error while trying to start the coordinator service

can anyone tell me what the problem might be in this error
I’m getting this error whenever I try starting the coordinator service

Exception in thread “main” io.druid.java.util.common.ISE: Extension [/druid-0.12.1/extensions/mysql-metadata-storage] specified in “druid.extensions.loadList” didn’t exist!?

at io.druid.initialization.Initialization.getExtensionFilesToLoad(Initialization.java:245)

at io.druid.initialization.Initialization$ServiceLoadingFromExtensions.addAllFromFileSystem(Initialization.java:176)

at io.druid.initialization.Initialization$ServiceLoadingFromExtensions.(Initialization.java:164)

at io.druid.initialization.Initialization$ServiceLoadingFromExtensions.(Initialization.java:150)

at io.druid.initialization.Initialization.getFromExtensions(Initialization.java:145)

Hi Dilip,

Looks like you need to download the mysql extension. It’s a separate download for licensing reasons (the mysql driver is lgpl). You can get it at http://druid.io/downloads.html (look for “mysql metadata store extension”).

1. Why do I need to download MySQL...
2. And to make it more clear I'm using docker compose to start different containers.
3. Later I'm entering different containers to start the services.
Is this the right way to do?

4. I have followed the these steps to make changes in conf:
( Instructions from the druid clustering documentation)

Configure addresses for Druid coordination
In this simple cluster, you will deploy a single Druid Coordinator, a single Druid Overlord, a single ZooKeeper instance, and an embedded Derby metadata store on the same server.

In conf/druid/_common/common.runtime.properties, replace "zk.service.host" with the address of the machine that runs your ZK instance:

druid.zk.service.host

In conf/druid/_common/common.runtime.properties, replace "metadata.storage.*" with the address of the machine that you will use as your metadata store:

druid.metadata.storage.connector.connectURI
druid.metadata.storage.connector.host

(Here I have used the container name for the address of the machine)

Apart from these conf changes I haven't made any changes.

I'm using the data the local data .

For the first question. How is druid depending on MySQL.

Druid needs some kind of metadata store, and you’ve got the “mysql-metadata-storage” extension in your loadList. I figured that was because you meant to use mysql, but maybe you haven’t intended to choose that one. Check here for your options: http://druid.io/docs/latest/dependencies/metadata-storage.html

The Druid whitepaper describes what we use metadata stores for: http://static.druid.io/docs/druid.pdf

the coordinator need to read the metadata from mysql, so druid need to have a mysql client, you may download the mysql extension through pull-depths. Please let me know if I’m incorrect.

在 2018年7月3日星期二 UTC+8下午1:33:56,dood写道: