fix(core): improve project config validation

We now validate that `project.environments` is an array and throw an
informative error if it isn't.

Previously, if `project.environments` was mistakenly formatted as a
map instead of an array, a cryptic type error would be printed ("Cannot
read property name of undefined"). We now clearly indicate the problem
to the user.

Additionally, the `joiSparseArray` schema can now properly handle
non-array inputs without failing cryptically.

core/src/config/common.ts

@@ -10,7 +10,7 @@ import Joi from "@hapi/joi"
 import Ajv from "ajv"
 import { splitLast } from "../util/util"
 import { deline, dedent } from "../util/string"
-import { cloneDeep } from "lodash"
+import { cloneDeep, isArray } from "lodash"
 import { joiPathPlaceholder } from "./validation"
 import { DEFAULT_API_VERSION } from "../constants"
 
@@ -415,7 +415,7 @@ joi = joi.extend({
   type: "sparseArray",
   coerce: {
     method(value) {
-      return { value: value && value.filter((v: any) => v !== undefined && v !== null) }
+      return { value: isArray(value) && value.filter((v: any) => v !== undefined && v !== null) }
     },
   },
 })

core/src/config/project.ts

@@ -133,13 +133,7 @@ export const environmentSchema = () =>
   })
 
 export const environmentsSchema = () =>
-  joi
-    .alternatives(
-      joiSparseArray(environmentSchema()).unique("name"),
-      // Allow a string as a shorthand for { name: foo }
-      joiSparseArray(joiUserIdentifier())
-    )
-    .description("A list of environments to configure for the project.")
+  joiSparseArray(environmentSchema()).unique("name").description("A list of environments to configure for the project.")
 
 export interface SourceConfig {
   name: string

core/src/garden.ts

@@ -40,7 +40,7 @@ import { TaskGraph, GraphResults, ProcessTasksOpts } from "./task-graph"
 import { getLogger } from "./logger/logger"
 import { PluginActionHandlers, GardenPlugin } from "./types/plugin/plugin"
 import { loadConfigResources, findProjectConfig, prepareModuleResource, GardenResource } from "./config/base"
-import { DeepPrimitiveMap, StringMap, PrimitiveMap } from "./config/common"
+import { DeepPrimitiveMap, StringMap, PrimitiveMap, joiSparseArray, joi } from "./config/common"
 import { BaseTask } from "./tasks/base"
 import { LocalConfigStore, ConfigStore, GlobalConfigStore, LinkedSource } from "./config-store"
 import { getLinkedSources, ExternalSourceType } from "./util/ext-source-util"
@@ -99,7 +99,7 @@ import { ProviderConfigContext } from "./config/template-contexts/provider"
 import { getSecrets } from "./enterprise/get-secrets"
 import { killSyncDaemon } from "./plugins/kubernetes/mutagen"
 import { ConfigContext } from "./config/template-contexts/base"
-import { validateSchema } from "./config/validation"
+import { validateSchema, validateWithPath } from "./config/validation"
 
 export interface ActionHandlerMap<T extends keyof PluginActionHandlers> {
   [actionName: string]: PluginActionHandlers[T]
@@ -1232,6 +1232,17 @@ export async function resolveGardenParams(currentDirectory: string, opts: Garden
   const gitHandler = new GitHandler(projectRoot, gardenDirPath, [], treeCache)
   const vcsBranch = (await gitHandler.getBranchName(log, projectRoot)) || ""
 
+  // Since we iterate/traverse them before fully validating them (which we do after resolving template strings), we
+  // validdate that `config.environments` and `config.providers` are both arrays.
+  // This prevents cryptic type errors when the user mistakely writes down e.g. a map instead of an array.
+  validateWithPath({
+    config: config.environments,
+    schema: joiSparseArray(joi.object()),
+    configType: "environments",
+    path: config.path,
+    projectRoot: config.path,
+  })
+
   const defaultEnvironmentName = resolveTemplateString(
     config.defaultEnvironment,
     new DefaultEnvironmentContext({

core/test/data/test-project-malformed-environments/garden.yml

@@ -0,0 +1,6 @@
+kind: Project
+name: test-project-malformed-environments
+environments:
+  name: local # This should result in an exception, because `environments` is a map instead of a array.
+providers:
+  - name: test-plugin

core/test/unit/src/garden.ts

@@ -218,6 +218,14 @@ describe("Garden", () => {
       await expectError(async () => TestGarden.factory(projectRootA, { environmentName: "garden-bla" }), "parameter")
     })
 
+    it("should throw if project.environments is not an array", async () => {
+      const projectRoot = join(dataDir, "test-project-malformed-environments")
+      await expectError(
+        async () => TestGarden.factory(projectRoot),
+        (err) => expect(err.message).to.match(/Error validating environments: value must be an array/)
+      )
+    })
+
     it("should set .garden as the default cache dir", async () => {
       const projectRoot = join(dataDir, "test-project-empty")
       const garden = await TestGarden.factory(projectRoot, { plugins: [testPlugin] })