Feature: An operator can provide a list of non-contiguous CIDRs for the overlay network

[ameowlia]

Proposed Change

As a CF operator
I want to provide multiple smaller cidrs for my overlay network instead of one big cidr
So that I don't have to find a huge amount of contiguous IPs to give to CF

Current Property

  network:
     description: "CIDR address block for overlay network.  Subnets for each diego cell are allocated out of this network."
     default: "10.255.0.0/16"

Desired Property

  network:
    description: | 
       A single CIDR address block or an array of CIDR address blocks for overlay network.  
       Subnets for each diego cell are allocated out of this network. CIDR address blocks must
       be the same size or larger than the subnet_prefix_length property.
    default: [ "10.255.0.0/16" ]

Acceptance criteria

Validations

• must be array OR a single CIDR (backward compatible)
• must be valid CIDRs
• must be non-overlapping CIDRs
• CIDRs must be the same size or larger than the subnet_prefix_length property

Acceptance

Valid Examples

network: [ "10.255.0.0/16" ]
network: [ "10.255.0.0/25", "10.255.60.0/25", "10.255.128.0/25" ]
network: "10.255.0.0/16"
network: "10.255.10.0/16"

Invalid Examples

# breaks the rule "must be array OR a single CIDR (backward compatible)"
network: "10.255.0.0/21,10.255.64.0/18,10.255.128.0/17"

# breaks the rule "must be valid CIDRs"
network: meow
network: ["meow"]
network: "10.300.0.0/21"
network: [ "10.255.0.0/50" ]

# breaks the rule "must be non-overlapping CIDRs"
network: [ "10.255.0.0/16", "10.255.10.0/16" ]

# breaks the rule "CIDRs must be the same size or larger than the subnet_prefix_length property"
network: [ "10.255.0.0/16", "10.250.10.10/32" ]

Related links

No response

[ameowlia]

Work is being done here: https://github.com/cloudfoundry/silk-release/commits/multiple-network-overlay-cidrs/