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Johannes Konings for AWS Community Builders

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Consideration about cdk-notifier and Tags

#aws #cdk #cdknotifier

Use case

As described here Use cdk-notifier to compare changes in pull requests, the cdk-notifier displays the diff between the feature branch and the main branch. In case of using tags in the CDK there a two ways to tag resources, which will have different consequences in the diff output of the cdk-notifier.

Tagging with Tags.of()

The documentation of CDK describes the tagging of resources with the Tags.of() method: https://docs.aws.amazon.com/cdk/v2/guide/tagging.html This could look like this:

Tags.of(app).add('branch', branchName);
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https://github.com/JohannesKonings/cdk-notifier-examples/blob/746c2b2bc0ecc0ecf3e8f0e6ff771a7430a45d04/src/main.ts#L23

The tag will then be added to all resources in the synthesized cloudformation template.

{ "Resources": { "TableCD117FA1": { "Type": "AWS::DynamoDB::Table", "Properties": { "AttributeDefinitions": [ { "AttributeName": "id", "AttributeType": "S" } ], "BillingMode": "PAY_PER_REQUEST", "KeySchema": [ { "AttributeName": "id", "KeyType": "HASH" } ], "TableName": "Table-tags-tags-of", "Tags": [ { "Key": "branch", "Value": "tags-tags-of" } ] }, ... } } }
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Because the tag is in the template, it will then be shown in the diff.

diff tag of

https://github.com/JohannesKonings/cdk-notifier-examples/pull/5

Tagging with stack properties

The other way is to pass the tags as stack properties (https://docs.aws.amazon.com/cdk/api/v2/docs/aws-cdk-lib.Stack.html#tags-1). This could look like this:

new CdkNotfifierFeatureStackExample(app, `cdk-notifier-feature-stacks-${branchName}`, { tags: { branch: branchName, }, });
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https://github.com/JohannesKonings/cdk-notifier-examples/blob/66874c06b8204b09781e9ad3ab8707590b948000/src/main.ts#L23

The tag will then be added to the stack properties and not to the template file.

{ "Resources": { "TableCD117FA1": { "Type": "AWS::DynamoDB::Table", "Properties": { "AttributeDefinitions": [ { "AttributeName": "id", "AttributeType": "S" } ], "BillingMode": "PAY_PER_REQUEST", "KeySchema": [ { "AttributeName": "id", "KeyType": "HASH" } ], "TableName": "Table-tags-stack-properties", }, ... } } }
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In cdk.out the tags are only in the manifest.json file.

{ "version": "36.0.0", "artifacts": { "cdk-notifier-feature-stacks-tags-stack-properties.assets": { "type": "cdk:asset-manifest", "properties": { "file": "cdk-notifier-feature-stacks-tags-stack-properties.assets.json", "requiresBootstrapStackVersion": 6, "bootstrapStackVersionSsmParameter": "/cdk-bootstrap/hnb659fds/version" } }, "cdk-notifier-feature-stacks-tags-stack-properties": { "type": "aws:cloudformation:stack", "environment": "aws://unknown-account/unknown-region", "properties": { "templateFile": "cdk-notifier-feature-stacks-tags-stack-properties.template.json", "terminationProtection": false, "tags": { "branch": "tags-stack-properties" }, "validateOnSynth": false, ... } } } }
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Then it will not be shown in the diff, and the cdk-notifier skip the pull request comment.

check the diff to main Deploying with stack postfix main Stack cdk-notifier-feature-stacks-main Hold on while we create a read-only change set to get a diff with accurate replacement information (use --no-change-set to use a less accurate but faster template-only diff) There were no differences ✨ Number of stacks with differences: 0 create cdk-notifier report BRANCH_NAME: tags-stack-properties GITHUB_OWNER: JohannesKonings GITHUB_REPO: $(echo JohannesKonings/cdk-notifier-examples | cut -d'/' -f2) time="2024-04-20T14:59:48Z" level=info msg="There is no diff detected for tag id diff-to-main. Skip posting diff."
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https://github.com/JohannesKonings/cdk-notifier-examples/actions/runs/8765869174/job/24057331666#step:6:55

Conclusion

If you want to see the tags in the diff output of the cdk-notifier, you should use the Tags.of() method to tag the resources. If not, you can go with the stack properties.

Code

GitHub logo JohannesKonings / cdk-notifier-examples




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