Files
litellm/tests/test_litellm/test_redis.py
T
2b8b614120 fix(redis): cache GCP IAM token to prevent async event loop blocking (#26441)
* fix(redis): cache GCP IAM token to prevent async event loop blocking

## Problem

GCPIAMCredentialProvider.get_credentials() calls _generate_gcp_iam_access_token
on every Redis connection establishment. This function performs synchronous HTTP
and gRPC calls (google-auth + google-cloud-iam) which block Python's asyncio
event loop while running.

Under concurrent load (e.g. connection pool warm-up, parallel health checks),
multiple connections are established simultaneously, each triggering an
independent blocking IAM token refresh. These refreshes serialise behind each
other inside the single-threaded event loop, causing individual Redis spans to
take 20-25 seconds instead of milliseconds.

Observed in production via Datadog APM: a single INCRBYFLOAT Redis span took
25.6 seconds (90% of a 28.4s trace), with GCP metadata + GenerateAccessToken
gRPC calls visible inside the span. This cascaded into aiohttp SocketTimeoutError
on upstream LLM API calls — not because the upstream was slow, but because the
event loop was frozen and the 30-second sock_read timer fired on a connection
that was never given CPU time.

## Fix

Add a module-level token cache (dict keyed by service account, value is
(token, expiry_monotonic)). _get_cached_gcp_iam_token() returns the cached
token on cache hit (no I/O), and refreshes only when expired using
double-checked locking so only one thread performs the network round-trip.

GCP IAM tokens are valid for 1 hour; the cache TTL is set to 55 minutes
(_GCP_IAM_TOKEN_TTL_SECONDS = 3300) to refresh safely before expiry.

The cache is shared across all GCPIAMCredentialProvider instances for the same
service account, so N concurrent Redis connections on the same pod share a
single token and avoid N concurrent blocking refreshes.

get_credentials_async() already used asyncio.to_thread (non-blocking), and is
updated to call _get_cached_gcp_iam_token so it also benefits from caching.

## Tests

- Updated existing test that expected a fresh token on every call to reflect
  the new caching behaviour.
- Added tests for: cache hit (no redundant I/O), cache expiry and refresh,
  and cache sharing across multiple provider instances.
- Added autouse fixture to clear the module-level cache between tests.

Co-Authored-By: Claude Sonnet 4.6 (1M context) <noreply@anthropic.com>

* refactor(redis): remove unused Optional import from _redis_credential_provider.py

* refactor(redis): improve documentation for GCPIAMCredentialProvider class

Updated the docstring for the GCPIAMCredentialProvider class to clarify its purpose and the caching mechanism for GCP IAM tokens. The changes enhance readability and maintainability by providing a more concise explanation of the token caching strategy and its benefits for Redis authentication.

* refactor(redis): improve documentation for GCPIAMCredentialProvider class

Updated the docstring for the GCPIAMCredentialProvider class to clarify its purpose and the caching mechanism for GCP IAM tokens. The changes enhance readability and maintainability by providing a more concise explanation of the token caching strategy and its benefits for Redis authentication.

---------

Co-authored-by: Claude Sonnet 4.6 (1M context) <noreply@anthropic.com>
2026-04-25 23:13:39 -07:00

471 lines
17 KiB
Python

import json
import os
from unittest.mock import MagicMock, patch
import pytest
import redis
import redis.asyncio as async_redis
from litellm._redis import (
_get_redis_cluster_kwargs,
get_redis_async_client,
get_redis_client,
get_redis_connection_pool,
get_redis_url_from_environment,
)
from litellm._redis_credential_provider import (
GCPIAMCredentialProvider,
_token_cache,
)
@pytest.fixture(autouse=True)
def clear_gcp_iam_token_cache():
"""Reset the module-level GCP IAM token cache between tests."""
_token_cache.clear()
yield
_token_cache.clear()
def test_get_redis_url_from_environment_single_url(monkeypatch):
"""Test when REDIS_URL is directly provided"""
# Set the environment variable
monkeypatch.setenv("REDIS_URL", "redis://redis-server:6379/0")
# Call the function to get the Redis URL
redis_url = get_redis_url_from_environment()
# Assert that the returned URL matches the expected value
assert redis_url == "redis://redis-server:6379/0"
def test_get_redis_url_from_environment_host_port(monkeypatch):
"""Test when REDIS_HOST and REDIS_PORT are provided"""
# Set the environment variables
monkeypatch.setenv("REDIS_HOST", "redis-server")
monkeypatch.setenv("REDIS_PORT", "6379")
# Ensure authentication variables are not set
monkeypatch.delenv("REDIS_USERNAME", raising=False)
monkeypatch.delenv("REDIS_PASSWORD", raising=False)
monkeypatch.delenv("REDIS_SSL", raising=False)
# Call the function to get the Redis URL
redis_url = get_redis_url_from_environment()
# Assert that the returned URL matches the expected value
assert redis_url == "redis://redis-server:6379"
def test_get_redis_url_from_environment_with_ssl(monkeypatch):
"""Test when SSL is enabled"""
# Set the environment variables
monkeypatch.setenv("REDIS_HOST", "redis-server")
monkeypatch.setenv("REDIS_PORT", "6379")
monkeypatch.setenv("REDIS_SSL", "true")
# Ensure authentication variables are not set
monkeypatch.delenv("REDIS_USERNAME", raising=False)
monkeypatch.delenv("REDIS_PASSWORD", raising=False)
# Call the function to get the Redis URL
redis_url = get_redis_url_from_environment()
# Assert that the returned URL uses rediss:// protocol
assert redis_url == "rediss://redis-server:6379"
def test_get_redis_url_from_environment_with_username_password(monkeypatch):
"""Test when username and password are provided"""
# Set the environment variables
monkeypatch.setenv("REDIS_HOST", "redis-server")
monkeypatch.setenv("REDIS_PORT", "6379")
monkeypatch.setenv("REDIS_USERNAME", "user")
monkeypatch.setenv("REDIS_PASSWORD", "password")
# Call the function to get the Redis URL
redis_url = get_redis_url_from_environment()
# Assert that the returned URL includes username:password@
assert redis_url == "redis://user:password@redis-server:6379"
def test_get_redis_url_from_environment_with_password_only(monkeypatch):
"""Test when only password is provided"""
# Set the environment variables
monkeypatch.setenv("REDIS_HOST", "redis-server")
monkeypatch.setenv("REDIS_PORT", "6379")
monkeypatch.setenv("REDIS_PASSWORD", "password")
# Ensure username is not set
monkeypatch.delenv("REDIS_USERNAME", raising=False)
monkeypatch.delenv("REDIS_SSL", raising=False)
# Call the function to get the Redis URL
redis_url = get_redis_url_from_environment()
# Assert that the returned URL includes :password@
assert redis_url == "redis://password@redis-server:6379"
def test_get_redis_url_from_environment_with_all_options(monkeypatch):
"""Test when all options are provided"""
# Set the environment variables
monkeypatch.setenv("REDIS_HOST", "redis-server")
monkeypatch.setenv("REDIS_PORT", "6379")
monkeypatch.setenv("REDIS_USERNAME", "user")
monkeypatch.setenv("REDIS_PASSWORD", "password")
monkeypatch.setenv("REDIS_SSL", "true")
# Call the function to get the Redis URL
redis_url = get_redis_url_from_environment()
# Assert that the returned URL includes all components
assert redis_url == "rediss://user:password@redis-server:6379"
def test_get_redis_url_from_environment_missing_host_port(monkeypatch):
"""Test error when required variables are missing"""
# Make sure these environment variables don't exist
monkeypatch.delenv("REDIS_URL", raising=False)
monkeypatch.delenv("REDIS_HOST", raising=False)
monkeypatch.delenv("REDIS_PORT", raising=False)
# Call the function and expect a ValueError
with pytest.raises(ValueError) as excinfo:
get_redis_url_from_environment()
# Check the error message
assert (
"Either 'REDIS_URL' or both 'REDIS_HOST' and 'REDIS_PORT' must be specified"
in str(excinfo.value)
)
def test_get_redis_url_from_environment_missing_port(monkeypatch):
"""Test error when only REDIS_HOST is provided but REDIS_PORT is missing"""
# Make sure REDIS_URL doesn't exist and set only REDIS_HOST
monkeypatch.delenv("REDIS_URL", raising=False)
monkeypatch.delenv("REDIS_PORT", raising=False)
monkeypatch.setenv("REDIS_HOST", "redis-server")
# Call the function and expect a ValueError
with pytest.raises(ValueError) as excinfo:
get_redis_url_from_environment()
# Check the error message
assert (
"Either 'REDIS_URL' or both 'REDIS_HOST' and 'REDIS_PORT' must be specified"
in str(excinfo.value)
)
def test_max_connections_in_cluster_kwargs():
"""Test that max_connections is included in Redis cluster kwargs"""
kwargs = _get_redis_cluster_kwargs()
assert (
"max_connections" in kwargs
), "max_connections should be in available Redis cluster kwargs"
def test_get_redis_async_client_with_connection_pool():
"""Test that connection_pool parameter is properly passed to Redis client"""
# Create a mock connection pool
mock_pool = MagicMock(spec=async_redis.BlockingConnectionPool)
# Mock the Redis client creation
with (
patch("litellm._redis.async_redis.Redis") as mock_redis,
patch("litellm._redis._get_redis_client_logic") as mock_logic,
):
# Configure mock to return basic redis kwargs
mock_logic.return_value = {"host": "localhost", "port": 6379, "db": 0}
# Call get_redis_async_client with connection_pool
get_redis_async_client(connection_pool=mock_pool)
# Verify Redis was called with connection_pool in kwargs
call_kwargs = mock_redis.call_args[1]
assert (
"connection_pool" in call_kwargs
), "connection_pool should be passed to Redis client"
assert (
call_kwargs["connection_pool"] == mock_pool
), "connection_pool should match the provided pool"
def test_get_redis_async_client_without_connection_pool():
"""Test that Redis client works without connection_pool parameter"""
with (
patch("litellm._redis.async_redis.Redis") as mock_redis,
patch("litellm._redis._get_redis_client_logic") as mock_logic,
):
# Configure mock to return basic redis kwargs
mock_logic.return_value = {"host": "localhost", "port": 6379, "db": 0}
# Call get_redis_async_client without connection_pool
get_redis_async_client()
# Verify Redis was called without connection_pool in kwargs
call_kwargs = mock_redis.call_args[1]
assert (
"connection_pool" not in call_kwargs
), "connection_pool should not be in kwargs when not provided"
def test_gcp_iam_credential_provider_get_credentials():
"""GCPIAMCredentialProvider.get_credentials() returns a token tuple."""
service_account = "projects/-/serviceAccounts/test@project.iam.gserviceaccount.com"
with patch(
"litellm._redis_credential_provider._generate_gcp_iam_access_token",
return_value="tok-1",
) as mock_gen:
provider = GCPIAMCredentialProvider(service_account)
creds = provider.get_credentials()
assert creds == ("tok-1",)
mock_gen.assert_called_once_with(service_account)
def test_gcp_iam_credential_provider_caches_token():
"""
Repeated calls to get_credentials() reuse the cached token and only call
_generate_gcp_iam_access_token once, avoiding redundant blocking I/O.
"""
service_account = "projects/-/serviceAccounts/test@project.iam.gserviceaccount.com"
with patch(
"litellm._redis_credential_provider._generate_gcp_iam_access_token",
return_value="tok-cached",
) as mock_gen:
provider = GCPIAMCredentialProvider(service_account)
results = [provider.get_credentials() for _ in range(5)]
assert all(r == ("tok-cached",) for r in results)
# Token must be fetched exactly once regardless of how many connections are established
mock_gen.assert_called_once_with(service_account)
def test_gcp_iam_credential_provider_refreshes_on_expiry():
"""
get_credentials() fetches a new token after the cached one expires,
ensuring connections always authenticate with a valid token.
"""
import time
import litellm._redis_credential_provider as cred_module
service_account = "projects/-/serviceAccounts/test@project.iam.gserviceaccount.com"
with patch(
"litellm._redis_credential_provider._generate_gcp_iam_access_token",
side_effect=["tok-1", "tok-2"],
) as mock_gen:
provider = GCPIAMCredentialProvider(service_account)
# First call — populates cache
assert provider.get_credentials() == ("tok-1",)
# Artificially expire the cached token
cred_module._token_cache[service_account] = ("tok-1", time.monotonic() - 1)
# Second call — cache miss, must refresh
assert provider.get_credentials() == ("tok-2",)
assert mock_gen.call_count == 2
def test_gcp_iam_credential_provider_cache_shared_across_instances():
"""
Multiple GCPIAMCredentialProvider instances for the same service account
share one cached token so concurrent Redis connections don't each trigger
a blocking IAM round-trip.
"""
service_account = (
"projects/-/serviceAccounts/shared@project.iam.gserviceaccount.com"
)
with patch(
"litellm._redis_credential_provider._generate_gcp_iam_access_token",
return_value="tok-shared",
) as mock_gen:
p1 = GCPIAMCredentialProvider(service_account)
p2 = GCPIAMCredentialProvider(service_account)
assert p1.get_credentials() == ("tok-shared",)
assert p2.get_credentials() == ("tok-shared",)
# Only one network call despite two provider instances
mock_gen.assert_called_once()
def test_get_redis_async_client_gcp_cluster_uses_credential_provider():
"""
When startup_nodes + gcp_service_account are provided, the async cluster client
must be constructed with a GCPIAMCredentialProvider — not a static password.
This ensures that the 1-hour IAM token expiry does not cause auth failures.
"""
startup_nodes = [{"host": "redis-node-1", "port": 6379}]
mock_connect_func = MagicMock()
mock_connect_func._gcp_service_account = (
"projects/-/serviceAccounts/sa@project.iam.gserviceaccount.com"
)
redis_kwargs = {
"startup_nodes": startup_nodes,
"redis_connect_func": mock_connect_func,
}
with (
patch("litellm._redis.async_redis.RedisCluster") as mock_cluster,
patch("litellm._redis._get_redis_client_logic", return_value=redis_kwargs),
):
get_redis_async_client()
assert mock_cluster.called
cluster_call_kwargs = mock_cluster.call_args[1]
# Must use credential_provider, not a static password
assert (
"credential_provider" in cluster_call_kwargs
), "async GCP cluster must use credential_provider for per-connection token refresh"
assert isinstance(
cluster_call_kwargs["credential_provider"], GCPIAMCredentialProvider
)
assert (
"password" not in cluster_call_kwargs
), "async GCP cluster must not use a static password (expires after 1h)"
@patch("litellm._redis.init_redis_cluster")
def test_sync_client_prefers_cluster_over_url(mock_init_cluster, monkeypatch):
"""
Test get_redis_client returns RedisCluster when startup_nodes is present even if
REDIS_URL is also set.
"""
monkeypatch.setenv("REDIS_URL", "redis://fallback-host:6379")
mock_init_cluster.return_value = MagicMock(spec=redis.RedisCluster)
startup_nodes = [{"host": "cluster-node.example.com", "port": 6379}]
get_redis_client(startup_nodes=startup_nodes)
mock_init_cluster.assert_called_once()
call_kwargs = mock_init_cluster.call_args[0][0]
assert (
"startup_nodes" in call_kwargs
), "startup_nodes must be forwarded to init_redis_cluster"
@patch("litellm._redis.async_redis.RedisCluster")
def test_async_client_prefers_cluster_over_url(mock_cluster_cls, monkeypatch):
"""
Test (1) get_redis_async_client returns async RedisCluster when startup_nodes is present
even if REDIS_URL is also set and (2) startup_nodes is forwarded to RedisCluster.
"""
monkeypatch.setenv("REDIS_URL", "redis://fallback-host:6379")
startup_nodes = [{"host": "cluster-node.example.com", "port": 6379}]
get_redis_async_client(startup_nodes=startup_nodes)
mock_cluster_cls.assert_called_once()
call_kwargs = mock_cluster_cls.call_args[1]
assert (
"startup_nodes" in call_kwargs
), "startup_nodes must be forwarded to async RedisCluster"
assert (
len(call_kwargs["startup_nodes"]) == 1
), "should forward exactly 1 cluster node"
@patch("litellm._redis.async_redis.RedisCluster")
def test_async_client_prefers_cluster_over_url_via_env_var(
mock_cluster_cls, monkeypatch
):
"""
Test get_redis_async_client returns async RedisCluster when REDIS_CLUSTER_NODES is set
even if REDIS_URL is also set.
"""
monkeypatch.setenv("REDIS_URL", "redis://fallback-host:6379")
monkeypatch.setenv(
"REDIS_CLUSTER_NODES",
json.dumps([{"host": "cluster-node.example.com", "port": 6379}]),
)
get_redis_async_client()
mock_cluster_cls.assert_called_once()
call_kwargs = mock_cluster_cls.call_args[1]
assert (
"startup_nodes" in call_kwargs
), "startup_nodes must be forwarded to async RedisCluster"
@patch("litellm._redis.init_redis_cluster")
def test_sync_client_prefers_cluster_over_url_via_env_var(
mock_init_cluster, monkeypatch
):
"""
Test get_redis_client returns RedisCluster when REDIS_CLUSTER_NODES is set even if
REDIS_URL is also set.
"""
monkeypatch.setenv("REDIS_URL", "redis://fallback-host:6379")
monkeypatch.setenv(
"REDIS_CLUSTER_NODES",
json.dumps([{"host": "cluster-node.example.com", "port": 6379}]),
)
mock_init_cluster.return_value = MagicMock(spec=redis.RedisCluster)
get_redis_client()
mock_init_cluster.assert_called_once()
call_kwargs = mock_init_cluster.call_args[0][0]
assert (
"startup_nodes" in call_kwargs
), "startup_nodes must be forwarded to init_redis_cluster"
assert len(call_kwargs["startup_nodes"]) == 1
@patch("litellm._redis.init_redis_cluster")
def test_sync_client_preserves_password_for_cluster_when_url_also_set(
mock_init_cluster, monkeypatch
):
"""
Test _get_redis_client_logic does not strip password from redis_kwargs when
startup_nodes is present even if REDIS_URL is also set.
"""
monkeypatch.setenv("REDIS_URL", "redis://fallback-host:6379")
monkeypatch.setenv("REDIS_PASSWORD", "secret")
mock_init_cluster.return_value = MagicMock(spec=redis.RedisCluster)
startup_nodes = [{"host": "cluster-node.example.com", "port": 6379}]
get_redis_client(startup_nodes=startup_nodes)
mock_init_cluster.assert_called_once()
call_kwargs = mock_init_cluster.call_args[0][0]
assert (
"password" in call_kwargs
), "password must not be stripped when routing to cluster"
assert call_kwargs["password"] == "secret"
def test_connection_pool_returns_none_for_cluster(monkeypatch):
"""Test get_redis_connection_pool returns None when startup_nodes is present."""
monkeypatch.setenv("REDIS_URL", "redis://fallback-host:6379")
startup_nodes = [{"host": "cluster-node.example.com", "port": 6379}]
result = get_redis_connection_pool(startup_nodes=startup_nodes)
assert result is None, "connection pool must be None for cluster mode"
@patch("litellm._redis.redis.Redis.from_url")
def test_sync_client_url_used_when_no_cluster(mock_from_url, monkeypatch):
"""
Test get_redis_client default to using URL path when no startup_nodes are provided.
"""
monkeypatch.setenv("REDIS_URL", "redis://plain-host:6379")
monkeypatch.delenv("REDIS_CLUSTER_NODES", raising=False)
get_redis_client()
mock_from_url.assert_called_once()