With the rise of DevOps, low-cost cloud computing, and container technologies, the way Java developers approach development today has changed dramatically. This practical guide helps you take advantage of microservices, serverless, and cloud native technologies using the latest DevOps techniques to simplify your build process and create hyperproductive teams.
Stephen Chin, Melissa McKay, Ixchel Ruiz, and Baruch Sadogursky help you evaluate an array of options. The list includes source control with Git, build declaration with Maven and Gradle, CI/CD with CircleCI, package management with Artifactory, containerization with Docker and Kubernetes, and much more. Whether you’re building applications with Jakarta EE, Spring Boot, Dropwizard, MicroProfile, Micronaut, or Quarkus, this comprehensive guide has you covered.
Explore software lifecycle best practices
Use DevSecOps methodologies to facilitate software development and delivery
Understand the business value of DevSecOps best practices
Manage and secure software dependencies
Develop and deploy applications using containers and cloud native technologies
Manage and administrate source control repositories and development processes
Use automation to set up and administer build pipelines
Identify common deployment patterns and antipatterns
Maintain and monitor software after deployment
About the Author
Stephen Chin is Head of Developer Relations at JFrog and author of The Definitive Guide to Modern Client Development, Raspberry Pi with Java, and Pro JavaFX Platform. He has keynoted numerous Java conferences around the world including Devoxx, JNation, JavaOne, Joker, and Open Source India. Stephen is an avid motorcyclist who has done evangelism tours in Europe, Japan, and Brazil, interviewing hackers in their natural habitat. When he is not traveling, he enjoys teaching kids how to do embedded and robot programming together with his teenage daughter. You can follow his hacking adventures at: http://steveonjava.com/.
Melissa McKay is currently a Developer Advocate with the JFrog Developer Relations team. She has been active in the software industry 20 years and her background and experience spans a slew of technologies and tools used in the development and operation of enterprise products and services. Melissa is a mom, software developer, Java geek, huge promoter of Java UNconferences, and is always on the lookout for ways to grow, learn, and improve development processes. She is active in the developer community, has spoken at CodeOne, Java Dev Day Mexico and assists with organizing the JCrete and JAlba Unconferences as well as Devoxx4Kids events.
Ixchel Ruiz has developed software applications and tools since 2000. Her research interests include Java, dynamic languages, client-side technologies, and testing. She is a Java Champion, Groundbreaker Ambassador, Hackergarten enthusiast, open source advocate, JUG leader, public speaker, and mentor.
Baruch Sadogursky (a.k.a JBaruch) is the Chief Sticker Officer @JFrog (also, Head of DevOps Advocacy) at JFrog. His passion is speaking about technology. Well, speaking in general, but doing it about technology makes him look smart, and 19 years of hi-tech experience sure helps. When he’s not on stage (or on a plane to get there), he learns about technology, people and how they work, or more precisely, don’t work together.
He is a co-author of the Liquid Software book, a CNCF ambassador and a passionate conference speaker on DevOps, DevSecOps, digital transformation, containers and cloud-native, artifact management and other topics, and is a regular at the industry’s most prestigious events including DockerCon, Devoxx, DevOps Days, OSCON, Qcon, JavaOne and many others. You can see some of his talks at jfrog.com/shownotes
This book will guide you through the implementation of the real-world Continuous Delivery using top-notch technologies. Instead of finishing this book thinking “I know what Continuous Delivery is, but I have no idea how to implement it”, you will end up with your machine set up with a Kubernetes cluster running Jenkins Pipelines in a distributed and scalable fashion (each Pipeline run on a new Jenkins slave dynamically allocated as a Kubernetes pod) to test (unit, integration, acceptance, performance and smoke tests), build (with Maven), release (to Artifactory), distribute (to Docker Hub) and deploy (on Kubernetes) a Spring Boot app to testing, staging and production environments implementing the Canary Release deployment pattern.
TABLE OF CONTENTS:
INTRODUCTION Agile Scrum Scrum and Continuous Integration Deployed vs Released Scrum and Continuous Delivery XP and Continuous Delivery Automated Tests Continuous Integration Feature Branch Continuous Delivery Continuous Delivery Pipeline Continuous Delivery vs Continuous Deployment Canary Release A/B Tests Feature Flags
NOTEPAD APP: AUTOMATED TESTS, MAVEN AND FLYWAY Pre-Requisites The Notepad Application Automated Tests Unit Tests Integration Tests Acceptance Tests Page Object Distributed Acceptance Tests with Selenium-Grid Smoke Tests Performance Tests with Gatling.io Apache Maven Maven Snapshot vs Release The Default Lifecycle and its Phases Maven Repositories Repository Manager (Artifactory) Maven Plugins: Surefire and Failsafe Maven Profile Running Unit Tests Running Integration Tests Running Acceptance Tests Running Smoke Tests Running Performance Tests Publish Artifacts to Artifactory with Maven Publish a Snapshot to Artifactory Publish a Release to Artifactory The release:prepare Goal The release:perform Goal Flyway
DOCKER Introduction to Docker Difference Between Container and Image Docker Hub Create your Account Official Docker Repositories Image Tags Non-Official Docker Images Create a Repository, an Image and Push it to Docker Hub Running Containers on Docker Running Containers as Daemons Container Clean Up Naming Containers Exposing Ports Persistent Data with Volumes Environment Variables Docker Networking Create a Bridge Network Container Static IP Address Linking Containers Most Used Docker Commands Images Containers Misc Building Docker Images: Dockerfile
JENKINS: PIPELINE AS CODE AND CHATOPS Jenkins Overview Jenkins Concepts Job (or Project) Build Artifact Workspace Executor Plugin Node, Master, and Agent (or Slave) ChatOps Create a Slack Workspace Integrate Slack with Jenkins Slack Notification Plugin Use Hubot to Interact with Jenkins Jenkins Pipeline Declarative Pipeline vs Scripted Pipeline Scripted Pipeline Using Docker with Jenkins Pipelines Running Docker from Within the Jenkins Container Scaling Jenkins with Slaves
KUBERNETES Why Kubernetes? Set up a Kubernetes Cluster using Vagrant Hands-on Introduction to Kubernetes Kubernetes Concepts Namespaces Pods Labels Replica Sets Services Service Discovery using DNS Service Discovery using Namespaces Volumes Handling External Configurations Config Maps Changing Logback Log Level at Runtime Secrets Using Secrets as Environment Variables Using Secrets as Files from a Pod Deployments Readiness Probes Liveness Probes Canary Release Kubernetes Architecture Kubernetes Master Components Etcd API Server Controller Manager Scheduler Kubernetes Node Components Service Proxy Kubelet cAdvisor Kubernetes Add-ons Web UI (Dashboard) Monitoring Kubernetes with Heapster, InfluxDB and Grafana Web UI Overview DNS
“A DevOps toolchain is a set or combination of tools that aid in the delivery, development, and management of software applications throughout the systems development life cycle, as coordinated by an organization that uses DevOps practices.
“In software, a toolchain is the set of programming tools that is used to perform a complex software development task or to create a software product, which is typically another computer program or a set of related programs. In general, the tools forming a toolchain are executed consecutively so the output or resulting environment state of each tool becomes the input or starting environment for the next one, but the term is also used when referring to a set of related tools that are not necessarily executed consecutively.
As DevOps is a set of practices that emphasizes the collaboration and communication of both software developers and other information technology (IT) professionals, while automating the process of software delivery and infrastructure changes, its implementation can include the definition of the series of tools used at various stages of the lifecycle; because DevOps is a cultural shift and collaboration between development and operations, there is no one product that can be considered a single DevOps tool. Instead a collection of tools, potentially from a variety of vendors, are used in one or more stages of the lifecycle.” (WP)
Tools and vendors in this category often overlap with other categories. Because DevOps is about breaking down silos, this is reflective in the activities and product solutions.[clarification needed]
Verify is directly associated with ensuring the quality of the software release; activities designed to ensure code quality is maintained and the highest quality is deployed to production. The main activities in this are:
Packaging refers to the activities involved once the release is ready for deployment, often also referred to as staging or Preproduction / “preprod”. This often includes tasks and activities such as:
Release staging and holding
Release related activities include schedule, orchestration, provisioning and deploying software into production and targeted environment. The specific Release activities include:
Configure activities fall under the operation side of DevOps. Once software is deployed, there may be additional IT infrastructure provisioning and configuration activities required. Specific activities including:
Infrastructure storage, database and network provisioning and configuring
Monitoring is an important link in a DevOps toolchain. It allows IT organization to identify specific issues of specific releases and to understand the impact on end-users. A summary of Monitor related activities are:
Information from monitoring activities often impacts Plan activities required for changes and for new release cycles.
Version Control is an important link in a DevOps toolchain and a component of software configuration management. Version Control is the management of changes to documents, computer programs, large web sites, and other collections of information. A summary of Version Control related activities are:
Compatibility with existent systems and protocols
Information from Version Control often supports Release activities required for changes and for new release cycles.
Maven addresses two aspects of building software: how software is built, and its dependencies. Unlike earlier tools like Apache Ant, it uses conventions for the build procedure, and only exceptions need to be written down. An XML file describes the software project being built, its dependencies on other external modules and components, the build order, directories, and required plug-ins. It comes with pre-defined targets for performing certain well-defined tasks such as compilation of code and its packaging. Maven dynamically downloads Java libraries and Maven plug-ins from one or more repositories such as the Maven 2 Central Repository, and stores them in a local cache. This local cache of downloaded artifacts can also be updated with artifacts created by local projects. Public repositories can also be updated.
Maven is built using a plugin-based architecture that allows it to make use of any application controllable through standard input. A C/C++ native plugin is maintained for Maven 2.
Alternative technologies like Gradle and sbt as build tools do not rely on XML, but keep the key concepts Maven introduced. With Apache Ivy, a dedicated dependency manager was developed as well that also supports Maven repositories.
The number of artifacts on Maven’s central repository has grown rapidly
Maven, created by Jason van Zyl, began as a sub-project of Apache Turbine in 2002. In 2003, it was voted on and accepted as a top level Apache Software Foundation project. In July 2004, Maven’s release was the critical first milestone, v1.0. Maven 2 was declared v2.0 in October 2005 after about six months in beta cycles. Maven 3.0 was released in October 2010 being mostly backwards compatible with Maven 2.
Maven 3.0 information began trickling out in 2008. After eight alpha releases, the first beta version of Maven 3.0 was released in April 2010. Maven 3.0 has reworked the core Project Builder infrastructure resulting in the POM’s file-based representation being decoupled from its in-memory object representation. This has expanded the possibility for Maven 3.0 add-ons to leverage non-XML based project definition files. Languages suggested include Ruby (already in private prototype by Jason van Zyl), YAML, and Groovy.
Special attention was given to ensuring backward compatibility of Maven 3 to Maven 2. For most projects, upgrading to Maven 3 will not require any adjustments of their project structure. The first beta of Maven 3 saw the introduction of a parallel build feature which leverages a configurable number of cores on a multi-core machine and is especially suited for large multi-module projects.
A directory structure for a Java project auto-generated by Maven
Maven projects are configured using a Project Object Model, which is stored in a pom.xml-file. An example file looks like:
<project><!-- model version is always 4.0.0 for Maven 2.x POMs --><modelVersion>4.0.0</modelVersion><!-- project coordinates, i.e. a group of values which uniquely identify this project --><groupId>com.mycompany.app</groupId><artifactId>my-app</artifactId><version>1.0</version><!-- library dependencies --><dependencies><dependency><!-- coordinates of the required library --><groupId>junit</groupId><artifactId>junit</artifactId><version>3.8.1</version><!-- this dependency is only used for running and compiling tests --><scope>test</scope></dependency></dependencies></project>
This POM only defines a unique identifier for the project (coordinates) and its dependency on the JUnit framework. However, that is already enough for building the project and running the unit tests associated with the project. Maven accomplishes this by embracing the idea of Convention over Configuration, that is, Maven provides default values for the project’s configuration.
The directory structure of a normal idiomatic Maven project has the following directory entries:
Contains the pom.xml and all subdirectories.
Contains the deliverable Java sourcecode for the project.
Contains the deliverable resources for the project, such as property files.
Contains the testing Java sourcecode (JUnit or TestNG test cases, for example) for the project.
Contains resources necessary for testing.
The command mvn package will compile all the Java files, run any tests, and package the deliverable code and resources into target/my-app-1.0.jar (assuming the artifactId is my-app and the version is 1.0.)
Using Maven, the user provides only configuration for the project, while the configurable plug-ins do the actual work of compiling the project, cleaning target directories, running unit tests, generating API documentation and so on. In general, users should not have to write plugins themselves. Contrast this with Ant and make, in which one writes imperative procedures for doing the aforementioned tasks.
A Project Object Model (POM) provides all the configuration for a single project. General configuration covers the project’s name, its owner and its dependencies on other projects. One can also configure individual phases of the build process, which are implemented as plugins. For example, one can configure the compiler-plugin to use Java version 1.5 for compilation, or specify packaging the project even if some unit tests fail.
Larger projects should be divided into several modules, or sub-projects, each with its own POM. One can then write a root POM through which one can compile all the modules with a single command. POMs can also inherit configuration from other POMs. All POMs inherit from the Super POM by default. The Super POM provides default configuration, such as default source directories, default plugins, and so on.
Most of Maven’s functionality is in plug-ins. A plugin provides a set of goals that can be executed using the command mvn [plugin-name]:[goal-name]. For example, a Java project can be compiled with the compiler-plugin’s compile-goal by running mvn compiler:compile.
There are Maven plugins for building, testing, source control management, running a web server, generating Eclipse project files, and much more. Plugins are introduced and configured in a <plugins>-section of a pom.xml file. Some basic plugins are included in every project by default, and they have sensible default settings.
However, it would be cumbersome if the archetypal build sequence of building, testing and packaging a software project required running each respective goal manually:
Maven’s lifecycle concept handles this issue.
Plugins are the primary way to extend Maven. Developing a Maven plugin can be done by extending the org.apache.maven.plugin.AbstractMojo class. Example code and explanation for a Maven plugin to create a cloud-based virtual machine running an application server is given in the article Automate development and management of cloud virtual machines.
The build lifecycle is a list of named phases that can be used to give order to goal execution. One of Maven’s standard lifecycles is the default lifecycle, which includes the following phases, in this order:
Goals provided by plugins can be associated with different phases of the lifecycle. For example, by default, the goal “compiler:compile” is associated with the “compile” phase, while the goal “surefire:test” is associated with the “test” phase. When the mvn test command is executed, Maven runs all goals associated with each of the phases up to and including the “test” phase. In such a case, Maven runs the “resources:resources” goal associated with the “process-resources” phase, then “compiler:compile”, and so on until it finally runs the “surefire:test” goal.
Maven also has standard phases for cleaning the project and for generating a project site. If cleaning were part of the default lifecycle, the project would be cleaned every time it was built. This is clearly undesirable, so cleaning has been given its own lifecycle.
Standard lifecycles enable users new to a project the ability to accurately build, test and install every Maven project by issuing the single command mvn install. By default, Maven packages the POM file in generated JAR and WAR files. Tools like diet4j can use this information to recursively resolve and run Maven modules at run-time without requiring an “uber”-jar that contains all project code.
A central feature in Maven is dependency management. Maven’s dependency-handling mechanism is organized around a coordinate system identifying individual artifacts such as software libraries or modules. The POM example above references the JUnit coordinates as a direct dependency of the project. A project that needs, say, the Hibernate library simply has to declare Hibernate’s project coordinates in its POM. Maven will automatically download the dependency and the dependencies that Hibernate itself needs (called transitive dependencies) and store them in the user’s local repository. Maven 2 Central Repository is used by default to search for libraries, but one can configure the repositories to be used (e.g., company-private repositories) within the POM.
The fundamental difference between Maven and Ant is that Maven’s design regards all projects as having a certain structure and a set of supported task work-flows (e.g., getting resources from source control, compiling the project, unit testing, etc.). While most software projects in effect support these operations and actually do have a well-defined structure, Maven requires that this structure and the operation implementation details be defined in the POM file. Thus, Maven relies on a convention on how to define projects and on the list of work-flows that are generally supported in all projects.
There are search engines such as The Central Repository Search Engine which can be used to find out coordinates for different open-source libraries and frameworks.
Projects developed on a single machine can depend on each other through the local repository. The local repository is a simple folder structure that acts both as a cache for downloaded dependencies and as a centralized storage place for locally built artifacts. The Maven command mvn install builds a project and places its binaries in the local repository. Then other projects can utilize this project by specifying its coordinates in their POMs.
Add-ons to several popular integrated development environments targeting the Java programming language exist to provide integration of Maven with the IDE’s build mechanism and source editing tools, allowing Maven to compile projects from within the IDE, and also to set the classpath for code completion, highlighting compiler errors, etc. Examples of popular IDEs supporting development with Maven include:
These add-ons also provide the ability to edit the POM or use the POM to determine a project’s complete set of dependencies directly within the IDE.
Some built-in features of IDEs are forfeited when the IDE no longer performs compilation. For example, Eclipse’s JDT has the ability to recompile a single Java source file after it has been edited. Many IDEs work with a flat set of projects instead of the hierarchy of folders preferred by Maven. This complicates the use of SCM systems in IDEs when using Maven.