caddy_verbose_auth_fail_config2.json5

{
  // Disable admin for test
  "admin": {
    "disabled": true
  },
  "apps": {
    "http": {
      // Use http to avoid having to provision an ssl cert
      "http_port": 4444,
      "servers": {
        "srv0": {
          "listen": [
            ":4444"
          ],
          // Simple authentication route that will invariably fail (since
          // nothing is allowed)
          "routes": [{
            "handle": [
              {
                "handler": "static_error",
                "status_code": "501"
              }
            ]
          }],
          // Based on the error code, we either want to redirect or return an
          // error.
          "errors": {
            "routes": [{
              // Put status_code in the vars so we can access it from the
              // vars matcher
              "handle": [{
                "handler": "vars",
                "status_code": "{http.error.status_code}"
              }]
            },
            // Insert actual error handling routes here
            // Restore default behavior if error handling route does not match
            {
              // If status code is not 401 and not empty, return the error code
              // in the response
              "match": [{
                "not": {
                  "vars": {
                    "status_code": ""
                  }
                }
              }],
              "handle": [{
                "handler": "static_response",
                "status_code": "{http.error.status_code}"
              }],
              "terminal": true
            },
            {
              // If status code is empty (e.g. an error other than HandlerError
              // was returned), return 500
              "handle": [{
                "handler": "static_response",
                "status_code": "500"
              }],
              "terminal": true
            }]
          }
        }
      }
    }
  }
}