Redfish

Fri, 22 May 2026 00:00:00 +0000

Redfish is a DMTF standard that defines a RESTful API for out-of-band server management. It replaces IPMI’s aging binary protocol with JSON over HTTPS — same capabilities (power control, sensors, firmware, console), but with a proper API, role-based access control, and standard authentication. Supported by all major server vendors on current-generation hardware.

Why Redfish over IPMI

	IPMI	Redfish
Protocol	Binary, UDP 623	HTTPS (REST/JSON)
Auth	RAKP (has CVEs)	HTTP Basic / Session tokens
Encryption	Optional (IPMI 2.0)	Always (TLS)
Discoverability	No	Yes (hypermedia)
Scripting	ipmitool flags	curl, Python, any HTTP client
Extensibility	Vendor OEM extensions	Structured OEM namespaces
Maturity	Established, aging	Modern, actively developed

Redfish is not universally available — older hardware (pre-2015 roughly) has IPMI only. Both coexist on many current systems; IPMI is still useful for compatibility. See IPMI.

Vendor implementations

Vendor	BMC	Redfish support
Dell	iDRAC 8+	Full, v1.0+
HPE	iLO 4+	Full (iLO 5 most complete)
Supermicro	BMC (X11+)	Full
Lenovo	XClarity	Full
Intel	BMC on server boards	Partial
OpenBMC	Open-source BMC firmware	Full (used by Facebook, Google infra)
AMI MegaRAC	OEM BMC firmware	Full

API structure

Redfish uses a consistent URL hierarchy rooted at /redfish/v1/. Navigation is hypermedia-driven — the root returns links to subsystems, and you follow them.

/redfish/v1/
├── Systems/ ← compute systems (servers)
│ └── 1/
│ ├── Processors/
│ ├── Memory/
│ ├── Storage/
│ └── Actions/ComputerSystem.Reset
├── Chassis/ ← physical chassis, power, thermal
│ └── 1/
│ ├── Power/ ← PSU status, power consumption
│ └── Thermal/ ← temperatures, fan speeds
├── Managers/ ← the BMC itself
│ └── 1/
│ └── NetworkInterfaces/
└── UpdateService/ ← firmware updates

Usage with curl

BMC="https://192.168.1.10"
USER="admin"
PASS="password"

# Get system overview
curl -sk -u "$USER:$PASS" "$BMC/redfish/v1/Systems/1" | jq .

# Power state
curl -sk -u "$USER:$PASS" "$BMC/redfish/v1/Systems/1" | jq .PowerState

# Power on
curl -sk -u "$USER:$PASS" -X POST \
 -H "Content-Type: application/json" \
 -d '{"ResetType":"On"}' \
 "$BMC/redfish/v1/Systems/1/Actions/ComputerSystem.Reset"

# Power off (graceful)
curl -sk -u "$USER:$PASS" -X POST \
 -H "Content-Type: application/json" \
 -d '{"ResetType":"GracefulShutdown"}' \
 "$BMC/redfish/v1/Systems/1/Actions/ComputerSystem.Reset"

# Force off
curl -sk -u "$USER:$PASS" -X POST \
 -H "Content-Type: application/json" \
 -d '{"ResetType":"ForceOff"}' \
 "$BMC/redfish/v1/Systems/1/Actions/ComputerSystem.Reset"

# Thermal — CPU temps, fan speeds
curl -sk -u "$USER:$PASS" "$BMC/redfish/v1/Chassis/1/Thermal" | jq '.Temperatures[] | {Name, ReadingCelsius}'

Reset types vary by vendor — check AllowableValues in the action schema:

curl -sk -u "$USER:$PASS" \
 "$BMC/redfish/v1/Systems/1" | jq '.Actions["#ComputerSystem.Reset"]["ResetType@Redfish.AllowableValues"]'

Python — sushy

sushy is the reference Python library for Redfish, used by OpenStack Ironic:

import sushy

client = sushy.Sushy("https://192.168.1.10", username="admin", password="password", verify=False)

system = client.get_system("/redfish/v1/Systems/1")
print(system.power_state) # On / Off
system.reset_system(sushy.RESET_ON)
system.reset_system(sushy.RESET_FORCE_OFF)

Session-based auth

For scripts making many requests, create a session to avoid re-authenticating on every call:

# Create session
SESSION=$(curl -sk -X POST \
 -H "Content-Type: application/json" \
 -d '{"UserName":"admin","Password":"password"}' \
 "https://192.168.1.10/redfish/v1/SessionService/Sessions" \
 -D -)

TOKEN=$(echo "$SESSION" | grep -i X-Auth-Token | awk '{print $2}' | tr -d '\r')

# Use token
curl -sk -H "X-Auth-Token: $TOKEN" \
 "https://192.168.1.10/redfish/v1/Systems/1" | jq .PowerState

Firmware updates

Redfish standardises firmware update via UpdateService:

# Check current firmware
curl -sk -u "$USER:$PASS" "$BMC/redfish/v1/UpdateService/FirmwareInventory" | jq .

# Push update (multipart, vendor-specific details vary)
curl -sk -u "$USER:$PASS" -X POST \
 -H "Content-Type: application/octet-stream" \
 --data-binary @firmware.bin \
 "$BMC/redfish/v1/UpdateService/update"

Vendor tooling (Dell racadm, HPE iLOrest) is often more reliable than raw curl for firmware updates.

IPMI — older binary protocol, still needed for pre-Redfish hardware
Out-of-band management overview
Hardware provisioning — PXE boot and bare-metal provisioning

Api on Backend Engineering Strategy Tools