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Custom <strong>logging</strong> alerts - <strong>logging</strong> | Observability | OpenShift Container Platform 4.16
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Custom logging alerts

In logging 5.7 and later versions, users can configure the LokiStack deployment to produce customized alerts and recorded metrics. If you want to use customized alerting and recording rules, you must enable the LokiStack ruler component.

LokiStack log-based alerts and recorded metrics are triggered by providing LogQL expressions to the ruler component. The Loki Operator manages a ruler that is optimized for the selected LokiStack size, which can be 1x.extra-small, 1x.small, or 1x.medium.

To provide these expressions, you must create an AlertingRule custom resource (CR) containing Prometheus-compatible alerting rules, or a RecordingRule CR containing Prometheus-compatible recording rules.

Administrators can configure log-based alerts or recorded metrics for application, audit, or infrastructure tenants. Users without administrator permissions can configure log-based alerts or recorded metrics for application tenants of the applications that they have access to.

Application, audit, and infrastructure alerts are sent by default to the OpenShift Container Platform monitoring stack Alertmanager in the openshift-monitoring namespace, unless you have disabled the local Alertmanager instance. If the Alertmanager that is used to monitor user-defined projects in the openshift-user-workload-monitoring namespace is enabled, application alerts are sent to the Alertmanager in this namespace by default.

Configuring the ruler

When the LokiStack ruler component is enabled, users can define a group of LogQL expressions that trigger logging alerts or recorded metrics.

Administrators can enable the ruler by modifying the LokiStack custom resource (CR).

Prerequisites

  • You have installed the Red Hat OpenShift logging Operator and the Loki Operator.

  • You have created a LokiStack CR.

  • You have administrator permissions.

Procedure

  • Enable the ruler by ensuring that the LokiStack CR contains the following spec configuration:

    apiVersion: loki.grafana.com/v1
kind: LokiStack
metadata:
  name: <name>
  namespace: <namespace>
spec:
# ...
  rules:
    enabled: true (1)
    selector:
      matchLabels:
        openshift.io/<label_name>: "true" (2)
    namespaceSelector:
      matchLabels:
        openshift.io/<label_name>: "true" (3)
    1 Enable Loki alerting and recording rules in your cluster.
    2 Add a custom label that can be added to namespaces where you want to enable the use of logging alerts and metrics.
    3 Add a custom label that can be added to namespaces where you want to enable the use of logging alerts and metrics.

Authorizing LokiStack rules RBAC permissions

Administrators can allow users to create and manage their own alerting and recording rules by binding cluster roles to usernames. Cluster roles are defined as ClusterRole objects that contain necessary role-based access control (RBAC) permissions for users.

In logging 5.8 and later, the following cluster roles for alerting and recording rules are available for LokiStack:

Rule name Description

alertingrules.loki.grafana.com-v1-admin

Users with this role have administrative-level access to manage alerting rules. This cluster role grants permissions to create, read, update, delete, list, and watch AlertingRule resources within the loki.grafana.com/v1 API group.

alertingrules.loki.grafana.com-v1-crdview

Users with this role can view the definitions of Custom Resource Definitions (CRDs) related to AlertingRule resources within the loki.grafana.com/v1 API group, but do not have permissions for modifying or managing these resources.

alertingrules.loki.grafana.com-v1-edit

Users with this role have permission to create, update, and delete AlertingRule resources.

alertingrules.loki.grafana.com-v1-view

Users with this role can read AlertingRule resources within the loki.grafana.com/v1 API group. They can inspect configurations, labels, and annotations for existing alerting rules but cannot make any modifications to them.

recordingrules.loki.grafana.com-v1-admin

Users with this role have administrative-level access to manage recording rules. This cluster role grants permissions to create, read, update, delete, list, and watch RecordingRule resources within the loki.grafana.com/v1 API group.

recordingrules.loki.grafana.com-v1-crdview

Users with this role can view the definitions of Custom Resource Definitions (CRDs) related to RecordingRule resources within the loki.grafana.com/v1 API group, but do not have permissions for modifying or managing these resources.

recordingrules.loki.grafana.com-v1-edit

Users with this role have permission to create, update, and delete RecordingRule resources.

recordingrules.loki.grafana.com-v1-view

Users with this role can read RecordingRule resources within the loki.grafana.com/v1 API group. They can inspect configurations, labels, and annotations for existing alerting rules but cannot make any modifications to them.

Examples

To apply cluster roles for a user, you must bind an existing cluster role to a specific username.

Cluster roles can be cluster or namespace scoped, depending on which type of role binding you use. When a RoleBinding object is used, as when using the oc adm policy add-role-to-user command, the cluster role only applies to the specified namespace. When a ClusterRoleBinding object is used, as when using the oc adm policy add-cluster-role-to-user command, the cluster role applies to all namespaces in the cluster.

The following example command gives the specified user create, read, update and delete (CRUD) permissions for alerting rules in a specific namespace in the cluster:

Example cluster role binding command for alerting rule CRUD permissions in a specific namespace
$ oc adm policy add-role-to-user alertingrules.loki.grafana.com-v1-admin -n <namespace> <username>

The following command gives the specified user administrator permissions for alerting rules in all namespaces:

Example cluster role binding command for administrator permissions
$ oc adm policy add-cluster-role-to-user alertingrules.loki.grafana.com-v1-admin <username>
Additional resources

Creating a log-based alerting rule with Loki

The AlertingRule CR contains a set of specifications and webhook validation definitions to declare groups of alerting rules for a single LokiStack instance. In addition, the webhook validation definition provides support for rule validation conditions:

  • If an AlertingRule CR includes an invalid interval period, it is an invalid alerting rule

  • If an AlertingRule CR includes an invalid for period, it is an invalid alerting rule.

  • If an AlertingRule CR includes an invalid LogQL expr, it is an invalid alerting rule.

  • If an AlertingRule CR includes two groups with the same name, it is an invalid alerting rule.

  • If none of above applies, an alerting rule is considered valid.

Tenant type Valid namespaces for AlertingRule CRs

application

audit

openshift-logging

infrastructure

openshift-/*, kube-/\*, default
Prerequisites

  • Red Hat OpenShift logging Operator 5.7 and later

  • OpenShift Container Platform 4.13 and later

Procedure

  1. Create an AlertingRule custom resource (CR):

    Example infrastructure AlertingRule CR
      apiVersion: loki.grafana.com/v1
  kind: AlertingRule
  metadata:
    name: loki-operator-alerts
    namespace: openshift-operators-redhat (1)
    labels: (2)
      openshift.io/<label_name>: "true"
  spec:
    tenantID: "infrastructure" (3)
    groups:
      - name: LokiOperatorHighReconciliationError
        rules:
          - alert: HighPercentageError
            expr: | (4)
              sum(rate({kubernetes_namespace_name="openshift-operators-redhat", kubernetes_pod_name=~"loki-operator-controller-manager.*"} |= "error" [1m])) by (job)
                /
              sum(rate({kubernetes_namespace_name="openshift-operators-redhat", kubernetes_pod_name=~"loki-operator-controller-manager.*"}[1m])) by (job)
                > 0.01
            for: 10s
            labels:
              severity: critical (5)
            annotations:
              summary: High Loki Operator Reconciliation Errors (6)
              description: High Loki Operator Reconciliation Errors (7)
    1 The namespace where this AlertingRule CR is created must have a label matching the LokiStack spec.rules.namespaceSelector definition.
    2 The labels block must match the LokiStack spec.rules.selector definition.
    3 AlertingRule CRs for infrastructure tenants are only supported in the openshift-*, kube-\*, or default namespaces.
    4 The value for kubernetes_namespace_name: must match the value for metadata.namespace.
    5 The value of this mandatory field must be critical, warning, or info.
    6 This field is mandatory.
    7 This field is mandatory.
    Example application AlertingRule CR
      apiVersion: loki.grafana.com/v1
  kind: AlertingRule
  metadata:
    name: app-user-workload
    namespace: app-ns (1)
    labels: (2)
      openshift.io/<label_name>: "true"
  spec:
    tenantID: "application"
    groups:
      - name: AppUserWorkloadHighError
        rules:
          - alert:
            expr: | (3)
            sum(rate({kubernetes_namespace_name="app-ns", kubernetes_pod_name=~"podName.*"} |= "error" [1m])) by (job)
            for: 10s
            labels:
              severity: critical (4)
            annotations:
              summary:  (5)
              description:  (6)
    1 The namespace where this AlertingRule CR is created must have a label matching the LokiStack spec.rules.namespaceSelector definition.
    2 The labels block must match the LokiStack spec.rules.selector definition.
    3 Value for kubernetes_namespace_name: must match the value for metadata.namespace.
    4 The value of this mandatory field must be critical, warning, or info.
    5 The value of this mandatory field is a summary of the rule.
    6 The value of this mandatory field is a detailed description of the rule.

  2. Apply the AlertingRule CR:

    $ oc apply -f <filename>.yaml

Additional resources