Authentication information is not given in the correct format error when calling Azure Rest API in Microsoft Flow - rest

Question

When I try to call this https://learn.microsoft.com/en-us/rest/api/storageservices/get-blob-metadata api in microsoft flow I always get this error with 400 bad request.
I edited my authorization header regarding this answer https://stackoverflow.com/a/22029178/10389562 but couldn't get what am I doing wrong.
Method: GET
Uri: https://myaccount.blob.core.windows.net/containername/blobname?comp=metadata
Headers :
{
"Authorization": "SharedKey storageaccountname: primary key in the storage
account properties",
"x-ms-date": "Thu, 21 Sep 2018 23:45:00 GMT",
"x-ms-version": "2018-03-28"
}
After call this API I got this output
<?xml version="1.0" encoding="utf-8"?><Error>
<Code>InvalidAuthenticationInfo</Code><Message>Authentication information is
not given in the correct format. Check the value of Authorization header.
RequestId:f3b3051b-601e-00a4-4b3c-51c58d000000
Time:2018-09-20T23:46:40.6659210Z</Message></Error>
Thanks for any help

Answer 1

Update
In Microsoft Flow, calling Rest Api against Azure Storage seems not a valid way. Authorization needs x-ms-* headers sent by the flow(like x-ms-tracking-id,x-ms-workflow-id,etc.) adding to stringStr, which is not under our control. What's more, signature is only valid for 15m since generated.
There's a built-in Get Blob Metadata action. And for Storage, other common actions are available as well.
To set blob metadata, I suggest to host the logic in Azure function.
Follow this tutorial to create Function app and a httptrigger function, remember to choose the Storage Account where we need to set blob metadata.
Replace the httptrigger sample with code below, and modify metadataName to what you need.
#r "Microsoft.WindowsAzure.Storage"
using System.Net;
using Microsoft.WindowsAzure.Storage;
using Microsoft.WindowsAzure.Storage.Blob;
public static async Task<HttpResponseMessage> Run(HttpRequestMessage req, TraceWriter log)
{
dynamic data = await req.Content.ReadAsAsync<object>();
if (data == null)
{
return req.CreateResponse(HttpStatusCode.BadRequest, "No request body posted");
}
else
{
string metadata = data.metadata;
string blobName = data.blobName;
string containerName = data.containerName;
try
{
CloudStorageAccount storageAccount = CloudStorageAccount.Parse(Environment.GetEnvironmentVariable("AzureWebJobsStorage"));
CloudBlobClient blobClient = storageAccount.CreateCloudBlobClient();
CloudBlobContainer blobContainer = blobClient.GetContainerReference(containerName);
CloudBlob blob = blobContainer.GetBlobReference(blobName);
blob.Metadata.Add("metadataName", metadata);
blob.SetMetadata();
}
catch (Exception e)
{
log.Error(e.ToString());
return req.CreateResponse(HttpStatusCode.InternalServerError, "Fail to set metadata");
}
return (string.IsNullOrEmpty(metadata) || string.IsNullOrEmpty(blobName) || string.IsNullOrEmpty(containerName))
? req.CreateResponse(HttpStatusCode.BadRequest, "Please pass necessary parameters in the request body")
: req.CreateResponse(HttpStatusCode.OK, $"Metadata of {blobName} has been set");
}
}
In Microsoft Flow, create a Http action, post content below to the function url got in step 2.
{
"metadata": "test",
"blobName":"myblob",
"containerName":"mycontainer"
}