If a Codebuild project runs on a custom image that has awscli preinstalled, but not configured for that AWS account, would it be still possible to run aws * in that project's buildspec without updating its AWS credentials there first?
In other words, are these credentials made available by Codebuild (e.g. via providing this information in automatically picked up environment variables) , or if I am using a custom image, it is up to me to take care of that explicitly, and aws * is only expected to work in buildspec out of the box without additional efforts on Codebuild managed images?
(I mean configuration/credentials for the account and role the Codebuild project in question operates in)
When you attach an IAM service role with your AWS Codebuild project, you don't need to configure AWS cli. IAM service role is part of environment configuration and this role will be assumed whenever you try to access resources in AWS. This goes same for your custom image for AWS Codebuild as well.