fix(codebuild): correctly handle permissions for Projects inside VPC. (#2662)

A CodeBuild Project needs to have appropriate EC2 permissions on creation
when it uses a VPC. However, the default Policy that a Project Role has
depends on the Project itself (for CloudWatch Logs permissions).
Because of that, add a dependency between the Policy containing the EC2
permissions and the Project.

BREAKING CHANGE: the method addToRoleInlinePolicy in CodeBuild's Project class has been removed.

Fixes #2651
Fixes #2652

Author: skinny85

packages/@aws-cdk/aws-codebuild/README.md

@@ -77,7 +77,7 @@ import s3 = require('@aws-cdk/aws-s3');
 const bucket = new s3.Bucket(this, 'MyBucket');
 new codebuild.Project(this, 'MyProject', {
   source: codebuild.Source.s3({
-    bucket: bucket,
+    bucket,
     path: 'path/to/file.zip',
   }),
 });
@@ -138,7 +138,10 @@ With S3 caching, the cache is stored in an S3 bucket which is available from mul
 
 ```typescript
 new codebuild.Project(this, 'Project', {
-  source: new codebuild.CodePipelineSource(),
+  source: codebuild.Source.bitBucket({
+    owner: 'awslabs',
+    repo: 'aws-cdk',
+  }),
   cache: codebuild.Cache.bucket(new Bucket(this, 'Bucket'))
 });
 ```
@@ -153,7 +156,9 @@ With local caching, the cache is stored on the codebuild instance itself. CodeBu
 
 ```typescript
 new codebuild.Project(this, 'Project', {
-  source: new codebuild.CodePipelineSource(),
+  source: codebuild.Source.gitHubEnterprise({
+    httpsCloneUrl: 'https://my-github-enterprise.com/owner/repo',
+  }),
   cache: codebuild.Cache.local(LocalCacheMode.DockerLayer, LocalCacheMode.Custom)
 });
 ```
@@ -262,10 +267,10 @@ with their identifier.
 
 So, a buildspec for the above Project could look something like this:
 
-```ts
+```typescript
 const project = new codebuild.Project(this, 'MyProject', {
   // secondary sources and artifacts as above...
-  buildSpec: {
+  buildSpec: codebuild.BuildSpec.fromObject({
     version: '0.2',
     phases: {
       build: {
@@ -285,7 +290,7 @@ const project = new codebuild.Project(this, 'MyProject', {
         },
       },
     },
-  },
+  }),
 });
 ```
 
@@ -330,8 +335,10 @@ const securityGroup = new ec2.SecurityGroup(stack, 'SecurityGroup1', {
     groupName: 'MySecurityGroup',
     vpc: vpc,
 });
-new Project(stack, 'MyProject', {
-    buildScript: new assets.ZipDirectoryAsset(stack, 'Bundle', { path: 'script_bundle' }),
+new codebuild.Project(stack, 'MyProject', {
+    buildSpec: codebuild.BuildSpec.fromObject({
+      // ...
+    }),
     securityGroups: [securityGroup],
     vpc: vpc
 });

packages/@aws-cdk/aws-codebuild/lib/project.ts

@@ -5,7 +5,7 @@ import ecr = require('@aws-cdk/aws-ecr');
 import events = require('@aws-cdk/aws-events');
 import iam = require('@aws-cdk/aws-iam');
 import kms = require('@aws-cdk/aws-kms');
-import { Aws, Construct, IResource, Lazy, PhysicalName, Resource, ResourceIdentifiers, Stack } from '@aws-cdk/cdk';
+import { Aws, CfnResource, Construct, IResource, Lazy, PhysicalName, Resource, ResourceIdentifiers, Stack } from '@aws-cdk/cdk';
 import { IArtifacts } from './artifacts';
 import { BuildSpec } from './build-spec';
 import { Cache } from './cache';
@@ -699,6 +699,8 @@ export class Project extends ProjectBase {
       vpcConfig: this.configureVpc(props),
     });
 
+    this.addVpcRequiredPermissions(props, resource);
+
     const resourceIdentifiers = new ResourceIdentifiers(this, {
       arn: resource.attrArn,
       name: resource.refAsString,
@@ -718,20 +720,6 @@ export class Project extends ProjectBase {
     }
   }
 
-  /**
-   * Add a permission only if there's a policy attached.
-   * @param statement The permissions statement to add
-   */
-  public addToRoleInlinePolicy(statement: iam.PolicyStatement) {
-    if (this.role) {
-      const policy = new iam.Policy(this, 'PolicyDocument', {
-        policyName: 'CodeBuildEC2Policy',
-        statements: [statement]
-      });
-      this.role.attachInlinePolicy(policy);
-    }
-  }
-
   /**
    * Adds a secondary source to the Project.
    *
@@ -869,31 +857,55 @@ export class Project extends ProjectBase {
     }
     this._connections = new ec2.Connections({ securityGroups });
 
-    this.addToRoleInlinePolicy(new iam.PolicyStatement({
-      resources: ['*'],
-      actions: [
-        'ec2:CreateNetworkInterface', 'ec2:DescribeNetworkInterfaces',
-        'ec2:DeleteNetworkInterface', 'ec2:DescribeSubnets',
-        'ec2:DescribeSecurityGroups', 'ec2:DescribeDhcpOptions',
-        'ec2:DescribeVpcs']
-    }));
-    this.addToRolePolicy(new iam.PolicyStatement({
+    return {
+      vpcId: props.vpc.vpcId,
+      subnets: props.vpc.selectSubnets(props.subnetSelection).subnetIds,
+      securityGroupIds: this.connections.securityGroups.map(s => s.securityGroupId)
+    };
+  }
+
+  private addVpcRequiredPermissions(props: ProjectProps, project: CfnProject): void {
+    if (!props.vpc || !this.role) {
+      return;
+    }
+
+    this.role.addToPolicy(new iam.PolicyStatement({
       resources: [`arn:aws:ec2:${Aws.region}:${Aws.accountId}:network-interface/*`],
       actions: ['ec2:CreateNetworkInterfacePermission'],
       conditions: {
         StringEquals: {
-          "ec2:Subnet": props.vpc
+          'ec2:Subnet': props.vpc
             .selectSubnets(props.subnetSelection).subnetIds
             .map(si => `arn:aws:ec2:${Aws.region}:${Aws.accountId}:subnet/${si}`),
-          "ec2:AuthorizedService": "codebuild.amazonaws.com"
-        }
-      }
+          'ec2:AuthorizedService': 'codebuild.amazonaws.com'
+        },
+      },
     }));
-    return {
-      vpcId: props.vpc.vpcId,
-      subnets: props.vpc.selectSubnets(props.subnetSelection).subnetIds,
-      securityGroupIds: this.connections.securityGroups.map(s => s.securityGroupId)
-    };
+
+    const policy = new iam.Policy(this, 'PolicyDocument', {
+      policyName: 'CodeBuildEC2Policy',
+      statements: [
+        new iam.PolicyStatement({
+          resources: ['*'],
+          actions: [
+            'ec2:CreateNetworkInterface',
+            'ec2:DescribeNetworkInterfaces',
+            'ec2:DeleteNetworkInterface',
+            'ec2:DescribeSubnets',
+            'ec2:DescribeSecurityGroups',
+            'ec2:DescribeDhcpOptions',
+            'ec2:DescribeVpcs',
+          ],
+        }),
+      ],
+    });
+    this.role.attachInlinePolicy(policy);
+
+    // add an explicit dependency between the EC2 Policy and this Project -
+    // otherwise, creating the Project fails,
+    // as it requires these permissions to be already attached to the Project's Role
+    const cfnPolicy = policy.node.findChild('Resource') as CfnResource;
+    project.addDependsOn(cfnPolicy);
   }
 
   private validateCodePipelineSettings(artifacts: IArtifacts) {

packages/@aws-cdk/aws-codebuild/test/integ.project-vpc.expected.json

@@ -423,7 +423,10 @@
             "Ref": "MyVPCAFB07A31"
           }
         }
-      }
+      },
+      "DependsOn": [
+        "MyProjectPolicyDocument646EE0F2"
+      ]
     }
   }
 }

packages/@aws-cdk/aws-codebuild/test/test.project.ts

@@ -1,4 +1,6 @@
 import { expect, haveResource, haveResourceLike, not } from '@aws-cdk/assert';
+import ec2 = require('@aws-cdk/aws-ec2');
+import iam = require('@aws-cdk/aws-iam');
 import { Bucket } from '@aws-cdk/aws-s3';
 import cdk = require('@aws-cdk/cdk');
 import { Test } from 'nodeunit';
@@ -232,4 +234,25 @@ export = {
 
     test.done();
   },
+
+  'can use an imported Role for a Project within a VPC'(test: Test) {
+    const stack = new cdk.Stack();
+
+    const importedRole = iam.Role.fromRoleArn(stack, 'Role', 'arn:aws:iam::1234567890:role/service-role/codebuild-bruiser-service-role');
+    const vpc = new ec2.Vpc(stack, 'Vpc');
+
+    new codebuild.Project(stack, 'Project', {
+      source: codebuild.Source.gitHubEnterprise({
+        httpsCloneUrl: 'https://mygithub-enterprise.com/myuser/myrepo',
+      }),
+      role: importedRole,
+      vpc,
+    });
+
+    expect(stack).to(haveResourceLike('AWS::CodeBuild::Project', {
+      // no need to do any assertions
+    }));
+
+    test.done();
+  },
 };