Revert "fix(aso-overlay): add Surrogate-Key header so Fastly purge actually invalidates (SITES-48140)"

This reverts commit 863c0dd.

Author: Abhishek Garg

src/controllers/redirects.js

@@ -272,11 +272,6 @@ function RedirectsController(ctx) {
           'content-type': 'text/plain; charset=utf-8',
           ...(etag ? { etag } : {}),
           'cache-control': OVERLAY_CACHE_CONTROL,
-          // Same Surrogate-Key as the 200 so any 304 stragglers still on the
-          // old TTL can be purged by the same call. Fastly stores the header
-          // for edge state; RFC 7232 requires we carry cache-control + etag,
-          // and Surrogate-Key is an operationally-linked companion.
-          'surrogate-key': `aso-overlay-${service}`,
         });
       }
 
@@ -291,12 +286,6 @@ function RedirectsController(ctx) {
         'cache-control': OVERLAY_CACHE_CONTROL,
         // Include ETag so a subsequent poll can conditionally revalidate.
         ...(etag ? { etag } : {}),
-        // Fastly surrogate key so Mystique can targeted-purge this tenant's
-        // overlay on Deploy (see mystique#3381). Namespaced with `aso-overlay-`
-        // prefix so future overlays under different routes don't collide with
-        // this key space. Fastly VCL strips the /config/<tier>/ prefix before
-        // reaching origin, so we only need per-service uniqueness (not per-tier).
-        'surrogate-key': `aso-overlay-${service}`,
       });
     } catch (err) {
       const code = err.$metadata?.httpStatusCode;

test/controllers/redirects.test.js

@@ -98,10 +98,6 @@ describe('RedirectsController', () => {
     expect(response.headers.get('content-type')).to.equal('text/plain; charset=utf-8');
     expect(response.headers.get('cache-control')).to.equal('max-age=10');
     expect(response.headers.get('etag')).to.equal(ETAG);
-    // Surrogate-Key enables Mystique to targeted-purge this tenant's overlay
-    // via Fastly's key-purge endpoint (POST /service/<sid>/purge/<key>) after
-    // a successful S3 write. See mystique#3381.
-    expect(response.headers.get('surrogate-key')).to.equal(`aso-overlay-${SERVICE}`);
     expect(await response.text()).to.equal(overlay);
     // Resolves the site by the p<program>/e<env> external ids parsed from the service.
     expect(mockDataAccess.Site.findByExternalOwnerIdAndExternalSiteId
@@ -158,8 +154,6 @@ describe('RedirectsController', () => {
     expect(response.headers.get('etag')).to.equal(ETAG);
     expect(response.headers.get('cache-control')).to.equal('max-age=10');
     expect(response.headers.get('content-type')).to.equal('text/plain; charset=utf-8');
-    // Surrogate-Key echoed on 304 so purges hit both HIT and NOT_MODIFIED entries.
-    expect(response.headers.get('surrogate-key')).to.equal(`aso-overlay-${SERVICE}`);
     expect(await response.text()).to.equal('');
     // Body never deserialized when returning 304 — the transformToString cost is elided.
     expect(bodyStub.called).to.be.false;