start/stop processor via nifi api

[#1]

Hi,

I'm trying to start and stop processors via the nifi api version 1.0.0. I'm getting status code 409 returned and the message is "afb7dcf1-0157-1000-9450-ea0931a67e0f is not stopped."

I have read previous articles about the optimistic locking and I am supplying the version and client id but I'm still getting this error. Any ideas? Here is a snippet of my python code:

process_group = nifiapi.find_process_group(process_group_name)
if process_group is None:
    return None
processors = nifiapi.get_processors_by_pg(process_group["id"])
if processors is None:
    return None
for processor in processors['processors']:
    processor["revision"]["clientId"] = str(uuid.uuid4())
    processor["status"]["runStatus"] = "STOPPED"
    logging.debug("Updating processor: {}".format(json.dumps(processor)))
    nifiapi.update_processor(processor) # this makes the put request

[#2 · Accepted solution]

ok I figured it out. Since I was taking the processor object returned from my 'get' call and just modifying a few fields, it thought I was trying to do an update on the object. You cannot do this while it is running so that was the error message. I modified my request to only contain the minimum number of fields (i think) to stop the processor. I'm still unclear whether I need to set status.runStatus and/or component.state to STOPPED to get what I want as they both seem to indicate the same thing. Anyway, the below request works:

modified_processor = {
    'revision': {
        'version': processor["revision"]["version"],
        'clientId': str(uuid.uuid4())
    },
    'status': {
        'runStatus': status
    },
    'component': {
        'id': processor['id'],
        'state': status
    },
    'id' : processor['id']
}

[#3]

It gave JSON syntax error, with double quotes - worked fine.

{ "revision": { "version": 8, "clientId": "test" }, "status": { "runStatus": "RUNNING" }, "component": { "id": "8bb725ef-0158-1000-478b-da5903184807", "state": "RUNNING" }, "id": "8bb725ef-0158-1000-478b-da5903184807" }

But sometimes the GET request gets timed out - is the nifi-api service reliable?

[#4]

@ Frank Maritato Is there a way to start and stop processors using nifi - api??

Can you please elaborate with the endpoints to start/stop processors?

[#5]

Sure! The endpoint for updating a processor is a PUT request against /processors/[processor_id] where you would post json similar to what I have above. The runStatus should be either "STOPPED" or "RUNNING". You have to include the clientId or the version in the request. The 'component' field is also required. I discovered all this by reading the code since there really isn't a user guide on how to use these endpoints.

As part of my script, I was getting to the list of processors by the name of the process group. So my flow is:

GET /flow/search_results?q=[process_group_name]

Then I get a list of processors for that group with:

GET /process-groups/[process_group_id]/processors

I loop through each of those results with the PUT request I mentioned above. Hope this helps!

[#6]

Thanks for the reply @Frank Maritato

I tried using Put request against /processors/"processor_id" and the json is

{ "component":{ "id":"5444685a-0158-1000-0407-0bd70a8688ef" }, "status":{ "runStatus":"STOPPED" } }.

But got an error saying "Revision must be specified." What is Revision? Also , you specified that clientID or version should be included. Can you please define these? and/or From where we can get these values?

Thanks

[#7]

You will need to do a Get on that processor first. The revision/version is contained in that json and you just pass it thru for your Put request.

GET /processors/{id}

returning json will have something like this:

{
  "status": { ... },
  "component": { ... },
  "revision": {
    "version": 1
  }
}

So you would just take that whole revision element and add it to your Put payload.

clientId is any string that identifies your tool/app. In my example above, I was just generating a random uuid.

Hope this helps!

[#8]

@Frank Maritato Thanks for the Information.

[#9]

@Frank Maritato I am trying to start a processor group.Here is the command

curl -i -X PUT -H 'Content-Type:application/json' -d '{"component": {"id":"<processorgroup_id>","parentGroupId":"<parentgroup_id>","state":"RUNNING"},"revision": {"clientId":"<client_id>","version": 2}}' http://hostname:port/nifi-api/process-groups/>

I am facing:

HTTP/1.1 400 Bad Request Date: Tue, 20 Dec 2016 06:43:43 GMT Content-Type: text/plain Transfer-Encoding: chunked Server: Jetty(9.3.9.v20160517) Message body is malformed. Unable to map into expected format.

is there any issue in above api request??

[#10]

@Gayathri Rajendran My processor update json looks like this:

{
  "status": {
    "runStatus": "RUNNING"
  },
  "component": {
    "state": "RUNNING",
    "id": "01571000-f7fb-1da4-7d70-b6be89100354"
  },
  "id": "01571000-f7fb-1da4-7d70-b6be89100354",
  "revision": {
    "version": 1,
    "clientId": "c4cd2dc5-a57f-4025-aa4b-7e29118ce795"
  }
}

You may need to add the separate "status" object in there. Also, I've never specified a parentGroupId so I'm not sure if that is necessary.

Lastly, you may need to add a -H 'Accept:application/json' to your curl command as well.

Hope this helps!