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Connect to Amazon S3



I'm trying to connect Amazon S3 creating a custom connector with the REST API they provide. 

The problem is that is necessary to generate a signature based in the API key and other values. The signature is valid for 7 days, so it not possible to generate once outside - it would be pointless to generate a process that aims to be automatic needing a manual input.


Is there a way to generate HMAC signatures in a custom connector for Microsoft Flow?


If the connection is not Oauth 2.0, the custom connector is extremely rigid in the options they provide.


Is there any solution that doesn't involve using Azure Functions? 

Community Support
Community Support

Hi @acanepaecon,


It seems that you have created a custom connector to Amazon S3 using REST API.


Here is a doc on Amazon S3 REST API Introduction, hope it could be a reference for you:


While Oauth 2.0 is required when registering Custom API, please check the following docs for more details:



Best regards,

Mabel Mao

Community Support Team _ Mabel Mao
If this post helps, then please consider Accept it as the solution to help the other members find it more quickly.

Hi @v-yamao-msft,


Seems like you didn't read my message, I've already read those. The problem relies on the creation of a signature, that's where the problem is.

It will be cool to generate the signature inside flow, as a custom connector.



I’ve been thinking about how to tackle this issue as well. My issue is slightly different, I need to generate an AWS signature v4 to pass in a header to AWS API gateway. Flow and logic apps seem to have no native Authenticaton options for AWS which is a shame. The only way I’ve thought on how to do this is put an Azure function http trigger in front of the AWS api gateway, and have it use oauth or something that flow CAN talk to and have the Azure function contain the logic to build the aws signature to then pass to AWS. Not elegant but no other option? It would be great to have AWS connectors in flow for s3, dynamodb, etc

The API appraoch with S3 buckets is way too painful/complex and slow. I found a workaround.   Use the SFTP-as-a-service that connects to S3  then use the SFTP action in Flow 🙂

New Member

Hello @acanepaecon and sorry to dig up this old thread. This is admittedly a shameless plug to my blog (and the approach is inline with what @asdfaf4 already suggested) but provides an easy and seamless way to integrate PowerAutomate (Flow) and Amazon AWS S3 buckets using SFTP at a very reasonable cost:


Just wanted to add this to the list of workarounds.

Thank you and enjoy the day,

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