java 43 lines · 8 steps

How a tenant-resolution filter works in Spring

A servlet filter reads a tenant header, validates it against the database, and binds it to thread-local context for the request.

Explained by highlit
Spring Intermediate multi-tenancy servlet-filter thread-local request-lifecycle validation
1@Component
2@Order(Ordered.HIGHEST_PRECEDENCE)
3public class TenantResolutionFilter extends OncePerRequestFilter {
4 
5 private static final String TENANT_HEADER = "X-Tenant-ID";
6 
7 private final TenantRepository tenantRepository;
8 
9 public TenantResolutionFilter(TenantRepository tenantRepository) {
10 this.tenantRepository = tenantRepository;
11 }
12 
13 @Override
14 protected void doFilterInternal(HttpServletRequest request,
15 HttpServletResponse response,
16 FilterChain filterChain) throws ServletException, IOException {
17 String tenantId = request.getHeader(TENANT_HEADER);
18 
19 if (!StringUtils.hasText(tenantId)) {
20 response.sendError(HttpStatus.BAD_REQUEST.value(), "Missing " + TENANT_HEADER + " header");
21 return;
22 }
23 
24 Tenant tenant = tenantRepository.findByExternalId(tenantId).orElse(null);
25 if (tenant == null || !tenant.isActive()) {
26 response.sendError(HttpStatus.FORBIDDEN.value(), "Unknown or inactive tenant");
27 return;
28 }
29 
30 try {
31 TenantContext.setCurrentTenant(tenant);
32 response.setHeader(TENANT_HEADER, tenant.getExternalId());
33 filterChain.doFilter(request, response);
34 } finally {
35 TenantContext.clear();
36 }
37 }
38 
39 @Override
40 protected boolean shouldNotFilter(HttpServletRequest request) {
41 return request.getRequestURI().startsWith("/actuator");
42 }
43}
01 / 01
STEP 01

Walkthrough

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Three takeaways
  1. 1Running a filter at highest precedence lets you establish request-scoped context before any other component executes.
  2. 2Thread-local context must always be cleared in a finally block to avoid leaking state across pooled request threads.
  3. 3Validating identity early and failing with the right HTTP status keeps invalid requests out of your business logic.

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