jqm.jar Update-Schema
+
+        echo "### Creating node ${JQM_NODE_NAME}"
+        java -jar jqm.jar New-Node -n ${JQM_NODE_NAME}
+
+        # mark the node as existing
+        echo 1 > /jqm/db/${JQM_NODE_NAME}
+
+        # Apply template
+        if [ ! "x${JQM_CREATE_NODE_TEMPLATE}" = "x" ]
+        then
+            echo "#### Applying template ${JQM_CREATE_NODE_TEMPLATE} to new JQM node"
+            java -jar jqm.jar Install-NodeTemplate -t ${JQM_CREATE_NODE_TEMPLATE} -n ${JQM_NODE_NAME} -i ${JQM_NODE_WS_INTERFACE}
+        fi
+
+        # Jobs
+        echo "### Importing local job definitions inside database"
+        java -jar jqm.jar Import-JobDef -f ./jobs/
+    else
+        echo "### Node ${JQM_NODE_NAME} already exists inside database configuration, skipping config"
+    fi
+fi
+
+if [ "${JQM_INIT_MODE}" = "CLUSTER" ]
+then
+    echo "### Checking configuration in database for node ${JQM_NODE_NAME} - Cluster mode."
+    java -jar jqm.jar Get-NodeCount >/jqm/tmp/nodes.txt
+    if [ ! $? -eq 0 ]
+    then
+        echo "cannot check node status, java failure"
+        return 1
+    fi
+
+    cat /jqm/tmp/nodes.txt | grep "Already existing: ${JQM_NODE_NAME}"
+    if [ $? -eq 0 ]
+    then
+        echo "### Node ${JQM_NODE_NAME} already exists inside database configuration, skipping config"
+    else
+        echo "#### Node does not exist (as seen by the database). Cluster mode."
+
+        echo "### Waiting for templates import"
+        $(exit 0)
+        while [ $? -eq 0 ]
+        do
+            # no templates yet - wait one second and retry
+            sleep 1
+            java -jar jqm.jar Get-NodeCount >/jqm/tmp/nodes.txt
+            grep "Existing nodes: 0" /jqm/tmp/nodes.txt
+        done
+
+        echo "### Creating node ${JQM_NODE_NAME}"
+        java -jar jqm.jar New-Node -n ${JQM_NODE_NAME}
+
+        # mark the node as existing
+        echo 1 > /jqm/db/${JQM_NODE_NAME}
+
+        # Apply template
+        if [ ! "x${JQM_CREATE_NODE_TEMPLATE}" = "x" ]
+        then
+            echo "#### Applying template ${JQM_CREATE_NODE_TEMPLATE} to new JQM node"
+            java -jar jqm.jar Install-NodeTemplate -t ${JQM_CREATE_NODE_TEMPLATE} -n ${JQM_NODE_NAME} -i ${JQM_NODE_WS_INTERFACE}
+        fi
+    fi
+fi
+
+if [ "${JQM_INIT_MODE}" = "UPDATER" ]
+then
+    echo "### Updating database schema"
+    java -jar jqm.jar Update-Schema
+
+    echo "### Importing local job definitions inside database"
+    java -jar jqm.jar Import-JobDef -f ./jobs/
+
+    echo "### Listing nodes"
+    java -jar jqm.jar get-nodecount >/jqm/tmp/nodes.txt
+    type /jqm/tmp/nodes.txt
+
+    # If first node, upload template and initial configuration.
+    grep "Existing nodes: 0" /jqm/tmp/nodes.txt
+    if [ $? -eq 0 ]
+    then
+        echo "### No nodes yet - uploading templates and initial configuration to database"
+        java -jar jqm.jar Import-ClusterConfiguration -f selfConfig.swarm.xml
+    fi
+
+    return 0
+fi
+
+# Go!
+echo "### Starting JQM node ${JQM_NODE_NAME}"
+java -D"com.enioka.jqm.interface=0.0.0.0" ${JAVA_OPTS} -jar jqm.jar Start-Node -n ${JQM_NODE_NAME}