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Documentation Index

Fetch the complete documentation index at: https://notes.kodekloud.com/llms.txt

Use this file to discover all available pages before exploring further.

In this lesson, we’ve covered the core tasks for service registration and discovery with Consul. By understanding these five areas, you’ll be able to register, monitor, and query services reliably.

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1. Interpreting a Service Registration

Every service registration file or API call includes several fields that tell Consul how to manage your service:
  • ID: A unique identifier (defaults to the service name if not set).
  • Name: Logical service name used for discovery.
  • Tags: Custom labels for grouping or routing.
  • Port: Listening port of your service.
  • Address: Optional IP address (otherwise uses the agent’s IP).
  • Checks: Health check definitions (see next section).
A well-structured registration makes automated tooling and monitoring far easier to implement.

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2. Registering a Service

You have three primary options to register a new service:
MethodDescriptionExample
HTTP APISend a PUT request to the local Consul agent.curl --request PUT --data @svc.json http://localhost:8500/v1/agent/service/register
Config Directory FileDrop a JSON or HCL file into /etc/consul.d/ and reload the agent./etc/consul.d/my-service.hcl then consul reload
Direct CLI Config ReferencePoint the agent to a specific file and trigger a reload.consul agent -config-file=/path/to/service.json
After adding or modifying a file in the config directory, always run consul reload to apply changes without downtime.

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3. Adding Health Checks

Health checks ensure Consul only routes traffic to healthy instances. Common check types:
  • HTTP 
    {
  "http": "http://localhost:8080/health",
  "interval": "10s",
  "timeout": "1s"
}
  • TCP 
    {
  "tcp": "localhost:8080",
  "interval": "10s"
}
  • Script 
    {
  "script": "/usr/local/bin/check.sh",
  "interval": "15s"
}
See the Consul Health Checks guide for advanced options.

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4. Querying the Service Catalog

Verify your services and their health status using:
InterfaceCommand / QueryNotes
DNSdig @127.0.0.1 -p 8600 web.service.consul SRVNative DNS lookup for service discovery
HTTP APIcurl http://localhost:8500/v1/catalog/service/webDetailed JSON output, including node info
Web UIBrowse http://localhost:8500/ui/servicesInteractive view of all registered services

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5. Prepared Queries & Failover

Prepared queries let you define advanced routing and failover rules:
  1. Create a Prepared Query 
    curl --request PUT --data @prepared.json http://localhost:8500/v1/query
  2. Define Failover Strategy
    Include multiple service pools with weights or priorities.
  3. Execute via API or DNS
    • HTTP: GET /v1/query/{query_id}/execute
    • DNS: dig @127.0.0.1 -p 8600 {query_name}.query.consul SRV
Prepared queries automatically reroute traffic when services become unhealthy.

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