Sure. Thanks for re-validating different corner cases with me. Yup, we can update more details in leader-only section about using single LB VIP while accessing clustered db via ovn-nbctl/ovn-sbctl for sure to avoid confusion.
On Wed, Aug 14, 2019 at 3:21 PM Han Zhou <[email protected]> wrote: > Hi Aginwala, thanks for the testing. The change of this patch will cause > the IDL to avoid connecting to a follower if "leader_only" is set to > "true". It is the same behavior as before when multiple remotes are used, > but now it just does the same even when a single remote is used, because > the single remote could be a VIP, so it is desired behavior. For > ovn-nbctl, "leader_only" is default to true, so it is expected that it > refuses to connect if the remote is a follower. However, if you are using > daemon mode ovn-nbctl, and if you didn't set "--no-leader-only", it should > keep retrying until it connects to a leader (depends on LB redirecting to > different servers). I agree this may cause some confusion when a user of > ovn-nbctl connects to only a single remote of a cluster, he/she could get > failure if --no-leader-only is not specified, but it is better than let > user believe they are connected to a leader while in reality connected to a > follower. Maybe I can improve the ovn-nbctl/sbctl documentation to emphasis > this to avoid confusion. > > On Tue, Aug 13, 2019 at 7:13 PM aginwala <[email protected]> wrote: > >> >> >> On Tue, Aug 13, 2019 at 7:07 PM aginwala <[email protected]> wrote: >> >>> Thanks for the fixes. Found a bug in current code which breaks both >>> nbctl with local socket and daemon mode on follower nodes. Also nbctl >>> daemon mode always tries to connect to leader node by default which also >>> failed to connect. >>> e.g. export OVN_NB_DB=tcp:<lb_vip>:6641; ovn-nbctl --pidfile --detach. >>> >>> 2019-08-14T01:07:06Z|00036|ovsdb_idl|INFO|unix:/var/run/openvswitch/ovnnb_db.sock: >>> clustered database server is not cluster leader; trying another server >>> 2019-08-14T01:07:06Z|00037|reconnect|DBG|unix:/var/run/openvswitch/ovnnb_db.sock: >>> entering RECONNECT >>> 2019-08-14T01:07:06Z|00038|ovsdb_idl|DBG|unix:/var/run/openvswitch/ovnnb_db.sock: >>> SERVER_MONITOR_COND_REQUESTED -> RETRY at lib/ovsdb-idl.c:1917 >>> 2019-08-14T01:07:06Z|00039|poll_loop|DBG|wakeup due to 0-ms timeout at >>> lib/reconnect.c:643 >>> 2019-08-14T01:07:06Z|00040|reconnect|INFO|unix:/var/run/openvswitch/ovnnb_db.sock: >>> connection attempt timed out >>> 2019-08-14T01:07:06Z|00041|reconnect|INFO|unix:/var/run/openvswitch/ovnnb_db.sock: >>> waiting 2 seconds before reconnect >>> 2019-08-14T01:07:06Z|00042|reconnect|DBG|unix:/var/run/openvswitch/ovnnb_db.sock: >>> entering BACKOFF >>> >>> Need to explicitly specify no-leader-only to work around. ovn-nbctl >>> --pidfile --detach --no-leader-only. >>> For LB VIP, since LB sees all nodes are active, connections are >>> established to all cluster nodes equally. I am using round robin setting >>> for LB VIP for 3 node cluster using raft. >>> >>> Hence, are we always going to avoid this behavior because this is >>> forcing to always connect to leader and not to followers? So if we use this >>> approach, idl will show ovn-nbctl: tcp:<lb_vip>:6641: database connection >>> failed () if requests reaches followers and only processes success if >>> request reaches leader node with this patch. >>> >>> >>> On Tue, Aug 13, 2019 at 9:23 AM Han Zhou <[email protected]> wrote: >>> >>>> From: Han Zhou <[email protected]> >>>> >>>> When clustered mode is used, the client needs to retry connecting >>>> to new servers when certain failures happen. Today it is allowed to >>>> retry new connection only if multiple remotes are used, which prevents >>>> using LB VIP with clustered nodes. This patch makes sure the retry >>>> logic works when using LB VIP: although same IP is used for retrying, >>>> the LB can actually redirect the connection to a new node. >>>> >>>> Signed-off-by: Han Zhou <[email protected]> >>>> --- >>>> lib/ovsdb-idl.c | 11 +++------- >>>> tests/ovsdb-cluster.at | 57 >>>> ++++++++++++++++++++++++++++++++++++++++++++++++++ >>>> tests/test-ovsdb.c | 1 + >>>> 3 files changed, 61 insertions(+), 8 deletions(-) >>>> >>>> diff --git a/lib/ovsdb-idl.c b/lib/ovsdb-idl.c >>>> index 1a6a4af..190143f 100644 >>>> --- a/lib/ovsdb-idl.c >>>> +++ b/lib/ovsdb-idl.c >>>> @@ -657,12 +657,8 @@ ovsdb_idl_state_to_string(enum ovsdb_idl_state >>>> state) >>>> static void >>>> ovsdb_idl_retry_at(struct ovsdb_idl *idl, const char *where) >>>> { >>>> - if (idl->session && jsonrpc_session_get_n_remotes(idl->session) > >>>> 1) { >>>> - ovsdb_idl_force_reconnect(idl); >>>> - ovsdb_idl_transition_at(idl, IDL_S_RETRY, where); >>>> - } else { >>>> - ovsdb_idl_transition_at(idl, IDL_S_ERROR, where); >>>> - } >>>> + ovsdb_idl_force_reconnect(idl); >>>> + ovsdb_idl_transition_at(idl, IDL_S_RETRY, where); >>>> } >>>> >>>> static void >>>> @@ -1895,8 +1891,7 @@ ovsdb_idl_check_server_db(struct ovsdb_idl *idl) >>>> if (!database) { >>>> VLOG_INFO_RL(&rl, "%s: server does not have %s database", >>>> server_name, idl->data.class_->database); >>>> - } else if (!strcmp(database->model, "clustered") >>>> - && jsonrpc_session_get_n_remotes(idl->session) > 1) { >>>> + } else if (!strcmp(database->model, "clustered")) { >>>> >>> > I think this check jsonrpc_session_get_n_remotes(idl->session) > 1 is >>> still needed for follower nodes for monitor condition to avoid this bug. >>> Correct me if I am wrong or missed any case. >>> >>> uint64_t index = database->n_index ? *database->index : 0; >>>> >>>> if (!database->schema) { >>>> diff --git a/tests/ovsdb-cluster.at b/tests/ovsdb-cluster.at >>>> index 4701272..6a13843 100644 >>>> --- a/tests/ovsdb-cluster.at >>>> +++ b/tests/ovsdb-cluster.at >>>> @@ -63,6 +63,63 @@ m4_define([OVSDB_CHECK_EXECUTION], >>>> EXECUTION_EXAMPLES >>>> >>>> >>>> +AT_BANNER([OVSDB - disconnect from cluster]) >>>> + >>>> +# When a node is disconnected from the cluster, the IDL should >>>> disconnect >>>> +# and retry even if it uses a single remote, because the remote IP can >>>> be >>>> +# a VIP on a load-balance. >>>> +AT_SETUP([OVSDB cluster - disconnect from cluster, single remote]) >>>> +AT_KEYWORDS([ovsdb server negative unix cluster disconnect]) >>>> + >>>> +schema_name=`ovsdb-tool schema-name $abs_srcdir/idltest.ovsschema` >>>> +ordinal_schema > schema >>>> +AT_CHECK([ovsdb-tool '-vPATTERN:console:%c|%p|%m' create-cluster s1.db >>>> $abs_srcdir/idltest.ovsschema unix:s1.raft], [0], [], [stderr]) >>>> +cid=`ovsdb-tool db-cid s1.db` >>>> +schema_name=`ovsdb-tool schema-name $abs_srcdir/idltest.ovsschema` >>>> +for i in `seq 2 3`; do >>>> + AT_CHECK([ovsdb-tool join-cluster s$i.db $schema_name >>>> unix:s$i.raft unix:s1.raft]) >>>> +done >>>> + >>>> +on_exit 'kill `cat *.pid`' >>>> +for i in `seq 3`; do >>>> + AT_CHECK([ovsdb-server -v -vconsole:off -vsyslog:off --detach >>>> --no-chdir --log-file=s$i.log --pidfile=s$i.pid --unixctl=s$i >>>> --remote=punix:s$i.ovsdb s$i.db]) >>>> +done >>>> +for i in `seq 3`; do >>>> + AT_CHECK([ovsdb_client_wait unix:s$i.ovsdb $schema_name connected]) >>>> +done >>>> + >>>> +AT_CHECK([ovsdb-client transact unix:s1.ovsdb '[["idltest", >>>> + {"op": "insert", >>>> + "table": "simple", >>>> + "row": {"i": 1}}]]'], [0], [ignore], [ignore]) >>>> + >>>> +# Connect to a single remote s3. Use "wait" to trigger a non-op >>>> transaction so >>>> +# that test-ovsdb will not quit. >>>> + >>>> +on_exit 'pkill test-ovsdb' >>>> +test-ovsdb '-vPATTERN:console:test-ovsdb|%c|%m' -v -t10 idl >>>> unix:s3.ovsdb '[["idltest", >>>> + {"op": "wait", >>>> + "table": "simple", >>>> + "where": [["i", "==", 1]], >>>> + "columns": ["i"], >>>> + "until": "==", >>>> + "rows": [{"i": 1}]}]]' > test-ovsdb.log 2>&1 & >>>> + >>>> +OVS_WAIT_UNTIL([grep "000: i=1" test-ovsdb.log]) >>>> + >>>> +# Shutdown the other 2 servers so that s3 is disconnected from the >>>> cluster. >>>> +for i in 2 1; do >>>> + OVS_APP_EXIT_AND_WAIT_BY_TARGET([`pwd`/s$i], [s$i.pid]) >>>> +done >>>> + >>>> +# The test-ovsdb should detect the disconnect and retry. >>>> +OVS_WAIT_UNTIL([grep disconnect test-ovsdb.log]) >>>> + >>>> +OVS_APP_EXIT_AND_WAIT_BY_TARGET([`pwd`/s3], [s3.pid]) >>>> + >>>> +AT_CLEANUP >>>> + >>>> + >>>> OVS_START_SHELL_HELPERS >>>> # ovsdb_cluster_failure_test SCHEMA_FUNC OUTPUT TRANSACTION... >>>> ovsdb_cluster_failure_test () { >>>> diff --git a/tests/test-ovsdb.c b/tests/test-ovsdb.c >>>> index 187eb28..b1a4be3 100644 >>>> --- a/tests/test-ovsdb.c >>>> +++ b/tests/test-ovsdb.c >>>> @@ -2412,6 +2412,7 @@ do_idl(struct ovs_cmdl_context *ctx) >>>> track = ((struct test_ovsdb_pvt_context *)(ctx->pvt))->track; >>>> >>>> idl = ovsdb_idl_create(ctx->argv[1], &idltest_idl_class, true, >>>> true); >>>> + ovsdb_idl_set_leader_only(idl, false); >>>> if (ctx->argc > 2) { >>>> struct stream *stream; >>>> >>>> -- >>>> 2.1.0 >>>> >>>> _______________________________________________ >>>> dev mailing list >>>> [email protected] >>>> https://mail.openvswitch.org/mailman/listinfo/ovs-dev >>>> >>> _______________________________________________ dev mailing list [email protected] https://mail.openvswitch.org/mailman/listinfo/ovs-dev
