Embedded assets base path

[dicki]

I’m having trouble using the v5emb module with my current setup, as the static assets are being referenced to without the base path of my application.

In my environments applications run behind an ingress with path-based routing inside a Kubernetes cluster.

Meaning for instance that Api1 receives its request with URL http://localhost/api1/…. All of the static assets are being attempted to be loaded using http://localhost/…] (notice the missing api1.

I believe there is way of configuring this asset base path using vearutop/statigz? But I don’t understand how to do so.

Any chance of someone shedding some light on this for me?

[vearutop]

Hi, base path can be provided as an argument of handler constructor.

Please check an example.

package main

import (
	"net/http"

	"github.com/swaggest/swgui/v5emb"
)

func main() {
	http.Handle("/api1/docs/", v5emb.New(
		"Petstore",
		"https://petstore3.swagger.io/api/v3/openapi.json",
		"/api1/docs/",						// <----------- base path
	))

	http.HandleFunc("/", func(writer http.ResponseWriter, request *http.Request) {
		_, _ = writer.Write([]byte("Hello World!"))
	})

	println("docs at http://localhost:8080/api1/docs/")
	_ = http.ListenAndServe("localhost:8080", http.DefaultServeMux)
}

Let me know if I misunderstood the issue.

[dicki]

I can't manage to get that working correctly.

Because my service is behind a path-based ingress the static assets need to have the path from the ingress added to them for the HTML.

So my current config looks like this:

...
h := swgui.New("api1", "/api1/docs/openapi.json", "/docs")
s.router.GET("/docs", gin.WrapH(h))
s.router.GET("/docs/openapi.json", gin.WrapH(s.oapiCollector))
...

So when invoking my service I don't do http://localhost/docs but http://localhost/api1/docs and the api1 is handled by the ingress which routes the request to my API. Hence I would need to be able to specify a static assets base path, for the generation of the Swagger UI HTML.

I can however just use the CDN version which works fine but I would've been happier with the embedded version.

[vearutop]

Is there a reason to have

h := swgui.New("api1", "/api1/docs/openapi.json", "/docs")

instead of

h := swgui.New("api1", "/api1/docs/openapi.json", "/api1/docs")

?

[dicki]

The request are being forwarded and rewritten by the ingress. They change from localhost/api1/docs to localhost:8080/docs.

Here’s an example of someone dealing with the same issue.

Maybe I could prepend the external route, that gets rewritten by the ingress, to the Swagger UI generation by utilising the x-forwarded-prefix header. Like mentioned here.

But it’s only the static assets that need to have this prepended to them.

[dicki]

I've solved it.

...
basePath := "/docs"
uiPath := basePath + "/*any"
jsonPath := "/openapi.json"

s.router.GET(jsonPath, gin.WrapH(s.oapiCollector))
s.router.GET(uiPath, func(c *gin.Context) {
	// This helps with reverse proxying done by ingress
	// It allows us to serve the OpenAPI UI using a dynamic path specified by the ingress
	// without the application having to know about it
	forwardedPrefix := c.GetHeader("x-forwarded-prefix") // This returns an empty string if not found
	c.Request.URL.Path = forwardedPrefix + c.Request.URL.Path
	swgui.New(s.oapiCollector.Reflector().Spec.Title(), forwardedPrefix+jsonPath, forwardedPrefix+basePath).ServeHTTP(c.Writer, c.Request)
})
...

A prerequisite here is applying the following config to the service's ingress. Which populates request redirected to the service with the x-forwarded-prefix.

This allows my service to be agnostic to any reverse proxy rewriting the incoming requests.

{{- if .Values.ingress.enabled -}}
{{- $fullName := include "microservice.fullname" . -}}
apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: {{ $fullName }}
  labels:
    {{- include "microservice.labels" . | nindent 4 }}
  annotations:
    kubernetes.io/ingress.class: nginx
    nginx.ingress.kubernetes.io/ssl-redirect: "false"
    nginx.ingress.kubernetes.io/rewrite-target: /$2
    nginx.ingress.kubernetes.io/x-forwarded-prefix: /{{ $fullName }} <------
    cert-manager.io/cluster-issuer: letsencrypt-production
spec:
...

Thanks for taking the time for responding to me.