From f846b3fdee22afc98740074026c6374403087ca6 Mon Sep 17 00:00:00 2001
From: Campbell Pool <campbell.pool@epicgames.com>
Date: Fri, 19 Jun 2026 12:18:59 -0700
Subject: [PATCH] feat(artifact): unblock v4+ on self-hosted GHES when
 ACTIONS_RESULTS_URL is set

The current isGhes() check returns true for any GitHub Server URL that
isn't github.com, *.ghe.com, or *.localhost. When isGhes() returns true,
client.ts throws GHESNotSupportedError on every upload, download, and
list call - so the artifact-v4+ family is completely blocked on
self-hosted GHES instances.

This made sense at v4 launch when the artifact-storage-v2 backend was
github.com-only. GHES 3.13 added the v2 backend, and 3.16+ has full
production support, but the hostname-based gate doesn't reflect that:
it continues to throw on any GHES regardless of release.

The runtime already exposes a clean signal for whether v2 is reachable:
the runner sets ACTIONS_RESULTS_URL exactly when the storage backend is
available. The artifact client's own getResultsServiceUrl() in the same
package throws if ACTIONS_RESULTS_URL is unset, so it's already a
precondition for the upload/download/list paths to succeed. Treating
that env var as the authority on "is the v2 backend reachable here?"
unblocks GHES 3.13+ without changing behaviour anywhere else.

Compatibility:

  - github.com / *.ghe.com / *.localhost: hostname check returns
    isGhes()=false. No change.
  - GHES <3.13 (no v2 backend, ACTIONS_RESULTS_URL unset): hostname is
    GHES-shaped, env var is missing -> isGhes()=true -> existing
    GHESNotSupportedError. No change.
  - GHES 3.13+ (v2 backend present, ACTIONS_RESULTS_URL set): hostname
    is GHES-shaped, env var IS set -> isGhes()=false -> upload /
    download / list proceed normally. This is the unblock.

Tests added in packages/artifact/__tests__/config.test.ts cover both
new branches; the existing 'enterprise hostname' test is kept and now
explicitly verifies the unset-env-var case.
---
 packages/artifact/__tests__/config.test.ts    | 19 ++++++++++++++++++-
 .../artifact/src/internal/shared/config.ts    | 16 +++++++++++++++-
 2 files changed, 33 insertions(+), 2 deletions(-)

diff --git a/packages/artifact/__tests__/config.test.ts b/packages/artifact/__tests__/config.test.ts
index 3d14ace2b2..7d3be228e0 100644
--- a/packages/artifact/__tests__/config.test.ts
+++ b/packages/artifact/__tests__/config.test.ts
@@ -15,6 +15,11 @@ beforeEach(() => {
 })
 
 describe('isGhes', () => {
+  beforeEach(() => {
+    delete process.env.GITHUB_SERVER_URL
+    delete process.env.ACTIONS_RESULTS_URL
+  })
+
   it('should return false when the request domain is github.com', () => {
     process.env.GITHUB_SERVER_URL = 'https://github.com'
     expect(config.isGhes()).toBe(false)
@@ -35,10 +40,22 @@ describe('isGhes', () => {
     expect(config.isGhes()).toBe(false)
   })
 
-  it('should return false when the request domain is specific to an enterprise', () => {
+  it('should return true on a self-hosted enterprise hostname when ACTIONS_RESULTS_URL is unset', () => {
     process.env.GITHUB_SERVER_URL = 'https://my-enterprise.github.com'
     expect(config.isGhes()).toBe(true)
   })
+
+  it('should return false on a self-hosted enterprise hostname when ACTIONS_RESULTS_URL is set (v2 backend available)', () => {
+    process.env.GITHUB_SERVER_URL = 'https://my-enterprise.github.com'
+    process.env.ACTIONS_RESULTS_URL = 'https://results.example.com/'
+    expect(config.isGhes()).toBe(false)
+  })
+
+  it('should ignore ACTIONS_RESULTS_URL on github.com (already returns false there)', () => {
+    process.env.GITHUB_SERVER_URL = 'https://github.com'
+    process.env.ACTIONS_RESULTS_URL = 'https://results.example.com/'
+    expect(config.isGhes()).toBe(false)
+  })
 })
 
 describe('uploadChunkTimeoutEnv', () => {
diff --git a/packages/artifact/src/internal/shared/config.ts b/packages/artifact/src/internal/shared/config.ts
index 0a275fd5ee..2991f69f8e 100644
--- a/packages/artifact/src/internal/shared/config.ts
+++ b/packages/artifact/src/internal/shared/config.ts
@@ -34,7 +34,21 @@ export function isGhes(): boolean {
   const isGheHost = hostname.endsWith('.GHE.COM')
   const isLocalHost = hostname.endsWith('.LOCALHOST')
 
-  return !isGitHubHost && !isGheHost && !isLocalHost
+  const hostnameLooksLikeGhes =
+    !isGitHubHost && !isGheHost && !isLocalHost
+
+  // GHES 3.13+ ships the artifact-storage-v2 backend that the v4+
+  // artifact client requires. The runner exposes the backend's
+  // presence via ACTIONS_RESULTS_URL (which getResultsServiceUrl()
+  // already requires for upload/download/list to function). When
+  // that env var is set we know the backend is reachable, so an
+  // unrecognised hostname does not need to short-circuit into a
+  // GHESNotSupportedError.
+  if (hostnameLooksLikeGhes && process.env['ACTIONS_RESULTS_URL']) {
+    return false
+  }
+
+  return hostnameLooksLikeGhes
 }
 
 export function getGitHubWorkspaceDir(): string {