Wrong endpoint URL getting used

[sjmorgan81]

Q&A (please complete the following information)

• OS: Windows
• Browser: Firefox
• Version: 72.0.1
• Method of installation: NuGet (Swashbuckle.AspNetCore.SwaggerUI)
• Swagger-UI version: 3.24.3
• Swagger/OpenAPI version: OpenAPI 3.0.1

Content & configuration

Example Swagger/OpenAPI definition:

{
  "openapi": "3.0.1",
  "info": {
    "title": "",
    "contact": {
      "name": "Simon Morgan",
      "email": ""
    },
    "version": "v1"
  },
  "paths": {
    "/Address/LpiKey": {
      "get": {
        "tags": [
          "Address"
        ],
        "summary": "Retrieve the address with the specified LPI key.",
        "parameters": [
          {
            "name": "lpiKey",
            "in": "query",
            "description": "The LPI of the address to retrieve.",
            "required": true,
            "schema": {
              "type": "string"
            }
          }
        ],
        "responses": {
          "200": {
            "description": "Success",
            "content": {
              "text/plain": {
                "schema": {
                  "$ref": "#/components/schemas/Address"
                }
              },
              "application/json": {
                "schema": {
                  "$ref": "#/components/schemas/Address"
                }
              },
              "text/json": {
                "schema": {
                  "$ref": "#/components/schemas/Address"
                }
              }
            }
          }
        }
      }
    },
    "/Address/Uprn": {
      "get": {
        "tags": [
          "Address"
        ],
        "summary": "Retrieve the address with the specified UPRN.",
        "parameters": [
          {
            "name": "uprn",
            "in": "query",
            "description": "The UPRN of the address to retrieve.",
            "required": true,
            "schema": {
              "type": "integer",
              "format": "int64"
            }
          },
          {
            "name": "language",
            "in": "query",
            "description": "The language of the address.",
            "schema": {
              "type": "string",
              "default": "ENG",
              "nullable": true
            }
          }
        ],
        "responses": {
          "200": {
            "description": "Success",
            "content": {
              "text/plain": {
                "schema": {
                  "$ref": "#/components/schemas/Address"
                }
              },
              "application/json": {
                "schema": {
                  "$ref": "#/components/schemas/Address"
                }
              },
              "text/json": {
                "schema": {
                  "$ref": "#/components/schemas/Address"
                }
              }
            }
          }
        }
      }
    },
    "/Address/Postcode": {
      "get": {
        "tags": [
          "Address"
        ],
        "summary": "Search for addresses with the specified postcode.",
        "parameters": [
          {
            "name": "postcode",
            "in": "query",
            "description": "The postcode of the addresses to retrieve.",
            "required": true,
            "schema": {
              "maxLength": 8,
              "minLength": 5,
              "type": "string"
            }
          },
          {
            "name": "language",
            "in": "query",
            "description": "The language of the addresses.",
            "schema": {
              "type": "string",
              "default": "ENG",
              "nullable": true
            }
          }
        ],
        "responses": {
          "200": {
            "description": "Success",
            "content": {
              "text/plain": {
                "schema": {
                  "type": "array",
                  "items": {
                    "$ref": "#/components/schemas/Address"
                  },
                  "nullable": true
                }
              },
              "application/json": {
                "schema": {
                  "type": "array",
                  "items": {
                    "$ref": "#/components/schemas/Address"
                  },
                  "nullable": true
                }
              },
              "text/json": {
                "schema": {
                  "type": "array",
                  "items": {
                    "$ref": "#/components/schemas/Address"
                  },
                  "nullable": true
                }
              }
            }
          }
        }
      }
    },
    "/Address/IdentifierAndPostcode": {
      "get": {
        "tags": [
          "Address"
        ],
        "summary": "Search for addresses with the specified identifier and postcode.",
        "parameters": [
          {
            "name": "identifier",
            "in": "query",
            "description": "The house name, number or organisation used to identify a property.",
            "required": true,
            "schema": {
              "type": "string"
            }
          },
          {
            "name": "postcode",
            "in": "query",
            "description": "The postcode of the addresses to search.",
            "required": true,
            "schema": {
              "type": "string"
            }
          },
          {
            "name": "language",
            "in": "query",
            "description": "The language of the addresses.",
            "schema": {
              "type": "string",
              "default": "ENG",
              "nullable": true
            }
          }
        ],
        "responses": {
          "200": {
            "description": "Success",
            "content": {
              "text/plain": {
                "schema": {
                  "type": "array",
                  "items": {
                    "$ref": "#/components/schemas/Address"
                  },
                  "nullable": true
                }
              },
              "application/json": {
                "schema": {
                  "type": "array",
                  "items": {
                    "$ref": "#/components/schemas/Address"
                  },
                  "nullable": true
                }
              },
              "text/json": {
                "schema": {
                  "type": "array",
                  "items": {
                    "$ref": "#/components/schemas/Address"
                  },
                  "nullable": true
                }
              }
            }
          }
        }
      }
    }
  },
  "components": {
    "schemas": {
      "Address": {
        "type": "object",
        "properties": {
          "uprn": {
            "type": "integer",
            "format": "int64"
          },
          "lpiKey": {
            "type": "string",
            "nullable": true
          },
          "organisation": {
            "type": "string",
            "nullable": true
          },
          "saoText": {
            "type": "string",
            "nullable": true
          },
          "saoRange": {
            "type": "string",
            "nullable": true
          },
          "paoText": {
            "type": "string",
            "nullable": true
          },
          "paoRange": {
            "type": "string",
            "nullable": true
          },
          "street": {
            "type": "string",
            "nullable": true
          },
          "locality": {
            "type": "string",
            "nullable": true
          },
          "town": {
            "type": "string",
            "nullable": true
          },
          "administrativeArea": {
            "type": "string",
            "nullable": true
          },
          "postcode": {
            "type": "string",
            "nullable": true
          },
          "xCoordinate": {
            "type": "number",
            "format": "double"
          },
          "yCoordinate": {
            "type": "number",
            "format": "double"
          },
          "latitude": {
            "type": "number",
            "format": "double"
          },
          "longitude": {
            "type": "number",
            "format": "double"
          },
          "language": {
            "type": "string",
            "nullable": true
          },
          "singleLineAddressLabel": {
            "type": "string",
            "nullable": true,
            "readOnly": true
          },
          "multiLineAddressLabel": {
            "type": "string",
            "nullable": true,
            "readOnly": true
          }
        },
        "nullable": true
      }
    }
  }
}

Swagger-UI configuration options:

app.UseSwaggerUI(options =>
{
    options.SwaggerEndpoint("swagger/v1/swagger.json", API_NAME);
    options.RoutePrefix = string.Empty;
});

Describe the bug you're encountering

The root of my deployed API is http://example.net/foo/. However, when I use "Try it out", instead of a the request getting sent to a URL such as http://example.net/foo/Address/LpiKey?lpiKey=123 it gets sent to http://example.net/Address/LpiKey?lpiKey=123 (i.e. the "foo" directory where the app is hosted and where I navigate to get the Swagger UI is missing).

This only happens the app is running under IIS. It works fine when it's running on my local machine using Kestrel.

To reproduce...

1. Go to http://example.net/foo/
2. Click on one of the various "Try it out" buttons
3. Enter the required fields and click "Execute"

Expected behavior

A request is sent to one of the http://example.net/foo/... endpoints.

[hkosova]

Since your API definition does not specify servers, the base path for requests defaults to /. To change the base path to http://example.net/foo, add the following servers section to your API definition:

"servers": [
  {"url": "http://example.net/foo"}   // or just "/foo"
]

[velmohan]

I am having this issue in .NET 6 project. I am sorry but where do we add this setting?

Since your API definition does not specify servers, the base path for requests defaults to /. To change the base path to http://example.net/foo, add the following servers section to your API definition:

"servers": [
  {"url": "http://example.net/foo"}   // or just "/foo"
]

I am having this issue in .NET 6 project. I am sorry but where do we add this setting?

[sjmorgan81]

@velmohan In my case it's an ASP.NET project and I add it via the Configure method of my Startup.cs:

app.UseSwagger(options => options.PreSerializeFilters.Add((swagger, httpReq) =>
{
    if (httpReq.Host.Host == "example.net")
    {
        swagger.Servers = new List<OpenApiServer> { new OpenApiServer { Url = "/foo", Description = "Blah blah blah" } };
    }
}));

[velmohan]

Thank you @sjmorgan81. That worked for me.

[TheHunter]

Sorry but this is not a real solution, because the path should be deduced by original request sent by behind reverse proxies. An example on nginx ingress controller (k8s), you can have two endpoints for the same application, and only one of them could work.

In this case, how can be able to resolve swagger ?