Silences

A silence is a way to temporarily suppress notifications. Each silence has:

• A description - explaining why the silence was created
• A duration - specified by from and until timestamps in RFC3339 format
• A scope - defined through selectors and filters to target specific resources
• A recursive flag - to apply silence to child resources

note

Notifications that aren't sent due to silence are still visible in the notification history for auditing purposes.

---
apiVersion: mission-control.flanksource.com/v1
kind: NotificationSilence
metadata:
  name: test-env-silence
spec:
  from: "2025-01-01"
  until: "2025-02-01"
  description: >
    Silence notifications from all resources in test and stage namespaces
    for the next 30 days
  selectors:
    - namespace: test
    - namespace: stage

Use cases

• Planned maintenance or deployments - Silence notifications from a namespace or helm release and optionally all their children
• Non-critical resources - Suppress notifications from resources that routinely trigger expected and harmless alerts
• Known issues - Temporarily silence alerts for known issues that can't be immediately resolved due to dependencies or resource constraints

Creating Silences

Silences can be created in multiple ways:

1. Through the notification page UI
2. Using the silence button on Slack notifications (when using default templates)
3. By applying a NotificationSilence custom resource

Field	Description	Scheme	Template Env
description	A description explaining the purpose of the silence	string
filter	A CEL expression that determines whether to apply the silence. The silence is only applied if the filter evaluates to true.	CEL	CheckEvents ConfigEvents ComponentEvents
from	Start time of the silence period in RFC3339 format or datetime	string
recursive	When true, the silence applies to all child resources of the matched resources. For example, silencing a namespace would silence all deployments, statefulsets, pods, etc. within it.	boolean
selectors	List of resource selectors to target specific resources by their kind and name	[]ResourceSelector
until	End time of the silence period in RFC3339 format or datetime	string

Resource Selector

Field	Description	Scheme
kind	The kind of resource to select (e.g., 'Kubernetes::StatefulSet', 'Kubernetes::Pod')	string
name	The name of the resource to select	string

Resource Selection

Silences can target resources in two ways:

1. Selectors: Direct resource matching using kind and name
2. Filters: Complex matching using CEL expressions

Selectors

Selectors provide a straightforward way to target specific resources by their kind and name. Multiple selectors can be specified to target different resources.

Filters

A filter is a CEL expression that evaluates to a boolean value. The notification is silenced when the filter returns true. Filters provide powerful, flexible matching capabilities.

Filter Examples

Filter	Description
check.type == 'http'	Silences HTTP check notifications
regexp.Match("^check-[0-9]+", check.name)	Matches checks with prefix check-
config.name == "postgresql" && config.type == "Kubernetes::StatefulSet"	Silences notifications from a specific StatefulSet
config.type == "Kubernetes::Pod" && catalog.traverse(config.id, "Kubernetes::Namespace", "incoming").size > 0 && catalog.traverse(config.id, "Kubernetes::Namespace", "incoming")[0].tags.?env.orValue("") == "prod"	Matches pods in production namespaces

Available Template Variables

Filters can reference these variables:

• CheckEvents
• ConfigEvents
• ComponentEvents

Recursive Mode

When recursive: true is set, the silence applies to all child resources of the matched resources. For example:

• Silencing a namespace affects all deployments, statefulsets, pods, etc. within it
• Silencing a statefulset affects all its pods