OperationError deploying gcloud function publish

Question

I am attempting to run through the introduction to Google Cloud Pub/Sub Triggers. When running the example code:

gcloud functions deploy publish --runtime nodejs8 --trigger-http

I get the following error:

ERROR: (gcloud.functions.deploy) OperationError: code=3, message=Function failed on loading user code. Error message: Node.js module defined by file index.js is expected to export function named publish

The logs on stackdriver show:

D 2019-11-18T23:53:41.689Z publish Node.js module defined by file index.js is expected to export function named publish  
E 2019-11-18T23:53:41.761Z Cloud Functions CreateFunction us-central1:publish <email> INVALID_ARGUMENT Cloud Functions CreateFunction us-central1:publish <email> 
E 2019-11-18T23:54:15.667Z Cloud Functions UpdateFunction us-central1:publish <email> FAILED_PRECONDITION Cloud Functions UpdateFunction us-central1:publish <email> 

Answer 1

Turns out I was attempting to deploy from the wrong directory. The correct index.js file included the function definition, and allowed successful deployment of the function.