Created question in FIWARE Q/A platform on 02-03-2018 at 15:03
Please, ANSWER this question AT https://stackoverflow.com/questions/49070738/problems-running-cygnus-with-postgresql

Question:
Problems running Cygnus with Postgresql

Description:
So I have installed Cygnus and in the simple test configuration case which I took from here (https://github.com/telefonicaid/fiware-cygnus/blob/master/cygnus-ngsi/README.md) everything works fine.

But I need Postgresql as a backend for my application.
For this I adjusted the agent_1.conf file with all postgresql parameters found from http://fiware-cygnus.readthedocs.io/en/latest/cygnus-ngsi/installation_and_administration_guide/ngsi_agent_conf/

cygnus-ngsi.sources = http-source
cygnus-ngsi.sinks = postgresql-sink
cygnus-ngsi.channels = postgresql-channel

cygnus-ngsi.sources.http-source.channels = hdfs-channel mysql-channel ckan-channel mongo-channel sth-channel kafka-channel dynamo-channel postgresql-channel
cygnus-ngsi.sources.http-source.type = org.apache.flume.source.http.HTTPSource
cygnus-ngsi.sources.http-source.port = 5050
cygnus-ngsi.sources.http-source.handler = com.telefonica.iot.cygnus.handlers.NGSIRestHandler
cygnus-ngsi.sources.http-source.handler.notification_target = /notify
cygnus-ngsi.sources.http-source.handler.default_service = default
cygnus-ngsi.sources.http-source.handler.default_service_path = /
cygnus-ngsi.sources.http-source.interceptors = ts gi
cygnus-ngsi.sources.http-source.interceptors.gi.type = com.telefonica.iot.cygnus.interceptors.NGSIGroupingInterceptor$Builder
cygnus-ngsi.sources.http-source.interceptors.gi.grouping_rules_conf_file = /usr/cygnus/conf/grouping_rules.conf

cygnus-ngsi.sinks.postgresql-sink.channel = postgresql-channel
cygnus-ngsi.sinks.postgresql-sink.type = com.telefonica.iot.cygnus.sinks.NGSIPostgreSQLSink
cygnus-ngsi.sinks.postgresql-sink.postgresql_host = 127.0.0.1
cygnus-ngsi.sinks.postgresql-sink.postgresql_port = 5432
cygnus-ngsi.sinks.postgresql-sink.postgresql_database = myUser
cygnus-ngsi.sinks.postgresql-sink.postgresql_username = mydb
cygnus-ngsi.sinks.postgresql-sink.postgresql_password = xxxx
cygnus-ngsi.sinks.postgresql-sink.attr_persistence = row
cygnus-ngsi.sinks.postgresql-sink.batch_size = 100
cygnus-ngsi.sinks.postgresql-sink.batch_timeout = 30
cygnus-ngsi.sinks.postgresql-sink.batch_ttl = 10

1. postgresql-channel configuration
   cygnus-ngsi.channels.postgresql-channel.type = memory
   cygnus-ngsi.channels.postgresql-channel.capacity = 1000
   cygnus-ngsi.channels.postgresql-channel.transactionCapacity = 100

I didn'r really find any information about other files I am supposed to change and aren't really sure if all parameters are correct.
I also tried the sample configuration from here http://fiware-cygnus.readthedocs.io/en/latest/cygnus-ngsi/flume_extensions_catalogue/ngsi_postgresql_sink/index.html

Cygnus seems to start correctly but all if I try to send a notification I get connection refused