Spark Cluster starting issue - hadoop

Question

I'm new to spark, and trying to setup spark cluster. I did following things to set-up and check status of spark cluster, but not sure about status.
I tried to check master-ip:8081 (8080, 4040, 4041) in the browser, but didn't see any results. To start with, I set-up and started hadoop cluster.
JPS gives:
2436 SecondaryNameNode
2708 NodeManager
2151 NameNode
5495 Master
2252 DataNode
2606 ResourceManager
5710 Jps
Question (Was it necessary to start hadoop?)
In Master /usr/local/spark/conf/slaves
localhost
slave-node-1
slave-node-2
Now, to start Spark; Master Started with
$SPARK_HOME/sbin/start-master.sh
And tested with
ps -ef|grep spark
hduser 5495 1 0 18:12 pts/0 00:00:04 /usr/local/java/bin/java -cp /usr/local/spark/conf/:/usr/local/spark/jars/*:/usr/local/hadoop/etc/hadoop/ -Xmx1g org.apache.spark.deploy.master.Master --host master-hostname --port 7077 --webui-port 8080
On slave node 1
$SPARK_HOME/sbin/start-slave.sh spark://205.147.102.19:7077
Tested with
ps -ef|grep spark
hduser 1847 1 20 18:24 pts/0 00:00:04 /usr/local/java/bin/java -cp /usr/local/spark/conf/:/usr/local/spark/jars/* -Xmx1g org.apache.spark.deploy.worker.Worker --webui-port 8081 spark://master-ip:7077
Same on slave-node 2
$SPARK_HOME/sbin/start-slave.sh spark://master-ip:7077
ps -ef|grep spark
hduser 1948 1 3 18:18 pts/0 00:00:03 /usr/local/java/bin/java -cp /usr/local/spark/conf/:/usr/local/spark/jars/* -Xmx1g org.apache.spark.deploy.worker.Worker --webui-port 8081 spark://master-ip:7077
I was not able to see anything on the web console of spark.. so I thought problem may be with firewall. Here is my iptables..
iptables -L -nv
Chain INPUT (policy ACCEPT 0 packets, 0 bytes)
pkts bytes target prot opt in out source destination
6136 587K fail2ban-ssh tcp -- * * 0.0.0.0/0 0.0.0.0/0 multiport dports 22
151K 25M ACCEPT all -- * * 0.0.0.0/0 0.0.0.0/0 state RELATED,ESTABLISHED
6 280 ACCEPT icmp -- * * 0.0.0.0/0 0.0.0.0/0
579 34740 ACCEPT all -- lo * 0.0.0.0/0 0.0.0.0/0
34860 2856K ACCEPT all -- eth1 * 0.0.0.0/0 0.0.0.0/0
145 7608 ACCEPT tcp -- * * 0.0.0.0/0 0.0.0.0/0 state NEW tcp dpt:22
56156 5994K REJECT all -- * * 0.0.0.0/0 0.0.0.0/0 reject-with icmp-host-prohibited
0 0 ACCEPT tcp -- * * 0.0.0.0/0 0.0.0.0/0 tcp dpt:8080
0 0 ACCEPT tcp -- * * 0.0.0.0/0 0.0.0.0/0 tcp dpt:8081
Chain FORWARD (policy ACCEPT 0 packets, 0 bytes)
pkts bytes target prot opt in out source destination
0 0 REJECT all -- * * 0.0.0.0/0 0.0.0.0/0 reject-with icmp-host-prohibited
Chain OUTPUT (policy ACCEPT 3531 packets, 464K bytes)
pkts bytes target prot opt in out source destination
Chain fail2ban-ssh (1 references)
pkts bytes target prot opt in out source destination
2 120 REJECT all -- * * 218.87.109.153 0.0.0.0/0 reject-with icmp-port-unreachable
5794 554K RETURN all -- * * 0.0.0.0/0 0.0.0.0/0
I'm trying all I can to see if spark-cluster is set-up and how to check it properly. And if cluster is set-up, why am I not able to check that on web-console? What could be wrong? Any pointers would be helpful...
EDIT - ADDING LOGS after spark-shell --master local command (in the master)
17/01/11 18:12:46 INFO util.Utils: Successfully started service 'sparkMaster' on port 7077.
17/01/11 18:12:47 INFO master.Master: Starting Spark master at spark://master:7077
17/01/11 18:12:47 INFO master.Master: Running Spark version 2.1.0
17/01/11 18:12:47 INFO util.log: Logging initialized #3326ms
17/01/11 18:12:47 INFO server.Server: jetty-9.2.z-SNAPSHOT
17/01/11 18:12:47 INFO handler.ContextHandler: Started o.s.j.s.ServletContextHandler#20f0b5ff{/app,null,AVAILABLE}
17/01/11 18:12:47 INFO handler.ContextHandler: Started o.s.j.s.ServletContextHandler#734e74b2{/app/json,null,AVAILABLE}
17/01/11 18:12:47 INFO handler.ContextHandler: Started o.s.j.s.ServletContextHandler#1bc45d76{/,null,AVAILABLE}
17/01/11 18:12:47 INFO handler.ContextHandler: Started o.s.j.s.ServletContextHandler#6a274a23{/json,null,AVAILABLE}
17/01/11 18:12:47 INFO handler.ContextHandler: Started o.s.j.s.ServletContextHandler#4f5d45d5{/static,null,AVAILABLE}
17/01/11 18:12:47 INFO handler.ContextHandler: Started o.s.j.s.ServletContextHandler#4fb65368{/app/kill,null,AVAILABLE}
17/01/11 18:12:47 INFO handler.ContextHandler: Started o.s.j.s.ServletContextHandler#76208805{/driver/kill,null,AVAILABLE}
17/01/11 18:12:47 INFO server.ServerConnector: Started ServerConnector#258dbadd{HTTP/1.1}{0.0.0.0:8080}
17/01/11 18:12:47 INFO server.Server: Started #3580ms
17/01/11 18:12:47 INFO util.Utils: Successfully started service 'MasterUI' on port 8080.
17/01/11 18:12:47 INFO ui.MasterWebUI: Bound MasterWebUI to 0.0.0.0, and started at http://master:8080
17/01/11 18:12:47 INFO server.Server: jetty-9.2.z-SNAPSHOT
17/01/11 18:12:47 INFO handler.ContextHandler: Started o.s.j.s.ServletContextHandler#1cfbb7e9{/,null,AVAILABLE}
17/01/11 18:12:47 INFO server.ServerConnector: Started ServerConnector#2f7af4e{HTTP/1.1}{master:6066}
17/01/11 18:12:47 INFO server.Server: Started #3628ms
17/01/11 18:12:47 INFO util.Utils: Successfully started service on port 6066.
17/01/11 18:12:47 INFO rest.StandaloneRestServer: Started REST server for submitting applications on port 6066
17/01/11 18:12:47 INFO handler.ContextHandler: Started o.s.j.s.ServletContextHandler#799d5f4f{/metrics/master/json,null,AVAILABLE}
17/01/11 18:12:47 INFO handler.ContextHandler: Started o.s.j.s.ServletContextHandler#647c46e3{/metrics/applications/json,null,AVAILABLE}
17/01/11 18:12:47 INFO master.Master: I have been elected leader! New state: ALIVE
In slave nodes-
17/01/11 18:22:46 INFO Worker: Connecting to master master:7077...
17/01/11 18:22:46 WARN Worker: Failed to connect to master master:7077
Tonnes of java errors..
17/01/11 18:31:18 ERROR Worker: All masters are unresponsive! Giving up.

Answer 1

Spark Web UI start when you are creating SparkContext
Try to run spark-shell --master yourmaster:7077 and then open Spark UI. You can also use spark-sumit to submit some application, then SparkContext will be created.
Example spark-submit, from Spark documentation:
./bin/spark-submit \
--class org.apache.spark.examples.SparkPi \
--master spark://207.184.161.138:7077 \
--deploy-mode cluster \
--supervise \
--executor-memory 20G \
--total-executor-cores 100 \
/path/to/examples.jar \
1000
Answer to first question: you must start Hadoop components if you want to use HDFS or YARN. If not, they can be not started
Also you can go to /etc/hosts/ and remove line with 127.0.0.1 or set MASTER_IP variable in Spark configuration to proper host name

Answer 2

The problem was IP tables. most other things were fine. So I just followed instructions here https://wiki.debian.org/iptables to fix IP tables, and it worked for me. Only thing that you should know which ports will be used for spark/hadoop etc. I opened 8080, 54310, 50070, 7077 (some defaults used by many for hadoop and spark installation)...