Serverless部署AWS应用时引用账号ID遇类型错误的解决咨询

That error pops up because !Ref "AWS::AccountId" is a CloudFormation intrinsic function, but Serverless Framework doesn’t parse CloudFormation functions directly in the custom block. It treats that !Ref as a YAML object instead of a string, which triggers the "non string value" mismatch when you try to reference it later.

Here are the most straightforward fixes:

1. Use Serverless’s Built-in aws.accountId Variable #

Serverless automatically pulls your current AWS account ID during deployment, so you can skip defining it in custom entirely and use this built-in variable directly:

provider:
  name: aws
  runtime: go1.x
  stage: dev
  region: us-east-1
  environment:
    ACCOUNT_ID: ${aws.accountId}
myRoleArn: arn:aws:iam::${aws.accountId}:role/xxxxxxxx

This is the simplest approach—no extra setup required, and aws.accountId is guaranteed to be a string, so you won’t hit type issues.

2. Keep It in the custom Block (If Needed) #

If you specifically want to retain the account ID in your custom section, use Serverless’s cf variable syntax to resolve the CloudFormation reference properly:

custom:
  accountId: ${cf:AWS::AccountId}
provider:
  name: aws
  runtime: go1.x
  stage: dev
  region: us-east-1
  environment:
    ACCOUNT_ID: ${self:custom.accountId}
myRoleArn: arn:aws:iam::${self:custom.accountId}:role/xxxxxxxx

Quick Note: #

CloudFormation functions like !Ref work perfectly in the resources block (where you define native CloudFormation resources), but in Serverless’s top-level config areas (like custom, provider.environment, or custom ARN fields), you need to use Serverless’s own variable resolution system instead of raw CloudFormation syntax.

内容的提问来源于stack exchange，提问作者Dattatray