From 20f55e379581c497b91f9578954e965c8e3bc223 Mon Sep 17 00:00:00 2001
From: Sam Rose <hello@samwho.dev>
Date: Wed, 9 Oct 2024 12:29:17 +0100
Subject: [PATCH] Still fetch flags when the user is not logged in.

---
 .../backend-core/src/features/features.ts     | 38 +++++++------
 .../src/features/tests/features.spec.ts       | 55 ++++++++++++++++++-
 2 files changed, 75 insertions(+), 18 deletions(-)

diff --git a/packages/backend-core/src/features/features.ts b/packages/backend-core/src/features/features.ts
index 90a395d52a..305c53ff3a 100644
--- a/packages/backend-core/src/features/features.ts
+++ b/packages/backend-core/src/features/features.ts
@@ -1,7 +1,8 @@
 import env from "../environment"
+import * as crypto from "crypto"
 import * as context from "../context"
 import { PostHog, PostHogOptions } from "posthog-node"
-import { FeatureFlag, IdentityType, UserCtx } from "@budibase/types"
+import { FeatureFlag, UserCtx } from "@budibase/types"
 import tracer from "dd-trace"
 import { Duration } from "../utils"
 
@@ -224,24 +225,29 @@ export class FlagSet<V extends Flag<any>, T extends { [key: string]: V }> {
       }
 
       const identity = context.getIdentity()
-      tags[`identity.type`] = identity?.type
-      tags[`identity.tenantId`] = identity?.tenantId
-      tags[`identity._id`] = identity?._id
 
-      if (posthog && identity?.type === IdentityType.USER) {
+      let userId = identity?._id
+      if (!userId && ctx?.ip) {
+        userId = crypto.createHash("sha512").update(ctx.ip).digest("hex")
+      }
+
+      let tenantId = identity?.tenantId
+      if (!tenantId) {
+        tenantId = currentTenantId
+      }
+
+      tags[`identity.type`] = identity?.type
+      tags[`identity._id`] = identity?._id
+      tags[`tenantId`] = tenantId
+      tags[`userId`] = userId
+
+      if (posthog && userId) {
         tags[`readFromPostHog`] = true
 
-        const personProperties: Record<string, string> = {}
-        if (identity.tenantId) {
-          personProperties.tenantId = identity.tenantId
-        }
-
-        const posthogFlags = await posthog.getAllFlagsAndPayloads(
-          identity._id,
-          {
-            personProperties,
-          }
-        )
+        const personProperties: Record<string, string> = { tenantId }
+        const posthogFlags = await posthog.getAllFlagsAndPayloads(userId, {
+          personProperties,
+        })
 
         for (const [name, value] of Object.entries(posthogFlags.featureFlags)) {
           if (!this.isFlagName(name)) {
diff --git a/packages/backend-core/src/features/tests/features.spec.ts b/packages/backend-core/src/features/tests/features.spec.ts
index 01c9bfa3c6..bf01ad67f3 100644
--- a/packages/backend-core/src/features/tests/features.spec.ts
+++ b/packages/backend-core/src/features/tests/features.spec.ts
@@ -4,6 +4,7 @@ import * as context from "../../context"
 import environment, { withEnv } from "../../environment"
 import nodeFetch from "node-fetch"
 import nock from "nock"
+import * as crypto from "crypto"
 
 const schema = {
   TEST_BOOLEAN: Flag.boolean(false),
@@ -27,10 +28,14 @@ interface PostHogFlags {
   featureFlagPayloads?: Record<string, string>
 }
 
-function mockPosthogFlags(flags: PostHogFlags) {
+function mockPosthogFlags(
+  flags: PostHogFlags,
+  opts?: { token?: string; distinct_id?: string }
+) {
+  const { token = "test", distinct_id = "us_1234" } = opts || {}
   nock("https://us.i.posthog.com")
     .post("/decide/?v=3", body => {
-      return body.token === "test" && body.distinct_id === "us_1234"
+      return body.token === token && body.distinct_id === distinct_id
     })
     .reply(200, flags)
     .persist()
@@ -214,6 +219,14 @@ describe("feature flags", () => {
       lastName: "User",
     }
 
+    // We need to pass in node-fetch here otherwise nock won't get used
+    // because posthog-node uses axios under the hood.
+    init({
+      fetch: (url, opts) => {
+        return nodeFetch(url, opts)
+      },
+    })
+
     nock("https://us.i.posthog.com")
       .post("/decide/?v=3", body => {
         return body.token === "test" && body.distinct_id === "us_1234"
@@ -230,4 +243,42 @@ describe("feature flags", () => {
       }
     )
   })
+
+  it("should still get flags when user is logged out", async () => {
+    const env: Partial<typeof environment> = {
+      SELF_HOSTED: false,
+      POSTHOG_FEATURE_FLAGS_ENABLED: "true",
+      POSTHOG_API_HOST: "https://us.i.posthog.com",
+      POSTHOG_TOKEN: "test",
+    }
+
+    const ctx = { ip: "127.0.0.1" } as UserCtx
+    const hashedIp = crypto.createHash("sha512").update(ctx.ip).digest("hex")
+
+    await withEnv(env, async () => {
+      mockPosthogFlags(
+        {
+          featureFlags: { TEST_BOOLEAN: true },
+        },
+        {
+          distinct_id: hashedIp,
+        }
+      )
+
+      // We need to pass in node-fetch here otherwise nock won't get used
+      // because posthog-node uses axios under the hood.
+      init({
+        fetch: (url, opts) => {
+          return nodeFetch(url, opts)
+        },
+      })
+
+      await context.doInTenant("default", async () => {
+        const result = await flags.fetch(ctx)
+        expect(result.TEST_BOOLEAN).toBe(true)
+      })
+
+      shutdown()
+    })
+  })
 })