[Feature Flags] Add APM transaction + better example code (elastic#19…

…9671) Co-authored-by: kibanamachine <[email protected]>
tkajtoch · Nov 12, 2024 · d55ce92 · d55ce92
1 parent ec50f2a
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diff --git a/examples/feature_flags_example/public/components/app.tsx b/examples/feature_flags_example/public/components/app.tsx
@@ -8,24 +8,15 @@
  */
 
 import React from 'react';
-import {
-  EuiHorizontalRule,
-  EuiPageTemplate,
-  EuiTitle,
-  EuiText,
-  EuiLink,
-  EuiListGroup,
-  EuiListGroupItem,
-} from '@elastic/eui';
+import { EuiHorizontalRule, EuiPageTemplate, EuiTitle, EuiText, EuiLink } from '@elastic/eui';
 import type { CoreStart, FeatureFlagsStart } from '@kbn/core/public';
 
-import useObservable from 'react-use/lib/useObservable';
-import {
-  FeatureFlagExampleBoolean,
-  FeatureFlagExampleNumber,
-  FeatureFlagExampleString,
-} from '../../common/feature_flags';
 import { PLUGIN_NAME } from '../../common';
+import {
+  FeatureFlagsFullList,
+  FeatureFlagsReactiveList,
+  FeatureFlagsStaticList,
+} from './feature_flags_list';
 
 interface FeatureFlagsExampleAppDeps {
   featureFlags: FeatureFlagsStart;
@@ -34,16 +25,6 @@ interface FeatureFlagsExampleAppDeps {
 }
 
 export const FeatureFlagsExampleApp = ({ featureFlags }: FeatureFlagsExampleAppDeps) => {
-  // Fetching the feature flags synchronously
-  const bool = featureFlags.getBooleanValue(FeatureFlagExampleBoolean, false);
-  const str = featureFlags.getStringValue(FeatureFlagExampleString, 'red');
-  const num = featureFlags.getNumberValue(FeatureFlagExampleNumber, 1);
-
-  // Use React Hooks to observe feature flags changes
-  const bool$ = useObservable(featureFlags.getBooleanValue$(FeatureFlagExampleBoolean, false));
-  const str$ = useObservable(featureFlags.getStringValue$(FeatureFlagExampleString, 'red'));
-  const num$ = useObservable(featureFlags.getNumberValue$(FeatureFlagExampleNumber, 1));
-
   return (
     <>
       <EuiPageTemplate>
@@ -67,22 +48,21 @@ export const FeatureFlagsExampleApp = ({ featureFlags }: FeatureFlagsExampleAppD
               .
             </p>
             <EuiHorizontalRule />
-            <EuiListGroup>
-              <p>
-                The feature flags are:
-                <EuiListGroupItem label={`${FeatureFlagExampleBoolean}: ${bool}`} />
-                <EuiListGroupItem label={`${FeatureFlagExampleString}: ${str}`} />
-                <EuiListGroupItem label={`${FeatureFlagExampleNumber}: ${num}`} />
-              </p>
-            </EuiListGroup>
-            <EuiListGroup>
-              <p>
-                The <strong>observed</strong> feature flags are:
-                <EuiListGroupItem label={`${FeatureFlagExampleBoolean}: ${bool$}`} />
-                <EuiListGroupItem label={`${FeatureFlagExampleString}: ${str$}`} />
-                <EuiListGroupItem label={`${FeatureFlagExampleNumber}: ${num$}`} />
-              </p>
-            </EuiListGroup>
+            <h3>Rendered separately</h3>
+            <p>
+              Each list are 2 different components, so only the reactive one is re-rendered when the
+              feature flag is updated and the static one keeps the value until the next refresh.
+            </p>
+            <FeatureFlagsStaticList featureFlags={featureFlags} />
+            <FeatureFlagsReactiveList featureFlags={featureFlags} />
+            <EuiHorizontalRule />
+            <h3>Rendered together</h3>
+            <p>
+              `useObservable` causes a full re-render of the component, updating the{' '}
+              <i>statically</i>
+              evaluated flags as well.
+            </p>
+            <FeatureFlagsFullList featureFlags={featureFlags} />
           </EuiText>
         </EuiPageTemplate.Section>
       </EuiPageTemplate>

diff --git a/examples/feature_flags_example/public/components/feature_flags_list.tsx b/examples/feature_flags_example/public/components/feature_flags_list.tsx
@@ -0,0 +1,91 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the "Elastic License
+ * 2.0", the "GNU Affero General Public License v3.0 only", and the "Server Side
+ * Public License v 1"; you may not use this file except in compliance with, at
+ * your election, the "Elastic License 2.0", the "GNU Affero General Public
+ * License v3.0 only", or the "Server Side Public License, v 1".
+ */
+
+import { EuiListGroup, EuiListGroupItem } from '@elastic/eui';
+import React from 'react';
+import type { FeatureFlagsStart } from '@kbn/core-feature-flags-browser';
+import useObservable from 'react-use/lib/useObservable';
+import {
+  FeatureFlagExampleBoolean,
+  FeatureFlagExampleNumber,
+  FeatureFlagExampleString,
+} from '../../common/feature_flags';
+
+export interface FeatureFlagsListProps {
+  featureFlags: FeatureFlagsStart;
+}
+
+export const FeatureFlagsStaticList = ({ featureFlags }: FeatureFlagsListProps) => {
+  // Fetching the feature flags synchronously
+  const bool = featureFlags.getBooleanValue(FeatureFlagExampleBoolean, false);
+  const str = featureFlags.getStringValue(FeatureFlagExampleString, 'red');
+  const num = featureFlags.getNumberValue(FeatureFlagExampleNumber, 1);
+
+  return (
+    <EuiListGroup>
+      <p>
+        The feature flags are:
+        <EuiListGroupItem label={`${FeatureFlagExampleBoolean}: ${bool}`} />
+        <EuiListGroupItem label={`${FeatureFlagExampleString}: ${str}`} />
+        <EuiListGroupItem label={`${FeatureFlagExampleNumber}: ${num}`} />
+      </p>
+    </EuiListGroup>
+  );
+};
+
+export const FeatureFlagsReactiveList = ({ featureFlags }: FeatureFlagsListProps) => {
+  // Use React Hooks to observe feature flags changes
+  const bool$ = useObservable(featureFlags.getBooleanValue$(FeatureFlagExampleBoolean, false));
+  const str$ = useObservable(featureFlags.getStringValue$(FeatureFlagExampleString, 'red'));
+  const num$ = useObservable(featureFlags.getNumberValue$(FeatureFlagExampleNumber, 1));
+
+  return (
+    <EuiListGroup>
+      <p>
+        The <strong>observed</strong> feature flags are:
+        <EuiListGroupItem label={`${FeatureFlagExampleBoolean}: ${bool$}`} />
+        <EuiListGroupItem label={`${FeatureFlagExampleString}: ${str$}`} />
+        <EuiListGroupItem label={`${FeatureFlagExampleNumber}: ${num$}`} />
+      </p>
+    </EuiListGroup>
+  );
+};
+
+export const FeatureFlagsFullList = ({ featureFlags }: FeatureFlagsListProps) => {
+  // Fetching the feature flags synchronously
+  const bool = featureFlags.getBooleanValue(FeatureFlagExampleBoolean, false);
+  const str = featureFlags.getStringValue(FeatureFlagExampleString, 'red');
+  const num = featureFlags.getNumberValue(FeatureFlagExampleNumber, 1);
+
+  // Use React Hooks to observe feature flags changes
+  const bool$ = useObservable(featureFlags.getBooleanValue$(FeatureFlagExampleBoolean, false));
+  const str$ = useObservable(featureFlags.getStringValue$(FeatureFlagExampleString, 'red'));
+  const num$ = useObservable(featureFlags.getNumberValue$(FeatureFlagExampleNumber, 1));
+
+  return (
+    <>
+      <EuiListGroup>
+        <p>
+          The feature flags are:
+          <EuiListGroupItem label={`${FeatureFlagExampleBoolean}: ${bool}`} />
+          <EuiListGroupItem label={`${FeatureFlagExampleString}: ${str}`} />
+          <EuiListGroupItem label={`${FeatureFlagExampleNumber}: ${num}`} />
+        </p>
+      </EuiListGroup>
+      <EuiListGroup>
+        <p>
+          The <strong>observed</strong> feature flags are:
+          <EuiListGroupItem label={`${FeatureFlagExampleBoolean}: ${bool$}`} />
+          <EuiListGroupItem label={`${FeatureFlagExampleString}: ${str$}`} />
+          <EuiListGroupItem label={`${FeatureFlagExampleNumber}: ${num$}`} />
+        </p>
+      </EuiListGroup>
+    </>
+  );
+};
diff --git a/examples/feature_flags_example/tsconfig.json b/examples/feature_flags_example/tsconfig.json
@@ -20,5 +20,6 @@
     "@kbn/core-plugins-server",
     "@kbn/config-schema",
     "@kbn/developer-examples-plugin",
+    "@kbn/core-feature-flags-browser",
   ]
 }
diff --git a/packages/core/feature-flags/README.mdx b/packages/core/feature-flags/README.mdx
@@ -15,7 +15,7 @@ The service is always enabled, however, it will return the fallback value if a f
 Kibana only registers a provider when running on Elastic Cloud Hosted/Serverless. And even in those scenarios, we expect that some customers might 
 have network restrictions that might not allow the flags to evaluate. The fallback value must provide a non-broken experience to users.
 
-:warning: Feature Flags are considered dynamic configuration and cannot be used for settings that require restarting Kibana.
+⚠️Feature Flags are considered dynamic configuration and cannot be used for settings that require restarting Kibana.
 One example of invalid use cases are settings used during the `setup` lifecycle of the plugin, such as settings that define 
 if an HTTP route is registered or not. Instead, you should always register the route, and return `404 - Not found` in the route 
 handler if the feature flag returns a _disabled_ state.  

diff --git a/packages/core/feature-flags/core-feature-flags-browser-internal/src/feature_flags_service.ts b/packages/core/feature-flags/core-feature-flags-browser-internal/src/feature_flags_service.ts
@@ -68,7 +68,15 @@ export class FeatureFlagsService {
         if (this.isProviderReadyPromise) {
           throw new Error('A provider has already been set. This API cannot be called twice.');
         }
+        const transaction = apm.startTransaction('set-provider', 'feature-flags');
         this.isProviderReadyPromise = OpenFeature.setProviderAndWait(provider);
+        this.isProviderReadyPromise
+          .then(() => transaction?.end())
+          .catch((err) => {
+            this.logger.error(err);
+            apm.captureError(err);
+            transaction?.end();
+          });
       },
       appendContext: (contextToAppend) => this.appendContext(contextToAppend),
     };