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fix(appconfig): scope generated alarm role policy to '*' for composite alarm support #29171

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merged 11 commits into from
Feb 20, 2024
Merged

fix(appconfig): scope generated alarm role policy to '*' for composite alarm support #29171

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e3f1873
fix(appconfig): correctly scope composite alarm policy to '*'
chenjane-dev Feb 19, 2024
24577ff
fix(appconfig): scope generated alarm role policy to '*' for composit…
chenjane-dev Feb 19, 2024
41c3922
rename private method
chenjane-dev Feb 19, 2024
0f0b773
update integ tests and add reasoning for full scope policy
chenjane-dev Feb 20, 2024
3c1ef5b
Merge branch 'main' into composite-alarm
chenjane-dev Feb 20, 2024
8f419ff
update role logical id
chenjane-dev Feb 20, 2024
c07e6ea
fix eslint
chenjane-dev Feb 20, 2024
316d421
Merge branch 'aws:main' into composite-alarm
chenjane-dev Feb 20, 2024
c393c86
update integ tests and add reasoning for full scope policy
chenjane-dev Feb 20, 2024
b778fb4
fix eslint
chenjane-dev Feb 20, 2024
7aa65c9
update snapshot
chenjane-dev Feb 20, 2024
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24 changes: 10 additions & 14 deletions packages/@aws-cdk/aws-appconfig-alpha/lib/environment.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -5,6 +5,7 @@ import * as iam from 'aws-cdk-lib/aws-iam';
import { Construct } from 'constructs';
import { IApplication } from './application';
import { ActionPoint, IEventDestination, ExtensionOptions, IExtension, IExtensible, ExtensibleBase } from './extension';
import { getHash } from './private/hash';

/**
* Attributes of an existing AWS AppConfig environment to import it.
Expand Down Expand Up @@ -252,11 +253,11 @@ export class Environment extends EnvironmentBase {
applicationId: this.applicationId,
name: this.name,
description: this.description,
monitors: this.monitors?.map((monitor, index) => {
monitors: this.monitors?.map((monitor) => {
return {
alarmArn: monitor.alarmArn,
...(monitor.monitorType === MonitorType.CLOUDWATCH
? { alarmRoleArn: monitor.alarmRoleArn || this.createAlarmRole(monitor, index).roleArn }
? { alarmRoleArn: monitor.alarmRoleArn || this.createOrGetAlarmRole().roleArn }
: { alarmRoleArn: monitor.alarmRoleArn }),
};
}),
Expand All @@ -274,24 +275,20 @@ export class Environment extends EnvironmentBase {
this.application.addExistingEnvironment(this);
}

private createAlarmRole(monitor: Monitor, index: number): iam.IRole {
const logicalId = monitor.isCompositeAlarm ? 'RoleCompositeAlarm' : `Role${index}`;
private createOrGetAlarmRole(): iam.IRole {
// the name is guaranteed to be set in line 243
const logicalId = `Role${getHash(this.name!)}`;
const existingRole = this.node.tryFindChild(logicalId) as iam.IRole;
if (existingRole) {
return existingRole;
}
const alarmArn = monitor.isCompositeAlarm
? this.stack.formatArn({
service: 'cloudwatch',
resource: 'alarm',
resourceName: '*',
arnFormat: ArnFormat.COLON_RESOURCE_NAME,
})
: monitor.alarmArn;
// this scope is fine for cloudwatch:DescribeAlarms since it is readonly
// and it is required for composite alarms
// https://docs.aws.amazon.com/AmazonCloudWatch/latest/APIReference/API_DescribeAlarms.html
const policy = new iam.PolicyStatement({
effect: iam.Effect.ALLOW,
actions: ['cloudwatch:DescribeAlarms'],
resources: [alarmArn],
resources: ['*'],
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Why '*' and not monitor.alarmArn? I don't like the default to all resources from a security perspective, so if this has to stay, we have to document exactly why we are doing it this way. * sends off alarm bells in a lot of customer use cases.

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The integ test already tests this because there is only one policy being created now with resource set to *.

Yeah, I discussed this with a senior engineer on my team and it is only being scoped to all resources for DescribeAlarms so I think this should be okay. But, after doing some personal testing, I found out that the original policy we had for composite alarms actually works when scoped narrower than * so the CW docs must be incorrect here. We could change this to that if you want too

https://docs.aws.amazon.com/AmazonCloudWatch/latest/APIReference/API_DescribeAlarms.html

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@kaizencc kaizencc Feb 20, 2024 •
edited
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re: integ test

the test checks if the policy is being created with the resource set to *. it does not yet test that that policy can be used successfully. i argue that the latter is the important part, the former is simply a unit test.

edit: you know what I'm fine with this as is. disregard the above statement.

re: resource

since it is just a scope for describeAlarms, i.e. a readonly prop, we should be fine with *. Can you document in the code that we are okay with this for the readonly permissions and link to the doc page?

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updated

});
const document = new iam.PolicyDocument({
statements: [policy],
Expand Down Expand Up @@ -338,7 +335,6 @@ export abstract class Monitor {
alarmArn: alarm.alarmArn,
alarmRoleArn: alarmRole?.roleArn,
monitorType: MonitorType.CLOUDWATCH,
isCompositeAlarm: alarm instanceof cloudwatch.CompositeAlarm,
};
}

Expand Down
80 changes: 37 additions & 43 deletions packages/@aws-cdk/aws-appconfig-alpha/test/environment.test.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -140,7 +140,7 @@ describe('environment', () => {
},
AlarmRoleArn: {
'Fn::GetAtt': [
'MyEnvironmentRole01C8C013F',
'MyEnvironmentRole1E6113D2F07A1',
'Arn',
],
},
Expand All @@ -154,12 +154,7 @@ describe('environment', () => {
Statement: [
{
Effect: iam.Effect.ALLOW,
Resource: {
'Fn::GetAtt': [
'Alarm7103F465',
'Arn',
],
},
Resource: '*',
Action: 'cloudwatch:DescribeAlarms',
},
],
Expand Down Expand Up @@ -272,7 +267,7 @@ describe('environment', () => {
},
AlarmRoleArn: {
'Fn::GetAtt': [
'MyEnvironmentRoleCompositeAlarm8C2A0542',
'MyEnvironmentRole1E6113D2F07A1',
'Arn',
],
},
Expand All @@ -286,20 +281,7 @@ describe('environment', () => {
Statement: [
{
Effect: iam.Effect.ALLOW,
Resource: {
'Fn::Join': [
'',
[
'arn:',
{ Ref: 'AWS::Partition' },
':cloudwatch:',
{ Ref: 'AWS::Region' },
':',
{ Ref: 'AWS::AccountId' },
':alarm:*',
],
],
},
Resource: '*',
Action: 'cloudwatch:DescribeAlarms',
},
],
Expand Down Expand Up @@ -357,7 +339,7 @@ describe('environment', () => {
},
AlarmRoleArn: {
'Fn::GetAtt': [
'MyEnvironmentRoleCompositeAlarm8C2A0542',
'MyEnvironmentRole1E6113D2F07A1',
'Arn',
],
},
Expand All @@ -371,7 +353,7 @@ describe('environment', () => {
},
AlarmRoleArn: {
'Fn::GetAtt': [
'MyEnvironmentRoleCompositeAlarm8C2A0542',
'MyEnvironmentRole1E6113D2F07A1',
'Arn',
],
},
Expand All @@ -385,20 +367,7 @@ describe('environment', () => {
Statement: [
{
Effect: iam.Effect.ALLOW,
Resource: {
'Fn::Join': [
'',
[
'arn:',
{ Ref: 'AWS::Partition' },
':cloudwatch:',
{ Ref: 'AWS::Region' },
':',
{ Ref: 'AWS::AccountId' },
':alarm:*',
],
],
},
Resource: '*',
Action: 'cloudwatch:DescribeAlarms',
},
],
Expand All @@ -409,7 +378,7 @@ describe('environment', () => {
});
});

test('environment with monitors with two alarms', () => {
test('environment with monitors with multiple alarms', () => {
const stack = new cdk.Stack();
const app = new Application(stack, 'MyAppConfig');
const alarm1 = new Alarm(stack, 'Alarm1', {
Expand All @@ -432,17 +401,28 @@ describe('environment', () => {
},
),
});
const alarm3 = new Alarm(stack, 'Alarm3', {
threshold: 5,
evaluationPeriods: 5,
metric: new Metric(
{
namespace: 'aws',
metricName: 'myMetric',
},
),
});
new Environment(stack, 'MyEnvironment', {
environmentName: 'TestEnv',
application: app,
monitors: [
Monitor.fromCloudWatchAlarm(alarm1),
Monitor.fromCloudWatchAlarm(alarm2),
Monitor.fromCloudWatchAlarm(alarm3),
],
});

Template.fromStack(stack).resourceCountIs('AWS::CloudWatch::Alarm', 2);
Template.fromStack(stack).resourceCountIs('AWS::IAM::Role', 2);
Template.fromStack(stack).resourceCountIs('AWS::CloudWatch::Alarm', 3);
Template.fromStack(stack).resourceCountIs('AWS::IAM::Role', 1);
Template.fromStack(stack).hasResourceProperties('AWS::AppConfig::Environment', {
Name: 'TestEnv',
ApplicationId: {
Expand All @@ -458,7 +438,7 @@ describe('environment', () => {
},
AlarmRoleArn: {
'Fn::GetAtt': [
'MyEnvironmentRole01C8C013F',
'MyEnvironmentRole1E6113D2F07A1',
'Arn',
],
},
Expand All @@ -472,7 +452,21 @@ describe('environment', () => {
},
AlarmRoleArn: {
'Fn::GetAtt': [
'MyEnvironmentRole135A2CEE4',
'MyEnvironmentRole1E6113D2F07A1',
'Arn',
],
},
},
{
AlarmArn: {
'Fn::GetAtt': [
'Alarm32341D8D9',
'Arn',
],
},
AlarmRoleArn: {
'Fn::GetAtt': [
'MyEnvironmentRole1E6113D2F07A1',
'Arn',
],
},
Expand Down
2 changes: 1 addition & 1 deletion ...g.environment.js.snapshot/appconfigenvironmentDefaultTestDeployAssert75BD28E7.assets.json
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6 changes: 3 additions & 3 deletions ...-appconfig-alpha/test/integ.environment.js.snapshot/aws-appconfig-environment.assets.json
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