Files
scylladb/api/api_init.hh
Botond Dénes 26b812067b Merge 'Add an API to trigger snapshot in Raft servers' from Kamil Braun
This allows the user of `raft::server` to cause it to create a snapshot
and truncate the Raft log (leaving no trailing entries; in the future we
may extend the API to specify number of trailing entries left if
needed). In a later commit we'll add a REST endpoint to Scylla to
trigger group 0 snapshots.

One use case for this API is to create group 0 snapshots in Scylla
deployments which upgraded to Raft in version 5.2 and started with an
empty Raft log with no snapshot at the beginning. This causes problems,
e.g. when a new node bootstraps to the cluster, it will not receive a
snapshot that would contain both schema and group 0 history, which would
then lead to inconsistent schema state and trigger assertion failures as
observed in scylladb/scylladb#16683.

In 5.4 the logic of initial group 0 setup was changed to start the Raft
log with a snapshot at index 1 (ff386e7a44)
but a problem remains with these existing deployments coming from 5.2,
we need a way to trigger a snapshot in them (other than performing 1000
arbitrary schema changes).

Another potential use case in the future would be to trigger snapshots
based on external memory pressure in tablet Raft groups (for strongly
consistent tables).

The PR adds the API to `raft::server` and a HTTP endpoint that uses it.

In a follow-up PR, we plan to modify group 0 server startup logic to automatically
call this API if it sees that no snapshot is present yet (to automatically
fix the aforementioned 5.2 deployments once they upgrade.)

Closes scylladb/scylladb#16816

* github.com:scylladb/scylladb:
  raft: remove `empty()` from `fsm_output`
  test: add test for manual triggering of Raft snapshots
  api: add HTTP endpoint to trigger Raft snapshots
  raft: server: add `trigger_snapshot` API
  raft: server: track last persisted snapshot descriptor index
  raft: server: framework for handling server requests
  raft: server: inline `poll_fsm_output`
  raft: server: fix indentation
  raft: server: move `io_fiber`'s processing of `batch` to a separate function
  raft: move `poll_output()` from `fsm` to `server`
  raft: move `_sm_events` from `fsm` to `server`
  raft: fsm: remove constructor used only in tests
  raft: fsm: move trace message from `poll_output` to `has_output`
  raft: fsm: extract `has_output()`
  raft: pass `max_trailing_entries` through `fsm_output` to `store_snapshot_descriptor`
  raft: server: pass `*_aborted` to `set_exception` call

(cherry picked from commit d202d32f81)

Backport note: the HTTP API is only started if raft_group_registry is
started.
2024-02-02 12:35:46 +01:00

125 lines
4.3 KiB
C++

/*
* Copyright 2016 ScylaDB
*/
/*
* SPDX-License-Identifier: AGPL-3.0-or-later
*/
#pragma once
#include <seastar/http/httpd.hh>
#include <seastar/core/future.hh>
#include "replica/database_fwd.hh"
#include "tasks/task_manager.hh"
#include "seastarx.hh"
using request = http::request;
using reply = http::reply;
namespace service {
class load_meter;
class storage_proxy;
class storage_service;
class raft_group0_client;
class raft_group_registry;
} // namespace service
class sstables_loader;
namespace streaming {
class stream_manager;
}
namespace locator {
class token_metadata;
class shared_token_metadata;
class snitch_ptr;
} // namespace locator
namespace cql_transport { class controller; }
class thrift_controller;
namespace db {
class snapshot_ctl;
class config;
namespace view {
class view_builder;
}
class system_keyspace;
}
namespace netw { class messaging_service; }
class repair_service;
namespace gms {
class gossiper;
}
namespace auth { class service; }
namespace api {
struct http_context {
sstring api_dir;
sstring api_doc;
httpd::http_server_control http_server;
distributed<replica::database>& db;
service::load_meter& lmeter;
const sharded<locator::shared_token_metadata>& shared_token_metadata;
sharded<tasks::task_manager>& tm;
http_context(distributed<replica::database>& _db,
service::load_meter& _lm, const sharded<locator::shared_token_metadata>& _stm, sharded<tasks::task_manager>& _tm)
: db(_db), lmeter(_lm), shared_token_metadata(_stm), tm(_tm) {
}
const locator::token_metadata& get_token_metadata();
};
future<> set_server_init(http_context& ctx);
future<> set_server_config(http_context& ctx, const db::config& cfg);
future<> set_server_snitch(http_context& ctx, sharded<locator::snitch_ptr>& snitch);
future<> unset_server_snitch(http_context& ctx);
future<> set_server_storage_service(http_context& ctx, sharded<service::storage_service>& ss, service::raft_group0_client&);
future<> unset_server_storage_service(http_context& ctx);
future<> set_server_sstables_loader(http_context& ctx, sharded<sstables_loader>& sst_loader);
future<> unset_server_sstables_loader(http_context& ctx);
future<> set_server_view_builder(http_context& ctx, sharded<db::view::view_builder>& vb);
future<> unset_server_view_builder(http_context& ctx);
future<> set_server_repair(http_context& ctx, sharded<repair_service>& repair);
future<> unset_server_repair(http_context& ctx);
future<> set_transport_controller(http_context& ctx, cql_transport::controller& ctl);
future<> unset_transport_controller(http_context& ctx);
future<> set_rpc_controller(http_context& ctx, thrift_controller& ctl);
future<> unset_rpc_controller(http_context& ctx);
future<> set_server_authorization_cache(http_context& ctx, sharded<auth::service> &auth_service);
future<> unset_server_authorization_cache(http_context& ctx);
future<> set_server_snapshot(http_context& ctx, sharded<db::snapshot_ctl>& snap_ctl);
future<> unset_server_snapshot(http_context& ctx);
future<> set_server_gossip(http_context& ctx, sharded<gms::gossiper>& g);
future<> set_server_load_sstable(http_context& ctx, sharded<db::system_keyspace>& sys_ks);
future<> unset_server_load_sstable(http_context& ctx);
future<> set_server_messaging_service(http_context& ctx, sharded<netw::messaging_service>& ms);
future<> unset_server_messaging_service(http_context& ctx);
future<> set_server_storage_proxy(http_context& ctx, sharded<service::storage_proxy>& proxy);
future<> unset_server_storage_proxy(http_context& ctx);
future<> set_server_stream_manager(http_context& ctx, sharded<streaming::stream_manager>& sm);
future<> unset_server_stream_manager(http_context& ctx);
future<> set_hinted_handoff(http_context& ctx, sharded<service::storage_proxy>& p);
future<> unset_hinted_handoff(http_context& ctx);
future<> set_server_gossip_settle(http_context& ctx, sharded<gms::gossiper>& g);
future<> set_server_cache(http_context& ctx);
future<> set_server_compaction_manager(http_context& ctx);
future<> set_server_done(http_context& ctx);
future<> set_server_task_manager(http_context& ctx, lw_shared_ptr<db::config> cfg);
future<> set_server_task_manager_test(http_context& ctx);
future<> set_server_raft(http_context&, sharded<service::raft_group_registry>&);
future<> unset_server_raft(http_context&);
}