Changes for multi schematic Services

Follow the generic updates before starting with the following changes

General update for services to be Central-Instance compatible

Application.properties variables to be added

1. state.level.tenantid.length=2
   State-level tenant value will be picked from the full tenant-id separated by the '.' dot. once the tenant-id is separated by dot the resulting array of size given above will be considered state level.
   is.environment.central.instance=true

2. Declares whether the environment in which the service is deployed belong to a central-instance kind of setup.
   

3. The both above said variable has to be overridden in the values YAML file of the respective service to pick up the values from the environment.

     {{- if index .Values "global" "is-environment-central-instance" }}        
     - name: IS_ENVIRONMENT_CENTRAL_INSTANCE
       valueFrom:
         configMapKeyRef:
           name: egov-config
           key: is-environment-central-instance
     {{- end }}
     {{- if index .Values "global" "is-environment-central-instance" }}        
     - name: STATE_LEVEL_TENANTID_LENGTH
       valueFrom:
         configMapKeyRef:
           name: egov-config
           key: state-level-tenantid-length
     {{- end }}

4. The host of the state-specific services referred by this service should be changed to the internal gateway host for tenant-based(namespace) redirection.

     - name: EGOV_MDMS_HOST
       valueFrom:
         configMapKeyRef:
           name: egov-service-host
           key: internal-gateway

   Sample values YAML file to refer to the above-said changes

   https://github.com/egovernments/DIGIT-DevOps/blob/central-instance/deploy-as-code/helm/charts/municipal-services/property-services/values.yaml
   

5. If this service allows the search of data without tenant-id then the following validation should be added to all the search APIs belonging to the service. searches without state-level tenant-id (as described by this variable - state.level.tenantid.length) will render the application useless, so the following is mandatory

   	if(configs.getIsEnvironmentCentralInstance() && criteria.getTenantId() == null)
   		throw new CustomException("EG_PT_INVALID_SEARCH"," TenantId is mandatory for search ");
   	else if(configs.getIsEnvironmentCentralInstance() && criteria.getTenantId().split("\\.").length < configs.getStateLevelTenantIdLength())
   		throw new CustomException("EG_PT_INVALID_SEARCH"," TenantId should be mandatorily " + configs.getStateLevelTenantIdLength() + " levels for search");

6. Update the Kafka producer in the service with the following code to enable the service to post to a tenant(namespace) specific topic based on the tenant-id.

   @Service
   @Slf4j
   public class Producer {
   
   	@Autowired
   	private CustomKafkaTemplate<String, Object> kafkaTemplate;
   	
   	@Autowired
   	private PropertyConfiguration configs;
   
   	public void push(String tenantId, String topic, Object value) {
   
   		String updatedTopic = topic;
   		if (configs.getIsEnvironmentCentralInstance()) {
   
   			String[] tenants = tenantId.split("\\.");
   			if (tenants.length > 1)
   				updatedTopic = tenants[1].concat("-").concat(topic);
   		}
   		log.info("The Kafka topic for the tenantId : " + tenantId + " is : " + updatedTopic);
   		kafkaTemplate.send(updatedTopic, value);
   	}
   } 

7. Replace all the table names in the queries present with the {schema} placeholder
   

   private static String PROEPRTY_AUDIT_QUERY = "select property from {schema}.eg_pt_property_audit where propertyid=?";

8. Add the following Schema replacer utility method and use the same to replace all queries with the respective schema.
   

   	/**
   	 * Method to fetch the state name from the tenantId
   	 * 
   	 * @param query
   	 * @param tenantId
   	 * @return
   	 */
   	public String replaceSchemaPlaceholder(String query, String tenantId) {
   
   		String finalQuery = null;
   		if (tenantId.contains(".")) {
   			String schemaName = tenantId.split("\\.")[1];
   			finalQuery = query.replace(PTConstants.SCHEMA_REPLACE_STRING, schemaName);
   		} else {
   			finalQuery = query.replace(PTConstants.SCHEMA_REPLACE_STRING.concat("."), "");
   		}
   		return finalQuery;
   	}
   	
      /*
   	* Sample method example to replace query with schema
   	*/	
   	public List<String> getPropertyIds(Set<String> ownerIds, String tenantId) {
   
   		List<Object> preparedStmtList = new ArrayList<>();
   		String query = queryBuilder.getPropertyIdsQuery(ownerIds, tenantId, preparedStmtList);
   		query = util.replaceSchemaPlaceholder(query, tenantId);
   		return jdbcTemplate.queryForList(query, preparedStmtList.toArray(), String.class);
   	}

9. Change the persister config to alter the Kafka topic names for the configs belonging to your respective multi-schema service. The kafka topic name should be appended with the schema name of the respective state schema.