Listing all user realms by email #38138

yegortokmakov · 2025-03-16T09:09:18Z

yegortokmakov
Mar 16, 2025

We are using Keycloak to implement multi-tenant IAM. In our setup, we create a new realm per “customer,” and a user with the same email can be part of multiple realms. On the SSO page, before redirecting the user to the realm they want to authenticate against, we want to show a list of available realms for them to choose from.

One approach we explored is to have a custom provider that exposes a REST resource/endpoint extension:

    @GET
    @Path("/{email}")
    @Produces(MediaType.APPLICATION_JSON)
    @Operation(summary = "Realms list endpoint", description = "Get a list of organizations the user belongs to. Used during authentication process.")
    @APIResponse(responseCode = "200", description = "An array of organizations the user belongs to.", content = {
            @Content(schema = @Schema(implementation = RealmIdName.class, type = SchemaType.ARRAY)) })
    public Response getUserRealms(
            @Parameter(description = "User email address.", required = true) @PathParam("email") String email) {
        checkAuth();

        List<Map<String, String>> realmList = session.realms().getRealmsStream()
                .filter(realmModel -> realmModel.isEnabled())
                .filter(realmModel -> realmModel.getName() != "master")
                .filter(realmModel -> session.users().getUserByEmail(realmModel, email) != null)
                .map(realmModel -> Map.of("realm", realmModel.getName(), "displayName", realmModel.getDisplayName()))
                .toList();

        return Response.ok(realmList).build();
    }

It works fine, but there are a couple of points I wanted to clarify with the Keycloak community:

How do others implement such functionality? Are there any built-in endpoints we might have missed?
Would the maintainers be open to a contribution to include this as part of the core Keycloak?

Thanks!

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Listing all user realms by email #38138

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yegortokmakov Mar 16, 2025

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yegortokmakov
Mar 16, 2025