Using Named Credentials to send API key in Authorization header

Question

I'm trying to make use of Salesforce Named Credentials to securely store the API Key and call endpoint accordingly.

I tried to pass a custom API Key to an endpoint as below.

HttpRequest req = new HttpRequest();
req.setMethod('GET');
req.setEndpoint('callout:API_endpoint'+'/customers');
req.setHeader('Authorization', '{!$Credential.Password}');   // Password contains 'Basic <<Base64EncodedKeyValue>>'
HTTPResponse res = new HTTP().send(req);
System.debug('res '+res.getBody());

But it's throwing the 401 - Unauthorized response.

1. Is there a way to check the final request code e.g. like in postman request code?
2. If I use the hard-coded http request attributes + remote site (without using named credential), it's working perfectly. Is it possible to override Authorization ? and How do I use Named credential to override Authorization header correctly?

Much appreciate any help/comment/thoughts on this? Cheers!

Answer 1

1. By pointing your callout to a service that logs/echoes the request. ngrok is one popular option that proxies/tunnels a request.
2. When setting up the Named Credential, do this:

• Select Named Principal as the Identity Type
• Select Password Authentication as the Authentication Protocol.
  • Set the Username field to any (bogus) value. It will not be used.
  • Compose the value of Password field by concatenating string 'Basic ' (note the extra space) with a base64-encoded value of your plaintext password.
• Confirm that Generate Authorization Header is NOT checked
• Confirm that Allow Merge Fields in HTTP Header IS checked