aws-cdk: cdk 2.1.0 synth, diff subcommands fail with "AssertDescription: CDK bootstrap stack version 6 required...". cdk 2.1.0 deploy subcommand succeeds.

IF YOU ARE COMING HERE AND STILL NOT UNDERSTANDING THIS THREAD (because you scrolled too fast, like me, and missed @chesterm8’s write up)

This is NOT an error. YOUR CODE IS FINE.

The cdk synth step creates a number of resources for your app. One of those resources is a check that the deploying tool has the correct version. This is an error that would happen, IF you ran cdk deploy with an out-of-date bootstrap. The AssertDescription would then be the error shown at that point.

This is a “UX” bug because it happens to be the last thing in the diff for the stack after synth, and it catches you unaware and takes a minute to parse out.

There is an “easy” fix - print “CDK synth succeeded” on stderr and exit 0 as the last step of synth.

This is a pretty confusing thing to see when just starting with CDK. I get it now, but I would still consider it a UX bug.

As per the comment above https://github.com/aws/aws-cdk/issues/17942#issuecomment-992295898 this is not a bug/issue that needs to be fixed or worked around. The text being seen is the error message that would get printed if there were a CDK version issue. You are seeing it because you have printed out the contents of your CF stack and it is stored in there as a string.

It is very clearly a confusing UX situation that should be resolved, but you don’t need to start turning off CDK features to get rid of this part of your CDK stack.

I just had a fresh install of aws-cdk 2.25.0 from cdk init app --language typescript confirmed problem still exist.

...
Rules:
  CheckBootstrapVersion:
    Assertions:
      - Assert:
          Fn::Not:
            - Fn::Contains:
                - - "1"
                  - "2"
                  - "3"
                  - "4"
                  - "5"
                - Ref: BootstrapVersion
        AssertDescription: CDK bootstrap stack version 6 required. Please run 'cdk bootstrap' with a recent version of the CDK CLI.

from @njlynch’s comment https://github.com/aws/aws-cdk/issues/17942#issuecomment-992295898

It will show up in the diff until it is deployed, and then will only show up if there’s a change, same as any other CloudFormation template element.

For the assertion issue also happen in cdk synth. So it is impossible to do the first deploy before I want to confirm what to be deployed by studying the output of cdk synth (synthesized CloudFormation template).

Workaround for typescript

For those who want to check the result before the first deploy, I suggest to temporarily add "@aws-cdk/core:newStyleStackSynthesis": false in your cdk.json

  "context": {
    "@aws-cdk/aws-apigateway:usagePlanKeyOrderInsensitiveId": true,
    "@aws-cdk/core:stackRelativeExports": true,
    "@aws-cdk/aws-rds:lowercaseDbIdentifier": true,
    "@aws-cdk/aws-lambda:recognizeVersionProps": true,
    "@aws-cdk/aws-cloudfront:defaultSecurityPolicyTLSv1.2_2021": true,
    "@aws-cdk-containers/ecs-service-extensions:enableDefaultLogDriver": true,
    "@aws-cdk/aws-ec2:uniqueImdsv2TemplateName": true,
    "@aws-cdk/core:checkSecretUsage": true,
    "@aws-cdk/aws-iam:minimizePolicies": true,
+    "@aws-cdk/core:newStyleStackSynthesis": false,
    "@aws-cdk/core:target-partitions": [
      "aws",
      "aws-cn"
    ]
  }

After that, I can get the output

Allow me to communicate that this “error”, has wasted many valuable minutes of my life.

Correction - cdk diff may not failing. It reports the cdk version check rule under “Other Changes”, at the end of its output. The output looks good otherwise. […] I had interpreted that as failure. Maybe it’s not. Would mind chiming in on this and clarifying the purpose of always seeing this new CheckBootstrapVersion rule going forward? Thanks!

CDK v2 enables the “new-style stack synthesizer” by default (e.g., DefaultStackSynthesizer), which was previously enabled for v1 by setting the @aws-cdk/core:newStyleStackSynthesis feature flag. The DefaultStackSynthesizer uses conventionally named roles and concrete asset storage locations, versus the LegacyStackSynthesizer, which has restricted cross-environment abilities and uses CloudFormation parameters for assets.

With the default synthesizer, the CheckBootstrapVersion rule is added to the Stack’s template as a safety check, to verify that the bootstrap stack in the target environment meets the minimum requirements of the current stack. The AssertDescription being shown is the failure message a user would see on deploy if their bootstrap stack was not up-to-date. The inclusion of this element is not a failure, merely a new element for stacks that are being upgraded from the legacy synthesizer. It will show up in the diff until it is deployed, and then will only show up if there’s a change, same as any other CloudFormation template element.

Hope that helps! Let me know if you have any follow-ups on that.

Hahaha this is a very weird things. It took me some time to realize it wasnt an error and merely an attribute value. I highly recommend it not being the last line on the console

This is very confusing. I’ve read through the thread and here is what I think I’ve learned. Please correct me if I’m wrong.

The message Please run 'cdk bootstrap' with a recent version of the CDK CLI. in the output is not a warning or error being generated as a result of the command being run currently. Instead it is the content of an assertion that is being added to the stack to detect potential problems in the future. So in the future if an out-of-date version is detected, this message will be shown.

This is a pretty confusing thing to see when just starting with CDK. I get it now, but I would still consider it a UX bug.

same here, created new stack and seeing this warning is weird dev experience.

One more necrobump… I had “this problem” with a pipelines stack that worked from from cli cdk deploy. In this case, the cdk project was in a subdirectory of the project and while I was building fine because I included in the commands cd cdk-dir I forgot to update the primaryOutputDirectory as well and overlooked the reason the build was failing.

        primaryOutputDirectory: 'cdk-build/cdk.out',   <--- forgot this
        commands: [
          'cd cdk-build',
          'npm ci',
          'npm run build',
          'npx cdk synth',
        ],

cdk deploy is helpfully printing the error message it would have printed had there actually been an error? That’s very, um, proactive?

IF YOU ARE COMING HERE AND STILL NOT UNDERSTANDING THIS THREAD (because you scrolled too fast, like me, and missed @chesterm8’s write up)

This is NOT an error. YOUR CODE IS FINE.

The cdk synth step creates a number of resources for your app. One of those resources is a check that the deploying tool has the correct version. This is an error that would happen, IF you ran cdk deploy with an out-of-date bootstrap. The AssertDescription would then be the error shown at that point.

This is a “UX” bug because it happens to be the last thing in the diff for the stack after synth, and it catches you unaware and takes a minute to parse out.

There is an “easy” fix - print “CDK synth succeeded” on stderr and exit 0 as the last step of synth.

There is an ‘easier’ fix - For AWS to stop publishing tools that mislead and confuse, and to do the job that all AWS customers pay them for.

@robertd thanks. My issue is that the feature seems not to be working correctly. The version check is “bootstrap version is not 1, 2, 3, 4, 5”, i.e. version is >= 6. My bootstrap version is 9 (verified by inspecting the SSM parameter …/cdk-bootstrap/hnb659fds/version). So I should pass this check. But I am failing it. So the cdk variable “BootstrapVersion” that synch is checking must have the value 1, or 2, or 3, or 4, or 5. That value would be wrong.

Does that make sense? Thanks.

This documentation needs to be updated to reflect the actual user experience. https://docs.aws.amazon.com/cdk/v2/guide/hello_world.html

2024 and i just got the “error” and came here to understand how it works LOL

Correction - cdk diff may not failing. It reports the cdk version check rule under “Other Changes”, at the end of its output. The output looks good otherwise. […] I had interpreted that as failure. Maybe it’s not. Would mind chiming in on this and clarifying the purpose of always seeing this new CheckBootstrapVersion rule going forward? Thanks!

CDK v2 enables the “new-style stack synthesizer” by default (e.g., DefaultStackSynthesizer), which was previously enabled for v1 by setting the @aws-cdk/core:newStyleStackSynthesis feature flag. The DefaultStackSynthesizer uses conventionally named roles and concrete asset storage locations, versus the LegacyStackSynthesizer, which has restricted cross-environment abilities and uses CloudFormation parameters for assets.

With the default synthesizer, the CheckBootstrapVersion rule is added to the Stack’s template as a safety check, to verify that the bootstrap stack in the target environment meets the minimum requirements of the current stack. The AssertDescription being shown is the failure message a user would see on deploy if their bootstrap stack was not up-to-date. The inclusion of this element is not a failure, merely a new element for stacks that are being upgraded from the legacy synthesizer. It will show up in the diff until it is deployed, and then will only show up if there’s a change, same as any other CloudFormation template element.

Hope that helps! Let me know if you have any follow-ups on that.

I see it’s not an error now - but it is really confusing! Hopefully AWS will fix this one day…

Why not just fix the UX issue?