Validate az CIDRs

[kteague]

What problems do you have? There are a number of ways to configure segments that can't be provisioned.

What solutions could solve that problem? Validate the configuration and raise an error if it's invalid.

If you have 2 AZs, you can leave az1_cidr or az2_cidr blank and then the Segments stack fails with an error:

          segments:
            public:
              # az1_cidr: 10.20.1.0/24
              az2_cidr: 10.20.2.0/24
              internet_access: true
            private:
              az1_cidr: 10.20.3.0/24
              # az2_cidr: 10.20.4.0/24

ERROR: ClientError

An error occurred (ValidationError) when calling the CreateStack operation: Unresolved resource dependencies [SubnetAZ2] in the Outputs block of the template

[kteague]

If you leave az's blank in the segments with a EC2 NAT Gateway you get:

  File "/Users/kteague/water/paco/src/paco/stack/stack_group.py", line 86, in add_new_stack
    stack.template = template_class(stack, self.paco_ctx, **extra_context)
  File "/Users/kteague/water/paco/src/paco/cftemplates/security_groups.py", line 59, in __init__
    self.create_group_rules(sg_group_id, sg_name, sg_config, template)
  File "/Users/kteague/water/paco/src/paco/cftemplates/security_groups.py", line 166, in create_group_rules
    rule_res = tropo_rule_method.from_dict(rule_name, rule_dict)
  File "/Users/kteague/water/troposphere/build/lib/troposphere/__init__.py", line 302, in from_dict
    return cls._from_dict(title, **d)
  File "/Users/kteague/water/troposphere/build/lib/troposphere/__init__.py", line 297, in _from_dict
    return cls(title, **props)
  File "/Users/kteague/water/troposphere/build/lib/troposphere/__init__.py", line 127, in __init__
    self.__setattr__(k, v)
  File "/Users/kteague/water/troposphere/build/lib/troposphere/__init__.py", line 214, in __setattr__
    self._raise_type(name, value, expected_type)
  File "/Users/kteague/water/troposphere/build/lib/troposphere/__init__.py", line 228, in _raise_type
    raise TypeError('%s: %s.%s is %s, expected %s' % (self.__class__,
TypeError: <class 'troposphere.ec2.SecurityGroupIngress'>: ec2az1B9F2B38CIngressSubnetAZ.SourceSecurityGroupId is <class 'NoneType'>, expected <class 'str'>