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Plugin

Siren decouples provider and receiver as a plugin. The purpose is to ease the extension of new plugin. We welcome all contributions to add new plugin.

Base Plugin​

Siren provides base plugin in plugins/providers/base and plugins/receivers/base which needs to be embedded in all plugins service struct. By doing so, you just need to implement all interface's methods that you only need. You don't need to implement unnecessary methods, the unimplemented methods one will already be handled by the base plugin.

Provider Plugin​

Provider responsibility is to accept incoming rules configuration from Siren and send alerts to the designated Siren's Hook API. Supported providers are:

See Extend section for more information about adding new provider plugins.

Interface​

type ProviderPlugin interface {
    // AlertTransformer
    TransformToAlerts(ctx context.Context, providerID uint64, body map[string]interface{}) ([]*alert.Alert, int, error) 

    // ConfigSyncer
    SyncRuntimeConfig(ctx context.Context, namespaceID uint64, namespaceURN string, prov provider.Provider) error
    
    // RuleUploader
    UpsertRule(ctx context.Context, namespaceURN string, prov provider.Provider, rl *rule.Rule, templateToUpdate *template.Template) error
}
  • AlertTransformer interface is being used by alert service to transform incoming alert body in Siren's Hook API to a list of *alert.Alert.
  • ConfigSyncer interface is being used by namespace service to synchronize runtime-provider configs for a specific namespace. In cortex, it is being used to sync alertmanager config.
  • RuleUploader interface is being used to upsert rules to the provider. It support templatization of rules.

Configurations​

Siren provider plugin could have a server level configuration called AppConfig. It is a configuration of provider plugin that is being loaded when the Siren app is started. It can be set up via environment variable or config file. Usually this is a generic config of a specific provider regardless which namespace the provider is attached to. If your plugin requires AppConfig, you can set the config inside plugins/providers/config.go.

Receiver Plugin​

Receiver defines where a notification Siren sends to. Supported receivers are:

See Extend section for more information about adding new receiver plugins.

Interface​

type ReceiverPlugin interface {
    // Config Resolver
    PreHookDBTransformConfigs(ctx context.Context, configurations map[string]interface{}) (map[string]interface{}, error)
    PostHookDBTransformConfigs(ctx context.Context, configurations map[string]interface{}) (map[string]interface{}, error)
    BuildData(ctx context.Context, configurations map[string]interface{}) (map[string]interface{}, error)
    
    // Notifier
    PreHookQueueTransformConfigs(ctx context.Context, notificationConfigMap map[string]interface{}) (map[string]interface{}, error)
    PostHookQueueTransformConfigs(ctx context.Context, notificationConfigMap map[string]interface{}) (map[string]interface{}, error)
    GetSystemDefaultTemplate() string
    Send(ctx context.Context, notificationMessage notification.Message) (bool, error)
}

  • ConfigResolver interface is being used by receiver service to manage receivers. It is an interface for the receiver to resolve all configs and functions.

    • BuildData is optional. It is being used in Get and List Receivers where data field in Receiver is being populated to send back custom information to the users. Slack receiver uses this to show what channels does the slack receiver support in a workspace.
    • PreHookDBTransformConfigs is being used to transform configs (e.g. encryption) before the config is being stored in the DB.
    • PostHookDBTransformConfigs is being used to transform configs (e.g. decryption) after the config is being fetched from the DB.

  • Notifier interface is being used by notification service and consists of all functionalities to publish notifications.

    • PreHookQueueTransformConfigs is being used to transform configs (e.g. encryption) before the config is being enqueued.
    • PostHookQueueTransformConfigs is being used to transform configs (e.g. decryption) after the config is being dequeued.
    • GetSystemDefaultTemplate assigns default template for alert notifications. It is expected for Siren Hook API to transform the data into the alert notification default template variables.
    • Send handles how message is being sent. The first return argument is retryable boolean to indicate whether an error is a retryable error or not. If it is API call, usually response status code 429 or 5xx is retriable. You can use pkg/retrier to retry the call.

Configurations​

Siren receiver plugin could have several configs:

  1. ReceiverConfig
    • A config that will be part of receiver.Receiver struct and will be stored inside the DB's receivers table.
  2. SubscriptionConfig (optional)
    • Only if needed
    • Defined and used if the receivers inside subscription requires another additional configs rather than ReceiverConfig. For example, Slack stores encrypted token when storing receiver information inside the DB but has another config channel_name on subscription level.
  3. NotificationConfig
    • Embeds ReceiverConfig and SubscriptionConfig (if exists).
  4. AppConfig
    • A config of receiver plugin that is being loaded when the Siren app is started. AppConfig can be set up via environment variable or config file. Usually this is a generic config of a specific receiver regardless where the notification is being sent to (e.g. http config, receiver host, etc...). If your plugin requires AppConfig, you can set the config inside plugins/receivers/config.go.

In Siren receiver plugins, all configs will be transform back and forth from map[string]interface{} to struct using mitchellh/mapstructure. You might also need to add more functions to validate and transform configs to map[string]interface{}.

Alert Notification Default Template​

Each receiver might want to have a specific template to transform alerts into a receiver's contract. In that case one needs to define a template in a .goyaml file inside plugins/receivers/{type}/config/{template_file_name}.goyaml. It is expected for all TransformToAlerts implemented in providers to populate all fields in *alert.Alert model. Siren will transform *alert.Alert into notification.Notification model and populate the Data and Labels of notification with the same variable keys. Below are the supported variables that could be used inside the template.

Data
- id
- status ("firing"/"resolved")
- resource
- template
- metricValue
- metricName
- generator_url
- num_alerts_firing
- dashboard
- playbook
- summary

Labels
- severity ("WARNING"/"CRITICAL")
- alertname
- other labels defined in the alert rules