Nifi executeprocess does not generate realtime data

[#1]

Hi, i have questions. I'm followed the REALTIME EVENT PROCESSING IN HADOOP WITH NIFI, KAFKA AND STORM and got stuck. Why execute process in Nifi does not generate realtime data although i can execute /root/iot-truck-streaming/stream-simulator/generate.sh from shell. I used the template in that tutorial and also i followed that tutorial.

Another is why i use template from ANALYZE TRAFFIC PATTERNS WITH APACHE NIFI . I can run it. But i don't see the exact output file in output folder. I just can see "trafficLocs_data_for_simulator.zip_raw=true" file in output folder although i have waited for long time.

Thanks!

[#2 · Accepted solution]

Hello,

Sorry to hear that you're having trouble with our tutorial. I think there must be some error happening when the ExecuteProcess runs the shell script. But the processor ignores the stderr stream of the process by default, and currently, no bulletin error or log message are shown, then it's difficult to investigate what went wrong.

I think there's some room for improvement for this, and going to look further. In a meanwhile, please use 'Redirect Error Stream' to capture error output of the process to see what is happening, as shown in the attached image.

Thanks!

[#3]

Ok, here is error: "sh: /root/iot-truck-streaming/stream-simulator/generate.sh: Permission denied. "

So, how can i do?. Thanks!

[#4]

Hi,

To add executable permission to the file to every user (since I am not sure which user runs NiFi process on your environment), use following command:

chmod +x /root/iot-truck-streaming/stream-simulator/generate.sh

You might need to add sudo at the beginning of the command based on who you are logged in with:

sudo chmod +x /root/iot-truck-streaming/stream-simulator/generate.sh

Hope it works.

(Sorry, I pasted the above command wrong, updated.)

[#5]

Hi, i don't have a clue how to create nifi user, currently there is no nifi user being showed here. I see in ambari dashboard on nifi config that nifi_user and nifi_group is both nifi!?. What do you mean" add executable permission :

sudo /root/iot-truck-streaming/stream-simulator/generate.sh

". You mean add it to shell or to processor property?.

screenshot-24.png

[#6]

Hi, i've follow your guide, executed two commands above, but there's nothing changes. Currently i'm running as anonymous user. I don't know how to create secure user. I think it relevant to the problem. I look for guide to do that but it is complicate.

[#7]

Hi, I posted the comment without 'chmod +x' command above.. sorry about that. Please login to the sandbox machine by SSH and execute 'chmod +x /root/iot-truck-streaming/stream-simulator/generate.sh' command to add execution permission to the shell script file. Then NiFi will be able to run the sh from ExecuteProcess.

[#8]

I tried options of chmod and also chown to nifi user but error still exists even after full 777 permission on file and also folder. Please advice.

[#9]

I did read this thread and did all suggested options but error still exists as permission denied. Please advice.

[#10]

Hi @Mothilal marimuthu thanks for sharing that. I'll check it again to see if there's anything else needed.

[#11]

Hello,

I followed the tutorial once again and found what caused this.

The tutorial instructs to install NiFi via Ambari. Then the NiFi process is started by 'nifi' user on sandbox.

On the other hand, it instructs to clone the 'iot-truck-streaming' project from github, under 'root' home directory (/root).

So, even if we add execute permission to the sh file, nifi user can't access anything under /root directory.

Copying /root/iot-truck-streaming dir to /home/nifi would be a work-around:

# ssh into sandbox with root user, then:
cp -rp /root/iot-truck-streaming /home/nifi

Then, specify:

/home/nifi/iot-truck-streaming/stream-simulator/generate.sh

as 'Command Arguments' on NiFi.

[#12]

thanks it worked!!

[#13]

Thanks and it helps. Appreciate your support.

[#14]

@kkawamura i have run

1. cp -rp /root/iot-truck-streaming /home/nifi and changed the command arg but still after completion of storm deployment there is no data emitted from kafka spout maybe because nifi does not ingest data in kafka. pls help i m stuck on it

[#15]

@kkawamura i have referred this link https://github.com/hortonworks-gallery/tutorials/blob/master/2015-09-25-processing-real-time-event-s... for working on kafka and storm and for ingestion in hbase and hive followed following steps of link http://saptak.in/writing/2015/09/24/ingesting-real-time-streams-hive-hbase

[#16]

@fazila

Would you share NiFi UI screenshot around data ingestion part? Also, please try the steps explained at the answer on this thread above, "Redirect Error Stream' to capture error output of the process to see what is happening, as shown in the attached image." to see if the generate.sh have issue.

[#17]

@kkawamura my nifi service home path is /home/nifi-0.6.0.1.2.0.1-1 and i have pasted iot-streaming in /home/nifi this is shown

and also when i gave command arg in execute process /root/iot-truck-streaming, i m able to see nifi data in /root/nifi_output/truck_events. execute-process.png

[#18]

@fazila

when i gave command arg in execute process /root/iot-truck-streaming, i m able to see nifi data in /root/nifi_output/truck_events

Does this mean ExecuteProcess was able to run the shell command but output data is written in /root/iot-truck-streaming directory?

The generate shell doesn't need an argument. I haven't tried to pass an argument but IIRC it generates data to its standard output, and NiFi ExecuteProcess will read data from that standard output, then create FlowFiles containing the generated data.

No FlowFile was generated when you only specify the shell path at 'Command Arguments' processor property?

Also, just in case, since 'Batch Duration' is 10 sec, you need to leave ExecuteProcess running at least for 10 sec to see generated FlowFile.