How to send an http POST multipart/form-data request with a file attached using Apache-nifi's InvokeHttp processor?

Question

I am trying to send a multipart/form-data request to a POST API using Nifi's InvokeHTTP processor. This request takes a JSON and a file. The request headers and request body in Postman look something like this:

POST /delivery/deliverPackage
User-Agent: PostmanRuntime/7.6.1
Accept: */*
Host: example.hostname:port
accept-encoding: gzip, deflate
content-type: multipart/form-data; boundary=--------------------------161413078116998145311888
content-length: 1115
json={ "destinationProtocol" : "HL7", "destinationFormat": "HL7_V2_ORU", "destinationType": "example", "destinationConnectionParams":{ "URI": "example", "HOST": "example", "PORT": "example" } }file=[object Object]

where the file object contains the file details I am trying to send.

I want to send this multipart/form-data request in Nifi. Based on an answer I saw on one of the forums, I am trying to create this request body in the content of the FlowFile using the ReplaceText processor before sending the FlowFile to an InvokeHttp processor. The FlowFile content looks something like this:

POST /delivery/deliverPackage
User-Agent: curl/7.46.0
Accept: */*
Host: example.hostname:port
accept-encoding: gzip, deflate
content-type: multipart/form-data; boundary=--------------------------161413078116998145311888
content-length: 1115

--------------------------161413078116998145311888
Content-Disposition: form-data; json="{ "destinationProtocol" : "HL7", "destinationFormat": "HL7_V2_ORU", "destinationType": "example", "destinationConnectionParams":{ "URI": "example", "HOST": "example", "PORT": "example" } }"

anonymous
--------------------------161413078116998145311888
Content-Disposition: form-data; name="file"; filename="/path/to/file/in/localsystem.HL7”
Content-Type: text/plain

contents of the file
--------------------------161413078116998145311888--

This doesn't seem to be working though, it doesn't look right. I am pretty new to Nifi. Can anyone help me understand what I'm doing wrong or give some insights on handling this properly?

EDIT

I have instead tried to use an ExecuteStreamCommand processor to simply run the curl command with command arguments -

-X POST;"https://example.hostname:port/delivery/deliverPackage?json=%7B%20%22destinationProtocol%22%20%3A%20%22HL7%22%2C%20%22destinationFormat%22%3A%20%22HL7_V2_ORU%22%2C%20%22destinationType%22%3A%20%22example%22%2C%20%22destinationConnectionParams%22%3A%7B%20%22URI%22%3A%20%22example%3A%2F%2Fexample%3A15050%22%2C%20%22HOST%22%3A%20%22example%22%2C%20%22PORT%22%3A%20%22example%22%20%7D%20%7D";-H "Content-Type: multipart/form-data";-F "file=@/path/to/file/in/localsystem.HL7";

This works, but I wanted to know how to do it using the InvokeHttp processor. Any help is greatly appreciated!

Answer 1

You can do this by using: GenerateFlowFile -> InvokeHTTP.

The GenerateFlowFile would create the payload (in your case the content of localsystem.HL7) of your post in the Custom Text field.

The InvokeHTTP will need to have Content-Type as ${mime.type} - default value and then see what the output is after your POST