API Deployment - How to use?

In the linked documentation, I see all necessary description ... did you try this? What failed? Any error messages?

Not sure that I understand syntax of body.

I need to deploy downloaded ZIP file in my local file system from source environment to target environment using API

Am I right if I use this modified body request?

curl --location --request
POST 'mysite.appiancloud.com/.../deployments' \
--header 'Appian-API-Key: <my API key>' \
--form 'json="{
      \"name\": \"My Test Release v1.0\",
      \"description\": \"Test application for deploying in target env\", 
      \"packageFileName\": \"<HERE NEED PASTE LOCAL ABSOLUTE PATH TO MY DOWNLOADED ZIP>\"
   }"' \
--form 'randomKey1=@"Fraud Investigation Management Release 1.0.zip"' \ <-- What does this string do?

I think that the curl documentation will help you to understand this syntax better.

Is there a specific reason to go that way and not just use the Appian infrastructure based deployment?

>> I think that the curl documentation will help you to understand this syntax better.

It is not cURL syntax related, it is Appian specifics related. I have two self-hosted environments (ENV1 and ENV2). I want to transfer my application from ENV1 to ENV2. ENV1 not connected ENV2. I can download my application as zip and I want to upload it not manually but via API in ENV2.

I want to understand how to describe where is my zip file is located in \"packageFileName\" field.

If it possible

>>Is there a specific reason to go that way and not just use the Appian infrastructure based deployment?

Unfortunately, yes

I checked this URL: https://stackoverflow.com/questions/46960397/using-curl-for-multipart-form-data-with-a-file-upload

--form, is the name of the form parameter and the file to attach. This needs to refer to the full path of the file on your disk.

The packageFilename is then just the name of the file.