Generate JSON schema for Tarantool's cluster configuration

cluster-config-json-schema.lua

#!/usr/bin/env tarantool

local json = require('json')
local cluster_config = require('internal.config.cluster_config')

local scalars = {}

scalars.string = {
    jsonschema = {
        type = 'string',
    },
}

scalars.number = {
    jsonschema = {
        type = 'number',
    },
}

scalars['string, number'] = {
    jsonschema = {
        type = {'string', 'number'},
    },
}

scalars['number, string'] = {
    jsonschema = {
        type = {'string', 'number'},
    },
}

scalars.integer = {
    jsonschema = {
        type = 'integer',
    },
}

scalars.boolean = {
    jsonschema = {
        type = 'boolean',
    },
}

scalars.any = {
    jsonschema = {},
}

local function is_scalar(schema)
    return scalars[schema.type] ~= nil
end

local function extract_validate_no_repeat()
    local schema = require('internal.config.utils.schema')
    local nups = debug.getinfo(schema.set).nups
    for i = 1, nups do
        local k, v = debug.getupvalue(schema.set, i)
        if k == 'validate_no_repeat' then
            return v
        end
    end
end

local validate_no_repeat = extract_validate_no_repeat()
assert(type(validate_no_repeat) == 'function')

local function set_common_fields(res, schema)
    -- Ignores apply_default_if.
    res.default = schema.default
    res.enum = schema.allowed_values
    return setmetatable(res, {
        __serialize = 'map',
    })
end

local function traverse_impl(schema)
    if is_scalar(schema) then
        local scalar_def = scalars[schema.type]
        assert(scalar_def ~= nil)
        return set_common_fields(table.copy(scalar_def.jsonschema), schema)
    elseif schema.type == 'record' then
        local properties = {}
        for field_name, field_def in pairs(schema.fields) do
            properties[field_name] = traverse_impl(field_def)
        end
        return set_common_fields({
            type = 'object',
            properties = properties,
            additionalProperties = false,
        }, schema)
    elseif schema.type == 'map' then
        assert(schema.key.type == 'string')
        return set_common_fields({
            type = 'object',
            additionalProperties = traverse_impl(schema.value),
        }, schema)
    elseif schema.type == 'array' then
        local res = {
            type = 'array',
            items = traverse_impl(schema.items),
        }
        if schema.validate == validate_no_repeat then
            res.uniqueItems = true
        end
        return set_common_fields(res, schema)
    else
        assert(false)
    end
end

local function traverse(schema_obj)
    local res = traverse_impl(rawget(schema_obj, 'schema'))
    res['$schema'] = 'https://json-schema.org/draft/2020-12/schema'
    return res
end

local jsonschema = traverse(cluster_config)
print(json.encode(jsonschema))