This commit creates a new probe_and_replicate.txt interactive test. The
test creates a complete Raft log configuration and demonstrates how a
leader probes and replicates to each of its followers. The log
configuration constructed is identical to the one present in Figure 7 of
the raft paper (https://raft.github.io/raft.pdf), which looks like:
```
1 2 3 4 5 6 7 8 9 10 11 12
n1: [1][1][1][4][4][5][5][6][6][6]
n2: [1][1][1][4][4][5][5][6][6]
n3: [1][1][1][4]
n4: [1][1][1][4][4][5][5][6][6][6][6]
n5: [1][1][1][4][4][5][5][6][7][7][7][7]
n6: [1][1][1][4][4][4][4]
n7: [1][1][1][2][2][2][3][3][3][3][3]
```
Once in this state, we then elect node 1 as the leader and stabilize the
entire raft group. This demonstrates how a newly elected leader probes
for matching indexes, overwrites conflicting entries, and catches up all
followers.
This will be useful to demonstrate the impact of more efficient probing
behavior.
Marked all 'integrational, e2e' as skipped in the --short mode.
Thanks to this we will be able to significantly simplify ./test script.
The run currently takes ~23s.
With (follow up) move of ~clientv3/snapshot to integration tests (as
part of modularization), we can expect this to fall to 5-10s.
```
% time go test --short ./... --count=1
ok go.etcd.io/etcd/v3 0.098s
? go.etcd.io/etcd/v3/Documentation/learning/lock/client [no test files]
? go.etcd.io/etcd/v3/Documentation/learning/lock/storage [no test files]
ok go.etcd.io/etcd/v3/auth 0.724s
? go.etcd.io/etcd/v3/auth/authpb [no test files]
ok go.etcd.io/etcd/v3/client 0.166s
ok go.etcd.io/etcd/v3/client/integration 0.166s
ok go.etcd.io/etcd/v3/clientv3 3.219s
ok go.etcd.io/etcd/v3/clientv3/balancer 1.102s
? go.etcd.io/etcd/v3/clientv3/balancer/connectivity [no test files]
? go.etcd.io/etcd/v3/clientv3/balancer/picker [no test files]
? go.etcd.io/etcd/v3/clientv3/balancer/resolver/endpoint [no test files]
ok go.etcd.io/etcd/v3/clientv3/clientv3util 0.096s [no tests to run]
ok go.etcd.io/etcd/v3/clientv3/concurrency 3.323s
? go.etcd.io/etcd/v3/clientv3/credentials [no test files]
ok go.etcd.io/etcd/v3/clientv3/integration 0.131s
? go.etcd.io/etcd/v3/clientv3/leasing [no test files]
? go.etcd.io/etcd/v3/clientv3/mirror [no test files]
ok go.etcd.io/etcd/v3/clientv3/namespace 0.041s
ok go.etcd.io/etcd/v3/clientv3/naming 0.115s
ok go.etcd.io/etcd/v3/clientv3/ordering 0.121s
ok go.etcd.io/etcd/v3/clientv3/snapshot 19.325s
ok go.etcd.io/etcd/v3/clientv3/yaml 0.090s
ok go.etcd.io/etcd/v3/contrib/raftexample 7.572s
? go.etcd.io/etcd/v3/contrib/recipes [no test files]
ok go.etcd.io/etcd/v3/embed 0.282s
ok go.etcd.io/etcd/v3/etcdctl 0.054s
? go.etcd.io/etcd/v3/etcdctl/ctlv2 [no test files]
ok go.etcd.io/etcd/v3/etcdctl/ctlv2/command 0.117s
? go.etcd.io/etcd/v3/etcdctl/ctlv3 [no test files]
ok go.etcd.io/etcd/v3/etcdctl/ctlv3/command 0.070s
ok go.etcd.io/etcd/v3/etcdmain 0.172s
ok go.etcd.io/etcd/v3/etcdserver 1.698s
? go.etcd.io/etcd/v3/etcdserver/api [no test files]
ok go.etcd.io/etcd/v3/etcdserver/api/etcdhttp 0.075s
ok go.etcd.io/etcd/v3/etcdserver/api/membership 0.104s
? go.etcd.io/etcd/v3/etcdserver/api/membership/membershippb [no test files]
ok go.etcd.io/etcd/v3/etcdserver/api/rafthttp 0.181s
ok go.etcd.io/etcd/v3/etcdserver/api/snap 0.078s
? go.etcd.io/etcd/v3/etcdserver/api/snap/snappb [no test files]
ok go.etcd.io/etcd/v3/etcdserver/api/v2auth 0.142s
ok go.etcd.io/etcd/v3/etcdserver/api/v2discovery 0.035s
ok go.etcd.io/etcd/v3/etcdserver/api/v2error 0.043s
ok go.etcd.io/etcd/v3/etcdserver/api/v2http 0.070s
ok go.etcd.io/etcd/v3/etcdserver/api/v2http/httptypes 0.031s
? go.etcd.io/etcd/v3/etcdserver/api/v2stats [no test files]
ok go.etcd.io/etcd/v3/etcdserver/api/v2store 0.645s
ok go.etcd.io/etcd/v3/etcdserver/api/v2v3 0.218s
? go.etcd.io/etcd/v3/etcdserver/api/v3alarm [no test files]
? go.etcd.io/etcd/v3/etcdserver/api/v3client [no test files]
ok go.etcd.io/etcd/v3/etcdserver/api/v3compactor 1.765s
? go.etcd.io/etcd/v3/etcdserver/api/v3election [no test files]
? go.etcd.io/etcd/v3/etcdserver/api/v3election/v3electionpb [no test files]
? go.etcd.io/etcd/v3/etcdserver/api/v3election/v3electionpb/gw [no test files]
? go.etcd.io/etcd/v3/etcdserver/api/v3lock [no test files]
? go.etcd.io/etcd/v3/etcdserver/api/v3lock/v3lockpb [no test files]
? go.etcd.io/etcd/v3/etcdserver/api/v3lock/v3lockpb/gw [no test files]
ok go.etcd.io/etcd/v3/etcdserver/api/v3rpc 0.091s
ok go.etcd.io/etcd/v3/etcdserver/api/v3rpc/rpctypes 0.012s
ok go.etcd.io/etcd/v3/etcdserver/cindex 0.054s
ok go.etcd.io/etcd/v3/etcdserver/etcdserverpb 0.039s
? go.etcd.io/etcd/v3/etcdserver/etcdserverpb/gw [no test files]
ok go.etcd.io/etcd/v3/functional/agent 0.094s
? go.etcd.io/etcd/v3/functional/cmd/etcd-agent [no test files]
? go.etcd.io/etcd/v3/functional/cmd/etcd-proxy [no test files]
? go.etcd.io/etcd/v3/functional/cmd/etcd-runner [no test files]
? go.etcd.io/etcd/v3/functional/cmd/etcd-tester [no test files]
ok go.etcd.io/etcd/v3/functional/rpcpb 0.060s
? go.etcd.io/etcd/v3/functional/runner [no test files]
ok go.etcd.io/etcd/v3/functional/tester 0.079s
ok go.etcd.io/etcd/v3/integration 0.684s
ok go.etcd.io/etcd/v3/integration/embed 0.101s
ok go.etcd.io/etcd/v3/lease 3.455s
ok go.etcd.io/etcd/v3/lease/leasehttp 2.185s
? go.etcd.io/etcd/v3/lease/leasepb [no test files]
ok go.etcd.io/etcd/v3/mvcc 7.246s
ok go.etcd.io/etcd/v3/mvcc/backend 0.354s
? go.etcd.io/etcd/v3/mvcc/mvccpb [no test files]
ok go.etcd.io/etcd/v3/pkg/adt 0.025s
? go.etcd.io/etcd/v3/pkg/contention [no test files]
? go.etcd.io/etcd/v3/pkg/cpuutil [no test files]
ok go.etcd.io/etcd/v3/pkg/crc 0.008s
? go.etcd.io/etcd/v3/pkg/debugutil [no test files]
ok go.etcd.io/etcd/v3/pkg/expect 0.015s
ok go.etcd.io/etcd/v3/pkg/fileutil 0.268s
ok go.etcd.io/etcd/v3/pkg/flags 0.021s
ok go.etcd.io/etcd/v3/pkg/httputil 0.020s
ok go.etcd.io/etcd/v3/pkg/idutil 0.008s
ok go.etcd.io/etcd/v3/pkg/ioutil 0.025s
ok go.etcd.io/etcd/v3/pkg/logutil 0.047s
? go.etcd.io/etcd/v3/pkg/mock/mockserver [no test files]
? go.etcd.io/etcd/v3/pkg/mock/mockstorage [no test files]
? go.etcd.io/etcd/v3/pkg/mock/mockstore [no test files]
? go.etcd.io/etcd/v3/pkg/mock/mockwait [no test files]
ok go.etcd.io/etcd/v3/pkg/netutil 1.024s
ok go.etcd.io/etcd/v3/pkg/osutil 0.021s
ok go.etcd.io/etcd/v3/pkg/pathutil 0.008s
ok go.etcd.io/etcd/v3/pkg/pbutil 0.008s
ok go.etcd.io/etcd/v3/pkg/proxy 4.081s
ok go.etcd.io/etcd/v3/pkg/report 0.008s
? go.etcd.io/etcd/v3/pkg/runtime [no test files]
ok go.etcd.io/etcd/v3/pkg/schedule 0.009s
ok go.etcd.io/etcd/v3/pkg/srv 0.019s
ok go.etcd.io/etcd/v3/pkg/stringutil 0.008s
? go.etcd.io/etcd/v3/pkg/systemd [no test files]
ok go.etcd.io/etcd/v3/pkg/testutil 0.023s
ok go.etcd.io/etcd/v3/pkg/tlsutil 3.965s
ok go.etcd.io/etcd/v3/pkg/traceutil 0.034s
ok go.etcd.io/etcd/v3/pkg/transport 0.532s
ok go.etcd.io/etcd/v3/pkg/types 0.028s
ok go.etcd.io/etcd/v3/pkg/wait 0.023s
ok go.etcd.io/etcd/v3/proxy/grpcproxy 0.101s
? go.etcd.io/etcd/v3/proxy/grpcproxy/adapter [no test files]
? go.etcd.io/etcd/v3/proxy/grpcproxy/cache [no test files]
ok go.etcd.io/etcd/v3/proxy/httpproxy 0.044s
ok go.etcd.io/etcd/v3/proxy/tcpproxy 0.047s
ok go.etcd.io/etcd/v3/raft 0.312s
ok go.etcd.io/etcd/v3/raft/confchange 0.183s
ok go.etcd.io/etcd/v3/raft/quorum 0.316s
ok go.etcd.io/etcd/v3/raft/raftpb 0.024s
ok go.etcd.io/etcd/v3/raft/rafttest 0.640s
ok go.etcd.io/etcd/v3/raft/tracker 0.026s
ok go.etcd.io/etcd/v3/tests/e2e 0.077s
? go.etcd.io/etcd/v3/tools/benchmark [no test files]
? go.etcd.io/etcd/v3/tools/benchmark/cmd [no test files]
? go.etcd.io/etcd/v3/tools/etcd-dump-db [no test files]
ok go.etcd.io/etcd/v3/tools/etcd-dump-logs 0.088s
? go.etcd.io/etcd/v3/tools/etcd-dump-metrics [no test files]
? go.etcd.io/etcd/v3/tools/local-tester/bridge [no test files]
? go.etcd.io/etcd/v3/version [no test files]
ok go.etcd.io/etcd/v3/wal 1.517s
? go.etcd.io/etcd/v3/wal/walpb [no test files]
go test --short ./... --count=1 76.12s user 12.57s system 375% cpu 23.635 total
```
This change makes the etcd package compatible with the existing Go
ecosystem for module versioning.
Used this tool to update package imports:
https://github.com/KSubedi/gomove
It has often been tedious to test the interactions between multi-member
Raft groups, especially when many steps were required to reach a certain
scenario. Often, this boilerplate was as boring as it is hard to write
and hard to maintain, making it attractive to resort to shortcuts
whenever possible, which in turn tended to undercut how meaningful and
maintainable the tests ended up being - that is, if the tests were even
written, which sometimes they weren't.
This change introduces a datadriven framework specifically for testing
deterministically the interaction between multiple members of a raft group
with the goal of reducing the friction for writing these tests to near
zero.
In the near term, this will be used to add thorough testing for joint
consensus (which is already available today, but wildly undertested),
but just converting an existing test into this framework has shown that
the concise representation and built-in inspection of log messages
highlights unexpected behavior much more readily than the previous unit
tests did (the test in question is `snapshot_succeed_via_app_resp`; the
reader is invited to compare the old and new version of it).
The main building block is `InteractionEnv`, which holds on to the state
of the whole system and exposes various relevant methods for
manipulating it, including but not limited to adding nodes, delivering
and dropping messages, and proposing configuration changes. All of this
is extensible so that in the future I hope to use it to explore the
phenomena discussed in
https://github.com/etcd-io/etcd/issues/7625#issuecomment-488798263
which requires injecting appropriate "crash points" in the Ready
handling loop. Discussions of the "what if X happened in state Y"
can quickly be made concrete by "scripting up an interaction test".
Additionally, this framework is intentionally not kept internal to the
raft package.. Though this is in its infancy, a goal is that it should
be possible for a suite of interaction tests to allow applications to
validate that their Storage implementation behaves accordingly, simply
by running a raft-provided interaction suite against their Storage.
