Spring Cloud Sleuth borrows Dapper’s terminology.
Span: The basic unit of work. For example, sending an RPC is a new span, as is sending a response to an RPC. Span’s are identified by a unique 64-bit ID for the span and another 64-bit ID for the trace the span is a part of. Spans also have other data, such as descriptions, key-value annotations, the ID of the span that caused them, and process ID’s (normally IP address).
Spans are started and stopped, and they keep track of their timing information. Once you create a span, you must stop it at some point in the future.
Trace: A set of spans forming a tree-like structure. For example, if you are running a distributed big-data store, a trace might be formed by a put request.
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Adds trace and span ids to the Slf4J MDC, so you can extract all the logs from a given trace or span in a log aggregator. Example configuration:
logging: pattern: console: '%d{yyyy-MM-dd HH:mm:ss.SSS} [trace=%X{X-Trace-Id:-},span=%X{X-Span-Id:-}] [%15.15t] %-40.40logger{39}: %m%n'
(notice the
%Xentries from the MDC). -
Provides an abstraction over common distributed tracing data models: traces, spans (forming a DAG), annotations, key-value annotations. Loosely based on HTrace, but Zipkin (Dapper) compatible.
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Instruments common ingress and egress points from Spring applications (servlet filter, rest template, scheduled actions).
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If
spring-cloud-sleuth-zipkinthen the app will generate and collect Zipkin-compatible traces (using Brave). By default it sends them via Thrift to a Zipkin collector service on localhost (port 9410). Configure the location of the service usingspring.zipkin.[host,port].
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Optionally run [Zipkin](https://github.com/openzipkin/zipkin), e.g. via docker compose (there’s a
docker-compose.ymlin [Spring Cloud Sleuth](https://github.com/spring-cloud-incubator/spring-cloud-sleuth), or in [Docker Zipkin](https://github.com/openzipkin/docker-zipkin) -
Run the sample application
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Hit
http://localhost:3380,http://localhost:3380/call,http://localhost:3380/asyncfor some interesting sample traces (the app callas back to itself). -
Goto
http://localhost:8082for zipkin web (8080 if running locally from source, the host is the docker host, so if you are using boot2docker it will be different)
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Warning
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The docker images for zipkin are old and don’t work very well (the UI in particular). Zipkin is in a state of flux, but it should settle down soon when there is an actual release. Best results actually come from building from source and running the jar files (the query and collector services need command line arguments, so check the zipkin README for updates). |
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Note
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You can see the zipkin spans without the UI (in logs) if you just provide a @Bean of type LogSpanCollector (there’s one commented out in the sample).
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To build the source you will need to install Apache Maven v3.0.6 or above and JDK 1.7.
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
$ mvn install -s .settings.xml
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Note
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You may need to increase the amount of memory available to Maven by setting
a MAVEN_OPTS environment variable with the value -Xmx512m -XX:MaxPermSize=128m
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The .settings.xml is only required the first time (or after updates
to dependencies). It is there to provide repository declarations so
that those do not need to be hard coded in the project poms.
For hints on how to build the project look in .travis.yml if there
is one. There should be a "script" and maybe "install" command. Also
look at the "services" section to see if any services need to be
running locally (e.g. mongo or rabbit). Ignore the git-related bits
that you might find in "before_install" since they will be able git
credentials and you already have those.
If you need mongo, rabbit or redis, see the README in the scripts demo repository for instructions. For example consider using the "fig.yml" with Fig to run them in Docker containers.
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.
If you don’t have an IDE preference we would recommend that you use Spring Tools Suite or Eclipse when working with the code. We use the m2eclipe eclipse plugin for maven support. Other IDEs and tools should also work without issue.
We recommend the m2eclipe eclipse plugin when working with eclipse. If you don’t already have m2eclipse installed it is available from the "eclipse marketplace".
Once the projects are imported into Eclipse you will also need to tell m2eclipse
to use the .settings.xml file for the projects. If you do not do this you may
see errors many different errors related to the POMs in the projects.
Open your Eclipse preferences, expand the Maven preferences, and select User Settings.
In the User Settings field click Browse and navigate to the Spring Cloud project you
imported selecting the .settings.xml file in that project. Click Apply and then OK to
save the preference changes.
If you prefer not to use m2eclipse you can generate eclipse project metadata using the following command:
$ mvn eclipse:eclipse
The generated eclipse projects can be imported by selecting import existing projects
from the file menu.
Spring Cloud uses [Project Lombok](http://projectlombok.org/features/index.html) to generate getters and setters etc. Compiling from the command line this shouldn’t cause any problems, but in an IDE you need to add an agent to the JVM. Full instructions can be found in the Lombok website. The sign that you need to do this is a lot of compiler errors to do with missing methods and fields, e.g.
The method getInitialStatus() is undefined for the type EurekaInstanceConfigBean EurekaDiscoveryClientConfiguration.java /spring-cloud-netflix-core/src/main/java/org/springframework/cloud/netflix/eureka line 120 Java Problem The method getInitialStatus() is undefined for the type EurekaInstanceConfigBean EurekaDiscoveryClientConfiguration.java /spring-cloud-netflix-core/src/main/java/org/springframework/cloud/netflix/eureka line 121 Java Problem The method setNonSecurePort(int) is undefined for the type EurekaInstanceConfigBean EurekaDiscoveryClientConfiguration.java /spring-cloud-netflix-core/src/main/java/org/springframework/cloud/netflix/eureka line 112 Java Problem The type EurekaInstanceConfigBean.IdentifyingDataCenterInfo must implement the inherited abstract method DataCenterInfo.getName() EurekaInstanceConfigBean.java /spring-cloud-netflix-core/src/main/java/org/springframework/cloud/netflix/eureka line 131 Java Problem The method getId() is undefined for the type ProxyRouteLocator.ProxyRouteSpec PreDecorationFilter.java /spring-cloud-netflix-core/src/main/java/org/springframework/cloud/netflix/zuul/filters/pre line 60 Java Problem The method getLocation() is undefined for the type ProxyRouteLocator.ProxyRouteSpec PreDecorationFilter.java /spring-cloud-netflix-core/src/main/java/org/springframework/cloud/netflix/zuul/filters/pre line 55 Java Problem
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.
Before we accept a non-trivial patch or pull request we will need you to sign the contributor’s 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.
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.
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Use the Spring Framework code format conventions. If you use Eclipse you can import formatter settings using the
eclipse-code-formatter.xmlfile 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
.javafiles to have a simple Javadoc class comment with at least an@authortag identifying you, and preferably at least a paragraph on what the class is for. -
Add the ASF license header comment to all new
.javafiles (copy from existing files in the project) -
Add yourself as an
@authorto the .java files that you modify substantially (more than cosmetic changes). -
Add some Javadocs and, if you change the namespace, some XSD doc elements.
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A few unit tests would help a lot as well — someone has to do it.
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If no-one else is using your branch, please rebase it against the current master (or other target branch in the main project).
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When writing a commit message please follow these conventions, if you are fixing an existing issue please add
Fixes gh-XXXXat the end of the commit message (where XXXX is the issue number).