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rpi-kubernetes-led-demo

Demonstrates using Kubernetes by deploying a container that toggles LEDs, in order to discuss key concepts such as deployment, services, labels, node selection, scaling, privileges etc.

First we need to build a cluster, for this check out the following awesome projects;

A Raspberry Pi 3 Kubernetes Cluster

[https://github.com/Project31](Project31 aims to deploy the Fabric8 applications on ARM64 architectures, in particular a cluster of RaspberryPi3 and Pine64.)

Wire rPi to breadboard

Turning on an LED with your Raspberry Pi's GPIO Pins

Start a Camel route using Pi4J

This route toggles the state of the GPIO pin every second.

    from("timer:default?period=1000").to("pi4j-gpio://GPIO_01?action=TOGGLE");

Build a fat jar

If using Spring then repackage as follows;

    <plugin>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-maven-plugin</artifactId>
    <version>${spring-boot.version}</version>
    <configuration>
        <mainClass>example.KubernetesLedDemo</mainClass>
    </configuration>
    <executions>
        <execution>
            <goals>
                <goal>repackage</goal>
            </goals>
        </execution>
    </executions>
  </plugin>

See if it works;

  mvn clean install

  sudo java -jar target/kubernetes-led-demo.jar

Now build the docker image and Kubernetes manifest

See fabric8-maven-plugin

    <plugin>
    <groupId>io.fabric8</groupId>
    <artifactId>fabric8-maven-plugin</artifactId>
    <version>3.1.92</version>
    <executions>
        <execution>
            <id>fmp</id>
            <goals>
                <goal>resource</goal>
                <goal>build</goal>
            </goals>
        </execution>
    </executions>
    <configuration>
        <images>
            <image>
                <name>${project.artifactId}:${project.version}</name>
                <build>
                    <from>hypriot/rpi-java:1.8.0</from>
                    <assembly>
                        <basedir>/app</basedir>
                        <descriptorRef>artifact</descriptorRef>
                    </assembly>
                    <entryPoint>
                        <arg>java</arg>
                        <arg>-jar</arg>
                        <arg>/app/${project.artifactId}.jar</arg>
                    </entryPoint>
                </build>
            </image>
        </images>

    </configuration>
  </plugin>

  NB Base image is Hypriot's Java 8 for rPi, to this we add the far-jar and configure the entry-point;

  mvn clean install

You can also run a prebuilt image that toggles the state of GPIO_01

docker run -it --privileged taariq/rpi-kubernetes-led-demo:1.0-SNAPSHOT

or specify a different pin

docker run -e gpioId=GPIO_02 -it --privileged taariq/rpi-kubernetes-led-demo:1.0-SNAPSHOT

test Docker

docker run -it --privileged --rm rpi-kubernetes-led-demo:1.0-SNAPSHOT

NB Run the container as privileged so wiringPi can access the device ( /dev/mem )

todo

  • fabric8-maven-plugin commands
  • kubectl to label nodes etc