litellm/tests/e2e_cassette_proxy/__init__.py
Cursor Agent 765aef4ff8
tests(e2e): add transport-agnostic recording proxy sidecar for e2e CI jobs
Introduces a mitmproxy-based recording HTTP/HTTPS sidecar that any CI
job can opt into to cache LLM-provider responses across runs. Unlike
the in-process VCR persister at tests/_vcr_redis_persister.py — which
can only intercept HTTP traffic from the same Python process where it
was loaded — this sidecar operates at the network layer, so it works
for any e2e job whose system-under-test runs in a Docker container
(every job under e2e_*, proxy_*, etc.).

Components

- tests/e2e_cassette_proxy/cache_key.py: pure-function cache-key
  derivation. Hashes (method, scheme, host, path, sorted query,
  allowlisted headers, canonical-JSON body); strips auth, tracing,
  and SDK-metadata headers so equivalent requests collide regardless
  of run-to-run noise.
- tests/e2e_cassette_proxy/redis_store.py: thin Redis wrapper that
  stores one (request, response) pair per key as MessagePack
  (JSON+base64 fallback). Caps per-key payload size, drops oversize
  responses with a log line, and never blocks the request path on
  Redis errors.
- tests/e2e_cassette_proxy/addon.py: mitmproxy addon that ties the
  two together. Hosts on the passthrough list (localhost, the proxy
  itself) are never cached; non-2xx upstream responses are not
  persisted.
- tests/e2e_cassette_proxy/Dockerfile: pinned python:3.12-slim base +
  pinned mitmproxy 11.0.2 + pinned redis-py + pinned msgpack.
- tests/e2e_cassette_proxy/trust_ca.sh: helper for SUT containers to
  trust the proxy CA in every Python / curl / boto3 / node trust
  store at once.
- tests/e2e_cassette_proxy/README.md: usage guide + opt-in checklist
  for other e2e jobs.

CI integration

- New reusable command 'start_cassette_proxy' in .circleci/config.yml.
  Builds the image, runs the sidecar wired to the project Redis, fetches
  the proxy CA, and exports CASSETTE_PROXY_URL / CASSETTE_PROXY_CA into
  $BASH_ENV for downstream steps.
- e2e_openai_endpoints is wired up as the canonical demo: two-line opt-in
  pattern documented in the README.
- Job logs include a 'Cassette-proxy stats' step that dumps the
  hit/miss/store summary via 'docker logs cassette-proxy | grep
  [E2ECASS]'.

Tests

- 31 hermetic unit tests under tests/test_litellm/e2e_cassette_proxy:
  - test_cache_key.py: 14 tests pinning equivalence-class behavior of
    the key derivation (auth header, tracing header, JSON key order,
    query order, host case all collapse; method/path/body/allowlisted
    headers / query-param values do not).
  - test_redis_store.py: 9 tests covering set/get round-trip, default
    TTL, binary body round-trip, oversize-payload rejection, corrupt-
    blob eviction, and graceful behavior when the Redis client raises.
  - test_addon.py: 8 tests using a fake-mitmproxy flow to exercise
    the addon end-to-end (passthrough miss, persist on 2xx, hit on
    canonicalized-equivalent re-request, no-persist on 5xx, host
    passthrough, replay-only 599-on-miss, record-only never serves
    cache).
- 31/31 pass.

Co-authored-by: Mateo Wang <mateo-berri@users.noreply.github.com>
2026-05-01 14:41:28 +00:00

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Python

"""HTTP recording proxy used by e2e CI jobs.
This is intentionally separate from the in-process VCR persister under
``tests/_vcr_redis_persister.py``: that one only sees HTTP traffic from
the pytest process, and so cannot record requests originating from the
LiteLLM proxy when it runs in a Docker container (the case in every CI
job under ``e2e_*`` and ``proxy_*``). This package runs as a sidecar
mitmproxy that any container can route egress through via ``HTTPS_PROXY``,
making the recording layer transport-agnostic and language-agnostic.
Public surface for unit tests:
- ``cache_key.derive_cache_key`` — pure function.
- ``redis_store.RedisCassetteStore`` — thin wrapper over ``redis.Redis``.
- ``addon.CassetteAddon`` — mitmproxy addon class.
"""