The Ratis LogService is an distributed, log implementation built on top of Apache Ratis. The LogService provides the ability to create named, durable, append-only data structures with the ability to perform linear reads.
The LogService is compose of two Ratis quorums: the metadata quorum and the log quorum. These can be launched manually or via docker-compose.
First, the project must be built:
$ mvn clean package -DskipTests
Then, the service can be launched.
Launch Metadata daemons:
$ mvn exec:java -Dexec.mainClass=org.apache.ratis.logservice.server.MetadataServer -Dexec.args="-p 9991 -d $HOME/logservice1 -h localhost -q localhost:9991,localhost:9992,localhost:9993"
$ mvn exec:java -Dexec.mainClass=org.apache.ratis.logservice.server.MetadataServer -Dexec.args="-p 9992 -d $HOME/logservice2 -h localhost -q localhost:9991,localhost:9992,localhost:9993"
$ mvn exec:java -Dexec.mainClass=org.apache.ratis.logservice.server.MetadataServer -Dexec.args="-p 9993 -d $HOME/logservice3 -h localhost -q localhost:9991,localhost:9992,localhost:9993"
Above, we have started three daemons that will form a quorum to act as the “LogService Metadata”. They will track what logs exist and the RAFT qs which service those logs.
Launch Worker daemons:
$ mvn exec:java -Dexec.mainClass=org.apache.ratis.logservice.server.LogServer -Dexec.args="-p 9951 -d $HOME/worker1 -h localhost -q localhost:9991,localhost:9992,localhost:9993"
$ mvn exec:java -Dexec.mainClass=org.apache.ratis.logservice.server.LogServer -Dexec.args="-p 9952 -d $HOME/worker2 -h localhost -q localhost:9991,localhost:9992,localhost:9993"
$ mvn exec:java -Dexec.mainClass=org.apache.ratis.logservice.server.LogServer -Dexec.args="-p 9953 -d $HOME/worker3 -h localhost -q localhost:9991,localhost:9992,localhost:9993"
Now, we have started three daemons which can service a single LogStream. They will register to the Metadata quorum, and the Metadata quorum will choose three of them to form a RAFT quorum to “host” a single Log.
Note: the q option here references to the Metadata quorum, not the worker quorum as is the case for the Metadata daemons.
Then, the LogService interactive shell can be used to interact with the software:
$ mvn exec:java -Dexec.mainClass=org.apache.ratis.logservice.shell.LogServiceShell -Dexec.args="-q localhost:9991,localhost:9992,localhost:9993"
Similarly, a full quorum can be started by building a docker container and then start the docker-compose cluster:
$ cd ratis-logservice && mvn package assembly:single -DskipTests $ docker build -t ratis-logservice --build-arg BINARY=target/ratis-logservice-0.4.0-SNAPSHOT-bin.tar.gz --build-arg VERSION=0.4.0-SNAPSHOT . $ docker-compose up
Then, a client container can be launched to connect to the cluster:
$ docker run --rm --network ratis-logservice_default -it ratis-logservice java -cp "/opt/ratis-logservice/current/conf:/opt/ratis-logservice/current/lib/*" org.apache.ratis.logservice.shell.LogServiceShell -q master1.logservice.ratis.org:9999,master2.logservice.ratis.org:9999,master3.logservice.ratis.org:9999
Take care that the correct network is provided to the LogServiceShell command.