outposts/proxy: fix url not being substituted for sign_out

Signed-off-by: Jens Langhammer <jens.langhammer@beryju.org>

internal/outpost/proxyv2/application/endpoint.go

@@ -0,0 +1,60 @@
+package application
+
+import (
+	"net/url"
+	"os"
+	"strings"
+
+	log "github.com/sirupsen/logrus"
+	"goauthentik.io/api"
+	"golang.org/x/oauth2"
+)
+
+type OIDCEndpoint struct {
+	oauth2.Endpoint
+	EndSessionEndpoint string
+}
+
+func GetOIDCEndpoint(p api.ProxyOutpostConfig, authentikHost string) OIDCEndpoint {
+	authUrl := p.OidcConfiguration.AuthorizationEndpoint
+	endUrl := p.OidcConfiguration.EndSessionEndpoint
+	if browserHost, found := os.LookupEnv("AUTHENTIK_HOST_BROWSER"); found {
+		host := os.Getenv("AUTHENTIK_HOST")
+		authUrl = strings.ReplaceAll(authUrl, host, browserHost)
+		endUrl = strings.ReplaceAll(endUrl, host, browserHost)
+	}
+	ep := OIDCEndpoint{
+		Endpoint: oauth2.Endpoint{
+			AuthURL:   authUrl,
+			TokenURL:  p.OidcConfiguration.TokenEndpoint,
+			AuthStyle: oauth2.AuthStyleInParams,
+		},
+		EndSessionEndpoint: endUrl,
+	}
+	authU, err := url.Parse(authUrl)
+	if err != nil {
+		return ep
+	}
+	endU, err := url.Parse(endUrl)
+	if err != nil {
+		return ep
+	}
+	if authU.Host != "localhost:8000" {
+		return ep
+	}
+	if authentikHost == "" {
+		log.Warning("Outpost has localhost/blank API Connection but no authentik_host is configured.")
+		return ep
+	}
+	aku, err := url.Parse(authentikHost)
+	if err != nil {
+		return ep
+	}
+	authU.Host = aku.Host
+	authU.Scheme = aku.Scheme
+	endU.Host = aku.Host
+	endU.Scheme = aku.Scheme
+	ep.AuthURL = authU.String()
+	ep.EndSessionEndpoint = endU.String()
+	return ep
+}