limit-brainstorm.txt

Table structures:

    limit_types:
        id uuid
        service string
        name string
        default int
        
    project_limits:
        id uuid
        limit_type_id uuid
        value integer
        project uuid
  
Example data:
    limit_types:
        3134fdb, compute, vCPU, 10
        18d864ff79e445fc789cebb19
    project_limits
        2234c2f, 3134fdb, 9, A
        2645049, 3134fdb, 4, C
  
Example hierarchy:
    A -> B
           -> C
           -> D
           
Example API:

    >>> # project not explicitly defined gets the service default
    >>> keystone.get_limits('compute', 'X')
    {
        'limits': {
            'vCPU': 10,
        },
    }
    >>> # root project get its limits
    >>> keystone.get_limits('compute', 'A')
    {
        'limits': {
            'vCPU': 9,
        },
    }
    >>> # child gets a mini tree
    >>> keystone.get_limits('compute', 'B')
    {
        'limits': {
            'vCPU': None,
        },
        'parent': {
            'name': 'A',
            'limits': {
                'vCPU': 9
            },
        },
    }
    >>> # grandchild gets a bigger tree
    >>> keystone.get_limits('compute', 'C')
    {
        'limits': {
            'vCPU': 4,
        },
        'parent':
            'name': 'B',
            'limits': {
                'vCPU': None,
            },
            'parent': {
                'name': 'A',
                'limits': {
                    'vCPU': 9,
                },
            },
        },
    }
    
Notes:

    1. There are lots of possiblities to flatten the nested structure
    2. We can add a `'siblings': []` at the same level as parent if we end up needing it.