Nifi InvokeHTTP processor not triggering response relationship - apache-nifi

Question

Consider the following flow which authenticates via HTTP to a service. I'm seeing an HTTP status code of 201 (created) come back, which should trigger the response relationship/flow. However as you can see in the log below, only the original relationship is triggered.
The Flow
Green lines indicate "response" flow. Magenta indicates "original" flow.
POST /token properties
Log
You can see here that the original relationship is triggered, but the response is not -- even though the status code, 201, is in the "success" range.
2023-01-29 15:22:08,341 INFO [Timer-Driven Process Thread-7] o.a.n.processors.standard.LogAttribute LogAttribute[id=fe0ace38-0185-1000-376d-8737d0e020f8] logging for flow file StandardFlowFileRecord[uuid=6b9f010a-f287-449c-8bef-94840c5cfa2f,claim=StandardContentClaim [resourceClaim=StandardResourceClaim[id=1674862641879-1, container=default, section=1], offset=13494, length=107],offset=0,name=6b9f010a-f287-449c-8bef-94840c5cfa2f,size=107]
---------------------ORIGINAL---------------------
FlowFile Properties
Key: 'entryDate'
Value: 'Sun Jan 29 15:22:07 UTC 2023'
Key: 'lineageStartDate'
Value: 'Sun Jan 29 15:22:07 UTC 2023'
Key: 'fileSize'
Value: '107'
FlowFile Attribute Map Content
Key: 'filename'
Value: '6b9f010a-f287-449c-8bef-94840c5cfa2f'
Key: 'invokehttp.request.duration'
Value: '738'
Key: 'invokehttp.request.url'
Value: '...'
Key: 'invokehttp.response.url'
Value: '...'
Key: 'invokehttp.status.code'
Value: '201'
Key: 'invokehttp.status.message'
Value: ''
Key: 'invokehttp.tx.id'
Value: 'efca13ac-16a1-4a27-a8e1-d04110d48523'
Key: 'mime.type'
Value: 'application/json'
Key: 'path'
Value: './'
Key: 'responseBody'
Value: '...'
Key: 'uuid'
Value: '6b9f010a-f287-449c-8bef-94840c5cfa2f'
---------------------ORIGINAL---------------------
The only thing I though of which might be causing an issue is that I'm writing the response body to an attribute. I tried to test by setting this attribute name to empty string but that just gives me an error in the log. I assumed that without the attribute name set, the response body would be the FlowFile sent to the response relationship, but that doesn't seem to be working.
Update: I created a second InvokeHTTP processor and replaced the relationships / disabled the old one. The flow worked correctly until I set the Response Body Attribute Name, and then the response relationship stopped triggering. I need to set this attribute though, so I can extract the error message from the response in the case of failure. I think I'll have to enable the Response Generation Required option, and check the status code in the response relationship flow. This is not ideal, though.

Answer 1

When you use Response Body Attribute Name, only original route is triggered. It's InvokeHTTP's behaviour, you can check documentation.
FlowFile attribute name used to write an HTTP response body for FlowFiles transferred to the Original relationship.
You can use this way for your problem,
InvokeHTTP (original route)-> RouteOnAttribute - (Success - ${invokehttp.status.code.ge(200):and(${invokehttp.status.code.le(299)})})
When you set Response Body Attribute Name attribute, it means that you don't want new flowfile, you want just add a new attribute to existing flowfile.