Features

• Java 17

• Spring Framework 6

• Spring Boot 3

• Dynamic routing

• Route matching built into Spring Handler Mapping

• Route matching on HTTP Request (Path, Method, Header, Host, etc…​)

• Filters scoped to Matching Route

• Filters can modify downstream HTTP Request and HTTP Response (Add/Remove Headers, Add/Remove Parameters, Rewrite Path, Set Path, Hystrix, etc…​)

• API or configuration driven

• Supports Spring Cloud DiscoveryClient for configuring Routes

Building

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 main. 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 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 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.

• Use the Spring Framework code format conventions. If you use Eclipse you can import formatter settings using the eclipse-code-formatter.xml file from the Spring Cloud Build project. If using IntelliJ, you can use the Eclipse Code Formatter Plugin to import the same file.

• Make sure all new .java files to have a simple Javadoc class comment with at least an @author tag identifying you, and preferably at least a paragraph on what the class is for.

• Add the ASF license header comment to all new .java files (copy from existing files in the project)

• Add yourself as an @author to the .java files that you modify substantially (more than cosmetic changes).

• Add some Javadocs and, if you change the namespace, some XSD doc elements.

• A few unit tests would help a lot as well — someone has to do it.

• If no-one else is using your branch, please rebase it against the current main (or other target branch in the main project).

• When writing a commit message please follow these conventions, if you are fixing an existing issue please add Fixes gh-XXXX at the end of the commit message (where XXXX is the issue number).

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

<properties>
<maven-checkstyle-plugin.failsOnError>true</maven-checkstyle-plugin.failsOnError> (1)
        <maven-checkstyle-plugin.failsOnViolation>true
        </maven-checkstyle-plugin.failsOnViolation> (2)
        <maven-checkstyle-plugin.includeTestSourceDirectory>true
        </maven-checkstyle-plugin.includeTestSourceDirectory> (3)
</properties>

<build>
        <plugins>
            <plugin> (4)
                <groupId>io.spring.javaformat</groupId>
                <artifactId>spring-javaformat-maven-plugin</artifactId>
            </plugin>
            <plugin> (5)
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-checkstyle-plugin</artifactId>
            </plugin>
        </plugins>

    <reporting>
        <plugins>
            <plugin> (5)
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-checkstyle-plugin</artifactId>
            </plugin>
        </plugins>
    </reporting>
</build>

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

<?xml version="1.0"?>
<!DOCTYPE suppressions PUBLIC
		"-//Puppy Crawl//DTD Suppressions 1.1//EN"
		"https://www.puppycrawl.com/dtds/suppressions_1_1.dtd">
<suppressions>
	<suppress files=".*ConfigServerApplication\.java" checks="HideUtilityClassConstructor"/>
	<suppress files=".*ConfigClientWatch\.java" checks="LineLengthCheck"/>
</suppressions>

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:

$ curl https://raw.githubusercontent.com/spring-cloud/spring-cloud-build/main/.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 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

Figure 1. 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.

Figure 2. Inspection profiles

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

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/main/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/main/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/main/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

<build>
    <plugins>
        <plugin>
            <groupId>org.basepom.maven</groupId>
            <artifactId>duplicate-finder-maven-plugin</artifactId>
        </plugin>
    </plugins>
</build>

For other properties, we have set defaults as listed in the 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:

<build>
    <plugins>
        <plugin>
            <groupId>org.basepom.maven</groupId>
            <artifactId>duplicate-finder-maven-plugin</artifactId>
            <configuration>
                <ignoredClassPatterns>
                    <ignoredClassPattern>org.joda.time.base.BaseDateTime</ignoredClassPattern>
                    <ignoredClassPattern>.*module-info</ignoredClassPattern>
                </ignoredClassPatterns>
                <ignoredResourcePatterns>
                    <ignoredResourcePattern>changelog.txt</ignoredResourcePattern>
                </ignoredResourcePatterns>
            </configuration>
        </plugin>
    </plugins>
</build>

Contributing

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 main. 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 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 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.

• Use the Spring Framework code format conventions. If you use Eclipse you can import formatter settings using the eclipse-code-formatter.xml file from the Spring Cloud Build project. If using IntelliJ, you can use the Eclipse Code Formatter Plugin to import the same file.

• Make sure all new .java files to have a simple Javadoc class comment with at least an @author tag identifying you, and preferably at least a paragraph on what the class is for.

• Add the ASF license header comment to all new .java files (copy from existing files in the project)

• Add yourself as an @author to the .java files that you modify substantially (more than cosmetic changes).

• Add some Javadocs and, if you change the namespace, some XSD doc elements.

• A few unit tests would help a lot as well — someone has to do it.

• If no-one else is using your branch, please rebase it against the current main (or other target branch in the main project).

• When writing a commit message please follow these conventions, if you are fixing an existing issue please add Fixes gh-XXXX at the end of the commit message (where XXXX is the issue number).

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

<properties>
<maven-checkstyle-plugin.failsOnError>true</maven-checkstyle-plugin.failsOnError> (1)
        <maven-checkstyle-plugin.failsOnViolation>true
        </maven-checkstyle-plugin.failsOnViolation> (2)
        <maven-checkstyle-plugin.includeTestSourceDirectory>true
        </maven-checkstyle-plugin.includeTestSourceDirectory> (3)
</properties>

<build>
        <plugins>
            <plugin> (4)
                <groupId>io.spring.javaformat</groupId>
                <artifactId>spring-javaformat-maven-plugin</artifactId>
            </plugin>
            <plugin> (5)
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-checkstyle-plugin</artifactId>
            </plugin>
        </plugins>

    <reporting>
        <plugins>
            <plugin> (5)
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-checkstyle-plugin</artifactId>
            </plugin>
        </plugins>
    </reporting>
</build>

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

<?xml version="1.0"?>
<!DOCTYPE suppressions PUBLIC
		"-//Puppy Crawl//DTD Suppressions 1.1//EN"
		"https://www.puppycrawl.com/dtds/suppressions_1_1.dtd">
<suppressions>
	<suppress files=".*ConfigServerApplication\.java" checks="HideUtilityClassConstructor"/>
	<suppress files=".*ConfigClientWatch\.java" checks="LineLengthCheck"/>
</suppressions>

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:

$ curl https://raw.githubusercontent.com/spring-cloud/spring-cloud-build/main/.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 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

Figure 3. 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.

Figure 4. Inspection profiles

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

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/main/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/main/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/main/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

<build>
    <plugins>
        <plugin>
            <groupId>org.basepom.maven</groupId>
            <artifactId>duplicate-finder-maven-plugin</artifactId>
        </plugin>
    </plugins>
</build>

For other properties, we have set defaults as listed in the 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:

<build>
    <plugins>
        <plugin>
            <groupId>org.basepom.maven</groupId>
            <artifactId>duplicate-finder-maven-plugin</artifactId>
            <configuration>
                <ignoredClassPatterns>
                    <ignoredClassPattern>org.joda.time.base.BaseDateTime</ignoredClassPattern>
                    <ignoredClassPattern>.*module-info</ignoredClassPattern>
                </ignoredClassPatterns>
                <ignoredResourcePatterns>
                    <ignoredResourcePattern>changelog.txt</ignoredResourcePattern>
                </ignoredResourcePatterns>
            </configuration>
        </plugin>
    </plugins>
</build>