Few tips using Zipkin

Zipkin is a very useful tracing solution while building microservice. (It is also useful at any service because it measure latency between two services). It becomes more and more popular but there are little documents. This post is few tips while adapting Zipkin in production.

Zipkin with Finatra

Zipkin is firstly made by Twitter and it supports Finatra (Base on Twitter Server and Finagle) well. Integrating Zipkin with Finatra is very simple.

1. Just add a dependency to project.(libraryDependencies in build.sbt)


com.twitter" %% "finagle-zipkin" %% finagle-version

2. And after that, just add Twitter flag while running Finatra Server. You can see Twitter flags when you add ‘-help’ end of jar or SBT. And all you need to know about flags related to Zipkin is

-thrift.name='thrift': Thrift server name // When Thrift Server
or
-http.name='http': Http server name // When Http Server
-com.twitter.finagle.zipkin.host='localhost:1463': Host to scribe traces to
-com.twitter.finagle.zipkin.initialSampleRate='0.001': Initial sample rate

Yes! when you add Twitter flags end of your application, it works! But sometimes, I have to check whether it is applied. Then you can check in Twitter Server admin. Its URL is ‘admin/clients/zipkin-tracer’.

스크린샷 2017-10-17 오후 10.27.42

If you set Zipkin Server properly, you can see your server address in ‘Set(Inet({Server Address}, Map()))’.

Add Twitter flag in SBT

When you want to add Twitter flags while in sbt run, you can add twitter flags like this

$ sbt 'run -help'

Existing instrumentations

Zipkin support many framework and language. If you want to find a supported framework, You can find it here.

Scribe

Above page, there are main 2 kinds of protocol, HTTP, and Scribe. As you know, Zipkin Server supports Http and Scribe. I was very curious what a Scribe is. You can see description in here. Simply to say, Scribe is logging protocol base on thrift.

com.twitter:finagle-zipkin

finagle-zipkin has two version. One is openzipkin/zipkin-finagle and another is finagle-zipkin in twitter/finagle. What is a difference between two things? openzipkin/zipkin-finagle is maintained by the openzipkin group. You can select protocol HTTP and Scribe. But, finagle-zipkin in twitter/finagle is little different. It supports only Scribe. so, if you want to connect with Finatra, you have to load Zipkin Server which supports Scribe.

Ports

Zipkin needs two port. One is 9411 which get HTTP Request. And 9410 which support Scribe. 9410 port is only opened when you enable Scribe support.

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Monitoring Micro Service With Zipkin

This post is recommended to read with an example. You can clone example in my Github – https://github.com/ktz-boilerplate/finatra-zipkin-example.

 

Micro Service is becoming trendy technology. But there are many things to consider during migrate our service to micro service. One of them is latency. We have to monitor each micro service and find out which service is a bottleneck and why does that happen. And Zipkin can be a reasonable answer.

Zipkin

Zipkin is monitoring solution about latency. It traces each micro service and calculates latencies so that we can trace which micro take lots of time and handle it. This solution is base on Google Dapper.

Example

Start Zipkin on Docker

First, we will test Zipkin solution on Docker. So, if you don’t have Docker in local, please install it. You can see how to install in Docker Documentation.

Now, let’s start Zipkin on Docker.

$ docker run -d -p 9411:9411 -p 9410:9410 -e SCRIBE_ENABLED=true openzipkin/zipkin

9411 port is Zipkin web UI and 9410 port is scribe port. And you have to enable scribe port to accept Thrift by SCRIBE_ENABLED=true. If you up Zipkin on Docker, then you can see web UI in here.

Zipkin Twitter Flag

Before start servers, Let’s look around for twitter flags related to Zipkin. If your server is not compatible to this flags, you have to version up Finatra.

-http.name: HTTP Server name which displayed in Zipkin.

-thrift.name: Thrift Server name which displayed in Zipkin.

-com.twitter.finagle.zipkin.host: Zipkin host and port number to pass trace span(data).

-com.twitter.finagle.zipkin.initialSampleRate: Sample rate. from 0 to 1.0. 1.0 is that trace all request and send to Zipkin.

Start Finatra HTTP Server

Now, go to project directory. You can see 5 sub-projects. One of them is Finatra HTTP-Server. Let’s start HTTP Server first.

$ sbt 'project http-server' "run -http.name=http-server -com.twitter.finagle.zipkin.host=localhost:9410 -com.twitter.finagle.zipkin.initialSampleRate=1"

Start Finatra Thrift Server

Now, let’s start another server. It’s Thrift Server

$ sbt 'project thrift-server' "-thrift.name=thrift-server -com.twitter.finagle.zipkin.host=localhost:9410 -com.twitter.finagle.zipkin.initialSampleRate=1"

Query Something.

Now connect to HTTP-Server and Query Something. There are some URL you can test.

get

  • /users
  • /user/:userId
  • /user/car/
  • /user/:userId/car

post

  • /user

For example, if you want to get all users. You can get by call http://localhost:8080/users

After some queries, you can see tracing status in Zipkin Web UI like this.

zipkinui1.png

The default setting is sort by longest latency first.

 

You can also see dependency like this.

dependency.png