diff --git a/Documentation/Routers/ReadWriteSplit.md b/Documentation/Routers/ReadWriteSplit.md index b18825f2a6..d834d9e186 100644 --- a/Documentation/Routers/ReadWriteSplit.md +++ b/Documentation/Routers/ReadWriteSplit.md @@ -1080,6 +1080,20 @@ Enabling this feature will increase memory usage of a session. The amount of memory stored per prepared statement is proportional to the length of the prepared SQL statement and the number of parameters the statement has. +### `read_only` + +- **Type**: [boolean](../Getting-Started/Configuration-Guide.md#booleans) +- **Mandatory**: No +- **Dynamic**: Yes +- **Default**: false + +If enabled, only read queries and read-only transactions are allowed. All write +queries will generate the following read-only error: + +``` +ERROR 1290 (HY000): The MariaDB server is running with the --read-only option so it cannot execute this statement +``` + ## Router Diagnostics The `router_diagnostics` output for a readwritesplit service contains the diff --git a/server/modules/routing/readwritesplit/readwritesplit.cc b/server/modules/routing/readwritesplit/readwritesplit.cc index 3355fb3da4..c971393883 100644 --- a/server/modules/routing/readwritesplit/readwritesplit.cc +++ b/server/modules/routing/readwritesplit/readwritesplit.cc @@ -232,6 +232,7 @@ RWSConfig::RWSConfig(SERVICE* service) add_native(&RWSConfig::m_v, &Values::optimistic_trx, &s_optimistic_trx); add_native(&RWSConfig::m_v, &Values::lazy_connect, &s_lazy_connect); add_native(&RWSConfig::m_v, &Values::reuse_ps, &s_reuse_ps); + add_native(&RWSConfig::m_v, &Values::read_only, &s_read_only); } bool RWSConfig::post_configure(const std::map& nested_params) diff --git a/server/modules/routing/readwritesplit/readwritesplit.hh b/server/modules/routing/readwritesplit/readwritesplit.hh index 7a6da2eb28..8d3ede9495 100644 --- a/server/modules/routing/readwritesplit/readwritesplit.hh +++ b/server/modules/routing/readwritesplit/readwritesplit.hh @@ -239,6 +239,10 @@ static cfg::ParamBool s_reuse_ps( &s_spec, "reuse_prepared_statements", "Reuse identical prepared statements inside the same connection", false, cfg::Param::AT_RUNTIME); +static cfg::ParamBool s_read_only( + &s_spec, "read_only", "Only allow read queries to be executed", + false, cfg::Param::AT_RUNTIME); + /** Function that returns a "score" for a server to enable comparison. * Smaller numbers are better. */ @@ -270,6 +274,7 @@ struct RWSConfig : public mxs::config::Configuration bool master_reconnection; /**< Allow changes in master server */ bool optimistic_trx; /**< Enable optimistic transactions */ bool lazy_connect; /**< Create connections only when needed */ + bool read_only; CausalReads causal_reads; seconds causal_reads_timeout; /**< Timeout, second parameter of function master_wait_gtid */ bool delayed_retry; /**< Delay routing if no target found */ diff --git a/server/modules/routing/readwritesplit/rwsplit_route_stmt.cc b/server/modules/routing/readwritesplit/rwsplit_route_stmt.cc index 2b86eab325..bcae229596 100644 --- a/server/modules/routing/readwritesplit/rwsplit_route_stmt.cc +++ b/server/modules/routing/readwritesplit/rwsplit_route_stmt.cc @@ -183,9 +183,7 @@ bool RWSplitSession::handle_routing_failure(GWBUF&& buffer, const RoutingPlan& r { MXB_INFO("Sending read-only error, no valid target found for %s", route_target_to_string(res.route_target)); - set_response(mariadb::create_error_packet(1, ER_OPTION_PREVENTS_STATEMENT, "HY000", - "The MariaDB server is running with the --read-only" - " option so it cannot execute this statement")); + queue_readonly_error(); discard_connection(m_current_master, "The original primary is not available"); } else if (res.route_target == TARGET_MASTER @@ -220,6 +218,13 @@ void RWSplitSession::send_readonly_error() RouterSession::clientReply(mariadb::create_error_packet(1, errnum, sqlstate, errmsg), route, reply); } +void RWSplitSession::queue_readonly_error() +{ + set_response(mariadb::create_error_packet(1, ER_OPTION_PREVENTS_STATEMENT, "HY000", + "The MariaDB server is running with the --read-only" + " option so it cannot execute this statement")); +} + bool RWSplitSession::query_not_supported(const GWBUF& querybuf) { bool unsupported = false; diff --git a/server/modules/routing/readwritesplit/rwsplitsession.cc b/server/modules/routing/readwritesplit/rwsplitsession.cc index 2c8afcd9da..d93a230d4c 100644 --- a/server/modules/routing/readwritesplit/rwsplitsession.cc +++ b/server/modules/routing/readwritesplit/rwsplitsession.cc @@ -112,7 +112,14 @@ bool RWSplitSession::route_query(GWBUF&& buffer) if (can_route_query(buffer, res, prev_trx_state)) { - if (need_gtid_probe(res)) + if (TARGET_IS_MASTER(res.route_target) && m_config->read_only) + { + // Revert any transaction state changes in case the statement changed it. + m_trx_tracker = prev_trx_state; + queue_readonly_error(); + return true; + } + else if (need_gtid_probe(res)) { m_query_queue.push_front(std::move(buffer)); std::tie(buffer, res) = start_gtid_probe(); diff --git a/server/modules/routing/readwritesplit/rwsplitsession.hh b/server/modules/routing/readwritesplit/rwsplitsession.hh index f50f0cfee8..d5550290e0 100644 --- a/server/modules/routing/readwritesplit/rwsplitsession.hh +++ b/server/modules/routing/readwritesplit/rwsplitsession.hh @@ -178,6 +178,7 @@ private: mxs::RWBackend* curr_master); void send_readonly_error(); + void queue_readonly_error(); bool query_not_supported(const GWBUF& querybuf); bool handle_causal_read_reply(GWBUF& writebuf, const mxs::Reply& reply, mxs::RWBackend* backend);