Aws cloudformation Error during build: Yum does not have gcc to install

I am creating a template to pre-install certain packages. The template can launch an instance and security group, but nothing is installed. At startup

/opt/aws/bin/cfn-init -s SIM --access-key=XXX --secret-key=XXX --region us-west-2  -r WebServer

      

        
        
        
      

    

I get: Build error: Yum doesn't have gcc to install

"Resources": {
        "WebServer": {
            "Metadata" : {
                "AWS::CloudFormation::Init" : {
                    "config" : {
                           "packages" : {
                          "yum" : {
                        "gcc " : [],
                        "make" : [],
                        "gcc-c++" : [],
                        "nginx" : [],
                        "zlib" : [],
                        "zlib-devel" : [],
                        "rubygems" : [],
                        "git-core" : [],
                        "selinux-policy-targeted" : [],
                        "selinux-policy-devel" : [],
                        "libmemcached" : [],
                        "libmemcached-devel" : []
                            }

      

        
        
        
      

    

How can I fix this?