Add OIDC configuration auto discovery support

docs/guide/ingress/annotations.md

@@ -622,6 +622,14 @@ ALB supports authentication with Cognito or OIDC. See [Authenticate Users Using
         ```
         alb.ingress.kubernetes.io/auth-idp-oidc: '{"issuer":"https://example.com","authorizationEndpoint":"https://authorization.example.com","tokenEndpoint":"https://token.example.com","userInfoEndpoint":"https://userinfo.example.com","secretName":"my-k8s-secret"}'
         ```
+
+    !!!tip ""
+        This annotation allows fetching OIDC configuration dynamically from the specified Discovery Endpoint (`https://example.auth0.com`). The endpoint should provide the necessary details: `issuer`, `authorizationEndpoint`, `tokenEndpoint`, and `userInfoEndpoint` in its JSON response. (Note: `discoveryEndpoint` will override other OIDC configuration fields)
+
+    !!example
+        ```
+        alb.ingress.kubernetes.io/auth-idp-oidc: '{"discoveryEndpoint":"https://example.auth0.com","secretName":"my-k8s-secret","authenticationRequestExtraParams":{"key":"value"}}'
+        ```
 
 - <a name="auth-on-unauthenticated-request">`alb.ingress.kubernetes.io/auth-on-unauthenticated-request`</a> specifies the behavior if the user is not authenticated.
 

pkg/ingress/auth_config_builder.go

@@ -2,8 +2,10 @@ package ingress
 
 import (
 	"context"
+
 	"github.com/pkg/errors"
 	"sigs.k8s.io/aws-load-balancer-controller/pkg/annotations"
+	"sigs.k8s.io/aws-load-balancer-controller/pkg/networking"
 )
 
 const (
@@ -12,6 +14,10 @@ const (
 	defaultAuthSessionCookieName        = "AWSELBAuthSessionCookie"
 	defaultAuthSessionTimeout           = 604800
 	defaultAuthOnUnauthenticatedRequest = "authenticate"
+	defaultIssuerKey                    = "issuer"
+	defaultAuthorizationEndpointKey     = "authorization_endpoint"
+	defaultTokenEndpointKey             = "token_endpoint"
+	defaultUserInfoEndpointKey          = "userinfo_endpoint"
 )
 
 // Auth config for Service / Ingresses
@@ -114,6 +120,17 @@ func (b *defaultAuthConfigBuilder) buildAuthIDPConfigOIDC(_ context.Context, svc
 	if !exists {
 		return nil, nil
 	}
+	if authIDP.DiscoveryEndpoint == "" {
+		return &authIDP, nil
+	}
+	oidcConfig, err := networking.GetOIDCConfiguration(authIDP.DiscoveryEndpoint)
+	if err != nil {
+		return nil, err
+	}
+	authIDP.Issuer = oidcConfig[defaultIssuerKey]
+	authIDP.AuthorizationEndpoint = oidcConfig[defaultAuthorizationEndpointKey]
+	authIDP.TokenEndpoint = oidcConfig[defaultTokenEndpointKey]
+	authIDP.UserInfoEndpoint = oidcConfig[defaultUserInfoEndpointKey]
 	return &authIDP, nil
 }
 

pkg/ingress/auth_config_builder_test.go

@@ -2,9 +2,10 @@ package ingress
 
 import (
 	"context"
+	"testing"
+
 	"github.com/stretchr/testify/assert"
 	"sigs.k8s.io/aws-load-balancer-controller/pkg/annotations"
-	"testing"
 )
 
 func Test_defaultAuthConfigBuilder_Build(t *testing.T) {
@@ -179,6 +180,66 @@ func Test_defaultAuthConfigBuilder_Build(t *testing.T) {
 				SessionTimeout:           86400,
 			},
 		},
+		{
+			name: "oidc configuration using auto discovery",
+			args: args{
+				svcAndIngAnnotations: map[string]string{
+					"alb.ingress.kubernetes.io/auth-idp-oidc":                   `{"discoveryEndpoint":"https://example.auth0.com","secretName":"my-k8s-secret","authenticationRequestExtraParams":{"key":"value"}}`,
+					"alb.ingress.kubernetes.io/auth-on-unauthenticated-request": "deny",
+					"alb.ingress.kubernetes.io/auth-scope":                      "email",
+					"alb.ingress.kubernetes.io/auth-session-cookie":             "my-cookie",
+					"alb.ingress.kubernetes.io/auth-session-timeout":            "86400",
+				},
+			},
+			want: AuthConfig{
+				Type: AuthTypeNone,
+				IDPConfigOIDC: &AuthIDPConfigOIDC{
+					Issuer:                "https://example.auth0.com/",
+					AuthorizationEndpoint: "https://example.auth0.com/authorize",
+					TokenEndpoint:         "https://example.auth0.com/oauth/token",
+					UserInfoEndpoint:      "https://example.auth0.com/userinfo",
+					SecretName:            "my-k8s-secret",
+					DiscoveryEndpoint:     "https://example.auth0.com",
+					AuthenticationRequestExtraParams: map[string]string{
+						"key": "value",
+					},
+				},
+				OnUnauthenticatedRequest: "deny",
+				Scope:                    "email",
+				SessionCookieName:        "my-cookie",
+				SessionTimeout:           86400,
+			},
+		},
+		{
+			name: "oidc configuration using auto discovery should ovveride issuer, authorizationEndpoint, tokenEndpoint and userInfoEndpoint",
+			args: args{
+				svcAndIngAnnotations: map[string]string{
+					"alb.ingress.kubernetes.io/auth-idp-oidc":                   `{"issuer":"https://example.com","authorizationEndpoint":"https://authorization.example.com","tokenEndpoint":"https://token.example.com","userInfoEndpoint":"https://userinfo.example.com","discoveryEndpoint":"https://example.auth0.com","secretName":"my-k8s-secret","authenticationRequestExtraParams":{"key":"value"}}`,
+					"alb.ingress.kubernetes.io/auth-on-unauthenticated-request": "deny",
+					"alb.ingress.kubernetes.io/auth-scope":                      "email",
+					"alb.ingress.kubernetes.io/auth-session-cookie":             "my-cookie",
+					"alb.ingress.kubernetes.io/auth-session-timeout":            "86400",
+				},
+			},
+			want: AuthConfig{
+				Type: AuthTypeNone,
+				IDPConfigOIDC: &AuthIDPConfigOIDC{
+					Issuer:                "https://example.auth0.com/",
+					AuthorizationEndpoint: "https://example.auth0.com/authorize",
+					TokenEndpoint:         "https://example.auth0.com/oauth/token",
+					UserInfoEndpoint:      "https://example.auth0.com/userinfo",
+					SecretName:            "my-k8s-secret",
+					DiscoveryEndpoint:     "https://example.auth0.com",
+					AuthenticationRequestExtraParams: map[string]string{
+						"key": "value",
+					},
+				},
+				OnUnauthenticatedRequest: "deny",
+				Scope:                    "email",
+				SessionCookieName:        "my-cookie",
+				SessionTimeout:           86400,
+			},
+		},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {

pkg/ingress/config_types.go

@@ -413,4 +413,8 @@ type AuthIDPConfigOIDC struct {
 	// The query parameters (up to 10) to include in the redirect request to the authorization endpoint.
 	// +optional
 	AuthenticationRequestExtraParams map[string]string `json:"authenticationRequestExtraParams,omitempty"`
+
+	// For IdP that supports discovery
+	// +optional
+	DiscoveryEndpoint string `json:"discoveryEndpoint,omitempty"`
 }

pkg/networking/utils.go

@@ -1,9 +1,22 @@
 package networking
 
 import (
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+	"net/netip"
+
 	awssdk "github.com/aws/aws-sdk-go/aws"
 	ec2sdk "github.com/aws/aws-sdk-go/service/ec2"
-	"net/netip"
+)
+
+const (
+	OIDCSuffix               = ".well-known/openid-configuration"
+	issuerKey                = "issuer"
+	authorizationEndpointKey = "authorization_endpoint"
+	tokenEndpointKey         = "token_endpoint"
+	userInfoEndpointKey      = "userinfo_endpoint"
 )
 
 // ParseCIDRs will parse CIDRs in string format into parsed IPPrefix
@@ -72,3 +85,31 @@ func GetSubnetAssociatedIPv6CIDRs(subnet *ec2sdk.Subnet) ([]netip.Prefix, error)
 	}
 	return ipv6CIDRs, nil
 }
+
+// GetOIDCConfiguration retrieves the OIDC configuration from the specified discoveryEndpoint.
+// should return a map with the following keys: issuer, authorization_endpoint, token_endpoint, userinfo_endpoint
+func GetOIDCConfiguration(discoveryEndpoint string) (map[string]string, error) {
+	discoveryEndpointUrl := fmt.Sprintf("%s/%s", discoveryEndpoint, OIDCSuffix)
+	req, err := http.NewRequest(http.MethodGet, discoveryEndpointUrl, nil)
+	if err != nil {
+		return nil, err
+	}
+	response, err := http.DefaultClient.Do(req)
+	if response.StatusCode != http.StatusOK {
+		return nil, fmt.Errorf("failed to get OIDC configuration. status code: %d", response.StatusCode)
+	}
+	defer response.Body.Close()
+	if err != nil {
+		return nil, err
+	}
+	body, err := io.ReadAll(response.Body)
+	if err != nil {
+		return nil, err
+	}
+	var ret map[string]string
+	json.Unmarshal([]byte(body), &ret)
+	if ret[issuerKey] == "" || ret[authorizationEndpointKey] == "" || ret[tokenEndpointKey] == "" || ret[userInfoEndpointKey] == "" {
+		return nil, fmt.Errorf("missing OIDC configuration for url: %s", discoveryEndpointUrl)
+	}
+	return ret, nil
+}