Container-less Java services

Development and deployment strategies for building container-less apps in Java inspired by lessons from the 12 Factor App, a methodology for building software-as-a-service apps for the cloud.

Cross posted from https://slides.com/gilday/container-less-java-services

Transcript

1. Self-contained Java
   Self-contained Java
   services
   services
   Johnathan Gilday
   Next Century Corporation
   2016-07-14
   

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2. Some motivation
   Some motivation
   At , we build a lot of services for our
   customers, often in Java
   Our services are getting trimmer and more plentiful
   Our development teams continue to become more
   involved with the infrastructure management and
   production operations
   We need to optimize the way we build and deploy these
   services. Abandoning the shared application container is
   one way
   Next Century
   

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3. What do I mean by
   What do I mean by
   container?
   container?
   Also called "application server"
   One process
   Manages one or more archives (WAR, EAR)
   Examples: Apache Tomcat, Wildfly, Glassfish
   

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4. To deploy application
   To deploy application
   archives to running
   archives to running
   containers:
   containers:
   1. Install container
   2. Build WAR
   3. Push WAR to container
   

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5. Containers Manage your
   Containers Manage your
   app's lifecycle
   app's lifecycle
   @WebListener
   public class AppInitializer implements ServletContextListener {
   @Override
   public void contextInitialized(final ServletContextEvent sce) {
   // container calls this method to initialize app
   }
   @Override
   public void contextDestroyed(final ServletContextEvent sce) {
   // container calls this method to shutdown app
   }
   }
   @WebServlet(name = "my-servlet", urlPatterns = "/my-servlet")
   public class MyServlet extends HttpServlet {
   @Override
   public void doGet(final HttpServletRequest req, final HttpServletResponse resp) {
   // container calls this method on incoming request
   }
   }
   

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6. When are
   When are
   containers
   containers
   helpful?
   helpful?
   

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7. Development Team
   Development Team
   Delivers a packaged application
   with dependencies outside of those
   provided by the container
   Delivers a configuration files and
   documentation for running the
   service
   Operations Team
   Operations Team
   Configures the operating system
   Configures the container
   May run multiple applications on
   the container
   Containers work best when there is a clear
   Containers work best when there is a clear
   separation of responsibilities between teams
   separation of responsibilities between teams
   developing and maintaining the application
   developing and maintaining the application
   

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8. What if
   What if
   there's just
   there's just
   one team?
   one team?
   

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9. Discrepancies between
   Discrepancies between
   application and container
   application and container
   cause headaches
   cause headaches
   Logging
   Configuration
   Dependencies (classpath)
   Test environments (mvn jetty:run vs container)
   

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10. Environment discrepancies
    Environment discrepancies
    cause headaches
    cause headaches
    Different versions of dependencies on the classpath
    Example: container provides a different version of
    servlet than the one used in testing
    Containers use varying strategies for classpath
    loading
    

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11. Proposed Solution:
    Proposed Solution:
    Deliver
    Deliver self-
    self-
    contained
    contained
    applications
    applications
    

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12. Self-contained apps
    Self-contained apps
    Live in their own process
    Embed their own web server
    Embed all their own dependencies
    Define their own means of configuration
    

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13. What does
    What does
    developing
    developing a
    a
    self-contained
    self-contained
    app look like?
    app look like?
    

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14. Runs in its own process
    Runs in its own process
    /**
    * Point of entry. Configure and start app
    */
    public class App {
    public static void main(final String[] args) {
    // configure application
    // register signal handlers if desired
    // run web server until app terminates
    }
    }
    Embraces Unix process model: use of environment
    variables, command-line args, signals, STDOUT,
    STDERR
    Easy to run
    Development and Production parity
    

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15. Embeds its own server
    Embeds its own server
    public static void main(final String[] args) {
    // start jetty
    logger.info("listening on port {}", port);
    final ResoureConfig rc = ResourceConfig.forApplication(app);
    final Server server = JettyHttpContainerFactory.createServer(baseUri, rc);
    try {
    server.start();
    server.join();
    } catch (Exception e) {
    throw new RuntimeException(e);
    }
    }
    "Don’t deploy your application in Jetty, deploy Jetty in
    your application!"
    Integrates well with Jersey via
    JettyHttpContainerFactory
    Jetty is not the only solution, but it’s mature and
    lightweight
    

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16. Bundles its dependencies
    Bundles its dependencies
    $ gradle shadowJar
    $ java -jar build/libs/my-app.jar
    listening on port 8000
    Sometimes called "fat jar", "uber jar", or "shadow jar"
    Prefer all dependencies bundled together: we don't
    want dependencies to change after building
    Easier than using shell scripts to build up a classpath
    argument for java
    Include main class in jar manifest
    

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17. Logs to STDOUT
    Logs to STDOUT
    
    
    
    
    %-5level %logger{5} - %msg%n
    
    
    
    
    
    
    Easy debugging
    One stream of log statements with flexible
    downstream processing
    Let production environment worry about filtering,
    rotation
    

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18. What does
    What does
    running
    running a self-
    a self-
    contained app
    contained app
    look like?
    look like?
    

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19. systemd managed daemon
    systemd managed daemon
    [Unit]
    Description=my-app service
    [Service]
    EnvironmentFile=-/etc/sysconfig/my-app
    ExecStart=/usr/bin/java \$JVM_OPTS -jar /opt/my-app/my-app-${version}-all.jar
    User=my-app
    Restart=on-failure
    [Install]
    WantedBy=multi-user.target
    Much easier than
    systemctl for start, stop, status, restart
    Automatic start on system boot
    Note: same command to start as used in
    development
    init scripts
    

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20. don't forget journald
    don't forget journald
    [vagrant@localhost ~]$ journalctl -fu how-to-microservice
    -- Logs begin at Thu 2016-07-14 00:07:10 UTC. --
    Jul 14 00:08:44 localhost.localdomain systemd[1]: Started how-to-microservice ser
    Jul 14 00:08:44 localhost.localdomain systemd[1]: Starting how-to-microservice se
    Jul 14 00:08:44 localhost.localdomain java[11726]: 2016-07-14T00:08:44,718Z INFO
    Captures STDOUT, STDERR from systemd managed
    daemons
    Easy to tail and grep your app's logs
    Highly configurable: log rotation, format, forwarding
    

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21. What does
    What does
    deploying
    deploying a
    a
    self-contained
    self-contained
    app look like?
    app look like?
    

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22. RPM
    RPM
    $ rpm -qlp build/distributions/how-to-microservice-0.0.4-1.e7.noarch.rpm
    /etc/how-to-microservice
    /etc/how-to-microservice/settings.conf
    /etc/sysconfig
    /etc/sysconfig/how-to-microservice
    /etc/systemd
    /etc/systemd/system
    /etc/systemd/system/how-to-microservice.service
    /opt/how-to-microservice
    /opt/how-to-microservice/how-to-microservice-0.0.4-SNAPSHOT-all.jar
    /opt/how-to-microservice/settings.conf
    Packages user install, config file template, systemd
    unit file, binaries, package dependencies (java)
    Host your own yum repository for easy updates
    (jenkins, Nexus)
    Establishes a common means for deploying your
    container-less apps
    

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23. Build RPM with Gradle
    Build RPM with Gradle
    task rpm(type: Rpm) {
    it.dependsOn shadowJar
    packageName = project.name
    version = '0.0.4'
    release = '1.e7'
    os = LINUX
    requires('java-1.8.0-openjdk')
    ...
    Netflix OSS nebula-ospackage-plugin gradle plugin
    Builds deb and rpm
    Host your own yum repository with Nexus, deploy
    with Gradle
    

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24. Test RPM with Vagrant
    Test RPM with Vagrant
    Vagrant.configure(2) do |config|
    config.vm.box = "geerlingguy/centos7"
    ...
    config.vm.provision "shell", inline: <sync_dir=/vagrant
    rpm=($sync_dir/build/distributions/*.rpm)
    if [ ! -f $rpm ]; then
    echo "how-to-microservice RPM not found"
    exit 1
    fi
    sudo yum erase -y how-to-microservice
    sudo yum install -y $rpm
    sudo systemctl restart how-to-microservice
    SHELL
    end
    Vagrant defines development virtual machines with Ruby DSL
    Vagrant shell provisioner installs RPM in the Vagrant virtual
    machine
    Rebuild virtual machine:
    vagrant destroy ­f && vagrant up
    

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25. What does
    What does
    dockerizing
    dockerizing a
    a
    self-contained
    self-contained
    app look like?
    app look like?
    

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26. Dockerfile
    Dockerfile
    FROM java:8
    MAINTAINER Johnathan Gilday
    COPY ./build/libs/how-to-microservice.jar /opt/how-to-microservice/
    EXPOSE 8000
    WORKDIR /opt/how-to-microservice
    CMD ["java", "-jar", "how-to-microservice.jar"]
    Manage a docker container instead of a systemd
    service
    Manage logs with docker log driver instead of
    journald
    Deploy a docker image instead of an RPM
    

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27. Thanks!
    Thanks!
    Sample self-contained jersey service
    Gradle plugin for building "fat jars"
    Netflix OSS Gradle plugins (including gradle-os-package)
    Nexus yum repository hosting
    Vagrant shell provisioner
    https://github.com/gilday/how-to-microservice
    https://github.com/johnrengelman/shadow
    https://nebula-plugins.github.io/
    https://books.sonatype.com/nexus-book/reference/yum-configuration.html
    https://www.vagrantup.com/docs/provisioning/shell.html
    

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