File Upload Over HTTP

[alexg-axis]

Implement File Upload over HTTP according to https://github.com/MicrosoftDocs/azure-docs/blob/master/articles/iot-hub/iot-hub-devguide-file-upload.md#device-initialize-a-file-upload.

Device:

• Implements a new HTTP transport with support for the file-related APIs
  • Initialize a file upload
  • Upload file using Azure storage APIs
  • Notify IoT Hub of a completed file upload

Service:

• Implements proper support for watching for file notifications

Closes #56

To test:

Set up an Azure IoTHub and an Azure Storage Account. Configure File Upload for the IoTHub to use the Storage Account.

go build -o iot-device cmd/iothub-device/main.go
go build -o iot-service cmd/iothub-service/main.go

Then, in one terminal:

export IOTHUB_SERVICE_CONNECTION_STRING="xxx"
./iot-service watch-file-notifications

In another terminal, upload a file:

export IOTHUB_DEVICE_CONNECTION_STRING="xxx"
./iot-device -transport http file-upload ./path/to/file.txt

After a few seconds the file notification will be printed.

{
    "deviceId": "my-device",
    "blobUri": "https://my-blob.blob.core.windows.net/iothub/my-device/file.txt",
    "blobName": "file.txt",
    "lastUpdatedTime": "2021-11-15T12:50:31Z",
    "blobSizeInBytes": 6,
    "enqueuedTimeUtc": "2021-11-15T12:50:32.3018639Z"
}

[alexg-axis]

Resources:

• https://github.com/MicrosoftDocs/azure-docs/blob/master/articles/iot-hub/iot-hub-devguide-file-upload.md#device-initialize-a-file-upload
• https://docs.microsoft.com/en-us/rest/api/storageservices/create-service-sas
• https://docs.microsoft.com/en-us/azure/iot-hub/iot-hub-node-node-file-upload
• https://github.com/MicrosoftDocs/azure-docs/blob/master/articles/iot-hub/iot-hub-configure-file-upload.md

[amenzhinsky]

Thanks for the PR, in general everything looks good, just a few thins to polish.

Please add at least one test

[amenzhinsky]

Thanks for the contribution