> ## Documentation Index
> Fetch the complete documentation index at: https://docs.xloud.tech/llms.txt
> Use this file to discover all available pages before exploring further.

# Health Monitors

> Configure TCP, HTTP, and HTTPS health checks to automatically remove unhealthy backend members from Xloud Load Balancer pools.

## Overview

Health monitors continuously probe pool members and automatically remove unhealthy
instances from rotation. When a member fails the configured number of consecutive probes,
it is marked `OFFLINE` and receives no traffic until it recovers. This guide covers all
supported monitor types, their configuration parameters, and best practices for different
application types.

<Note>
  **Prerequisites**

  * An active Xloud account with appropriate permissions
  * Access to the **Xloud Dashboard** or CLI configured with credentials
  * API credentials sourced (`source openrc.sh`)
</Note>

***

## Supported Monitor Types

| Type          | Protocol                          | Use Case                                          |
| ------------- | --------------------------------- | ------------------------------------------------- |
| `TCP`         | Layer 4 connection check          | Any TCP service — databases, custom protocols     |
| `HTTP`        | GET request + response code check | Web applications and REST APIs                    |
| `HTTPS`       | Encrypted GET request check       | HTTPS backends requiring secure probes            |
| `PING`        | ICMP echo                         | Basic host reachability test                      |
| `UDP-CONNECT` | UDP connection check              | UDP-based services                                |
| `TLS-HELLO`   | TLS handshake check               | Verify TLS is functional without full HTTPS probe |

***

## Configuration Parameters

| Parameter            | Description                                                    | Recommended |
| -------------------- | -------------------------------------------------------------- | ----------- |
| **Delay**            | Seconds between consecutive probes                             | `5–10`      |
| **Timeout**          | Seconds to wait for probe response before counting as failed   | `3–5`       |
| **Max Retries**      | Consecutive failures before marking member DOWN                | `3`         |
| **Max Retries Down** | Consecutive successes before restoring a DOWN member to ONLINE | `3`         |
| **URL Path**         | Path for HTTP/HTTPS monitors (must return expected code)       | `/health`   |
| **Expected Codes**   | Comma-separated HTTP status codes accepted as healthy          | `200`       |

<Tip>
  Set **Delay** to at least twice the **Timeout** value to prevent overlapping probes
  during slow response periods. For example: Delay=10, Timeout=5.
</Tip>

***

## Create a Health Monitor

<Tabs>
  <Tab title="Dashboard" icon="gauge">
    <Steps titleSize="h3">
      <Step title="Navigate to pool health monitor" icon="heart-pulse">
        Open your load balancer, select the **Pools** tab, and click the pool name.
        Select the **Health Monitor** sub-tab. Click **Create Health Monitor**.
      </Step>

      <Step title="Select monitor type" icon="settings">
        Select the type that matches your backend service. HTTP is appropriate for web
        applications; TCP is appropriate for databases and custom protocols.
      </Step>

      <Step title="Set timing parameters" icon="clock">
        | Field                                                                                | Recommended Value |
        | ------------------------------------------------------------------------------------ | ----------------- |
        | **Delay**                                                                            | `10`              |
        | **Timeout**                                                                          | `5`               |
        | **Max Retries**                                                                      | `3`               |
        | For HTTP monitors, set **URL Path** to a dedicated health endpoint (e.g., `/health`) |                   |
        | that returns HTTP 200 only when the application is fully ready.                      |                   |
      </Step>

      <Step title="Confirm creation" icon="circle-check">
        <Check>Health monitor is ACTIVE. View member operating status to verify probes are running.</Check>
      </Step>
    </Steps>
  </Tab>

  <Tab title="CLI" icon="terminal">
    ```bash title="Create HTTP health monitor" theme={null}
    openstack loadbalancer healthmonitor create \
      --name hm-http \
      --delay 10 \
      --timeout 5 \
      --max-retries 3 \
      --type HTTP \
      --url-path /health \
      --expected-codes 200 \
      pool-http
    ```

    ```bash title="Create TCP health monitor" theme={null}
    openstack loadbalancer healthmonitor create \
      --name hm-tcp \
      --delay 10 \
      --timeout 5 \
      --max-retries 3 \
      --type TCP \
      pool-db
    ```

    ```bash title="Create HTTPS health monitor" theme={null}
    openstack loadbalancer healthmonitor create \
      --name hm-https \
      --delay 10 \
      --timeout 5 \
      --max-retries 3 \
      --type HTTPS \
      --url-path /health \
      --expected-codes 200 \
      pool-secure
    ```
  </Tab>
</Tabs>

***

## View Member Health Status

After creating a health monitor, verify members are being probed and showing the correct
operating status:

```bash title="List member operating status" theme={null}
openstack loadbalancer member list pool-http \
  -c name -c address -c operating_status
```

Expected healthy output:

```
+--------+-------------+------------------+
| name   | address     | operating_status |
+--------+-------------+------------------+
| web-01 | 192.168.1.5 | ONLINE           |
| web-02 | 192.168.1.6 | ONLINE           |
+--------+-------------+------------------+
```

<Check>All members show `ONLINE` operating status — they are healthy and receiving traffic.</Check>

***

## Manage Health Monitors

<CodeGroup>
  ```bash title="Show health monitor details" theme={null}
  openstack loadbalancer healthmonitor show hm-http
  ```

  ```bash title="Update probe interval" theme={null}
  openstack loadbalancer healthmonitor set hm-http \
    --delay 5 \
    --timeout 3
  ```

  ```bash title="Delete health monitor" theme={null}
  openstack loadbalancer healthmonitor delete hm-http
  ```
</CodeGroup>

***

## Health Check Endpoint Design

For HTTP health monitors, implement a dedicated `/health` endpoint in your application:

<AccordionGroup>
  <Accordion title="What a health endpoint should check" icon="heart-pulse" defaultOpen>
    A good health endpoint verifies that all critical dependencies are available:

    * Database connection is alive
    * Cache layer (Redis, Memcached) is reachable
    * Required configuration is loaded
    * Application can accept requests (not in restart/initialization state)

    Return HTTP 200 only when all checks pass. Return HTTP 503 when any dependency is unavailable.
  </Accordion>

  <Accordion title="What a health endpoint should NOT do" icon="circle-x">
    * Do NOT make the health endpoint expensive (no full DB queries)
    * Do NOT require authentication (health probes run without credentials)
    * Do NOT check external dependencies not under your control (external APIs, third-party services)
    * Do NOT return 200 during graceful shutdown — return 503 to drain traffic before stopping
  </Accordion>
</AccordionGroup>

***

## Next Steps

<CardGroup cols={2}>
  <Card title="Pools" href="/services/load-balancer/pools" color="#197560">
    Manage the pools that health monitors are attached to.
  </Card>

  <Card title="Troubleshooting" href="/services/load-balancer/troubleshooting" color="#197560">
    Resolve OFFLINE member status and health probe failures.
  </Card>

  <Card title="Create Load Balancer" href="/services/load-balancer/create-lb" color="#197560">
    Create a complete load balancer setup with health monitoring from scratch.
  </Card>

  <Card title="Listeners" href="/services/load-balancer/listeners" color="#197560">
    Configure the protocol and ports that route traffic to your pools.
  </Card>
</CardGroup>