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Merge pull request #192771 from craigshoemaker/aca/observ
[Container Apps] Health probes
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‎articles/container-apps/TOC.yml

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href: application-lifecycle-management.md
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- name: Microservices
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href: microservices.md
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- name: Health probes
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href: health-probes.md
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- name: How-to guides
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items:
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- name: Scale an app

‎articles/container-apps/azure-resource-manager-api-spec.md

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@@ -162,6 +162,8 @@ Changes made to the `template` section are [revision-scope changes](revisions.md
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### <a name="container-app-examples"></a>Examples
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For details on health probes, refer to [Heath probes in Azure Container Apps](./health-probes.md).
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# [ARM template](#tab/arm-template)
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The following example ARM template deploys a container app.
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"resources": {
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"cpu": 0.5,
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"memory": "1Gi"
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}
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},
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"probes":[
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{
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"type":"liveness",
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"httpGet":{
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"path":"/health",
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"port":8080,
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"httpHeaders":[
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{
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"name":"Custom-Header",
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"value":"liveness probe"
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}]
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},
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"initialDelaySeconds":7,
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"periodSeconds":3
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},
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{
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"type":"readiness",
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"tcpSocket":
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{
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"port": 8081
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},
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"initialDelaySeconds": 10,
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"periodSeconds": 3
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},
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{
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"type": "startup",
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"httpGet": {
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"path": "/startup",
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"port": 8080,
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"httpHeaders": [
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{
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"name": "Custom-Header",
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"value": "startup probe"
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}]
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},
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"initialDelaySeconds": 3,
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"periodSeconds": 3
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}]
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}
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],
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"scale": {
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```yaml
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kind: containerapp
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location: northeurope
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location: canadacentral
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name: mycontainerapp
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resourceGroup: myresourcegroup
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type: Microsoft.App/containerApps
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resources:
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cpu: 0.5
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memory: 1Gi
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probes:
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- type: liveness
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httpGet:
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- path: "/health"
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port: 8080
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httpHeaders:
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- name: "Custom-Header"
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value: "liveness probe"
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initialDelaySeconds: 7
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periodSeconds: 3
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- type: readiness
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tcpSocket:
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- port: 8081
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initialDelaySeconds: 10
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periodSeconds: 3
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- type: startup
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httpGet:
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- path: "/startup"
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port: 8080
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httpHeaders:
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- name: "Custom-Header"
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value: "startup probe"
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initialDelaySeconds: 3
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periodSeconds: 3
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scale:
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minReplicas: 1
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maxReplicas: 3

‎articles/container-apps/health-probes.md

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---
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title: Health probes in Azure Container Apps
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description: Check startup, liveness, and readiness with Azure Container Apps health probes
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services: container-apps
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author: craigshoemaker
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ms.service: container-apps
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ms.topic: conceptual
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ms.date: 03/30/2022
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ms.author: cshoe
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---
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# Health probes in Azure Container Apps
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Health probes in Azure Container Apps are based on [Kubernetes health probes](https://kubernetes.io/docs/tasks/configure-pod-container/configure-liveness-readiness-startup-probes/). You can set up probes using either TCP or HTTP(S) exclusively.
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Container Apps support the following probes:
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- [Liveness](https://kubernetes.io/docs/tasks/configure-pod-container/configure-liveness-readiness-startup-probes/#define-a-liveness-command): Reports the overall health of your replica.
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- [Startup](https://kubernetes.io/docs/tasks/configure-pod-container/configure-liveness-readiness-startup-probes/#define-startup-probes): Delay reporting on a liveness or readiness state for slower apps with a startup probe.
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- [Readiness](https://kubernetes.io/docs/tasks/configure-pod-container/configure-liveness-readiness-startup-probes/#define-readiness-probes): Signals that a replica is ready to accept traffic.
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For a full listing of the specification supported in Azure Container Apps, refer to [Azure Rest API specs](https://github.com/Azure/azure-rest-api-specs/blob/main/specification/app/resource-manager/Microsoft.App/stable/2022-03-01/CommonDefinitions.json#L119-L236).
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## HTTP probes
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HTTP probes allow you to implement custom logic to check the status of application dependencies before reporting a healthy status. Configure your health probe endpoints to respond with an HTTP status code greater than or equal to `200` and less than `400` to indicate success. Any other response code outside this range indicates a failure.
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The following example demonstrates how to implement a liveness endpoint in JavaScript.
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```javascript
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const express = require('express');
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const app = express();
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app.get('/liveness', (req, res) => {
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let isSystemStable = false;
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// check for database availability
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// check filesystem structure
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// etc.
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// set isSystemStable to true if all checks pass
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if (isSystemStable) {
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res.status(200); // Success
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} else {
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res.status(503); // Service unavailable
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}
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})
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```
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## TCP probes
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TCP probes wait for a connection to be established with the server to indicate success. A probe failure is registered if no connection is made.
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## Restrictions
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- You can only add one of each probe type per container.
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- `exec` probes aren't supported.
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- Port values must be integers; named ports aren't supported.
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## Examples
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The following code listing shows how you can define health probes for your containers.
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The `...` placeholders denote omitted code. Refer to [Container Apps Preview ARM template API specification](./azure-resource-manager-api-spec.md) for full ARM template details.
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# [ARM template](#tab/arm-template)
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```json
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{
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...
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"containers":[
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{
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"image":"nginx",
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"name":"web",
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"probes": [
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{
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"type": "liveness",
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"httpGet": {
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"path": "/health",
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"port": 8080,
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"httpHeaders": [
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{
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"name": "Custom-Header",
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"value": "liveness probe"
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}],
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"initialDelaySeconds": 7,
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"periodSeconds": 3
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}
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},
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{
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"type": "readiness",
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"tcpSocket": {
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"port": 8081
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},
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"initialDelaySeconds": 10,
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"periodSeconds": 3
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},
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{
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"type": "startup",
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"httpGet": {
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"path": "/startup",
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"port": 8080,
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"httpHeaders": [
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{
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"name": "Custom-Header",
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"value": "startup probe"
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}],
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"initialDelaySeconds": 3,
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"periodSeconds": 3
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}
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}]
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}]
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...
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}
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```
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# [YAML](#tab/yaml)
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```yml
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...
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containers:
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- image: nginx
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name: web
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probes:
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- type: liveness
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httpGet:
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path: "/health"
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port: 8080
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httpHeaders:
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- name: Custom-Header
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value: "liveness probe"
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initialDelaySeconds: 7
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periodSeconds: 3
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- type: readiness
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tcpSocket:
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port: 8081
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initialDelaySeconds: 10
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periodSeconds: 3
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- type: startup
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httpGet:
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path: "/startup"
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port: 8080
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httpHeaders:
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- name: Custom-Header
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value: "startup probe"
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initialDelaySeconds: 3
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periodSeconds: 3
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...
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```
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---
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The optional [failureThreshold](https://kubernetes.io/docs/tasks/configure-pod-container/configure-liveness-readiness-startup-probes/#configure-probes) setting defines the number of attempts Kubernetes tries if the probe if execution fails. Attempts that exceed the `failureThreshold` amount cause different results for each probe. Refer to [Configure Liveness, Readiness and Startup Probes](https://kubernetes.io/docs/tasks/configure-pod-container/configure-liveness-readiness-startup-probes/#configure-probes) for details.
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## Next steps
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> [!div class="nextstepaction"]
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> [Monitor an app](monitor.md)

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