[PYTHON] When I tried to make a VPC with AWS CDK but couldn't make it

I tried to switch from CloudFormation to AWS CDK and the build failed well today, so make a note of the solution.

Thing you want to do

I just wanted to build an AWS sample ...! !! https://github.com/aws-samples/aws-cdk-examples/tree/master/python/ecs/fargate-load-balanced-service

Ruthless CREATE_FAILED

Unlike CloudFormation, the abstraction is intense, so you can create a VPC in one line. Instead, I don't know the contents at all.

Amazing magic code that VPC can do

vpc = ec2.Vpc(
  self, "MyVpc",
  max_azs=2
)

CREATE_FAILED ruthlessly shattering illusions

$ cdk deploy
~ Abbreviation ~
Do you wish to deploy these changes (y/n)? y
~ Abbreviation ~
  9/36 | 7:11:35 AM | CREATE_COMPLETE      | AWS::EC2::VPC                             | MyVpc (MyVpcF9F0CA6F) 
~ Abbreviation ~
 10/36 | 7:11:38 AM | CREATE_FAILED        | AWS::EC2::Subnet                          | MyVpc/PublicSubnet1/Subnet (MyVpcPublicSubnet1SubnetF123456) Value (ap-northeast-1a) for parameter availabilityZone is invalid. Subnets can currently only be created in the following availability zones: ap-northeast-1d, ap-northeast-1c, ap-northeast-1b. (Service: AmazonEC2; Status Code: 400; Error Code: InvalidParameterValue; Request ID: xxxxx-xxxx-xxxx-xxxx-xxxxxxxxx)

What he wanted to tell me

Subnets can currently only be created in the following availability zones: 
ap-northeast-1d, ap-northeast-1c, ap-northeast-1b.

Yes. I've been accustomed to being swayed by the Availability Zone when creating Subnets since CloudFormation. As soon as I get used to it, I want to solve it quickly, but I'm at a loss because I don't know what to do. I understand that I was angry when I tried to make ap-northeast-1a. To put it the other way around, I don't really know why I tried to make it there.

Solution

There is availability-zones specified in the file cdk.context.json, so if there is ʻap-northeast-1a`, delete it. If not specified, add the following contents.

`cdk.out/cdk.context.json`


  "availability-zones:account=123456789999:region=ap-northeast-1": [
    "ap-northeast-1b",
    "ap-northeast-1c",
    "ap-northeast-1d"
  ]

end

I was worried about 3 hours ... It was hard ... I still can't get along with CDK.

By the way, if you look at gitignore, it seems that cdk.context.json is ignored, but I would be grateful if any wise man who knows where to write this setting is really.

~ Addition ~ It was written that you should set it with a command, write it in cdk.json, or specify it in the source code ^ q ^

Through the --context option to the cdk command.

In the context key of the project's cdk.json file.

In the context key of a ~/cdk.json file.

In code using the construct.node.setContext method.

https://docs.aws.amazon.com/cdk/latest/guide/context.html