I'm not sure what to make of this discussion. Han, will you update the patch to update the documentation? It seems that, at a minimum, that is the conclusion here.
On Wed, Aug 14, 2019 at 06:40:45PM -0700, aginwala wrote: > 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 _______________________________________________ dev mailing list [email protected] https://mail.openvswitch.org/mailman/listinfo/ovs-dev
