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Overview

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.

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How Health Checks Work

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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

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Health Check vs Target Endpoint

Flexible Monitoring

The health check endpoint can be the same as your target, but you can also monitor a different endpoint. This allows you to create dedicated health check endpoints that provide more detailed service status information.

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Target Health States

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

Unknown

Initial State: Targets start in this state before first health checkTraffic Behavior: Unknown targets still route traffic normallyDuration: Until first health check completes

Unhealthy

Failed Checks: Target has failed health check criteriaTraffic Behavior: No traffic is routed to unhealthy targetsLoad Balancing: Excluded from load balancing rotation

Healthy

Passing Checks: Target is responding correctly to health checksTraffic Behavior: Receives traffic according to load balancing rulesLoad Balancing: Included in load balancing rotation

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Configuring Health Checks

1

Access Target Settings

In the Pangolin dashboard, navigate to your resource and locate the target in the table.
2

Open Health Check Configuration

Click the settings wheel (⚙️) next to the health check endpoint column.
3

Configure Health Check Parameters

Fill out the health check configuration with your desired parameters.
4

Save Configuration

Save your settings to enable health checking for the target.

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Health Check Parameters

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Endpoint Configuration

Health Check Target

Target Endpoint: The URL or address to monitor for health statusDefault Behavior: Usually the same as your target endpointCustom Endpoints: Can monitor different endpoints (e.g., /health, /status)

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Timing Configuration

Healthy Interval

Purpose: How often to check targets that are currently healthyTypical Range: 30-60 secondsConsideration: Less frequent checks reduce overhead

Unhealthy Interval

Purpose: How often to check targets that are currently unhealthyTypical Range: 10-30 secondsConsideration: More frequent checks enable faster recovery

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Response Configuration

Timeout Settings

Request Timeout: Maximum time to wait for a health check responseDefault Behavior: Requests exceeding timeout are considered failedRecommended: Set based on your service’s typical response time

HTTP Response Codes

Healthy Codes: Which HTTP status codes indicate a healthy targetCommon Settings: 200, 201, 202, 204Custom Codes: Configure based on your service’s health endpoint behavior

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Failover Behavior

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Automatic Traffic Exclusion

When a target becomes unhealthy:
1

Health Check Failure

Target fails to meet health check criteria (response code, timeout, etc.)
2

Status Update

Target status changes from “Healthy” to “Unhealthy”
3

Traffic Removal

Target is immediately removed from traffic routing configuration
4

Load Balancer Update

Load balancing configuration is updated to exclude the unhealthy target
5

Continued Monitoring

Health checks continue at the unhealthy interval for recovery detection

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Automatic Recovery

When an unhealthy target recovers:
1

Successful Health Check

Target begins responding correctly to health checks
2

Status Update

Target status changes from “Unhealthy” to “Healthy”
3

Traffic Restoration

Target is automatically added back to traffic routing
4

Load Balancer Update

Load balancing resumes including the recovered target

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High Availability Strategies

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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

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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
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