Reverse-proxy tests

tests/test_std_http_server_proxy.rs runs std.http.server behind nginx and Caddy (see reverse proxies). They need Docker and curl, so they run only when asked:

PLENTY_DOCKER_TESTS=1 cargo test --locked --test integration test_std_http_server_proxy::

Without the variable each test prints that it is skipped and passes, so the ordinary suite needs no Docker and does not slow down. With it, a missing Docker daemon or curl fails the tests. The first run pulls the two pinned images (about 70 MB each). Each test starts its own containers with --network host on free loopback ports, names them plenty-proxy-test-<pid>-<n> with the label plenty-test=proxy, and removes them when it ends, also on failure; nothing else is stopped or pruned. A test process killed outright leaves its containers running; list them with docker ps --filter label=plenty-test=proxy.

CI runs them in the proxy_tests job of .github/workflows/ci.yml on GitHub’s ubuntu-latest, which has Docker and curl. The job pulls nginx:1.30.6-alpine3.24 and caddy:2.11.7-alpine in an earlier step, so pulls are not timed with the tests; when the tests change an image tag, change the job’s pull step to match.