1.7c Redfish API: the modern RESTful replacement for IPMI

📦 Physical Realm 📖 What Is a Computer? Core Architecture for Absolute Beginners

🌐 Context Introduction

For decades, engineers managed servers remotely using IPMI (Intelligent Platform Management Interface) — a text-based, command-line tool that worked over a dedicated management network. While functional, IPMI has limitations: it is complex, insecure by default, and difficult to integrate with modern automation tools.

Enter Redfish — a modern, RESTful API standard developed by the DMTF (Distributed Management Task Force). Redfish uses HTTP/HTTPS and JSON to manage hardware, making it much easier to use with scripts, cloud-native tools, and modern programming languages. Think of it as "IPMI for the cloud era."

⚙️ What Is Redfish?

Redfish is an open-standard API that allows engineers to monitor, configure, and control server hardware remotely — without needing to be physically present in the data center.

Key characteristics: - RESTful — uses standard HTTP methods (GET, POST, PATCH, DELETE) - JSON-based — data is returned in easy-to-read JSON format - Secure — supports HTTPS, authentication, and role-based access - Scalable — can manage single servers or entire racks - Vendor-neutral — works across Dell, HPE, Supermicro, Lenovo, and others

🕵️ How Redfish Compares to IPMI

Feature IPMI Redfish
Protocol Binary (RMCP+) HTTP/HTTPS (REST)
Data format Raw bytes / IPMI commands JSON
Security Weak (plaintext often used) Strong (TLS, authentication)
Ease of use Requires specialized tools Works with curl, Python, Postman
Automation Difficult to script Easy to integrate with Ansible, Terraform
Scalability Single server at a time Single server or entire rack
Modern tooling Limited Cloud-native, CI/CD friendly

🛠️ Core Concepts of Redfish

📡 Resource Tree

Redfish organizes hardware into a tree of resources, each accessible via a unique URL. Common resources include:

  • Systems — the main server (CPU, memory, storage)
  • Chassis — physical enclosure (power supplies, fans, temperature)
  • Managers — the BMC (Baseboard Management Controller) itself
  • Power — power state and consumption
  • Thermal — temperature sensors and fan speeds
  • Storage — drives and RAID controllers

🔗 Example Resource Paths

  • Server system info: /redfish/v1/Systems/1
  • Power supplies: /redfish/v1/Chassis/1/Power
  • BMC firmware: /redfish/v1/Managers/1

🔐 Authentication

Redfish uses standard HTTP authentication: - Basic Auth — username and password (over HTTPS only) - Session-based — login once, get a session token - Token-based — use API keys for automation

📊 Visual Representation: Redfish API Resource Tree Hierarchy

This diagram maps out the hierarchical JSON resource tree schema utilized by the Redfish RESTful API to expose hardware components and configurations.

flowchart TD Root["Root: /redfish/v1/"] --> Systems["Systems: /redfish/v1/Systems/"] Root --> Chassis["Chassis: /redfish/v1/Chassis/"] Root --> Managers["Managers: /redfish/v1/Managers/"] Systems --> Sys1["System 1: /Systems/1"] Sys1 --> Storage["Storage: /Systems/1/Storage"] Sys1 --> Processors["Processors: /Systems/1/Processors"] Sys1 --> Memory["Memory: /Systems/1/Memory"] Chassis --> Ch1["Chassis 1: /Chassis/1"] Ch1 --> Thermal["Thermal: /Chassis/1/Thermal"] Ch1 --> Power["Power: /Chassis/1/Power"] Managers --> Mgr1["Manager 1: /Managers/1"] Mgr1 --> Network["NetworkProtocol: /Managers/1/NetworkProtocol"] Mgr1 --> Ethernet["EthernetInterfaces: /Managers/1/EthernetInterfaces"] class Root,Systems,Chassis,Managers system; class Sys1,Storage,Processors,Memory cpu; class Ch1,Thermal,Power system; class Mgr1,Network,Ethernet system; classDef cpu fill:#eafaf1,stroke:#76b900,stroke-width:2px,rx:6px,ry:6px; classDef memory fill:#f0f7ff,stroke:#3498db,stroke-width:1.5px,rx:4px,ry:4px; classDef system fill:#f1f5f9,stroke:#64748b,stroke-width:1.5px;

📊 Common Use Cases for Engineers

🔍 Monitoring Hardware Health

  • Check server power state (on/off)
  • View CPU temperature and fan speeds
  • Monitor disk drive status (healthy/failed)
  • Read system event logs

⚡ Controlling Server Power

  • Power on, power off, or restart a server
  • Perform a graceful shutdown or hard reset
  • Set power-on delay or boot order

🛡️ Firmware and BIOS Management

  • View current firmware versions
  • Update BIOS or BMC firmware remotely
  • Change BIOS settings (e.g., boot mode, power profile)

🔄 Automation and Orchestration

  • Integrate with Ansible, Terraform, or custom Python scripts
  • Automate server provisioning in data centers
  • Collect telemetry data for monitoring dashboards

🧪 Simple Example Workflow

Scenario: An engineer needs to check if a server is powered on.

  1. Send a GET request to the Redfish endpoint for the server's power state.
  2. Receive JSON response containing the current power state.
  3. Parse the JSON to extract the value (e.g., "On" or "Off").

For reference: 

GET /redfish/v1/Systems/1
Host: 192.168.1.100
Authorization: Basic base64(username:password)
Accept: application/json

📤 Output: {"PowerState": "On", "Status": {"State": "Enabled", "Health": "OK"}}

✅ Advantages Over IPMI

  • Easier to learn — if you know HTTP and JSON, you already know most of Redfish
  • Better security — built-in support for HTTPS and authentication
  • More automation-friendly — works with modern tools like curl, Python, and Ansible
  • Vendor-agnostic — same API works across different hardware brands
  • Richer data — JSON provides structured, human-readable information

🧩 Getting Started as a New Engineer

  1. Find the Redfish endpoint for your server (usually https://<BMC-IP>/redfish/v1/)
  2. Test with a browser — many BMCs have a web interface that shows Redfish data
  3. Use curl to send simple GET requests (e.g., curl -k https://admin:[email protected]/redfish/v1/Systems/1)
  4. Explore the resource tree — start with /redfish/v1/ and follow the links
  5. Read the vendor documentation — each manufacturer may have slight differences

📚 Key Takeaways

  • Redfish is the modern replacement for IPMI — simpler, more secure, and automation-ready
  • It uses standard web technologies — HTTP, JSON, and REST
  • It works across all major server vendors — Dell, HPE, Supermicro, Lenovo, etc.
  • It is essential for modern data center operations — especially for cloud-native and DevOps workflows
  • Start small — just checking power state or temperature is a great first step

💡 Pro Tip: If you can use a web browser to check a server's health, you can use Redfish. The API is just the same data, but in a machine-readable format.