Add Keycloak as a Link login option

apps/link/app/(login)/login/_components/Login.tsx

@@ -14,6 +14,7 @@ import {
   Google as GoogleIcon,
   Microsoft as MicrosoftIcon,
   Key as KeyIcon,
+  VpnKey as KeycloakIcon,
 } from "@mui/icons-material";
 import { signIn, getProviders } from "next-auth/react";
 import Image from "next/image";
@@ -200,6 +201,21 @@ export const Login: FC<LoginProps> = ({ session, baseURL }) => {
                       </IconButton>
                     </Grid>
                   )}
+                  {provider === "keycloak" && (
+                    <Grid item sx={{ width: "100%" }}>
+                      <IconButton
+                        sx={buttonStyles}
+                        onClick={() =>
+                          signIn("keycloak", {
+                            callbackUrl,
+                          })
+                        }
+                      >
+                        <KeycloakIcon sx={{ mr: 1 }} />
+                        Sign in with Keycloak
+                      </IconButton>
+                    </Grid>
+                  )}
                   {provider === "credentials" && (
                     <Grid item container spacing={3}>
                       <Grid item sx={{ width: "100%" }}>

apps/link/app/_lib/authentication.ts

@@ -11,6 +11,7 @@ import Google from "next-auth/providers/google";
 import Credentials from "next-auth/providers/credentials";
 import Apple from "next-auth/providers/apple";
 import AzureADProvider from "next-auth/providers/azure-ad";
+import Keycloak from "next-auth/providers/keycloak";
 import { createLogger } from "@link-stack/logger";
 
 const logger = createLogger('link-authentication');
@@ -101,6 +102,18 @@ if (process.env.GOOGLE_CLIENT_ID && process.env.GOOGLE_CLIENT_SECRET) {
       tenantId: process.env.AZURE_AD_TENANT_ID,
     }),
   );
+} else if (
+  process.env.KEYCLOAK_CLIENT_ID &&
+  process.env.KEYCLOAK_CLIENT_SECRET &&
+  process.env.KEYCLOAK_ISSUER
+) {
+  providers.push(
+    Keycloak({
+      clientId: process.env.KEYCLOAK_CLIENT_ID,
+      clientSecret: process.env.KEYCLOAK_CLIENT_SECRET,
+      issuer: process.env.KEYCLOAK_ISSUER,
+    }),
+  );
 } else {
   providers.push(
     Credentials({