spring-cloud-sleuth

//// 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. ////

:jdkversion: 1.8

image::https://github.com/spring-cloud/spring-cloud-sleuth/workflows/Build/badge.svg?style=svg["Build",link="https://github.com/spring-cloud/spring-cloud-sleuth/actions"] image::https://badges.gitter.im/spring-cloud/spring-cloud-sleuth.svg[Gitter,link="https://gitter.im/spring-cloud/spring-cloud-sleuth?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge"]

== Spring Cloud Sleuth

=== !!!! IMPORTANT !!!!

Spring Cloud Sleuth's last minor version is 3.1. You can check the https://github.com/spring-cloud/spring-cloud-sleuth/tree/3.1.x[3.1.x] branch for the latest commits.

WARNING: Spring Cloud Sleuth will not work with Spring Boot 3.x onward. The last major version of Spring Boot that Sleuth will support is 2.x.

The core of this project got moved to https://micrometer.io/docs/tracing[Micrometer Tracing] project and the instrumentations will be moved to https://micrometer.io/[Micrometer] and all respective projects (no longer all instrumentations will be done in a single repository.

You can check the https://github.com/micrometer-metrics/tracing/wiki/Spring-Cloud-Sleuth-3.1-Migration-Guide[Micrometer Tracing migration guide] to learn how to migrate from Spring Cloud Sleuth to Micrometer Tracing.

=== Introduction

Spring Cloud Sleuth provides Spring Boot auto-configuration for distributed tracing.

Sleuth configures everything you need to get started. This includes where trace data (spans) are reported to, how many traces to keep (sampling), if remote fields (baggage) are sent, and which libraries are traced.

=== Quick Start

Add Spring Cloud Sleuth to the classpath of a Spring Boot application (together with a Tracer implementation) and you will see trace IDs in logs. Example of Sleuth with Brave tracer:

[source,xml,indent=0,subs="verbatim,quotes,attributes"]

<!-- Spring Cloud Sleuth requires a Spring Cloud BOM -->
<dependencyManagement>
    <dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-dependencies</artifactId>
            <!-- Provide the latest stable Spring Cloud release train version (e.g. 2020.0.0) -->
            <version>${release.train.version}</version>
            <type>pom</type>
            <scope>import</scope>
        </dependency>
    </dependencies>
</dependencyManagement>

<dependencies>
    <!-- Boot's Web support -->
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>
    <!-- Sleuth with Brave tracer implementation -->
    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-sleuth</artifactId>
    </dependency>
</dependencies>

Consider the following HTTP handler:

[source,java,indent=0]

@RestController public class DemoController { private static Logger log = LoggerFactory.getLogger(DemoController.class);

@RequestMapping("/")
public String home() {
    log.info("Handling home");
    return "Hello World";
}

}

If you add that handler to a controller, you can see the calls to home() being traced in the logs (notice the 0b6aaf642574edd3 ids).

[indent=0]

2020-10-21 12:01:16.285 INFO [,0b6aaf642574edd3,0b6aaf642574edd3,true] 289589 --- [nio-9000-exec-1] DemoController : Handling home!

NOTE: Instead of logging the request in the handler explicitly, you could set logging.level.org.springframework.web.servlet.DispatcherServlet=DEBUG.

NOTE: Set spring.application.name=myService (for instance) to see the service name as well as the trace and span IDs.

== Documentation

Please visit the https://docs.spring.io/spring-cloud-sleuth/docs/[documentation page] to read more about the project.

== Building

:jdkversion: 1.8

=== 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: 3.1.x

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/3.1.x/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.

• 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 https://raw.githubusercontent.com/spring-cloud/spring-cloud-build/3.1.x/spring-cloud-dependencies-parent/eclipse-code-formatter.xml[Spring Cloud Build] project. If using IntelliJ, you can use the https://plugins.jetbrains.com/plugin/6546[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 master (or other target branch in the main project).
• When writing a commit message please follow https://tbaggery.com/2008/04/19/a-note-about-git-commit-messages.html[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

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

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:

$ curl https://raw.githubusercontent.com/spring-cloud/spring-cloud-build/3.1.x/.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/3.1.x/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/3.1.x/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/3.1.x/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/3.1.x/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]

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]