Feature flag debug UI

packages/backend-core/src/constants/misc.ts

@@ -9,6 +9,7 @@ export enum Cookie {
   ACCOUNT_RETURN_URL = "budibase:account:returnurl",
   DatasourceAuth = "budibase:datasourceauth",
   OIDC_CONFIG = "budibase:oidc:config",
+  FeatureFlags = "budibase:featureflags",
 }
 
 export { Header } from "@budibase/shared-core"

packages/backend-core/src/context/mainContext.ts

@@ -460,6 +460,17 @@ export function setFeatureFlags(key: string, value: Record<string, boolean>) {
   context.featureFlagCache[key] = value
 }
 
+export function getFeatureFlagOverrides(): Record<string, boolean> {
+  return getCurrentContext()?.featureFlagOverrides || {}
+}
+
+export async function doInFeatureFlagOverrideContext<T>(
+  value: Record<string, boolean>,
+  callback: () => Promise<T>
+) {
+  return await newContext({ featureFlagOverrides: value }, callback)
+}
+
 export function getTableForView(viewId: string): Table | undefined {
   const context = getCurrentContext()
   if (!context) {

packages/backend-core/src/context/types.ts

@@ -24,5 +24,6 @@ export type ContextMap = {
   featureFlagCache?: {
     [key: string]: Record<string, boolean>
   }
+  featureFlagOverrides?: Record<string, boolean>
   viewToTableCache?: Record<string, Table>
 }

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

@@ -175,6 +175,21 @@ export class FlagSet<T extends { [name: string]: boolean }> {
         }
       }
 
+      const overrides = context.getFeatureFlagOverrides()
+      for (const [key, value] of Object.entries(overrides)) {
+        if (!this.isFlagName(key)) {
+          continue
+        }
+
+        if (typeof value !== "boolean") {
+          continue
+        }
+
+        // @ts-expect-error - TS does not like you writing into a generic type.
+        flagValues[key] = value
+        tags[`flags.${key}.source`] = "override"
+      }
+
       context.setFeatureFlags(this.setId, flagValues)
       for (const [key, value] of Object.entries(flagValues)) {
         tags[`flags.${key}.value`] = value

packages/backend-core/src/middleware/featureFlagCookie.ts

@@ -0,0 +1,13 @@
+import { Ctx, FeatureFlagCookie } from "@budibase/types"
+import { Middleware, Next } from "koa"
+import { getCookie } from "../utils"
+import { Cookie } from "../constants"
+import { doInFeatureFlagOverrideContext } from "../context"
+
+export default (async (ctx: Ctx, next: Next) => {
+  const cookie = getCookie<FeatureFlagCookie>(ctx, Cookie.FeatureFlags)
+  const flags = cookie?.flags || {}
+  await doInFeatureFlagOverrideContext(flags, async () => {
+    await next()
+  })
+}) as Middleware

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

@@ -20,5 +20,6 @@ export { default as correlation } from "../logging/correlation/middleware"
 export { default as errorHandling } from "./errorHandling"
 export { default as querystringToBody } from "./querystringToBody"
 export { default as csp } from "./contentSecurityPolicy"
+export { default as featureFlagCookie } from "./featureFlagCookie"
 export * as joiValidator from "./joi-validator"
 export { default as ip } from "./ip"