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spring-projects-experimental / spring-cloud-square

Spring Cloud auto-configuration of Retrofit and OkHttp (with Spring Cloud LoadBalancer).
Apache License 2.0
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okhttpclient retrofit2 spring-cloud-loadbalancer spring-webclient square

readme

//// DO NOT EDIT THIS FILE. IT WAS GENERATED. Manual changes to this file will be lost when it is generated again. Edit the files in the src/main/asciidoc/ directory instead. ////

= Spring Cloud Square

image::https://github.com/spring-projects-experimental/spring-cloud-square/workflows/Build/badge.svg?style=svg["Build",link="https://github.com/spring-projects-experimental/spring-cloud-square/actions"]

https://pivotal.io/platform-as-a-service/migrating-to-cloud-native-application-architectures-ebook[Cloud Native] is a style of application development that encourages easy adoption of best practices in the areas of continuous delivery and value-driven development. A related discipline is that of building https://12factor.net/[12-factor Applications], in which development practices are aligned with delivery and operations goals -- for instance, by using declarative programming and management and monitoring. Spring Cloud facilitates these styles of development in a number of specific ways. The starting point is a set of features to which all components in a distributed system need easy access.

Many of those features are covered by https://projects.spring.io/spring-boot[Spring Boot], on which Spring Cloud builds. Some more features are delivered by Spring Cloud as two libraries: Spring Cloud Context and Spring Cloud Commons. Spring Cloud Context provides utilities and special services for the ApplicationContext of a Spring Cloud application (bootstrap context, encryption, refresh scope, and environment endpoints). Spring Cloud Commons is a set of abstractions and common classes used in different Spring Cloud implementations (such Spring Cloud Consul).

If you get an exception due to "Illegal key size" and you use Sun's JDK, you need to install the Java Cryptography Extension (JCE) Unlimited Strength Jurisdiction Policy Files. See the following links for more information:

Extract the files into the JDK/jre/lib/security folder for whichever version of JRE/JDK x64/x86 you use.

== Building

:jdkversion: 17

=== Basic Compile and Test

To build the source you will need to install JDK {jdkversion}.

Spring Cloud uses Maven for most build-related activities, and you should be able to get off the ground quite quickly by cloning the project you are interested in and typing

$ ./mvnw install

NOTE: You can also install Maven (>=3.3.3) yourself and run the mvn command in place of ./mvnw in the examples below. If you do that you also might need to add -P spring if your local Maven settings do not contain repository declarations for spring pre-release artifacts.

NOTE: Be aware that you might need to increase the amount of memory available to Maven by setting a MAVEN_OPTS environment variable with a value like -Xmx512m -XX:MaxPermSize=128m. We try to cover this in the .mvn configuration, so if you find you have to do it to make a build succeed, please raise a ticket to get the settings added to source control.

The projects that require middleware (i.e. Redis) for testing generally require that a local instance of Docker is installed and running.

=== Documentation

The spring-cloud-build module has a "docs" profile, and if you switch that on it will try to build asciidoc sources from src/main/asciidoc. As part of that process it will look for a README.adoc and process it by loading all the includes, but not parsing or rendering it, just copying it to ${main.basedir} (defaults to ${basedir}, i.e. the root of the project). If there are any changes in the README it will then show up after a Maven build as a modified file in the correct place. Just commit it and push the change.

=== Working with the code If you don't have an IDE preference we would recommend that you use https://www.springsource.com/developer/sts[Spring Tools Suite] or https://eclipse.org[Eclipse] when working with the code. We use the https://eclipse.org/m2e/[m2eclipse] eclipse plugin for maven support. Other IDEs and tools should also work without issue as long as they use Maven 3.3.3 or better.

==== Activate the Spring Maven profile Spring Cloud projects require the 'spring' Maven profile to be activated to resolve the spring milestone and snapshot repositories. Use your preferred IDE to set this profile to be active, or you may experience build errors.

==== Importing into eclipse with m2eclipse We recommend the https://eclipse.org/m2e/[m2eclipse] eclipse plugin when working with eclipse. If you don't already have m2eclipse installed it is available from the "eclipse marketplace".

NOTE: Older versions of m2e do not support Maven 3.3, so once the projects are imported into Eclipse you will also need to tell m2eclipse to use the right profile for the projects. If you see many different errors related to the POMs in the projects, check that you have an up to date installation. If you can't upgrade m2e, add the "spring" profile to your settings.xml. Alternatively you can copy the repository settings from the "spring" profile of the parent pom into your settings.xml.

==== Importing into eclipse without m2eclipse If you prefer not to use m2eclipse you can generate eclipse project metadata using the following command:

[indent=0]

$ ./mvnw eclipse:eclipse

The generated eclipse projects can be imported by selecting import existing projects from the file menu.

== Contributing

:spring-cloud-build-branch: master

Spring Cloud is released under the non-restrictive Apache 2.0 license, and follows a very standard Github development process, using Github tracker for issues and merging pull requests into master. If you want to contribute even something trivial please do not hesitate, but follow the guidelines below.

=== Sign the Contributor License Agreement Before we accept a non-trivial patch or pull request we will need you to sign the https://cla.pivotal.io/sign/spring[Contributor License Agreement]. Signing the contributor's agreement does not grant anyone commit rights to the main repository, but it does mean that we can accept your contributions, and you will get an author credit if we do. Active contributors might be asked to join the core team, and given the ability to merge pull requests.

=== Code of Conduct This project adheres to the Contributor Covenant https://github.com/spring-cloud/spring-cloud-build/blob/master/docs/src/main/asciidoc/code-of-conduct.adoc[code of conduct]. By participating, you are expected to uphold this code. Please report unacceptable behavior to spring-code-of-conduct@pivotal.io.

=== Code Conventions and Housekeeping None of these is essential for a pull request, but they will all help. They can also be added after the original pull request but before a merge.

=== Checkstyle

Spring Cloud Build comes with a set of checkstyle rules. You can find them in the spring-cloud-build-tools module. The most notable files under the module are:

.spring-cloud-build-tools/

└── src    ├── checkstyle    │   └── checkstyle-suppressions.xml <3>    └── main    └── resources    ├── checkstyle-header.txt <2>    └── checkstyle.xml <1>

<1> Default Checkstyle rules <2> File header setup <3> Default suppression rules ==== Checkstyle configuration Checkstyle rules are *disabled by default*. To add checkstyle to your project just define the following properties and plugins. .pom.xml ---- true <1> true <2> true <3> <4> io.spring.javaformat spring-javaformat-maven-plugin <5> org.apache.maven.plugins maven-checkstyle-plugin <5> org.apache.maven.plugins maven-checkstyle-plugin ---- <1> Fails the build upon Checkstyle errors <2> Fails the build upon Checkstyle violations <3> Checkstyle analyzes also the test sources <4> Add the Spring Java Format plugin that will reformat your code to pass most of the Checkstyle formatting rules <5> Add checkstyle plugin to your build and reporting phases If you need to suppress some rules (e.g. line length needs to be longer), then it's enough for you to define a file under `${project.root}/src/checkstyle/checkstyle-suppressions.xml` with your suppressions. Example: .projectRoot/src/checkstyle/checkstyle-suppresions.xml ---- ---- It's advisable to copy the `${spring-cloud-build.rootFolder}/.editorconfig` and `${spring-cloud-build.rootFolder}/.springformat` to your project. That way, some default formatting rules will be applied. You can do so by running this script: ```bash $ curl https://raw.githubusercontent.com/spring-cloud/spring-cloud-build/master/.editorconfig -o .editorconfig $ touch .springformat ``` === IDE setup ==== Intellij IDEA In order to setup Intellij you should import our coding conventions, inspection profiles and set up the checkstyle plugin. The following files can be found in the https://github.com/spring-cloud/spring-cloud-build/tree/master/spring-cloud-build-tools[Spring Cloud Build] project. .spring-cloud-build-tools/ ---- └── src    ├── checkstyle    │   └── checkstyle-suppressions.xml <3>    └── main    └── resources    ├── checkstyle-header.txt <2>    ├── checkstyle.xml <1>    └── intellij       ├── Intellij_Project_Defaults.xml <4>       └── Intellij_Spring_Boot_Java_Conventions.xml <5> ---- <1> Default Checkstyle rules <2> File header setup <3> Default suppression rules <4> Project defaults for Intellij that apply most of Checkstyle rules <5> Project style conventions for Intellij that apply most of Checkstyle rules .Code style image::https://raw.githubusercontent.com/spring-cloud/spring-cloud-build/{spring-cloud-build-branch}/docs/src/main/asciidoc/images/intellij-code-style.png[Code style] Go to `File` -> `Settings` -> `Editor` -> `Code style`. There click on the icon next to the `Scheme` section. There, click on the `Import Scheme` value and pick the `Intellij IDEA code style XML` option. Import the `spring-cloud-build-tools/src/main/resources/intellij/Intellij_Spring_Boot_Java_Conventions.xml` file. .Inspection profiles image::https://raw.githubusercontent.com/spring-cloud/spring-cloud-build/{spring-cloud-build-branch}/docs/src/main/asciidoc/images/intellij-inspections.png[Code style] Go to `File` -> `Settings` -> `Editor` -> `Inspections`. There click on the icon next to the `Profile` section. There, click on the `Import Profile` and import the `spring-cloud-build-tools/src/main/resources/intellij/Intellij_Project_Defaults.xml` file. .Checkstyle To have Intellij work with Checkstyle, you have to install the `Checkstyle` plugin. It's advisable to also install the `Assertions2Assertj` to automatically convert the JUnit assertions image::https://raw.githubusercontent.com/spring-cloud/spring-cloud-build/{spring-cloud-build-branch}/docs/src/main/asciidoc/images/intellij-checkstyle.png[Checkstyle] Go to `File` -> `Settings` -> `Other settings` -> `Checkstyle`. There click on the `+` icon in the `Configuration file` section. There, you'll have to define where the checkstyle rules should be picked from. In the image above, we've picked the rules from the cloned Spring Cloud Build repository. However, you can point to the Spring Cloud Build's GitHub repository (e.g. for the `checkstyle.xml` : `https://raw.githubusercontent.com/spring-cloud/spring-cloud-build/master/spring-cloud-build-tools/src/main/resources/checkstyle.xml`). We need to provide the following variables: - `checkstyle.header.file` - please point it to the Spring Cloud Build's, `spring-cloud-build-tools/src/main/resources/checkstyle-header.txt` file either in your cloned repo or via the `https://raw.githubusercontent.com/spring-cloud/spring-cloud-build/master/spring-cloud-build-tools/src/main/resources/checkstyle-header.txt` URL. - `checkstyle.suppressions.file` - default suppressions. Please point it to the Spring Cloud Build's, `spring-cloud-build-tools/src/checkstyle/checkstyle-suppressions.xml` file either in your cloned repo or via the `https://raw.githubusercontent.com/spring-cloud/spring-cloud-build/master/spring-cloud-build-tools/src/checkstyle/checkstyle-suppressions.xml` URL. - `checkstyle.additional.suppressions.file` - this variable corresponds to suppressions in your local project. E.g. you're working on `spring-cloud-contract`. Then point to the `project-root/src/checkstyle/checkstyle-suppressions.xml` folder. Example for `spring-cloud-contract` would be: `/home/username/spring-cloud-contract/src/checkstyle/checkstyle-suppressions.xml`. IMPORTANT: Remember to set the `Scan Scope` to `All sources` since we apply checkstyle rules for production and test sources. === Duplicate Finder Spring Cloud Build brings along the `basepom:duplicate-finder-maven-plugin`, that enables flagging duplicate and conflicting classes and resources on the java classpath. ==== Duplicate Finder configuration Duplicate finder is *enabled by default* and will run in the `verify` phase of your Maven build, but it will only take effect in your project if you add the `duplicate-finder-maven-plugin` to the `build` section of the projecst's `pom.xml`. .pom.xml [source,xml] ---- org.basepom.maven duplicate-finder-maven-plugin ---- For other properties, we have set defaults as listed in the https://github.com/basepom/duplicate-finder-maven-plugin/wiki[plugin documentation]. You can easily override them but setting the value of the selected property prefixed with `duplicate-finder-maven-plugin`. For example, set `duplicate-finder-maven-plugin.skip` to `true` in order to skip duplicates check in your build. If you need to add `ignoredClassPatterns` or `ignoredResourcePatterns` to your setup, make sure to add them in the plugin configuration section of your project: [source,xml] ---- org.basepom.maven duplicate-finder-maven-plugin org.joda.time.base.BaseDateTime .*module-info changelog.txt ---- == Quick Start :leveloffset: +1 This quick start walks through using https://docs.spring.io/spring-cloud-commons/docs/current/reference/html/#spring-cloud-loadbalancer[SC LoadBalancer] https://square.github.io/okhttp/[OkHttpClient] integration, load-balanced OkHttpClient-based Retrofit clients, and load-balanced https://docs.spring.io/spring-boot/docs/current/reference/html/spring-boot-features.html#boot-features-webclient[WebClient]-based https://square.github.io/retrofit/[Retrofit] clients. == OkHttpClient with Spring Cloud LoadBalancer First, add the `spring-cloud-square-okhttp` dependency to your project: [source,xml] ---- org.springframework.cloud spring-cloud-square-okhttp 0.4.1 ---- Then create a `@LoadBalanced`-annotated `OkHttpClient.Builder` bean: [source,java] ---- @Configuration class OkHttpClientConfig{ @Bean @LoadBalanced public OkHttpClient.Builder okHttpClientBuilder() { return new OkHttpClient.Builder(); } } ---- Now you can use the `serviceId` or virtual hostname rather than an actual `host:port` in your requests -- SC LoadBalancer resolves it by selecting one of the available service instances. [source,java] ---- Request request = new Request.Builder() .url("http://serviceId/hello").build(); Response response = builder.build().newCall(request).execute(); ---- == Retrofit with OkHttpClient and Spring Cloud LoadBalancer First, add the `spring-cloud-square-retrofit` and `spring-cloud-square-okhttp` dependencies to your project: [source,xml] ---- org.springframework.cloud spring-cloud-square-retrofit 0.4.1 org.springframework.cloud spring-cloud-square-okhttp 0.4.1 ---- Use the `@EnableRetrofitClients` annotation to let us automatically instantiate and inject Retrofit clients for you. Then create a `@LoadBalanced`-annotated `OkHttpClient.Builder` bean to be used under the hood: [source,java] ---- @Configuration @EnableRetrofitClients class OkHttpClientConfig { @Bean @LoadBalanced public OkHttpClient.Builder okHttpClientBuilder() { return new OkHttpClient.Builder(); } } ---- Create a Retrofit client and annotate it with `@RetrofitClient`, passing the `serviceId` of your service as argument (the annotation can also be used to pass a custom configuration that contains user-crated interceptors for the Retrofit client): [source,java] ---- @RetrofitClient("serviceId") interface HelloClient { @GET("/") Call hello(); } ---- Make sure to use Retrofit method annotations, such as `@GET("/")`. You can now inject the Retrofit client and use it to run load-balanced calls (by using `serviceId` instead of actual `host:port`): [source,java] ---- class AService { @Autowired HelloClient client; public String hello() throws IOException { return client.hello().execute().body(); } } ---- We created a full https://github.com/spring-cloud-samples/spring-cloud-square-retrofit-web[sample for load-balanced-OkHttpClient-based Retrofit clients]. == Retrofit with WebClient and Spring Cloud LoadBalancer First, add the `spring-cloud-square-retrofit` and `spring-boot-starter-webflux` starter dependencies to your project: [source,xml] ---- org.springframework.cloud spring-cloud-square-retrofit 0.4.1 org.springframework.boot spring-boot-starter-webflux ---- Use the `@EnableRetrofitClients` annotation to let us automatically instantiate and inject Retrofit clients for you. Then create a https://docs.spring.io/spring-cloud-commons/docs/current/reference/html/#webclinet-loadbalancer-client[`@LoadBalanced`-annotated `WebClient.Builder` bean] to be used under the hood: [source,java] ---- @Configuration @EnableRetrofitClients class OkHttpClientConfig { @Bean @LoadBalanced public WebClient.Builder webClientBuilder() { return WebClient.builder(); } } ---- Create a Retrofit client and annotate it with `@RetrofitClient`, passing the `serviceId` of your service as argument: [source,java] ---- @RetrofitClient("serviceId") interface HelloClient { @GET("/") Mono hello(); } ---- Make sure to use Retrofit method annotations, such as `@GET("/")`. You can now inject the Retrofit client and use it to run load-balanced calls (by using `serviceId` instead of actual `host:port`): [source,java] ---- class AService { @Autowired HelloClient client; public Mono hello() throws IOException { return client.hello(); } } ---- We created a full https://github.com/spring-cloud-samples/spring-cloud-square-retrofit-webclient[sample for load-balanced-WebClient-based Retrofit clients]. TIP: As the currently available release is a milestone, you need to add the Spring Milestone repository link to your projects for all the examples presented in this blog entry: [source,xml] ---- spring-milestones https://repo.spring.io/milestone ---- We recommend using dependency management for other Spring Cloud dependencies: [source,xml] ---- org.springframework.cloud spring-cloud-dependencies ${spring-cloud.version} pom import ---- :leveloffset!: == OkHttpClient integration with Spring Cloud This module supplies integration with Square's [`OkHttpClient`](https://square.github.io/okhttp/) and [Spring Cloud LoadBalancer](https://github.com/spring-cloud/spring-cloud-commons/spring-cloud-loadbalancer). An application interceptor is added to the `OkHttpClient` created by auto-configuration which resolves the scheme, host, and port from Spring Cloud LoadBalancer and rewrites the URL. By supporting `OkHttpClient`, it enables Square's [Retrofit](https://square.github.io/retrofit/) to use Spring Cloud LoadBalancer as well. See [`OkHttpLoadBalancerInterceptorTests`](https://github.com/spring-projects-experimental/spring-cloud-square/blob/main/spring-cloud-square-okhttp/src/test/java/org/springframework/cloud/square/okhttp/loadbalancer/OkHttpLoadBalancerInterceptorTests.java) for Spring Cloud LoadBalancer samples. == Spring WebClient Support was also added for Spring WebClient. This implements an `okhttp3.Call.Factory` that uses `WebClient` under the covers. This provides a fully non-blocking shim instead of using `okhttp3`. See [`WebClientRetrofitTests`](https://github.com/spring-projects-experimental/spring-cloud-square/blob/main/spring-cloud-square-retrofit-webclient/src/test/java/org/springframework/cloud/square/retrofit/webclient/WebClientRetrofitTests.java) for WebClient samples.