docs: add metrics-operator architecture

docs/content/en/docs/concepts/architecture/components/_index.md

@@ -28,36 +28,3 @@ style Scheduler fill:#d8e6f4,stroke:#fff,stroke-width:px,color:#006bb8
 style Lifecycle-Operator fill:#d8e6f4,stroke:#fff,stroke-width:px,color:#006bb8
 style Metrics-Operator fill:#d8e6f4,stroke:#fff,stroke-width:px,color:#006bb8
 ```
-
-**Keptn's Lifecycle Operator** is
-a Kubernetes [operator](https://kubernetes.io/docs/concepts/extend-kubernetes/operator/)
-that automates the deployment and management
-of the Keptn Lifecycle Controller components in a Kubernetes cluster.
-The Keptn Lifecycle Operator contains several controllers for **Keptn CRDs**
-and a **Mutating Webhook**.
-
-Here's a brief overview:
-
-**Keptn CRDs:** Keptn Lifecycle Operator contains
-several controllers that manage and reconcile different types of Keptn CRDs
-such as the Project Controller, Service Controller, and Stage Controller.
-
-**Mutating Webhook:** automatically injects Keptn labels
-and annotations into Kubernetes resources,
-such as deployments and services.
-These labels and annotations are used to enable Keptn's automation
-and monitoring capabilities.
-
-**Keptn's Lifecycle Metrics Operator**
-collects,  processes, and analyzes metrics data from a variety of sources.
-Once collected, this data, can be used to generate a variety of reports
-and dashboards that provide insights into the health and performance of the application and infrastructure.
-
-**Keptn's Lifecycle Scheduler** replaces the
-[Kubernetes scheduler](https://kubernetes.io/docs/concepts/scheduling-eviction/kube-scheduler/)
-to allow users to schedule events and tasks to occur
-at specific times during the application lifecycle.
-The Lifecycle Scheduler can trigger events such as
-deployment, testing, and remediation at specific times or intervals.
-The Keptn Scheduler guarantees that Pods are initiated only after
-the Pre-Deployment checks are completed.

docs/content/en/docs/concepts/architecture/components/lifecycle-operator/_index.md

@@ -0,0 +1,27 @@
+---
+title: Keptn Lifecycle Operator
+linktitle: Lifecycle Operator
+description: Basic understanding of Keptn's Lifecycle Operator
+weight: 80
+cascade:
+---
+
+
+**Keptn's Lifecycle Operator** is
+a Kubernetes [operator](https://kubernetes.io/docs/concepts/extend-kubernetes/operator/)
+that automates the deployment and management
+of the Keptn Lifecycle Controller components in a Kubernetes cluster.
+The Keptn Lifecycle Operator contains several controllers for **Keptn CRDs**
+and a **Mutating Webhook**.
+
+Here's a brief overview:
+
+**Keptn CRDs:** Keptn Lifecycle Operator contains
+several controllers that manage and reconcile different types of Keptn CRDs
+such as the Project Controller, Service Controller, and Stage Controller.
+
+**Mutating Webhook:** automatically injects Keptn labels
+and annotations into Kubernetes resources,
+such as deployments and services.
+These labels and annotations are used to enable Keptn's automation
+and monitoring capabilities.

docs/content/en/docs/concepts/architecture/components/metrics-operator/_index.md

@@ -0,0 +1,54 @@
+---
+title: Keptn Metrics Operator
+linktitle: Metrics Operator
+description: Basic understanding of Keptn's Metrics Operator
+weight: 80
+cascade:
+---
+
+
+The Keptn Metrics Operator collects, processes, and analyzes metrics data from a variety of sources.
+Once collected, this data, can be used to generate a variety of reports and dashboards
+that provide insights into the health and performance of the application and infrastructure.
+
+While Kubernetes does have two metrics servers, they have limitations.
+The custom and external APIs only allow you to use a single observability platform.
+The Keptn Metrics Operator solves this problem by providing a single entry point for
+all your metrics data, regardless of its source.
+Furthermore, due to the integration with the Kubernetes custom metrics API, these metrics are also
+compatible with the Kubernetes HorizontalPodAutoscaler (HPA) which enables the horizontal scaling of workloads
+based on metrics collected from multiple observability platforms such as Prometheus, Dynatrace or Datadog.
+
+The Metrics Operator consists of the following components:
+
+* Metrics Controller
+* Metrics Adapter
+
+```mermaid
+graph TD;
+    Metrics-Operator-->Metrics-Adapter;
+    Metrics-Operator-->Metrics-Controller
+style Metrics-Operator fill:#006bb8,stroke:#fff,stroke-width:px,color:#fff
+style Metrics-Adapter fill:#d8e6f4,stroke:#fff,stroke-width:px,color:#006bb8
+style Metrics-Controller fill:#d8e6f4,stroke:#fff,stroke-width:px,color:#006bb8
+```
+
+**Metrics adapter** is used to expose custom metrics from an application to external monitoring and alerting tools.
+The adapter exposes custom metrics on a specific endpoint where external monitoring and alerting tools can scrape them.
+It is an important component of the metrics operator as it allows for the collection and exposure of custom metrics,
+which can be used to gain insight into the behavior and performance of applications running on a Kubenetes cluster.
+
+**Metrics controller** is used to fetch metrics from a SLI provider.
+The controller reconciles a [`KeptnMetric`](../../../../yaml-crd-ref/metric.md) CR and
+updates its status with the metric value provided by the selected SLI provider.
+The steps in which the controller fetches metrics are given below:
+
+* It first fetches the `KeptnMetric` object to reconcile.
+* If the object is not found, it returns and lets Kubernetes handle deleting all associated resources.
+* If the object is found, the code checks that if the metric has been updated within the configured
+interval which is defined in the `Spec.FetchIntervalSeconds`.
+If not, then it skips reconciling and requeues the request for later.
+* If the metric should be reconciled, it fetches the provider defined in the `Spec.Provider.Name` field.
+* If the provider is not found, it returns and requeues the request for later.
+* If the provider is found, it loads the provider and evaluates the query defined in the `Spec.Query` field.
+* If the evaluation is succesful, it stores the fetched value in the status of the `KeptnMetric` object.

docs/content/en/docs/concepts/architecture/components/scheduler/_index.md

@@ -0,0 +1,16 @@
+---
+title: Keptn Lifecycle Scheduler
+linktitle: Scheduler
+description: Basic understanding of Keptn's Lifecycle Scheduler
+weight: 80
+cascade:
+---
+
+**Keptn's Lifecycle Scheduler** replaces the
+[Kubernetes scheduler](https://kubernetes.io/docs/concepts/scheduling-eviction/kube-scheduler/)
+to allow users to schedule events and tasks to occur
+at specific times during the application lifecycle.
+The Lifecycle Scheduler can trigger events such as
+deployment, testing, and remediation at specific times or intervals.
+The Keptn Scheduler guarantees that Pods are initiated only after
+the Pre-Deployment checks are completed.