[Fix] prevent shared backend model key from being polluted by per-deployment custom pricing (#20679)

* bug: custom price override for models

* added associated test
This commit is contained in:
Shivam Rawat
2026-02-09 19:38:44 -08:00
committed by GitHub
parent 36e0361187
commit 1ee43b11de
2 changed files with 276 additions and 1 deletions
+12 -1
View File
@@ -5925,9 +5925,20 @@ class Router:
deployment.litellm_params.custom_llm_provider + "/" + _model_name
)
# For the shared backend key, strip custom pricing fields so that
# one deployment's pricing overrides don't pollute another
# deployment sharing the same backend model name.
# Each deployment's full pricing is already stored under its
# unique model_id above.
_custom_pricing_fields = CustomPricingLiteLLMParams.model_fields.keys()
_shared_model_info = {
k: v
for k, v in _model_info.items()
if k not in _custom_pricing_fields
}
litellm.register_model(
model_cost={
_model_name: _model_info,
_model_name: _shared_model_info,
}
)
@@ -0,0 +1,264 @@
"""
Test that per-deployment custom pricing does not pollute the shared backend
model key in litellm.model_cost.
When two deployments share the same backend model (e.g. vertex_ai/gemini-2.5-flash)
and one has explicit zero-cost pricing in model_info, the other deployment
should still use the built-in pricing.
"""
import os
import sys
import pytest
sys.path.insert(
0, os.path.abspath("../../..")
) # Adds the parent directory to the system path
import litellm
from litellm import Router
def test_should_not_pollute_shared_key_with_zero_cost_pricing():
"""
When deployment A has input_cost_per_token=0 and deployment B has no
custom pricing, deployment B should still report the built-in pricing
(not zero).
"""
backend_model = "vertex_ai/gemini-2.5-flash"
# Grab built-in pricing before creating any router
builtin_info = litellm.get_model_info(model=backend_model)
builtin_input_cost = builtin_info["input_cost_per_token"]
builtin_output_cost = builtin_info["output_cost_per_token"]
# Sanity: built-in pricing should be non-zero for this model
assert builtin_input_cost > 0, "Test requires a model with non-zero built-in pricing"
assert builtin_output_cost > 0, "Test requires a model with non-zero built-in pricing"
router = Router(
model_list=[
# Deployment A: explicit zero-cost pricing
{
"model_name": "custom-zero-cost-model",
"litellm_params": {
"model": backend_model,
"api_key": "fake-key-1",
},
"model_info": {
"id": "deployment-a-zero-cost",
"input_cost_per_token": 0.0,
"output_cost_per_token": 0.0,
},
},
# Deployment B: no custom pricing, relies on built-in
{
"model_name": "standard-cost-model",
"litellm_params": {
"model": backend_model,
"api_key": "fake-key-2",
},
"model_info": {
"id": "deployment-b-builtin-cost",
},
},
],
)
# Deployment A: should report zero pricing via its unique model_id
info_a = router.get_deployment_model_info(
model_id="deployment-a-zero-cost",
model_name=backend_model,
)
assert info_a is not None
assert info_a["input_cost_per_token"] == 0.0
assert info_a["output_cost_per_token"] == 0.0
# Deployment B: should report built-in pricing, NOT zero
info_b = router.get_deployment_model_info(
model_id="deployment-b-builtin-cost",
model_name=backend_model,
)
assert info_b is not None
assert info_b["input_cost_per_token"] == builtin_input_cost, (
f"Deployment B should use built-in input cost {builtin_input_cost}, "
f"got {info_b['input_cost_per_token']}"
)
assert info_b["output_cost_per_token"] == builtin_output_cost, (
f"Deployment B should use built-in output cost {builtin_output_cost}, "
f"got {info_b['output_cost_per_token']}"
)
def test_should_not_pollute_shared_key_with_custom_nonzero_pricing():
"""
A deployment with custom (non-zero) pricing should not overwrite
the shared backend key's built-in pricing.
"""
backend_model = "vertex_ai/gemini-2.5-flash"
builtin_info = litellm.get_model_info(model=backend_model)
builtin_input_cost = builtin_info["input_cost_per_token"]
router = Router(
model_list=[
# Deployment with custom high pricing
{
"model_name": "expensive-model",
"litellm_params": {
"model": backend_model,
"api_key": "fake-key-3",
},
"model_info": {
"id": "deployment-expensive",
"input_cost_per_token": 0.99,
"output_cost_per_token": 0.99,
},
},
# Deployment relying on built-in pricing
{
"model_name": "standard-model",
"litellm_params": {
"model": backend_model,
"api_key": "fake-key-4",
},
"model_info": {
"id": "deployment-standard",
},
},
],
)
# Custom pricing deployment should see its custom values
info_expensive = router.get_deployment_model_info(
model_id="deployment-expensive",
model_name=backend_model,
)
assert info_expensive is not None
assert info_expensive["input_cost_per_token"] == 0.99
assert info_expensive["output_cost_per_token"] == 0.99
# Standard deployment should still see built-in pricing
info_standard = router.get_deployment_model_info(
model_id="deployment-standard",
model_name=backend_model,
)
assert info_standard is not None
assert info_standard["input_cost_per_token"] == builtin_input_cost, (
f"Standard deployment should use built-in pricing {builtin_input_cost}, "
f"got {info_standard['input_cost_per_token']}"
)
def test_should_store_full_pricing_under_deployment_model_id():
"""
Per-deployment pricing (including zero) should be stored and
retrievable via the unique model_id key in litellm.model_cost.
"""
backend_model = "vertex_ai/gemini-2.5-flash"
router = Router(
model_list=[
{
"model_name": "zero-cost-model",
"litellm_params": {
"model": backend_model,
"api_key": "fake-key-5",
},
"model_info": {
"id": "deployment-zero-check",
"input_cost_per_token": 0.0,
"output_cost_per_token": 0.0,
},
},
],
)
# The model_id entry should exist and have the zero pricing
entry = litellm.model_cost.get("deployment-zero-check")
assert entry is not None, "Deployment should be registered by model_id"
assert entry["input_cost_per_token"] == 0.0
assert entry["output_cost_per_token"] == 0.0
def test_should_preserve_builtin_pricing_regardless_of_deployment_order():
"""
The built-in pricing should be preserved no matter which deployment
is processed first (zero-cost first, or standard first).
"""
backend_model = "vertex_ai/gemini-2.5-flash"
builtin_info = litellm.get_model_info(model=backend_model)
builtin_input_cost = builtin_info["input_cost_per_token"]
builtin_output_cost = builtin_info["output_cost_per_token"]
# Order 1: standard first, then zero-cost
router1 = Router(
model_list=[
{
"model_name": "standard-first",
"litellm_params": {
"model": backend_model,
"api_key": "fake-key-6",
},
"model_info": {"id": "order1-standard"},
},
{
"model_name": "zero-cost-second",
"litellm_params": {
"model": backend_model,
"api_key": "fake-key-7",
},
"model_info": {
"id": "order1-zero",
"input_cost_per_token": 0.0,
"output_cost_per_token": 0.0,
},
},
],
)
info_std_1 = router1.get_deployment_model_info(
model_id="order1-standard", model_name=backend_model
)
assert info_std_1["input_cost_per_token"] == builtin_input_cost
assert info_std_1["output_cost_per_token"] == builtin_output_cost
# Order 2: zero-cost first, then standard
router2 = Router(
model_list=[
{
"model_name": "zero-cost-first",
"litellm_params": {
"model": backend_model,
"api_key": "fake-key-8",
},
"model_info": {
"id": "order2-zero",
"input_cost_per_token": 0.0,
"output_cost_per_token": 0.0,
},
},
{
"model_name": "standard-second",
"litellm_params": {
"model": backend_model,
"api_key": "fake-key-9",
},
"model_info": {"id": "order2-standard"},
},
],
)
info_std_2 = router2.get_deployment_model_info(
model_id="order2-standard", model_name=backend_model
)
assert info_std_2["input_cost_per_token"] == builtin_input_cost, (
f"Order should not matter. Expected {builtin_input_cost}, "
f"got {info_std_2['input_cost_per_token']}"
)
assert info_std_2["output_cost_per_token"] == builtin_output_cost, (
f"Order should not matter. Expected {builtin_output_cost}, "
f"got {info_std_2['output_cost_per_token']}"
)