要解决AWS Cognito联合登录的“build”环境问题，需要按照以下步骤进行操作：

1. 确保已经安装了AWS CLI并正确配置了凭证。
2. 确保已经设置了AWS Cognito用户池和身份池。

下面是一个示例代码来解决这个问题：

# 步骤1：安装AWS CLI并配置凭证
$ pip install awscli --upgrade --user
$ aws configure

# 步骤2：设置AWS Cognito用户池和身份池
$ aws cognito-idp create-user-pool --pool-name MyUserPool
$ aws cognito-identity create-identity-pool --identity-pool-name MyIdentityPool --allow-unauthenticated-identities --cognito-identity-providers providerName=cognito-idp.us-east-1.amazonaws.com/{userPoolId}

# 步骤3：创建AWS Cognito联合登录“build”环境
$ aws cognito-identity set-identity-pool-roles --identity-pool-id MyIdentityPoolId --roles authenticated=arn:aws:iam::123456789012:role/MyAuthenticatedRole,unauthenticated=arn:aws:iam::123456789012:role/MyUnauthenticatedRole
$ aws cognito-idp create-resource-server --user-pool-id MyUserPoolId --identifier MyResourceServer --name MyResourceServer
$ aws cognito-idp create-user-pool-domain --domain MyDomain --user-pool-id MyUserPoolId

# 步骤4：配置AWS Cognito联合登录“build”环境
$ aws cognito-idp describe-user-pool-domain --domain MyDomain

# 步骤5：验证AWS Cognito联合登录“build”环境
$ aws cognito-idp sign-up --region us-east-1 --client-id MyClientId --username MyUsername --password MyPassword
$ aws cognito-idp admin-confirm-sign-up --region us-east-1 --user-pool-id MyUserPoolId --username MyUsername
$ aws cognito-idp initiate-auth --region us-east-1 --auth-flow USER_PASSWORD_AUTH --client-id MyClientId --auth-parameters USERNAME=MyUsername,PASSWORD=MyPassword

请注意，上述代码中的示例参数（例如MyUserPoolId，MyClientId等）需要根据您的实际配置进行替换。