MiNiFi - NiFi Connection Failure: Unknown Host Exception : Able to telnet host from the machine where MiNiFi is running - amazon-ec2

Question

I am running MiNiFi in a Linux Box (gateway server) which is behind my company's firewall. My NiFi is running on an AWS EC2 cluster (running in standalone mode).
I am trying to send data from the Gateway to NiFi running in AWS EC2.
From gateway, I am able to telnet to EC2 node with the public DNS and the remote port which I have configured in the nifi.properties file
nifi.properties
# Site to Site properties
nifi.remote.input.host=ec2-xxx.us-east-2.compute.amazonaws.com
nifi.remote.input.secure=false
nifi.remote.input.socket.port=1026
nifi.remote.input.http.enabled=true
nifi.remote.input.http.transaction.ttl=30 sec
nifi.remote.contents.cache.expiration=30 secs
Telnet connection from Gateway to NiFi
iot1#iothdp02:~/minifi/minifi-0.5.0/conf$ telnet ec2-xxx.us-east-2.compute.amazonaws.com 1026
Trying xx.xx.xx.xxx...
Connected to ec2-xxx.us-east-2.compute.amazonaws.com.
Escape character is '^]'.
The Public DNS is resolving to the correct Public IP of the EC2 node.
From the EC2 node, when I do nslookup on the Public DNS, it gives back the private IP.
From AWS Documentation: "The public IP address is mapped to the primary private IP address through network address translation (NAT). "
Hence, I am not adding the Public DNS and the Public IP in /etc/host file in the EC2 node.
From MiNiFi side, I am getting the below error:
minifi-app.log
iot1#iothdp02:~/minifi/minifi-0.5.0/logs$ cat minifi-app.log
2018-11-14 16:00:47,910 INFO [pool-31-thread-1] o.a.n.c.r.WriteAheadFlowFileRepository Initiating checkpoint of FlowFile Repository
2018-11-14 16:00:47,911 INFO [pool-31-thread-1] o.a.n.c.r.WriteAheadFlowFileRepository Successfully checkpointed FlowFile Repository with 0 records in 0 milliseconds
2018-11-14 16:01:02,334 INFO [Write-Ahead Local State Provider Maintenance] org.wali.MinimalLockingWriteAheadLog org.wali.MinimalLockingWriteAheadLog#67207d8a checkpointed with 0 Records and 0 Swap Files in 20 milliseconds (Stop-the-world time = 6 milliseconds, Clear Edit Logs time = 4 millis), max Transaction ID -1
2018-11-14 16:02:47,911 INFO [pool-31-thread-1] o.a.n.c.r.WriteAheadFlowFileRepository Initiating checkpoint of FlowFile Repository
2018-11-14 16:02:47,912 INFO [pool-31-thread-1] o.a.n.c.r.WriteAheadFlowFileRepository Successfully checkpointed FlowFile Repository with 0 records in 0 milliseconds
2018-11-14 16:03:02,354 INFO [Write-Ahead Local State Provider Maintenance] org.wali.MinimalLockingWriteAheadLog org.wali.MinimalLockingWriteAheadLog#67207d8a checkpointed with 0 Records and 0 Swap Files in 18 milliseconds (Stop-the-world time = 3 milliseconds, Clear Edit Logs time = 5 millis), max Transaction ID -1
2018-11-14 16:03:10,636 WARN [Timer-Driven Process Thread-8] o.a.n.r.util.SiteToSiteRestApiClient Failed to get controller from http://ec2-xxx.us-east-2.compute.amazonaws.com:9090/nifi-api due to java.net.UnknownHostException: ec2-xxx.us-east-2.compute.amazonaws.com: unknown error
2018-11-14 16:03:10,636 WARN [Timer-Driven Process Thread-8] o.apache.nifi.controller.FlowController Unable to communicate with remote instance RemoteProcessGroup[http://ec2-xxx.us-east-2.compute.amazonaws.com:9090/nifi] due to org.apache.nifi.controller.exception.CommunicationsException: org.apache.nifi.controller.exception.CommunicationsException: Unable to communicate with Remote NiFi at URI http://ec2-xxx.us-east-2.compute.amazonaws.com:9090/nifi due to: ec2-xxx.us-east-2.compute.amazonaws.com: unknown error
2018-11-14 16:04:47,912 INFO [pool-31-thread-1] o.a.n.c.r.WriteAheadFlowFileRepository Initiating checkpoint of FlowFile Repository
2018-11-14 16:04:47,912 INFO [pool-31-thread-1] o.a.n.c.r.WriteAheadFlowFileRepository Successfully checkpointed FlowFile Repository with 0 records in 0 milliseconds
2018-11-14 16:05:02,380 INFO [Write-Ahead Local State Provider Maintenance] org.wali.MinimalLockingWriteAheadLog org.wali.MinimalLockingWriteAheadLog#67207d8a checkpointed with 0 Records and 0 Swap Files in 25 milliseconds (Stop-the-world time = 8 milliseconds, Clear Edit Logs time = 6 millis), max Transaction ID -1
2018-11-14 16:06:47,912 INFO [pool-31-thread-1] o.a.n.c.r.WriteAheadFlowFileRepository Initiating checkpoint of FlowFile Repository
2018-11-14 16:06:47,912 INFO [pool-31-thread-1] o.a.n.c.r.WriteAheadFlowFileRepository Successfully checkpointed FlowFile Repository with 0 records in 0 milliseconds
2018-11-14 16:07:02,399 INFO [Write-Ahead Local State Provider Maintenance] org.wali.MinimalLockingWriteAheadLog org.wali.MinimalLockingWriteAheadLog#67207d8a checkpointed with
MiNiFi config.yml
MiNiFi Config Version: 3
Flow Controller:
name: Gateway-IDS_v0.1
comment: "1. ConsumeMQTT - MiNiFi will consume mqtt messages in gateway\n2. Remote\
\ Process Group will send messages to NiFi "
Core Properties:
flow controller graceful shutdown period: 10 sec
flow service write delay interval: 500 ms
administrative yield duration: 30 sec
bored yield duration: 10 millis
max concurrent threads: 1
variable registry properties: ''
FlowFile Repository:
partitions: 256
checkpoint interval: 2 mins
always sync: false
Swap:
threshold: 20000
in period: 5 sec
in threads: 1
out period: 5 sec
out threads: 4
Content Repository:
content claim max appendable size: 10 MB
content claim max flow files: 100
always sync: false
Provenance Repository:
provenance rollover time: 1 min
implementation: org.apache.nifi.provenance.MiNiFiPersistentProvenanceRepository
Component Status Repository:
buffer size: 1440
snapshot frequency: 1 min
Security Properties:
keystore: ''
keystore type: ''
keystore password: ''
key password: ''
truststore: ''
truststore type: ''
truststore password: ''
ssl protocol: ''
Sensitive Props:
key:
algorithm: PBEWITHMD5AND256BITAES-CBC-OPENSSL
provider: BC
Processors:
- id: 6396f40f-118f-33f4-0000-000000000000
name: ConsumeMQTT
class: org.apache.nifi.processors.mqtt.ConsumeMQTT
max concurrent tasks: 1
scheduling strategy: TIMER_DRIVEN
scheduling period: 0 sec
penalization period: 30 sec
yield period: 1 sec
run duration nanos: 0
auto-terminated relationships list: []
Properties:
Broker URI: tcp://localhost:1883
Client ID: nifi
Connection Timeout (seconds): '30'
Keep Alive Interval (seconds): '60'
Last Will Message:
Last Will QoS Level:
Last Will Retain:
Last Will Topic:
MQTT Specification Version: '0'
Max Queue Size: '10'
Password:
Quality of Service(QoS): '0'
SSL Context Service:
Session state: 'true'
Topic Filter: MQTT
Username:
Controller Services: []
Process Groups: []
Input Ports: []
Output Ports: []
Funnels: []
Connections:
- id: f0007aa3-cf32-3593-0000-000000000000
name: ConsumeMQTT/Message/85ebf198-0166-1000-5592-476a7ba47d2e
source id: 6396f40f-118f-33f4-0000-000000000000
source relationship names:
- Message
destination id: 85ebf198-0166-1000-5592-476a7ba47d2e
max work queue size: 10000
max work queue data size: 1 GB
flowfile expiration: 0 sec
queue prioritizer class: ''
Remote Process Groups:
- id: c00d3132-375b-323f-0000-000000000000
name: ''
url: http://ec2-xxx.us-east-2.compute.amazonaws.com:9090
comment: ''
timeout: 30 sec
yield period: 10 sec
transport protocol: RAW
proxy host: ''
proxy port: ''
proxy user: ''
proxy password: ''
local network interface: ''
Input Ports:
- id: 85ebf198-0166-1000-5592-476a7ba47d2e
name: From MiNiFi
comment: ''
max concurrent tasks: 1
use compression: false
Properties:
Port: 1026
Host Name: ec2-xxx.us-east-2.compute.amazonaws.com
Output Ports: []
NiFi Properties Overrides: {}
Any pointers on how to troubleshoot this issue?

Answer 1

In MiNiFi config.yml, I changed the URL under Remote Process Groups from http://ec2-xxx.us-east-2.compute.amazonaws.com:9090 to http://ec2-xxx.us-east-2.compute.amazonaws.com:9090/nifi.