Jsonnet 库中的复杂验证

Question

我要做的是创建一个 libsonnet 库，对输入进行一些复杂的验证，但我不确定如何在 libsonnet 文件中实现此功能，而不会返回 null。

我正在尝试使用 Jsonnet 为 Hosted Graphite's Alerts API 生成 API 调用。想法是我们可以将所有警报存储在版本控制中，并在 CI / CD 管道中更新它们。我想防止错误，所以我根据上面的 API 规范定义了一些复杂的验证。我将以下内容另存为alerts.libsonnet：

local alert_criteria_types = [
  'above',
  'below',
  'missing',
  'outside_bounds',
];

local notification_types_strings = [
  'state_change',
];

local notification_types_arrays = [
  'every',
  'state_change',
];

local on_query_failure_types = [
  'ignore',
  'notify',
  null,
];

{
  local HostedGraphiteAlerts = self,

  new(
    name,
    metric,
    alert_criteria_type,
    additional_alert_criteria={},
    additional_criteria={},
    expression='a',
    scheduled_mutes=[],
    notification_channels=['Email me'],
    notification_type=null,
    info=null,
    on_query_failure='notify',
  )::

    // Simple checks
    assert std.member(alert_criteria_types, alert_criteria_type) : "Input 'alert_criteria_type' is not one of the types: %s." % std.join(', ', alert_criteria_types);
    assert std.member(on_query_failure_types, on_query_failure) : "Input 'on_query_failure_type' is not one of the types: %s." % std.join(', ', on_query_failure_types);

    // Advanced checks
    if notification_type != null && std.isString(notification_type) then
        assert std.member(notification_types_strings, notification_type) : "Input 'notification_type' is not one of the types: %s." % std.join(', ', notification_types_strings);

    if notification_type != null && std.isArray(notification_type) then
      assert std.member(notification_types_arrays, notification_type[0]) : "Input 'notification_type' is not one of the types: %s." % std.join(', ', notification_types_arrays);

    if notification_type != null && std.isArray(notification_type) then
        assert std.member(notification_types_arrays, notification_type[0]) : "Input 'notification_type' is not one of the types: %s." % std.join(', ', notification_types_arrays);

    if notification_type != null && std.isArray(notification_type) && notification_type[0] == 'every' then
        assert notification_type[1] != null : "Input 'notification_type' cannot have an empty entry for 'time_in_minutes' for notification type 'every'.";

    if notification_type != null && std.isArray(notification_type) && notification_type[0] == 'every' then
        assert std.isNumber(notification_type[1]) : "Input 'notification_type' must have a JSON 'number' type for notification type 'every'.";

    // Main
    {
      name: name,
      metric: metric,
      alert_criteria: {
        type: alert_criteria_type,
      } + additional_alert_criteria,
      additional_criteria: additional_criteria,
      expression: expression,
      scheduled_mutes: scheduled_mutes,
      notification_channels: notification_channels,
      notification_type: notification_type,
      info: info,
      on_query_failure: on_query_failure,
    },
}

这通过了基本的jsonnetfmt 检查，但问题是当我像这样在alerts.jsonnet 文件中使用它时：

local alerts = (import 'hosted_graphite.libsonnet').alerts;

alerts.new(
  name='something',
  metric='some.graphite.metric',
  alert_criteria_type='below',
)

这只是返回null：

$ jsonnet hosted_graphite/alerts.jsonnet
null

我知道这是因为它采用了第一个 assert 语句的值。但是这还能怎么做呢？

谢谢！

Answer 1

注意jsonnet 不是命令式语言，不要期望那些if 行会像脚本的一部分一样被评估。 将断言视为“虚拟”/不可见字段，必须始终评估为 true

下面实现了（我认为）你所追求的：

hosted_graphite.libsonnet

local alert_criteria_types = [
  'above',
  'below',
  'missing',
  'outside_bounds',
];

local notification_types_strings = [
  'state_change',
];

local notification_types_arrays = [
  'every',
  'state_change',
];

local on_query_failure_types = [
  'ignore',
  'notify',
  null,
];

{
  local HostedGraphiteAlerts = self,

  new(
    name,
    metric,
    alert_criteria_type,
    additional_alert_criteria={},
    additional_criteria={},
    expression='a',
    scheduled_mutes=[],
    notification_channels=['Email me'],
    notification_type=null,
    info=null,
    on_query_failure='notify',
  )::

    // Main
    {
      name: name,
      metric: metric,
      alert_criteria: {
        type: alert_criteria_type,
      } + additional_alert_criteria,
      additional_criteria: additional_criteria,
      expression: expression,
      scheduled_mutes: scheduled_mutes,
      notification_channels: notification_channels,
      notification_type: notification_type,
      info: info,
      on_query_failure: on_query_failure,

      // Simple checks
      assert std.member(alert_criteria_types, self.alert_criteria.type) : (
        "Input 'alert_criteria_type' is not one of the types: %s." % std.join(', ', alert_criteria_types)
      ),
      assert std.member(on_query_failure_types, self.on_query_failure) : (
        "Input 'on_query_failure_type' is not one of the types: %s." % std.join(', ', on_query_failure_types)
      ),

      // Advanced checks:
      // - 1st line is a conditional that must be false ('A||B' construct) to get 2nd line evaluated
      // - 2nd line is the "final" type/value check, must be true
      assert (self.notification_type == null || !std.isString(self.notification_type) ||
              std.member(notification_types_strings, self.notification_type)) : (
        "Input 'notification_type' string is not one of the types: %s." % std.join(', ', notification_types_strings)
      ),
      assert (self.notification_type == null || !std.isArray(self.notification_type) ||
              std.member(notification_types_arrays, self.notification_type[0])) : (
        "Input 'notification_type' array is not one of the types: %s." % std.join(', ', notification_types_arrays)
      ),
      assert (self.notification_type == null || !std.isArray(self.notification_type) ||
              self.notification_type != ['every', null]) : (
        "Input 'notification_type' cannot have an empty entry for 'time_in_minutes' for notification type 'every'."
      ),
      assert (self.notification_type == null || !std.isArray(self.notification_type) ||
              [self.notification_type[0], std.isNumber(self.notification_type[1])] == ['every', true]) : (
        "Input 'notification_type' must have a JSON 'number' type for notification type 'every'."
      ),
    },
}

alerts.jsonnet

local alerts = (import 'hosted_graphite.libsonnet');

{
  a0: alerts.new(
    name='something',
    metric='some.graphite.metric',
    alert_criteria_type='below',
  ),
  a1: alerts.new(
    name='something',
    metric='some.graphite.metric',
    alert_criteria_type='below',
    notification_type='state_change',
  ),
  a2: alerts.new(
    name='something',
    metric='some.graphite.metric',
    alert_criteria_type='below',
    notification_type=['every', 10],
  ),
}

请注意，我使用的是 self.<field> 而不是函数参数，这是一个很好的模式，可以在评估断言的同时允许派生/覆盖。

顺便说一句，我还建议查看 https://cuelang.org/，它与 jsonnet 在同一领域发挥作用但类型检查是语言不可或缺的一部分。