feat(medusa, utils): Allow object feature flags (#4701)

Feature flags can be set as follows:

**Environment variables**
```
MEDUSA_FF_ANALYTICS=true
MEDUSA_FF_WORKFLOWS=createProducts,addShippingMethods
```

**Project config**
```
{
  featureFlags: {
    analytics: true,
    workflows: {
      createProducts: true,
      addShippingMethods: true,
    }
  }
}
```

packages/medusa/src/api/routes/admin/products/create-product.ts

@@ -1,7 +1,3 @@
-import {
-  CreateProductVariantInput,
-  ProductVariantPricesCreateReq,
-} from "../../../../types/product-variant"
 import {
   IsArray,
   IsBoolean,
@@ -12,6 +8,7 @@ import {
   IsString,
   ValidateNested,
 } from "class-validator"
+import { defaultAdminProductFields, defaultAdminProductRelations } from "."
 import {
   PricingService,
   ProductService,
@@ -26,23 +23,26 @@ import {
   ProductTagReq,
   ProductTypeReq,
 } from "../../../../types/product"
+import {
+  CreateProductVariantInput,
+  ProductVariantPricesCreateReq,
+} from "../../../../types/product-variant"
 import {
   createVariantsTransaction,
   revertVariantTransaction,
 } from "./transaction/create-product-variant"
-import { defaultAdminProductFields, defaultAdminProductRelations } from "."
 
 import { DistributedTransaction } from "@medusajs/orchestration"
-import { EntityManager } from "typeorm"
-import { FeatureFlagDecorators } from "../../../../utils/feature-flag-decorators"
-import { FlagRouter } from "../../../../utils/flag-router"
 import { IInventoryService, WorkflowTypes } from "@medusajs/types"
-import { Logger } from "../../../../types/global"
-import { ProductStatus } from "../../../../models"
-import SalesChannelFeatureFlag from "../../../../loaders/feature-flags/sales-channels"
+import { FlagRouter } from "@medusajs/utils"
+import { Workflows, createProducts } from "@medusajs/workflows"
 import { Type } from "class-transformer"
+import { EntityManager } from "typeorm"
+import SalesChannelFeatureFlag from "../../../../loaders/feature-flags/sales-channels"
+import { ProductStatus } from "../../../../models"
+import { Logger } from "../../../../types/global"
 import { validator } from "../../../../utils"
-import { createProducts } from "@medusajs/workflows"
+import { FeatureFlagDecorators } from "../../../../utils/feature-flag-decorators"
 
 /**
  * @oas [post] /admin/products
@@ -132,7 +132,17 @@ export default async (req, res) => {
   const entityManager: EntityManager = req.scope.resolve("manager")
   const productModuleService = req.scope.resolve("productModuleService")
 
-  if (productModuleService) {
+  const isWorkflowEnabled = featureFlagRouter.isFeatureEnabled({
+    workflows: Workflows.CreateProducts,
+  })
+
+  if (isWorkflowEnabled && !productModuleService) {
+    logger.warn(
+      `Cannot run ${Workflows.CreateProducts} workflow without '@medusajs/product' installed`
+    )
+  }
+
+  if (isWorkflowEnabled && !!productModuleService) {
     const createProductWorkflow = createProducts(req.scope)
 
     const input = {

packages/medusa/src/loaders/__tests__/feature-flags.spec.ts

@@ -1,5 +1,5 @@
-import { resolve } from "path"
 import { mkdirSync, rmSync, writeFileSync } from "fs"
+import { resolve } from "path"
 
 import loadFeatureFlags from "../feature-flags"
 
@@ -67,6 +67,27 @@ describe("feature flags", () => {
     expect(flags.isFeatureEnabled("flag_1")).toEqual(false)
   })
 
+  it("should load a nested + simple flag from project", async () => {
+    writeFileSync(
+      resolve(getFolderTestTargetDirectoryPath("flags"), "test.js"),
+      buildFeatureFlag("test", false)
+    )
+
+    writeFileSync(
+      resolve(getFolderTestTargetDirectoryPath("flags"), "simpletest.js"),
+      buildFeatureFlag("simpletest", false)
+    )
+
+    const flags = await loadFeatureFlags(
+      { featureFlags: { test: { nested: true }, simpletest: true } },
+      undefined,
+      getFolderTestTargetDirectoryPath("flags")
+    )
+
+    expect(flags.isFeatureEnabled({ test: "nested" })).toEqual(true)
+    expect(flags.isFeatureEnabled("simpletest")).toEqual(true)
+  })
+
   it("should load the default feature flags", async () => {
     writeFileSync(
       resolve(getFolderTestTargetDirectoryPath("flags"), "flag-1.js"),

packages/medusa/src/loaders/feature-flags/index.ts

@@ -1,11 +1,15 @@
+import {
+  FlagRouter,
+  isObject,
+  isString,
+  objectFromStringPath,
+} from "@medusajs/utils"
 import glob from "glob"
-import path from "path"
-
 import { isDefined } from "medusa-core-utils"
 import { trackFeatureFlag } from "medusa-telemetry"
+import path from "path"
 import { FlagSettings } from "../../types/feature-flags"
 import { Logger } from "../../types/global"
-import { FlagRouter } from "../../utils/flag-router"
 
 const isTruthy = (val: string | boolean | undefined): boolean => {
   if (typeof val === "string") {
@@ -17,7 +21,9 @@ const isTruthy = (val: string | boolean | undefined): boolean => {
 export const featureFlagRouter = new FlagRouter({})
 
 export default (
-  configModule: { featureFlags?: Record<string, string | boolean> } = {},
+  configModule: {
+    featureFlags?: Record<string, string | boolean | Record<string, boolean>>
+  } = {},
   logger?: Logger,
   flagDirectory?: string
 ): FlagRouter => {
@@ -28,7 +34,7 @@ export default (
     ignore: ["**/index.js", "**/index.ts", "**/*.d.ts"],
   })
 
-  const flagConfig: Record<string, boolean> = {}
+  const flagConfig: Record<string, boolean | Record<string, boolean>> = {}
   for (const flag of supportedFlags) {
     const flagSettings: FlagSettings = require(flag).default
     if (!flagSettings) {
@@ -40,12 +46,31 @@ export default (
     let from
     if (isDefined(process.env[flagSettings.env_key])) {
       from = "environment"
+      const envVal = process.env[flagSettings.env_key]
+
+      // MEDUSA_FF_ANALYTICS="true"
       flagConfig[flagSettings.key] = isTruthy(process.env[flagSettings.env_key])
+
+      const parsedFromEnv = isString(envVal) ? envVal.split(",") : []
+
+      // MEDUSA_FF_WORKFLOWS=createProducts,deleteProducts
+      if (parsedFromEnv.length > 1) {
+        flagConfig[flagSettings.key] = objectFromStringPath(parsedFromEnv)
+      }
     } else if (isDefined(projectConfigFlags[flagSettings.key])) {
       from = "project config"
+
+      // featureFlags: { analytics: "true" | true }
       flagConfig[flagSettings.key] = isTruthy(
-        projectConfigFlags[flagSettings.key]
+        projectConfigFlags[flagSettings.key] as string | boolean
       )
+
+      // featureFlags: { workflows: { createProducts: true } }
+      if (isObject(projectConfigFlags[flagSettings.key])) {
+        flagConfig[flagSettings.key] = projectConfigFlags[
+          flagSettings.key
+        ] as Record<string, boolean>
+      }
     }
 
     if (logger && from) {

packages/medusa/src/loaders/feature-flags/workflows.ts

@@ -0,0 +1,10 @@
+import { FeatureFlagTypes } from "@medusajs/types"
+
+const WorkflowsFeatureFlag: FeatureFlagTypes.FlagSettings = {
+  key: "workflows",
+  default_val: false,
+  env_key: "MEDUSA_FF_WORKFLOWS",
+  description: "[WIP] Enable workflows",
+}
+
+export default WorkflowsFeatureFlag

packages/medusa/src/types/feature-flags.ts

@@ -21,7 +21,7 @@ export interface IFlagRouter {
  */
 export type FeatureFlagsResponse = {
   key: string
-  value: boolean
+  value: boolean | Record<string, boolean>
 }[]
 
 export type FlagSettings = {

packages/medusa/src/utils/flag-router.ts

@@ -1,21 +1,72 @@
-import { FeatureFlagsResponse, IFlagRouter } from "../types/feature-flags"
+import { FeatureFlagTypes } from "@medusajs/types"
+import { isObject, isString } from "@medusajs/utils"
 
-export class FlagRouter implements IFlagRouter {
-  private readonly flags: Record<string, boolean> = {}
+export class FlagRouter implements FeatureFlagTypes.IFlagRouter {
+  private readonly flags: Record<string, boolean | Record<string, boolean>> = {}
 
-  constructor(flags: Record<string, boolean>) {
+  constructor(flags: Record<string, boolean | Record<string, boolean>>) {
     this.flags = flags
   }
 
-  public isFeatureEnabled(key: string): boolean {
-    return !!this.flags[key]
+  /**
+   * Check if a feature flag is enabled.
+   * There are two ways of using this method:
+   * 1. `isFeatureEnabled("myFeatureFlag")`
+   * 2. `isFeatureEnabled({ myNestedFeatureFlag: "someNestedFlag" })`
+   * We use 1. for top-level feature flags and 2. for nested feature flags. Almost all flags are top-level.
+   * An example of a nested flag is workflows. To use it, you would do:
+   * `isFeatureEnabled({ workflows: Workflows.CreateCart })`
+   * @param flag - The flag to check
+   * @return {boolean} - Whether the flag is enabled or not
+   */
+  public isFeatureEnabled(flag: string | Record<string, string>): boolean {
+    if (isString(flag)) {
+      return !!this.flags[flag]
+    }
+
+    if (isObject(flag)) {
+      const [nestedFlag, value] = Object.entries(flag)[0]
+
+      if (typeof this.flags[nestedFlag] === "boolean") {
+        return this.flags[nestedFlag] as boolean
+      }
+
+      return !!this.flags[nestedFlag]?.[value]
+    }
+
+    throw Error("Flag must be a string or an object")
   }
 
-  public setFlag(key: string, value = true): void {
+  /**
+   * Sets a feature flag.
+   * Flags take two shapes:
+   * setFlag("myFeatureFlag", true)
+   * setFlag("myFeatureFlag", { nestedFlag: true })
+   * These shapes are used for top-level and nested flags respectively, as explained in isFeatureEnabled.
+   * @param key - The key of the flag to set.
+   * @param value - The value of the flag to set.
+   * @return {void} - void
+   */
+  public setFlag(
+    key: string,
+    value: boolean | { [key: string]: boolean }
+  ): void {
+    if (isObject(value)) {
+      const existing = this.flags[key]
+
+      if (!existing) {
+        this.flags[key] = value
+        return
+      }
+
+      this.flags[key] = { ...(this.flags[key] as object), ...value }
+      return
+    }
+
     this.flags[key] = value
   }
 
-  public listFlags(): FeatureFlagsResponse {
+  public listFlags(): FeatureFlagTypes.FeatureFlagsResponse {
     return Object.entries(this.flags || {}).map(([key, value]) => ({
       key,
       value,