plugin.rb

# frozen_string_literal: true

# name: discourse-prometheus-alert-receiver
# about: Receives a Prometheus webhook and creates a topic in Discourse
# version: 0.1
# url: https://github.com/discourse/discourse-prometheus-alert-receiver

enabled_site_setting :prometheus_alert_receiver_enabled

register_asset "stylesheets/topic-post.scss"

after_initialize do
  module ::DiscoursePrometheusAlertReceiver
    PLUGIN_NAME = "discourse-prometheus-alert-receiver".freeze

    PREVIOUS_TOPIC_CUSTOM_FIELD = "prom_previous_topic".freeze
    TOPIC_BODY_CUSTOM_FIELD = "prom_alert_topic_body".freeze
    TOPIC_BASE_TITLE_CUSTOM_FIELD = "prom_alert_topic_base_title".freeze

    class Engine < ::Rails::Engine
      engine_name PLUGIN_NAME
      isolate_namespace ::DiscoursePrometheusAlertReceiver
    end
  end

  require_relative "app/controllers/discourse_prometheus_alert_receiver/receiver_controller"
  require_relative "app/models/alert_receiver_alert"
  require_relative "app/serializers/alert_receiver_alert"
  require_relative "app/jobs/concerns/alert_post_mixin"
  require_relative "app/jobs/regular/process_alert"
  require_relative "app/jobs/regular/process_grouped_alerts"

  unless Rails.env.test?
    %i[tagging_enabled allow_duplicate_topic_titles].each do |setting|
      SiteSetting.public_send("#{setting}=", true) unless SiteSetting.public_send(setting)
    end
  end

  register_topic_custom_field_type(
    DiscoursePrometheusAlertReceiver::PREVIOUS_TOPIC_CUSTOM_FIELD,
    :integer,
  )
  register_topic_custom_field_type(
    DiscoursePrometheusAlertReceiver::TOPIC_BODY_CUSTOM_FIELD,
    :string,
  )
  register_topic_custom_field_type(
    DiscoursePrometheusAlertReceiver::TOPIC_BASE_TITLE_CUSTOM_FIELD,
    :string,
  )

  self.add_model_callback("Category", :after_destroy) do
    PluginStoreRow
      .where(plugin_name: ::DiscoursePrometheusAlertReceiver::PLUGIN_NAME)
      .where("value::json->>'category_id' = '?'", self.id)
      .destroy_all
  end

  self.add_model_callback("Group", :after_destroy) do
    PluginStoreRow
      .where(plugin_name: ::DiscoursePrometheusAlertReceiver::PLUGIN_NAME)
      .where("value::json->>'assignee_group_id' = '?'", self.id)
      .destroy_all
  end

  reloadable_patch { Topic.has_many :alert_receiver_alerts, dependent: :delete_all }

  add_class_method(:topic, :alerts_category_ids) do
    PluginStoreRow.where(plugin_name: ::DiscoursePrometheusAlertReceiver::PLUGIN_NAME).pluck(
      "value::json->'category_id'",
    )
  end

  add_class_method(:topic, :firing_alerts) do |category_ids = []|
    joins(:alert_receiver_alerts).where("alert_receiver_alerts.status": "firing").where(
      "not topics.closed AND topics.category_id IN (?)",
      (category_ids.presence || alerts_category_ids),
    )
  end

  add_to_serializer(
    :topic_view,
    :alert_data,
    include_condition: -> { object.topic.alert_receiver_alerts.present? },
  ) { ActiveModel::ArraySerializer.new(object.topic.alert_receiver_alerts) }

  on(:after_extract_linked_users) do |users, post|
    if post.post_number == 1 && post.user == Discourse.system_user &&
         post.topic.category&.slug == "alerts" # TODO: don't hardcode the category slug
      users.clear
    end
  end

  TopicQuery.add_custom_filter(
    DiscoursePrometheusAlertReceiver::PLUGIN_NAME,
  ) do |results, topic_query|
    options = topic_query.options

    if Topic.alerts_category_ids.include?(options[:category_id]) && options[:status] == "firing"
      results = results.firing_alerts([options[:category_id]])
    end

    results
  end

  require_dependency "admin_constraint"

  ::DiscoursePrometheusAlertReceiver::Engine.routes.draw do
    token_format = /[a-f0-9]{64}/
    post "/receiver/:token" => "receiver#receive", :token => token_format, :as => :receive
    post "/receiver/resync/:token" => "receiver#receive_grouped_alerts", :token => token_format
    post "/receiver/grouped/alerts/:token" => "receiver#receive_grouped_alerts",
         :token => token_format,
         :as => :receive_grouped_alerts
    post "/receiver/generate" => "receiver#generate_receiver_url",
         :constraints => AdminConstraint.new
  end

  Discourse::Application.routes.append do
    mount ::DiscoursePrometheusAlertReceiver::Engine, at: "/prometheus"
  end
end