Add DataDog tracing to feature flags.

packages/backend-core/src/features/index.ts

@@ -3,6 +3,7 @@ import * as context from "../context"
 import { cloneDeep } from "lodash"
 import { PostHog, PostHogOptions } from "posthog-node"
 import { IdentityType } from "@budibase/types"
+import tracer from "dd-trace"
 
 let posthog: PostHog | undefined
 export function init(opts?: PostHogOptions) {
@@ -119,9 +120,13 @@ function isFlagName(name: string): name is keyof Flags {
  * they will be accessed through this function as well.
  */
 export async function fetch(): Promise<Flags> {
+  return await tracer.trace("features.fetch", async span => {
+    const tags: Record<string, any> = {}
+
     const flags = defaultFlags()
 
     const currentTenantId = context.getTenantId()
+    const specificallySetFalse = new Set<string>()
 
     const split = (env.TENANT_FEATURE_FLAGS || "")
       .split(",")
@@ -136,6 +141,7 @@ export async function fetch(): Promise<Flags> {
         if (feature.startsWith("!")) {
           feature = feature.slice(1)
           value = false
+          specificallySetFalse.add(feature)
         }
 
         if (!isFlagName(feature)) {
@@ -148,6 +154,7 @@ export async function fetch(): Promise<Flags> {
 
         // @ts-ignore
         flags[feature] = value
+        tags[`flags.${feature}.source`] = "environment"
       }
     }
 
@@ -164,11 +171,18 @@ export async function fetch(): Promise<Flags> {
           continue
         }
 
+        if (flags[key] === true || specificallySetFalse.has(key)) {
+          // If the flag is already set to through environment variables, we
+          // don't want to override it back to false here.
+          continue
+        }
+
         const payload = posthogFlags.featureFlagPayloads?.[name]
 
         try {
           // @ts-ignore
           flags[key] = flag.parse(payload || value)
+          tags[`flags.${key}.source`] = "posthog"
         } catch (err) {
           // We don't want an invalid PostHog flag to break the app, so we just
           // log it and continue.
@@ -177,7 +191,13 @@ export async function fetch(): Promise<Flags> {
       }
     }
 
+    for (const [key, value] of Object.entries(flags)) {
+      tags[`flags.${key}.value`] = value
+    }
+    span?.addTags(tags)
+
     return flags
+  })
 }
 
 // Gets a single feature flag value. This is a convenience function for

packages/backend-core/src/features/tests/features.spec.ts

@@ -79,7 +79,7 @@ describe("feature flags", () => {
   describe("posthog", () => {
     const identity: IdentityContext = {
       _id: "us_1234",
-      tenantId: "budibase",
+      tenantId: "tenant1",
       type: IdentityType.USER,
       email: "test@example.com",
       firstName: "Test",
@@ -171,5 +171,41 @@ describe("feature flags", () => {
         await expect(fetch()).resolves.not.toThrow()
       })
     })
+
+    it("should not override flags set in the environment", async () => {
+      mockFlags({
+        featureFlags: {
+          _TEST_BOOLEAN: false,
+        },
+      })
+
+      await withEnv(
+        { TENANT_FEATURE_FLAGS: `${identity.tenantId}:_TEST_BOOLEAN` },
+        async () => {
+          await context.doInIdentityContext(identity, async () => {
+            const flags = await fetch()
+            expect(flags._TEST_BOOLEAN).toBe(true)
+          })
+        }
+      )
+    })
+
+    it("should not override flags set in the environment with a ! prefix", async () => {
+      mockFlags({
+        featureFlags: {
+          _TEST_BOOLEAN: true,
+        },
+      })
+
+      await withEnv(
+        { TENANT_FEATURE_FLAGS: `${identity.tenantId}:!_TEST_BOOLEAN` },
+        async () => {
+          await context.doInIdentityContext(identity, async () => {
+            const flags = await fetch()
+            expect(flags._TEST_BOOLEAN).toBe(false)
+          })
+        }
+      )
+    })
   })
 })