Python Azure Function throws "SSLCertVerificationError" when try to invoke on-prem API endpoint

Question

We have an azure function (linux) which runs python functions, one function should reach one of our on-prem servers (phpIPAM) via REST API. The server has valid certification, issued by our CA (we have 2 level CA environment: root CA-intermediate CA-host). When I try to invoke the API endpoint, I got the following message:

'Error: HTTPSConnectionPool(host=<host fqdn>, port=443): Max retries exceeded with url: /api/<APIAppName>/user (Caused by SSLError(SSLCertVerificationError(1, [SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed: self signed certificate in certificate chain

Answer 1

Hi @Béla Tóth

Thank you for posting your question on the Q&A platform. I'm glad that you were able to resolve your issue and thank you for posting your solution so that others experiencing the same thing can easily reference this!

Since the Microsoft Q&A community has a policy that the question author cannot accept their own answer, they can only accept answers by others, I'll repost your solution in case you'd like to Accept the answer.

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You have an Azure Function running on a Linux-based hosting plan. This function interacts with a on-premises server through a REST API. Your on-premises server uses a valid certificate issued by your CA and when issuing a request, the request ends in an error message, 'Error: HTTPSConnectionPool(host=.

To resolve your issue, you configured REQUESTS_CA_BUNDLE environment variable to the functions local certificate path, /etc/ssl/certs/.