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Data Service

Data service provides various services to save and fetch data from Apache Cassandra database. Spring WebFlux framework is used for reactive programming in order to stream the result records from Cassandra database.

Installation and Running of Apache Cassandra

  • Download latest Apache Cassandra release or archive release and extract the .gz or .tar file.
  • Find conf/cassandra.yaml file in CASSANDRA_HOME directory, were CASSANDRA_HOME is the path to the unzipped apache-cassandra directory.
  • Replace all the paths starting with /var/lib/cassandra/ with ../var/lib/cassandra/. This should update the properties data_file_directories, commitlog_directory and saved_caches_directory.
  • Go to CASSANDRA_HOME\bin directory and execute the command cassandra.bat to run cassandra.
  • Cassandra runs on default port 9042.
  • To enabled Authentication for Cassandra database, open conf/cassandra.yaml configuration file and update the below properties with these values.
    • authenticator: PasswordAuthenticator
    • authorizer: CassandraAuthorizer

All the above steps can be executed directly by running below runCassandra gradle task for windows.

$ gradle runCassandra

To run cassandra as a windows service

  • Download Apache commons daemon and extract to any given location.
  • Create a directory called daemon inside the CASSANDRA_HOME\bin directory.
  • Copy the prunsrv.exe from Apache commons daemon extracted directory, based on architecture (32bit/64bit) to the CASSANDRA_HOME\bin\daemon directory created earlier.
  • Go to CASSANDRA_HOME\bin directory and execute the command cassandra.bat install to install cassandra as a windows service.

Cassandra Client

  • To connect with cassandra database and create new keyspace (database) we use CSQL (Cassandra Query Language) Shell.

  • The cqlsh shell is compatible with Python 2.7 and requires it to be installed in the system to execute.

  • In order to setup python and cqlsh shell without admin privileges, download Standalone Python 2.7.9 for windows and extract it to C drive.

  • Then edit CASSANDRA_HOME\bin\cqlsh.bat file to add below set path command.

    setlocal SET PATH=%PATH%;c:\python 2.7.6

  • Go to CASSANDRA_HOME\bin directory and execute the command cqlsh.bat -u cassandra -p cassandra to connect to cassandra database.

  • Create simple keyspace using the command: CREATE KEYSPACE testdb WITH replication = {'class': 'SimpleStrategy', 'replication_factor': 1};

  • To use the testdb keyspace use the command: USE testdb;.

RazorSQL is Cassandra Database Browser which allows to view Keyspaces, Tables and Views.

Running the Data Service

Optionally spring.profiles.active can be passed with value production which enables logback to send all logs to Elastic Stack instead of logging in the console by default.

$ java -jar data-service/build/libs/data-service-0.0.1-SNAPSHOT.jar
	   -Dspring.profiles.active=production

Running Data Service on Kubernetes

First setup the cassandra-service which is required for running the data-service.

$ kubectl apply -f cassandra-service.yaml

Then create a docker image for data-service, tagging it with name data-service, and push the image to docker registry. Login into docker registry using username admin and password docker123.

$ sudo docker build --tag=data-service data-service
$ sudo docker tag data-service docker.registry.com:5000/data-service:latest
$ sudo docker login docker.registry.com:5000
$ sudo docker push docker.registry.com:5000/data-service

Finally deploy and create the data-service using below command.

$ kubectl apply -f data-service.yaml

Notes

  • Data service uses MapStruct for mapping between domain object to DTO object. MapStruct requires mapstruct-processor to be configured in gradle to generate the corresponding Mapper implementation for defined MapStruct interface. Hence it is highly recommended to run gradle build before running data-service to avoid Spring NoSuchBeanDefinitionException for MapStruct autowirings.