docs: document how to write create new keptnmetricsprovider (keptn#2939)

Signed-off-by: Geoffrey Israel <[email protected]>
Signed-off-by: odubajDT <[email protected]>
Co-authored-by: Meg McRoberts <[email protected]>
Co-authored-by: RealAnna <[email protected]>
Co-authored-by: odubajDT <[email protected]>

docs/docs/contribute/software/add-new-metric-provider.md

@@ -0,0 +1,124 @@
+---
+comments: true
+---
+
+# Add a metrics provider
+
+The
+[KeptnMetric](../../guides/evaluatemetrics.md)
+feature works with almost any data platform
+but Keptn requires that a metrics provider be defined
+for any data platform it uses as a data source.
+This guide gives instructions for creating a new metrics provider.
+For these instructions,
+we define a sample provider called `placeholder`.
+The steps to create your own metrics provider are:
+<!-- markdownlint-disable MD007 -->
+
+1. **Fork and clone** the
+[Keptn repository](https://github.com/keptn/lifecycle-toolkit).
+ For more information, see
+ [Fork and clone the repository](https://keptn.sh/stable/docs/contribute/general/git/fork-clone/).
+
+2. **Define the Provider Type:** In the `metrics-operator/controllers/common/providers/common.go` file,
+ define the constant `KeptnPlaceholderProviderType`.
+  In our example we use `"placeholder"`.
+
+    ```go
+    const KeptnPlaceholderProviderType = "placeholder"
+    ```
+
+3. **Implement the Provider:** Create a new folder inside the
+   [metrics-operator/controllers/common/providers](<https://github.com/keptn/lifecycle-toolkit/tree/main/metrics-operator/controllers/common/providers>).
+   Use the provider name as the name of the folder.
+   This name defines the string used to identify this provider
+   in the `spec.type` field of the
+   [KeptnMetricsProvider](../../reference/crd-reference/metricsprovider.md)
+   resource.
+   In this example, the folder is named `placeholder`.
+   Create a new Go package for the placeholder provider in that folder.
+   This package should contain a `struct` that implements the `KeptnSLIProvider` interface.
+   To fully implement the `KeptnSLIProvider` interface, it's necessary to implement the following functions.
+
+      * `EvaluateQuery`(Fetches metric values from the provider)
+        * This function fetches metric values based on the provided
+          metric query from the provider.
+          It evaluates the query and returns the metric values
+          along with any additional data if required.
+        * It takes as input a [KeptnMetric](../../reference/crd-reference/metric.md)
+          and [KeptnMetricsProvider](../../reference/crd-reference/metricsprovider.md)
+      * `EvaluateQueryForStep`(Fetches metric values with step interval from the provider)
+        * This function fetches metric values with a specified step interval from the placeholder provider.
+          It takes into account the metric query and the step interval provided, executes the query,
+          and returns the metric values along with any additional data if required.
+        * It takes as input a [KeptnMetric](../../reference/crd-reference/metric.md)
+          and [KeptnMetricsProvider](../../reference/crd-reference/metricsprovider.md)
+      * `FetchAnalysisValue`(Fetches analysis values from the provider) functions.
+        * This function fetches analysis values based on the provided query and time range from the
+          provider.
+          It evaluates the query within the specified time range and returns the analysis
+          values along with any additional data if required.
+        * It takes as input an [Analysis](../../reference/crd-reference/analysis.md),
+          resource that contains a `query` and a
+          [KeptnMetricsProvider](../../reference/crd-reference/metricsprovider.md) resource.
+
+     You can follow other existing implementations,
+     such as [prometheus.go](https://github.com/keptn/lifecycle-toolkit/blob/main/metrics-operator/controllers/common/providers/prometheus/prometheus.go),
+     as an example.
+
+     Each of the three functions expects a string containing a float value in it.
+     But for example purposes we returned some of the data accessible in the function.
+
+     Below is an example of a placeholder provider implementation.
+
+      ```go
+      {% include "./assets/example-code/placeholder-code-example.go" %}
+      ```
+
+      > **Note** Refer to the documentation of the
+      > [KeptnMetric](../../reference/crd-reference/metric.md)
+      > and
+      > [Analysis](../../reference/crd-reference/analysis.md)
+      > resources
+      > to understand what data should be retrieved from the methods inputs to compute accurate results.
+
+4. **Instantiate the Provider** in the `providers.NewProvider` function
+   in the `metrics-operator/controllers/common/providers/provider.go` file.
+   add a case for the `KeptnPlaceholderProviderType`.
+   Instantiate the placeholder provider struct and return it.
+
+    ```go
+    {% include "./assets/example-code/new-provider-function.go" %}
+    ```
+
+5. **Update the validation webhook and crd config:** To update the validation webhook and crd config of the metrics operator.
+   Add the provider name next to last providers on this
+   [line](https://github.com/keptn/lifecycle-toolkit/blob/main/metrics-operator/api/v1beta1/keptnmetricsprovider_types.go#L29)
+   to look like this
+
+    `// +kubebuilder:validation:Pattern:=prometheus|dynatrace|datadog|dql|placeholder`.
+
+     In the metric-operator directory run `make generate manifests` to update the metrics-operator crd config
+     Then modify the helm chart and the helm chart crd validation to match the update in the metrics-operator crd config
+
+6. **Add Test Cases:**
+     * Write a unit test to validate your implementation at the function level.
+       Unit tests ensure that individual
+       functions behave as expected and meet their functional requirements.
+
+     * Include a Chainsaw test to validate the behavior of Kubernetes resources managed by your code.
+       Chainsaw tests simulate real-world scenarios and interactions within a Kubernetes cluster, ensuring
+       the correctness of your Kubernetes configurations and deployments.
+
+        Below are the steps for adding an integration test.
+
+        * In the directory `test/chainsaw/testmetrics`, create a folder `metrics-provider-placeholder` in our case.
+        * Within the `keptn-metrics-placeholder` folder, create YAML file `00-install.yaml`.
+          * `00-install.yaml` contains a sample configuration that installs a valid `KeptnMetricsProvider`
+              in our case `placeholder` and it also defines a sample `KeptnMetric` configuration
+              representing a valid use case, while.
+        * Create a file named `chainsaw-test.yaml` and define the steps for the integration test in chainsaw-test.yaml.
+
+        > For more information checkout [an already existing integration test](https://github.com/keptn/lifecycle-toolkit/tree/main/test/chainsaw/testmetrics/metrics-provider)
+
+<!-- markdownlint-enable MD007 -->

docs/docs/contribute/software/assets/example-code/new-provider-function.go

@@ -0,0 +1,13 @@
+// Inside the providers package
+
+// NewProvider function
+func NewProvider(providerType string, log logr.Logger, k8sClient client.Client) (KeptnSLIProvider, error) {
+	switch strings.ToLower(providerType) {
+	case KeptnPlaceholderProviderType:
+		return &placeholder.KeptnPlaceholderProvider{
+			Log:        log,
+			HttpClient: http.Client{},
+		}, nil
+		// Other cases...
+	}
+}

docs/docs/contribute/software/assets/example-code/placeholder-code-example.go

@@ -0,0 +1,45 @@
+package placeholder
+
+import (
+	"context"
+	"fmt"
+	"net/http"
+	"time"
+
+	"github.com/go-logr/logr"
+	metricsapi "github.com/keptn/lifecycle-toolkit/metrics-operator/api/v1beta1"
+)
+
+type KeptnPlaceholderProvider struct {
+	Log        logr.Logger
+	HttpClient http.Client
+}
+
+func (d *KeptnPlaceholderProvider) FetchAnalysisValue(ctx context.Context, query string, analysis metricsapi.Analysis, provider *metricsapi.KeptnMetricsProvider) (string, error) {
+	return fmt.Sprintf("placeholder provider FetchAnalysisValue was called with query %s from %d to %d", query, analysis.GetFrom().Unix(), analysis.GetTo().Unix()), nil
+}
+
+func (d *KeptnPlaceholderProvider) EvaluateQuery(ctx context.Context, metric metricsapi.KeptnMetric, provider metricsapi.KeptnMetricsProvider) (string, []byte, error) {
+	return fmt.Sprintf("placeholder provider EvaluateQuery was called with query %s", metric.Spec.Query), nil, nil
+}
+
+func (d *KeptnPlaceholderProvider) EvaluateQueryForStep(ctx context.Context, metric metricsapi.KeptnMetric, provider metricsapi.KeptnMetricsProvider) ([]string, []byte, error) {
+	fromTime, toTime, stepInterval, err := getTimeRangeForStep(metric)
+	if err != nil {
+		return nil, nil, err
+	}
+	result := fmt.Sprintf("placeholder provider EvaluateQueryForStep was called with query %s from %d to %d at an interval %d", metric.Spec.Query, fromTime, toTime, stepInterval)
+	return []string{result}, nil, nil
+}
+
+func getTimeRangeForStep(metric metricsapi.KeptnMetric) (int64, int64, int64, error) {
+	intervalDuration, err := time.ParseDuration(metric.Spec.Range.Interval)
+	if err != nil {
+		return 0, 0, 0, err
+	}
+	stepDuration, err := time.ParseDuration(metric.Spec.Range.Step)
+	if err != nil {
+		return 0, 0, 0, err
+	}
+	return time.Now().Add(-intervalDuration).Unix(), time.Now().Unix(), stepDuration.Milliseconds(), nil
+}

mkdocs.yml

@@ -202,6 +202,7 @@ nav:
       - Software contributions:
           - docs/contribute/software/index.md
           - Software development environment: docs/contribute/software/dev-environ.md
+          - Add a metrics provider: docs/contribute/software/add-new-metric-provider.md
       - Documentation contributions:
           - docs/contribute/docs/index.md
           - Contribution guidelines for documentation: docs/contribute/docs/contrib-guidelines-docs.md