There is an official way, using input/output bindings.
I'd also recommend you install the Azure Functions VSCode Extension (and VSCode if your not already using it)

Samples

listen for updates in the database
cosmosTrigger1/function.json

{
  "bindings": [
    {
      "type": "cosmosDBTrigger",
      "name": "documents",
      "direction": "in",
      "leaseCollectionName": "leases",
      "connectionStringSetting": "AzureWebJobsStorage",
      "databaseName": "database",
      "collectionName": "collections",
      "createLeaseCollectionIfNotExists": "true"
    }
  ]
}

Docs

• CosmosDB Trigger
• Custom Handlers Basics

In the docs, any tab other than C# should have the same function.json as you should use with Rust.

Sidenote: This question could have been asked on StackOverflow as all this info is publicly documented but it takes a good amount of research and a while to understand!

Good luck with your handler and if you need some more help feel free to reply but I can't help with Rust code/syntax

from functions-custom-handlers.

This question could have been asked on StackOverflow

@fallsimply I have published the question on SO.
I'm waiting for your answer ))

from functions-custom-handlers.

For anyone who had the same issue. The cosmos db data can be found under Data.”name” ( name is the name you set on the in binding ) in the request body.

I was building my http triggers first and thought the behavior was the same with “enableForwardingHttpRequest” set to true, but this only works for http triggers with every other trigger the function host sends the raw data to a with a post method and route equal to the folder name where the function.json is found.

from functions-custom-handlers.