feat(cli): CcApi context provider can be configured to fail if listing does not find a specific count of resources (#251)

Fixes #257

As described in the issue, `CcApiContextProviderPlugin` should have the
way to ensure the result has exact one resource.

This PR adds the `expectedMatchCount` option to restrict the length of
results in `listResources()`.

Unit tests are added and modified ensure the changes.

---
By submitting this pull request, I confirm that my contribution is made
under the terms of the Apache-2.0 license

---------

Co-authored-by: Rico Huijbers <[email protected]>

Author: Tietew

packages/@aws-cdk/cloud-assembly-schema/lib/cloud-assembly/context-queries.ts

@@ -355,20 +355,20 @@ export interface KeyContextQuery extends ContextLookupRoleOptions {
 }
 
 /**
- * Query input for lookup up Cloudformation resources using CC API
+ * Query input for lookup up CloudFormation resources using CC API
  */
 export interface CcApiContextQuery extends ContextLookupRoleOptions {
   /**
-   * The Cloudformation resource type.
+   * The CloudFormation resource type.
    * See https://docs.aws.amazon.com/cloudcontrolapi/latest/userguide/supported-resources.html
    */
   readonly typeName: string;
 
   /**
    * Identifier of the resource to look up using `GetResource`.
    *
-   * Specifying exactIdentifier will return exactly one result, or throw an error.
-   *
+   * Specifying exactIdentifier will return exactly one result, or throw an error
+   * unless `ignoreErrorOnMissingContext` is set.
    *
    * @default - Either exactIdentifier or propertyMatch should be specified.
    */
@@ -377,7 +377,10 @@ export interface CcApiContextQuery extends ContextLookupRoleOptions {
   /**
    * Returns any resources matching these properties, using `ListResources`.
    *
-   * Specifying propertyMatch will return 0 or more results.
+   * By default, specifying propertyMatch will successfully return 0 or more
+   * results. To throw an error if the number of results is unexpected (and
+   * prevent the query results from being committed to context), specify
+   * `expectedMatchCount`.
    *
    * ## Notes on property completeness
    *
@@ -413,6 +416,23 @@ export interface CcApiContextQuery extends ContextLookupRoleOptions {
    */
   readonly propertiesToReturn: string[];
 
+  /**
+   * Expected count of results if `propertyMatch` is specified.
+   *
+   * If the expected result count does not match the actual count,
+   * by default an error is produced and the result is not committed to cached
+   * context, and the user can correct the situation and try again without
+   * having to manually clear out the context key using `cdk context --remove`
+   *
+   * If the value of * `ignoreErrorOnMissingContext` is `true`, the value of
+   * `expectedMatchCount` is `at-least-one | exactly-one` and the number
+   * of found resources is 0, `dummyValue` is returned and committed to context
+   * instead.
+   *
+   * @default 'any'
+   */
+  readonly expectedMatchCount?: 'any' | 'at-least-one' | 'at-most-one' | 'exactly-one';
+
   /**
    * The value to return if the resource was not found and `ignoreErrorOnMissingContext` is true.
    *
@@ -432,8 +452,8 @@ export interface CcApiContextQuery extends ContextLookupRoleOptions {
    *
    * - In case of an `exactIdentifier` lookup, return the `dummyValue` if the resource with
    *   that identifier was not found.
-   * - In case of a `propertyMatch` lookup, this setting currently does not have any effect,
-   *   as `propertyMatch` queries can legally return 0 resources.
+   * - In case of a `propertyMatch` lookup, return the `dummyValue` if `expectedMatchCount`
+   *   is `at-least-one | exactly-one` and the number of resources found was 0.
    *
    * if `ignoreErrorOnMissingContext` is set, `dummyValue` should be set and be an array.
    *

packages/@aws-cdk/cloud-assembly-schema/schema/cloud-assembly.schema.json

@@ -1024,19 +1024,19 @@
             ]
         },
         "CcApiContextQuery": {
-            "description": "Query input for lookup up Cloudformation resources using CC API",
+            "description": "Query input for lookup up CloudFormation resources using CC API",
             "type": "object",
             "properties": {
                 "typeName": {
-                    "description": "The Cloudformation resource type.\nSee https://docs.aws.amazon.com/cloudcontrolapi/latest/userguide/supported-resources.html",
+                    "description": "The CloudFormation resource type.\nSee https://docs.aws.amazon.com/cloudcontrolapi/latest/userguide/supported-resources.html",
                     "type": "string"
                 },
                 "exactIdentifier": {
-                    "description": "Identifier of the resource to look up using `GetResource`.\n\nSpecifying exactIdentifier will return exactly one result, or throw an error. (Default - Either exactIdentifier or propertyMatch should be specified.)",
+                    "description": "Identifier of the resource to look up using `GetResource`.\n\nSpecifying exactIdentifier will return exactly one result, or throw an error\nunless `ignoreErrorOnMissingContext` is set. (Default - Either exactIdentifier or propertyMatch should be specified.)",
                     "type": "string"
                 },
                 "propertyMatch": {
-                    "description": "Returns any resources matching these properties, using `ListResources`.\n\nSpecifying propertyMatch will return 0 or more results.\n\n## Notes on property completeness\n\nCloudControl API's `ListResources` may return fewer properties than\n`GetResource` would, depending on the resource implementation.\n\nThe resources that `propertyMatch` matches against will *only ever* be the\nproperties returned by the `ListResources` call. (Default - Either exactIdentifier or propertyMatch should be specified.)",
+                    "description": "Returns any resources matching these properties, using `ListResources`.\n\nBy default, specifying propertyMatch will successfully return 0 or more\nresults. To throw an error if the number of results is unexpected (and\nprevent the query results from being committed to context), specify\n`expectedMatchCount`.\n\n## Notes on property completeness\n\nCloudControl API's `ListResources` may return fewer properties than\n`GetResource` would, depending on the resource implementation.\n\nThe resources that `propertyMatch` matches against will *only ever* be the\nproperties returned by the `ListResources` call. (Default - Either exactIdentifier or propertyMatch should be specified.)",
                     "$ref": "#/definitions/Record<string,unknown>"
                 },
                 "propertiesToReturn": {
@@ -1046,11 +1046,21 @@
                         "type": "string"
                     }
                 },
+                "expectedMatchCount": {
+                    "description": "Expected count of results if `propertyMatch` is specified.\n\nIf the expected result count does not match the actual count,\nby default an error is produced and the result is not committed to cached\ncontext, and the user can correct the situation and try again without\nhaving to manually clear out the context key using `cdk context --remove`\n\nIf the value of * `ignoreErrorOnMissingContext` is `true`, the value of\n`expectedMatchCount` is `at-least-one | exactly-one` and the number\nof found resources is 0, `dummyValue` is returned and committed to context\ninstead. (Default 'any')",
+                    "enum": [
+                        "any",
+                        "at-least-one",
+                        "at-most-one",
+                        "exactly-one"
+                    ],
+                    "type": "string"
+                },
                 "dummyValue": {
                     "description": "The value to return if the resource was not found and `ignoreErrorOnMissingContext` is true.\n\nIf supplied, `dummyValue` should be an array of objects.\n\n`dummyValue` does not have to have elements, and it may have objects with\ndifferent properties than the properties in `propertiesToReturn`, but it\nwill be easiest for downstream code if the `dummyValue` conforms to\nthe expected response shape. (Default - No dummy value available)"
                 },
                 "ignoreErrorOnMissingContext": {
-                    "description": "Ignore an error and return the `dummyValue` instead if the resource was not found.\n\n- In case of an `exactIdentifier` lookup, return the `dummyValue` if the resource with\n  that identifier was not found.\n- In case of a `propertyMatch` lookup, this setting currently does not have any effect,\n  as `propertyMatch` queries can legally return 0 resources.\n\nif `ignoreErrorOnMissingContext` is set, `dummyValue` should be set and be an array.",
+                    "description": "Ignore an error and return the `dummyValue` instead if the resource was not found.\n\n- In case of an `exactIdentifier` lookup, return the `dummyValue` if the resource with\n  that identifier was not found.\n- In case of a `propertyMatch` lookup, return the `dummyValue` if `expectedMatchCount`\n  is `at-least-one | exactly-one` and the number of resources found was 0.\n\nif `ignoreErrorOnMissingContext` is set, `dummyValue` should be set and be an array.",
                     "default": false,
                     "type": "boolean"
                 },

packages/@aws-cdk/cloud-assembly-schema/schema/version.json

@@ -1,4 +1,4 @@
 {
-  "schemaHash": "5683db246fac20b864d94d7bceef24ebda1a38c8c1f8ef0d5978534097dc9504",
-  "revision": 42
+  "schemaHash": "78936b0f9299bbe47497dd77f8065d71e65d8d739a0413ad7698ad03b22ef83e",
+  "revision": 43
 }

packages/aws-cdk/lib/context-providers/cc-api-provider.ts

@@ -39,7 +39,7 @@ export class CcApiContextProviderPlugin implements ContextProviderPlugin {
         resources = await this.getResource(cloudControl, args.typeName, args.exactIdentifier);
       } else if (args.propertyMatch) {
         // use listResource
-        resources = await this.listResources(cloudControl, args.typeName, args.propertyMatch);
+        resources = await this.listResources(cloudControl, args.typeName, args.propertyMatch, args.expectedMatchCount);
       } else {
         throw new ContextProviderError(`Provider protocol error: neither exactIdentifier nor propertyMatch is specified in ${JSON.stringify(args)}.`);
       }
@@ -98,6 +98,7 @@ export class CcApiContextProviderPlugin implements ContextProviderPlugin {
     cc: ICloudControlClient,
     typeName: string,
     propertyMatch: Record<string, unknown>,
+    expectedMatchCount?: CcApiContextQuery['expectedMatchCount'],
   ): Promise<FoundResource[]> {
     try {
       const result = await cc.listResources({
@@ -113,6 +114,13 @@ export class CcApiContextProviderPlugin implements ContextProviderPlugin {
           });
         });
 
+      if ((expectedMatchCount === 'at-least-one' || expectedMatchCount === 'exactly-one') && found.length === 0) {
+        throw new ZeroResourcesFoundError(`Could not find any resources matching ${JSON.stringify(propertyMatch)}`);
+      }
+      if ((expectedMatchCount === 'at-most-one' || expectedMatchCount === 'exactly-one') && found.length > 1) {
+        throw new ContextProviderError(`Found ${found.length} resources matching ${JSON.stringify(propertyMatch)}; please narrow the search criteria`);
+      }
+
       return found;
     } catch (err: any) {
       if (!(err instanceof ContextProviderError) && !(err instanceof ZeroResourcesFoundError)) {

packages/aws-cdk/test/context-providers/cc-api-provider.test.ts

@@ -4,6 +4,14 @@ import { mockCloudControlClient, MockSdkProvider, restoreSdkMocksToDefault } fro
 
 let provider: CcApiContextProviderPlugin;
 
+const INDIFFERENT_PROPERTYMATCH_PROPS = {
+  account: '123456789012',
+  region: 'us-east-1',
+  typeName: 'AWS::RDS::DBInstance',
+  propertyMatch: { },
+  propertiesToReturn: ['Index'],
+};
+
 beforeEach(() => {
   provider = new CcApiContextProviderPlugin(new MockSdkProvider());
   restoreSdkMocksToDefault();
@@ -180,6 +188,87 @@ test('looks up RDS instance using CC API listResources - error in CC API', async
   ).rejects.toThrow('error while listing AWS::RDS::DBInstance resources'); // THEN
 });
 
+test.each([
+  [undefined],
+  ['any'],
+  ['at-most-one'],
+] as const)('return an empty array for empty result when expectedMatchCount is %s', async (expectedMatchCount) => {
+  // GIVEN
+  mockCloudControlClient.on(ListResourcesCommand).resolves({
+    ResourceDescriptions: [
+      { Identifier: 'pl-xxxx', Properties: '{"PrefixListName":"name1","PrefixListId":"pl-xxxx","OwnerId":"123456789012"}' },
+      { Identifier: 'pl-yyyy', Properties: '{"PrefixListName":"name1","PrefixListId":"pl-yyyy","OwnerId":"234567890123"}' },
+      { Identifier: 'pl-zzzz', Properties: '{"PrefixListName":"name2","PrefixListId":"pl-zzzz","OwnerId":"123456789012"}' },
+    ],
+  });
+
+  // WHEN
+  const results = await provider.getValue({
+    account: '123456789012',
+    region: 'us-east-1',
+    typeName: 'AWS::EC2::PrefixList',
+    propertyMatch: { PrefixListName: 'name3' },
+    propertiesToReturn: ['PrefixListId'],
+    expectedMatchCount,
+  });
+
+  // THEN
+  expect(results.length).toEqual(0);
+});
+
+
+test.each([
+  ['at-least-one'],
+  ['exactly-one']
+] as const)('throws an error for empty result when expectedMatchCount is %s', async (expectedMatchCount) => {
+  // GIVEN
+  mockCloudControlClient.on(ListResourcesCommand).resolves({
+    ResourceDescriptions: [
+      { Identifier: 'pl-xxxx', Properties: '{"PrefixListName":"name1","PrefixListId":"pl-xxxx","OwnerId":"123456789012"}' },
+      { Identifier: 'pl-yyyy', Properties: '{"PrefixListName":"name1","PrefixListId":"pl-yyyy","OwnerId":"234567890123"}' },
+      { Identifier: 'pl-zzzz', Properties: '{"PrefixListName":"name2","PrefixListId":"pl-zzzz","OwnerId":"123456789012"}' },
+    ],
+  });
+
+  await expect(
+    // WHEN
+    provider.getValue({
+      account: '123456789012',
+      region: 'us-east-1',
+      typeName: 'AWS::EC2::PrefixList',
+      propertyMatch: { PrefixListName: 'name3' },
+      propertiesToReturn: ['PrefixListId'],
+      expectedMatchCount,
+    }),
+  ).rejects.toThrow('Could not find any resources matching {"PrefixListName":"name3"}'); // THEN
+});
+
+test.each([
+  ['at-most-one'],
+  ['exactly-one']
+] as const)('throws an error for multiple results when expectedMatchCount is %s', async (expectedMatchCount) => {
+  // GIVEN
+  mockCloudControlClient.on(ListResourcesCommand).resolves({
+    ResourceDescriptions: [
+      { Identifier: 'pl-xxxx', Properties: '{"PrefixListName":"name1","PrefixListId":"pl-xxxx","OwnerId":"123456789012"}' },
+      { Identifier: 'pl-yyyy', Properties: '{"PrefixListName":"name1","PrefixListId":"pl-yyyy","OwnerId":"234567890123"}' },
+      { Identifier: 'pl-zzzz', Properties: '{"PrefixListName":"name2","PrefixListId":"pl-zzzz","OwnerId":"123456789012"}' },
+    ],
+  });
+
+  await expect(
+    // WHEN
+    provider.getValue({
+      account: '123456789012',
+      region: 'us-east-1',
+      typeName: 'AWS::EC2::PrefixList',
+      propertyMatch: { PrefixListName: 'name1' },
+      propertiesToReturn: ['PrefixListId'],
+      expectedMatchCount,
+    }),
+  ).rejects.toThrow('Found 2 resources matching {"PrefixListName":"name1"}'); // THEN
+});
+
 test('error by specifying both exactIdentifier and propertyMatch', async () => {
   // GIVEN
   mockCloudControlClient.on(GetResourceCommand).resolves({
@@ -425,6 +514,43 @@ describe('dummy value', () => {
       }),
     ).rejects.toThrow('dummyValue must be an array of objects');
   });
+
+  test.each(['at-least-one', 'exactly-one'] as const)('dummyValue is returned when list operation returns 0 values for expectedMatchCount %p', async (expectedMatchCount) => {
+    // GIVEN
+    mockCloudControlClient.on(ListResourcesCommand).resolves({
+      ResourceDescriptions: []
+    });
+
+    // WHEN/THEN
+    await expect(
+      provider.getValue({
+        ...INDIFFERENT_PROPERTYMATCH_PROPS,
+        expectedMatchCount,
+        ignoreErrorOnMissingContext: true,
+        dummyValue: [{ Dummy: true }],
+      }),
+    ).resolves.toEqual([{ Dummy: true }]);
+  });
+
+  test('ignoreErrorOnMissingContext does not suppress errors for at-most-one', async () => {
+    // GIVEN
+    mockCloudControlClient.on(ListResourcesCommand).resolves({
+      ResourceDescriptions: [
+        { Properties: JSON.stringify({ Index: 1 }) },
+        { Properties: JSON.stringify({ Index: 2 }) },
+      ]
+    });
+
+    // WHEN/THEN
+    await expect(
+      provider.getValue({
+        ...INDIFFERENT_PROPERTYMATCH_PROPS,
+        expectedMatchCount: 'at-most-one',
+        ignoreErrorOnMissingContext: true,
+        dummyValue: [{ Dummy: true }],
+      }),
+    ).rejects.toThrow(/Found 2 resources matching/);
+  });
 });
 /* eslint-enable */