%% A fake usage CLI, a local HTTP endpoint and a command whose whole job is to %% dump the environment it ran with: the three things usage_feed's loop has to %% get right (envelope on stdin, responses replayed, allowlist on commands) %% without a real provider, a real credential or the network. %% %% ALBEDO_USAGE_CORE points the driver's binary resolution at the fake, so the %% daemon is never involved: no route exercises this loop end to end yet. -module(albedo_usage_test_support). -export([start/0, stop/1, envelope/1, env_dump/1, request_line/1, break_binary/1, mono_ms/0, trickle_pid_gone/1]). %% eunit runs a module's tests in parallel ({inparallel, _} reaches into the %% module), and ALBEDO_USAGE_CORE is one global environment variable, so the %% fakes must not overlap. A registered name is the lock: it is held from %% start to stop, and the death of a crashed test process releases it. -define(LOCK, albedo_usage_fake). start() -> await_lock(), Dir = filename:join(tmp(), "albedo-usage-" ++ os:getpid() ++ "-" ++ integer_to_list(erlang:unique_integer([positive]))), ok = file:make_dir(Dir), {ok, Listen} = gen_tcp:listen(0, [binary, {active, false}, {reuseaddr, true}, {packet, raw}]), {ok, {_Address, Port}} = inet:sockname(Listen), Server = spawn(fun() -> serve(Listen, []) end), Url = io_lib:format("http://127.0.0.1:~B/usage", [Port]), Usage = filename:join(Dir, "usage"), Dump = filename:join(Dir, "env-dump.sh"), Trickle = filename:join(Dir, "trickle.sh"), write(Usage, fake_usage(Url, Dump, Trickle, filename:join(Dir, "envelope.txt"))), write(Dump, ["#!/bin/sh\nenv >", filename:join(Dir, "env.txt"), "\necho dumped\n"]), %% Prints its own pid, then a line forever: a command that always has %% output but never exits, for the deadline-kill test. write(Trickle, ["#!/bin/sh\necho $$ >", filename:join(Dir, "trickle.pid"), "\nwhile true; do\n echo tick\n sleep 0.2\ndone\n"]), ok = file:change_mode(Usage, 8#755), ok = file:change_mode(Dump, 8#755), ok = file:change_mode(Trickle, 8#755), os:putenv("ALBEDO_USAGE_CORE", Usage), os:putenv("ALBEDO_USAGE_TEST_CANARY", "leak"), {ok, #{dir => Dir, listen => Listen, server => Server, envelope => filename:join(Dir, "envelope.txt"), env => filename:join(Dir, "env.txt"), trickle_pid => filename:join(Dir, "trickle.pid")}}. stop(Ref) -> exit(maps:get(server, Ref), kill), gen_tcp:close(maps:get(listen, Ref)), os:unsetenv("ALBEDO_USAGE_CORE"), os:unsetenv("ALBEDO_USAGE_TEST_CANARY"), _ = file:del_dir_r(maps:get(dir, Ref)), catch unregister(?LOCK), nil. await_lock() -> case whereis(?LOCK) of Pid when is_pid(Pid) -> Ref = erlang:monitor(process, Pid), receive {'DOWN', Ref, process, Pid, _} -> ok after 15000 -> exit(usage_fake_lock_timeout) end, await_lock(); undefined -> try register(?LOCK, self()) of true -> ok catch _:_ -> await_lock() end end. envelope(Ref) -> read(maps:get(envelope, Ref)). env_dump(Ref) -> read(maps:get(env, Ref)). request_line(Ref) -> Server = maps:get(server, Ref), Server ! {requests, self()}, receive {requests, Server, Lines} -> Lines after 2000 -> [] end. %% Points resolution at a path that does not exist: the override must be %% authoritative, never silently falling back to PATH. break_binary(Ref) -> os:putenv("ALBEDO_USAGE_CORE", filename:join(maps:get(dir, Ref), "not-there")), nil. mono_ms() -> erlang:monotonic_time(millisecond). %% The trickle command is killed on timeout, not orphaned: its pid stops %% answering signal 0. The beam reaps its port children asynchronously, so %% the check polls briefly rather than asserting the very first probe. trickle_pid_gone(Ref) -> Path = maps:get(trickle_pid, Ref), case file:read_file(Path) of {ok, Bin} -> Pid = binary_to_integer(string:trim(Bin)), gone(Pid, 20); _ -> false end. gone(Pid, 0) -> signal(Pid) =/= 0; gone(Pid, N) -> case signal(Pid) of 0 -> timer:sleep(50), gone(Pid, N - 1); _ -> true end. %% Exit status of `kill -0 Pid`: 0 while the process exists. signal(Pid) -> Kill = case os:find_executable("kill") of false -> erlang:error({missing_test_dependency, "kill executable not found in PATH"}); Executable -> Executable end, Port = open_port({spawn_executable, Kill}, [{args, ["-0", integer_to_list(Pid)]}, exit_status, binary, hide]), receive {Port, {exit_status, Status}} -> Status after 1000 -> catch erlang:port_close(Port), 0 end. read(Path) -> case file:read_file(Path) of {ok, Bin} -> Bin; _ -> <<>> end. write(Path, Content) -> ok = file:write_file(Path, Content). tmp() -> case os:getenv("TMPDIR") of false -> "/tmp"; T -> T end. %% The fake core speaks the real protocol: one envelope line in (the whole %% history, on stdin), one step line out, and the provider name decides what %% kind of feed it is. The default feed answers round one with an http request %% and a command, and round two with a report built from the http body - so %% the loop, the envelope and the command environment are all load-bearing. fake_usage(Url, Dump, Trickle, EnvelopeLog) -> ["#!/usr/bin/env python3\n" "import json, sys\n" "line = sys.stdin.readline()\n" "open(", quote(EnvelopeLog), ", 'a').write(line)\n" "envelope = json.loads(line)\n" "provider = envelope.get('provider')\n" "responses = envelope.get('responses', [])\n" "if provider == 'endless':\n" " step = {'requests': [{'kind': 'command', 'command': 'true', 'args': []}]}\n" "elif provider == 'broken':\n" " step = {'report': {'limits': [], 'error': 'the provider is unreachable'}}\n" "elif provider == 'trickle':\n" " if responses:\n" " status = responses[-1][0]['status']\n" " step = {'report': {'limits': [], 'error': 'command answered %d' % status}}\n" " else:\n" " step = {'requests': [\n" " {'kind': 'command', 'command': ", quote(Trickle), ", 'args': [],\n" " 'timeoutMs': 1000}]}\n" "elif provider == 'missing-command' and responses:\n" " status = responses[-1][0]['status']\n" " step = {'report': {'limits': [], 'error': 'command answered %d' % status}}\n" "elif responses:\n" " body = json.loads(responses[-1][0]['body'])\n" " step = {'report': {\n" " 'accountId': 'acct-1', 'email': 'dawn@example.com', 'planType': 'token',\n" " 'limits': [{'id': 'five_hour', 'label': 'Session',\n" " 'usedPercent': body['pct'], 'windowLabel': '5h window',\n" " 'windowSeconds': 18000, 'resetsAt': 1893456000000,\n" " 'status': 'ok'}],\n" " 'error': None}}\n" "elif provider == 'missing-command':\n" " step = {'requests': [\n" " {'kind': 'command', 'command': 'no-such-binary-xyz', 'args': []}]}\n" "else:\n" " step = {'requests': [\n" " {'kind': 'http', 'method': 'GET', 'url': ", quote(Url), ",\n" " 'headers': [['accept', 'application/json']]},\n" " {'kind': 'command', 'command': ", quote(Dump), ", 'args': [],\n" " 'timeoutMs': 5000}]}\n" "print(json.dumps(step))\n"]. quote(Text) -> [$', Text, $']. serve(Listen, Acc) -> receive {requests, From} -> From ! {requests, self(), lists:reverse(Acc)} after 0 -> ok end, case gen_tcp:accept(Listen, 200) of {ok, Socket} -> case read_head(Socket, <<>>) of {ok, Head} -> [RequestLine | _] = binary:split(Head, <<"\r\n">>), Body = <<"{\"pct\":37}">>, ok = gen_tcp:send(Socket, [ <<"HTTP/1.1 200 OK\r\ncontent-type: application/json\r\n">>, <<"content-length: ">>, integer_to_binary(byte_size(Body)), <<"\r\n\r\n">>, Body]), gen_tcp:close(Socket), serve(Listen, [RequestLine | Acc]); _ -> gen_tcp:close(Socket), serve(Listen, Acc) end; {error, timeout} -> serve(Listen, Acc); _ -> ok end. read_head(Socket, Acc) -> case binary:match(Acc, <<"\r\n\r\n">>) of nomatch -> case gen_tcp:recv(Socket, 0, 5000) of {ok, Bytes} -> read_head(Socket, <>); Error -> Error end; _ -> {ok, Acc} end.