---
title: "Health Checks"
description: "Configure automated health monitoring and failover for resources"
---

Pangolin provides automated health checking for targets to ensure traffic is only routed to healthy services. Health checks are essential for building highly available services, as they automatically remove unhealthy targets from traffic routing and load balancing.

## How Health Checks Work

### Monitoring Process

Health checks operate continuously in the background:

1. **Periodic Checks**: Pangolin sends requests to your target endpoints at configured intervals.
2. **Status Evaluation**: Responses are evaluated against your configured criteria.
3. **Traffic Management**: Healthy targets receive traffic, unhealthy targets are excluded.
4. **Automatic Recovery**: Targets are automatically re-enabled when they become healthy again.

## Target Health States

Targets can exist in three distinct states that determine how traffic is routed:

<CardGroup cols={3}>
<Card title="Unknown" icon="question" color="#gray">
  **Initial State**: Targets start in this state before first health check
  
  **Traffic Behavior**: Unknown targets still route traffic normally
  
  **Duration**: Until first health check completes
</Card>

<Card title="Unhealthy" icon="x" color="#red">
  **Failed Checks**: Target has failed health check criteria
  
  **Traffic Behavior**: No traffic is routed to unhealthy targets
  
  **Load Balancing**: Excluded from load balancing rotation
</Card>

<Card title="Healthy" icon="check" color="#green">
  **Passing Checks**: Target is responding correctly to health checks
  
  **Traffic Behavior**: Receives traffic according to load balancing rules
  
  **Load Balancing**: Included in load balancing rotation
</Card>
</CardGroup>

## Configuring Health Checks

<Steps>
<Step title="Access Target Settings">
  In the Pangolin dashboard, navigate to your resource and locate the target in the table.
</Step>

<Step title="Open Health Check Configuration">
  Click the settings wheel (⚙️) next to the health check endpoint column.
</Step>

<Step title="Configure Health Check Parameters">
  Fill out the health check configuration with your desired parameters.
</Step>

<Step title="Save Configuration">
  Save your settings to enable health checking for the target.
</Step>
</Steps>

## Health Check Parameters

### Endpoint Configuration

- **Target Endpoint**: The URL or address to monitor for health status
- **Default Behavior**: Usually the same as your target endpoint
- **Custom Endpoints**: Can monitor different endpoints (e.g., `/health`, `/status`)

### Timing Configuration

#### Healthy Interval

- **Purpose**: How often to check targets that are currently healthy
- **Typical Range**: 30-60 seconds
- **Consideration**: Less frequent checks reduce overhead

#### Unhealthy Interval
  
- **Purpose**: How often to check targets that are currently unhealthy
- **Typical Range**: 10-30 seconds
- **Consideration**: More frequent checks enable faster recovery

### Response Configuration

#### Timeout Settings

- **Request Timeout**: Maximum time to wait for a health check response
- **Default Behavior**: Requests exceeding timeout are considered failed
- **Recommended**: Set based on your service's typical response time

#### HTTP Response Codes

- **Healthy Codes**: Which HTTP status codes indicate a healthy target
- **Common Settings**: 200, 201, 202, 204
- **Custom Codes**: Configure based on your service's health endpoint behavior

## High Availability Strategies

### Multi-Target Redundancy

#### Service Redundancy

Deploy multiple instances of your service across different targets to ensure availability even when some targets fail.

```
Resource: web-application
├── Target 1: web-01.local:8080 (Site A) - Healthy ✅
├── Target 2: web-02.local:8080 (Site A) - Unhealthy ❌
└── Target 3: web-03.local:8080 (Site B) - Healthy ✅

Traffic routes to: Target 1 & Target 3 only
```

### Cross-Site Failover

#### Geographic Distribution

Distribute targets across multiple sites to protect against site-level failures.

```
Resource: api-service
├── Primary Site Targets
│   ├── api-01.primary:8443 - Healthy ✅
│   └── api-02.primary:8443 - Healthy ✅
└── Backup Site Targets
    ├── api-01.backup:8443 - Healthy ✅
    └── api-02.backup:8443 - Healthy ✅

All targets receive traffic via load balancing
```
