How to build Serverless application with SAML auth via AWS SSO

saml-response.xml

<?xml version="1.0" encoding="UTF-8"?>
<saml2p:Response xmlns:saml2p="urn:oasis:names:tc:SAML:2.0:protocol" xmlns:ds="http://www.w3.org/2000/09/xmldsig#" xmlns:enc="http://www.w3.org/2001/04/xmlenc#" xmlns:saml2="urn:oasis:names:tc:SAML:2.0:assertion" xmlns:xsd="http://www.w3.org/2001/XMLSchema" Destination="https://URL_OF_OUR_ACS_ENDPOINT" ID="_99912501-3576-3163-b92o-9o0432k234nw" IssueInstant="2022-08-08T08:40:13.242Z" Version="2.0">
 <saml2:Issuer Format="urn:oasis:names:tc:SAML:2.0:nameid-format:entity">https://portal.sso.eu-central-1.amazonaws.com/saml/assertion/SDJFKL190DSKLNDSLFJ90233JDFJKA</saml2:Issuer>
 <ds:Signature>
  <ds:SignedInfo>
   <ds:CanonicalizationMethod Algorithm="http://www.w3.org/2001/10/xml-exc-c14n#"></ds:CanonicalizationMethod>
   <ds:SignatureMethod Algorithm="http://www.w3.org/2001/04/xmldsig-more#rsa-sha256"></ds:SignatureMethod>
   <ds:Reference URI="#_99912501-3576-3163-b92o-9o0432k234nw">
    <ds:Transforms>
     <ds:Transform Algorithm="http://www.w3.org/2000/09/xmldsig#enveloped-signature"></ds:Transform>
     <ds:Transform Algorithm="http://www.w3.org/2001/10/xml-exc-c14n#">
      <ec:InclusiveNamespaces xmlns:ec="http://www.w3.org/2001/10/xml-exc-c14n#" PrefixList="xsd"></ec:InclusiveNamespaces>
     </ds:Transform>
    </ds:Transforms>
    <ds:DigestMethod Algorithm="http://www.w3.org/2001/04/xmlenc#sha256"></ds:DigestMethod>
    <ds:DigestValue>jAvmUY8dxWmMCesftJT/XgJCF7g0St3LnR6rboRJFw8=</ds:DigestValue>
   </ds:Reference>
  </ds:SignedInfo>
  <ds:SignatureValue>SIGNATURE_VALUE_HERE</ds:SignatureValue>
  <ds:KeyInfo>
   <ds:X509Data>
    <ds:X509Certificate>CERTIFICATE_VALUE_HERE</ds:X509Certificate>
   </ds:X509Data>
  </ds:KeyInfo>
 </ds:Signature>
 <saml2p:Status>
  <saml2p:StatusCode Value="urn:oasis:names:tc:SAML:2.0:status:Success"></saml2p:StatusCode>
 </saml2p:Status>
 <saml2:Assertion ID="_b0er9l43-34g9-01vd-s34a-b23cf2d90d13" IssueInstant="2022-08-08T08:40:13.242Z" Version="2.0">
  <saml2:Issuer Format="urn:oasis:names:tc:SAML:2.0:nameid-format:entity">https://portal.sso.eu-central-1.amazonaws.com/saml/assertion/SDJFKL190DSKLNDSLFJ90233JDFJKA</saml2:Issuer>
  <ds:Signature>
   <ds:SignedInfo>
    <ds:CanonicalizationMethod Algorithm="http://www.w3.org/2001/10/xml-exc-c14n#"></ds:CanonicalizationMethod>
    <ds:SignatureMethod Algorithm="http://www.w3.org/2001/04/xmldsig-more#rsa-sha256"></ds:SignatureMethod>
    <ds:Reference URI="#_b0er9l43-34g9-01vd-s34a-b23cf2d90d13">
     <ds:Transforms>
      <ds:Transform Algorithm="http://www.w3.org/2000/09/xmldsig#enveloped-signature"></ds:Transform>
      <ds:Transform Algorithm="http://www.w3.org/2001/10/xml-exc-c14n#">
       <ec:InclusiveNamespaces xmlns:ec="http://www.w3.org/2001/10/xml-exc-c14n#" PrefixList="xsd"></ec:InclusiveNamespaces>
      </ds:Transform>
     </ds:Transforms>
     <ds:DigestMethod Algorithm="http://www.w3.org/2001/04/xmlenc#sha256"></ds:DigestMethod>
     <ds:DigestValue>78ZJrH0sYicjyKhdr2PrtIEX/lAKH0mqyI63w3N1oDY=</ds:DigestValue>
    </ds:Reference>
   </ds:SignedInfo>
   <ds:SignatureValue>
       SIGNATURE_VALUE_HERE
   </ds:SignatureValue>
   <ds:KeyInfo>
    <ds:X509Data>
     <ds:X509Certificate>CERTIFICATE_VALUE_HERE</ds:X509Certificate>
    </ds:X509Data>
   </ds:KeyInfo>
  </ds:Signature>
  <saml2:Subject>
   <saml2:NameID Format="urn:oasis:names:tc:SAML:2.0:nameid-format:persistent" SPNameQualifier="SomeAudience">123901g035-134r9091-7dd1-40b3-98fc-g1f0f9kn9123</saml2:NameID>
   <saml2:SubjectConfirmation Method="urn:oasis:names:tc:SAML:2.0:cm:bearer">
    <saml2:SubjectConfirmationData NotOnOrAfter="2022-08-08T09:40:13.242Z" Recipient="https://URL_OF_OUR_ACS_ENDPOINT"></saml2:SubjectConfirmationData>
   </saml2:SubjectConfirmation>
  </saml2:Subject>
  <saml2:Conditions NotBefore="2022-08-08T08:35:13.242Z" NotOnOrAfter="2022-08-08T09:40:13.242Z">
   <saml2:AudienceRestriction>
    <saml2:Audience>SomeAudience</saml2:Audience>
   </saml2:AudienceRestriction>
  </saml2:Conditions>
  <saml2:AuthnStatement AuthnInstant="2022-08-08T08:40:13.242Z" SessionIndex="_21eaa174-390e-4afd-ba00-2ec507862ddb" SessionNotOnOrAfter="2022-08-08T09:40:13.242Z">
   <saml2:AuthnContext>
    <saml2:AuthnContextClassRef>urn:oasis:names:tc:SAML:2.0:ac:classes:PasswordProtectedTransport</saml2:AuthnContextClassRef>
   </saml2:AuthnContext>
  </saml2:AuthnStatement>
  <saml2:AttributeStatement>
   <saml2:Attribute Name="email" NameFormat="urn:oasis:names:tc:SAML:2.0:attrname-format:basic">
    <saml2:AttributeValue xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:type="xsd:string">usersemail@hello.com</saml2:AttributeValue>
   </saml2:Attribute>
  </saml2:AttributeStatement>
 </saml2:Assertion>
</saml2p:Response>