[ovs-dev] [branch2.12] ovn-northd: Add the option to pause and resume
Justin Pettit
jpettit at ovn.org
Thu Aug 8 17:07:41 UTC 2019
Thanks. I merged this into branch-2.12.
--Justin
> On Jul 31, 2019, at 11:31 PM, nusiddiq at redhat.com wrote:
>
> From: Numan Siddique <nusiddiq at redhat.com>
>
> This patch adds 3 unixctl socket comments - pause, resume and is-paused.
>
> Usage: ovs-appctl -t ovn-northd pause/resume/is-paused
>
> This feature will be useful if the CMS wants to
> - deploy OVN DB servers in active/passive mode and
> - run ovn-northd on all these nodes and use unix ctl sockets to
> connect to the local OVN DB servers.
>
> On the nodes where OVN Db ovsdb-servers are in passive mode, the local ovn-northds
> will process the DB changes and compute logical flows to be thrown out later,
> because write transactions are not allowed by these ovsdb-servers. It results in
> unncessary CPU usage.
>
> With these commands, CMS can pause ovn-northd on these node. A node
> which becomes master, can resume the ovn-northd.
>
> One use case is to use this feature in ovn-kubernetes with the above deployment model.
>
> Acked-by: Mark Michelson <mmichels at redhat.com>
> Acked-by: Dumitru Ceara <dceara at redhat.com>
> Signed-off-by: Numan Siddique <nusiddiq at redhat.com>
> (cherry picked from ovn commit 03894e3e2374069c06ae97dafb24fb4fcb8c8e61)
> ---
> ovn/northd/ovn-northd.8.xml | 48 ++++++++++++++++
> ovn/northd/ovn-northd.c | 111 +++++++++++++++++++++++++++---------
> tests/ovn-northd.at | 38 ++++++++++++
> 3 files changed, 169 insertions(+), 28 deletions(-)
>
> diff --git a/ovn/northd/ovn-northd.8.xml b/ovn/northd/ovn-northd.8.xml
> index d2267de0e..1d0243656 100644
> --- a/ovn/northd/ovn-northd.8.xml
> +++ b/ovn/northd/ovn-northd.8.xml
> @@ -70,6 +70,23 @@
> <dd>
> Causes <code>ovn-northd</code> to gracefully terminate.
> </dd>
> +
> + <dt><code>pause</code></dt>
> + <dd>
> + Pauses the ovn-northd operation from processing any Northbound and
> + Southbound database changes.
> + </dd>
> +
> + <dt><code>resume</code></dt>
> + <dd>
> + Resumes the ovn-northd operation to process Northbound and
> + Southbound database contents and generate logical flows.
> + </dd>
> +
> + <dt><code>is-paused</code></dt>
> + <dd>
> + Returns "true" if ovn-northd is currently paused, "false" otherwise.
> + </dd>
> </dl>
> </p>
>
> @@ -82,6 +99,37 @@
> of <code>ovn-northd</code> will automatically take over.
> </p>
>
> + <h2> Active-Standby with multiple OVN DB servers</h2>
> + <p>
> + You may run multiple OVN DB servers in an OVN deployment with:
> + <ul>
> + <li>
> + OVN DB servers deployed in active/passive mode with one active
> + and multiple passive ovsdb-servers.
> + </li>
> +
> + <li>
> + <code>ovn-northd</code> also deployed on all these nodes,
> + using unix ctl sockets to connect to the local OVN DB servers.
> + </li>
> + </ul>
> + </p>
> +
> + <p>
> + In such deployments, the ovn-northds on the passive nodes will process
> + the DB changes and compute logical flows to be thrown out later,
> + because write transactions are not allowed by the passive ovsdb-servers.
> + It results in unnecessary CPU usage.
> + </p>
> +
> + <p>
> + With the help of runtime management command <code>pause</code>, you can
> + pause <code>ovn-northd</code> on these nodes. When a passive node
> + becomes master, you can use the runtime management command
> + <code>resume</code> to resume the <code>ovn-northd</code> to process the
> + DB changes.
> + </p>
> +
> <h1>Logical Flow Table Structure</h1>
>
> <p>
> diff --git a/ovn/northd/ovn-northd.c b/ovn/northd/ovn-northd.c
> index eb6c47cad..2e96e9cf4 100644
> --- a/ovn/northd/ovn-northd.c
> +++ b/ovn/northd/ovn-northd.c
> @@ -52,6 +52,9 @@
> VLOG_DEFINE_THIS_MODULE(ovn_northd);
>
> static unixctl_cb_func ovn_northd_exit;
> +static unixctl_cb_func ovn_northd_pause;
> +static unixctl_cb_func ovn_northd_resume;
> +static unixctl_cb_func ovn_northd_is_paused;
>
> struct northd_context {
> struct ovsdb_idl *ovnnb_idl;
> @@ -9182,6 +9185,7 @@ main(int argc, char *argv[])
> struct unixctl_server *unixctl;
> int retval;
> bool exiting;
> + bool paused;
>
> fatal_ignore_sigpipe();
> ovs_cmdl_proctitle_init(argc, argv);
> @@ -9196,6 +9200,10 @@ main(int argc, char *argv[])
> exit(EXIT_FAILURE);
> }
> unixctl_command_register("exit", "", 0, 0, ovn_northd_exit, &exiting);
> + unixctl_command_register("pause", "", 0, 0, ovn_northd_pause, &paused);
> + unixctl_command_register("resume", "", 0, 0, ovn_northd_resume, &paused);
> + unixctl_command_register("is-paused", "", 0, 0, ovn_northd_is_paused,
> + &paused);
>
> daemonize_complete();
>
> @@ -9384,34 +9392,51 @@ main(int argc, char *argv[])
>
> /* Main loop. */
> exiting = false;
> + paused = false;
> while (!exiting) {
> - struct northd_context ctx = {
> - .ovnnb_idl = ovnnb_idl_loop.idl,
> - .ovnnb_txn = ovsdb_idl_loop_run(&ovnnb_idl_loop),
> - .ovnsb_idl = ovnsb_idl_loop.idl,
> - .ovnsb_txn = ovsdb_idl_loop_run(&ovnsb_idl_loop),
> - .sbrec_ha_chassis_grp_by_name = sbrec_ha_chassis_grp_by_name,
> - .sbrec_mcast_group_by_name_dp = sbrec_mcast_group_by_name_dp,
> - .sbrec_ip_mcast_by_dp = sbrec_ip_mcast_by_dp,
> - };
> -
> - if (!had_lock && ovsdb_idl_has_lock(ovnsb_idl_loop.idl)) {
> - VLOG_INFO("ovn-northd lock acquired. "
> - "This ovn-northd instance is now active.");
> - had_lock = true;
> - } else if (had_lock && !ovsdb_idl_has_lock(ovnsb_idl_loop.idl)) {
> - VLOG_INFO("ovn-northd lock lost. "
> - "This ovn-northd instance is now on standby.");
> - had_lock = false;
> - }
> -
> - if (ovsdb_idl_has_lock(ovnsb_idl_loop.idl)) {
> - ovn_db_run(&ctx, sbrec_chassis_by_name, &ovnsb_idl_loop);
> - if (ctx.ovnsb_txn) {
> - check_and_add_supported_dhcp_opts_to_sb_db(&ctx);
> - check_and_add_supported_dhcpv6_opts_to_sb_db(&ctx);
> - check_and_update_rbac(&ctx);
> + if (!paused) {
> + struct northd_context ctx = {
> + .ovnnb_idl = ovnnb_idl_loop.idl,
> + .ovnnb_txn = ovsdb_idl_loop_run(&ovnnb_idl_loop),
> + .ovnsb_idl = ovnsb_idl_loop.idl,
> + .ovnsb_txn = ovsdb_idl_loop_run(&ovnsb_idl_loop),
> + .sbrec_ha_chassis_grp_by_name = sbrec_ha_chassis_grp_by_name,
> + .sbrec_mcast_group_by_name_dp = sbrec_mcast_group_by_name_dp,
> + .sbrec_ip_mcast_by_dp = sbrec_ip_mcast_by_dp,
> + };
> +
> + if (!had_lock && ovsdb_idl_has_lock(ovnsb_idl_loop.idl)) {
> + VLOG_INFO("ovn-northd lock acquired. "
> + "This ovn-northd instance is now active.");
> + had_lock = true;
> + } else if (had_lock && !ovsdb_idl_has_lock(ovnsb_idl_loop.idl)) {
> + VLOG_INFO("ovn-northd lock lost. "
> + "This ovn-northd instance is now on standby.");
> + had_lock = false;
> }
> +
> + if (ovsdb_idl_has_lock(ovnsb_idl_loop.idl)) {
> + ovn_db_run(&ctx, sbrec_chassis_by_name, &ovnsb_idl_loop);
> + if (ctx.ovnsb_txn) {
> + check_and_add_supported_dhcp_opts_to_sb_db(&ctx);
> + check_and_add_supported_dhcpv6_opts_to_sb_db(&ctx);
> + check_and_update_rbac(&ctx);
> + }
> + }
> +
> + ovsdb_idl_loop_commit_and_wait(&ovnnb_idl_loop);
> + ovsdb_idl_loop_commit_and_wait(&ovnsb_idl_loop);
> + } else {
> + /* ovn-northd is paused
> + * - we still want to handle any db updates and update the
> + * local IDL. Otherwise, when it is resumed, the local IDL
> + * copy will be out of sync.
> + * - but we don't want to create any txns.
> + * */
> + ovsdb_idl_run(ovnnb_idl_loop.idl);
> + ovsdb_idl_run(ovnsb_idl_loop.idl);
> + ovsdb_idl_wait(ovnnb_idl_loop.idl);
> + ovsdb_idl_wait(ovnsb_idl_loop.idl);
> }
>
> unixctl_server_run(unixctl);
> @@ -9419,8 +9444,6 @@ main(int argc, char *argv[])
> if (exiting) {
> poll_immediate_wake();
> }
> - ovsdb_idl_loop_commit_and_wait(&ovnnb_idl_loop);
> - ovsdb_idl_loop_commit_and_wait(&ovnsb_idl_loop);
>
> poll_block();
> if (should_service_stop()) {
> @@ -9445,3 +9468,35 @@ ovn_northd_exit(struct unixctl_conn *conn, int argc OVS_UNUSED,
>
> unixctl_command_reply(conn, NULL);
> }
> +
> +static void
> +ovn_northd_pause(struct unixctl_conn *conn, int argc OVS_UNUSED,
> + const char *argv[] OVS_UNUSED, void *pause_)
> +{
> + bool *pause = pause_;
> + *pause = true;
> +
> + unixctl_command_reply(conn, NULL);
> +}
> +
> +static void
> +ovn_northd_resume(struct unixctl_conn *conn, int argc OVS_UNUSED,
> + const char *argv[] OVS_UNUSED, void *pause_)
> +{
> + bool *pause = pause_;
> + *pause = false;
> +
> + unixctl_command_reply(conn, NULL);
> +}
> +
> +static void
> +ovn_northd_is_paused(struct unixctl_conn *conn, int argc OVS_UNUSED,
> + const char *argv[] OVS_UNUSED, void *paused_)
> +{
> + bool *paused = paused_;
> + if (*paused) {
> + unixctl_command_reply(conn, "true");
> + } else {
> + unixctl_command_reply(conn, "false");
> + }
> +}
> diff --git a/tests/ovn-northd.at b/tests/ovn-northd.at
> index 62e58fd0e..0dea04edc 100644
> --- a/tests/ovn-northd.at
> +++ b/tests/ovn-northd.at
> @@ -898,3 +898,41 @@ as northd
> OVS_APP_EXIT_AND_WAIT([ovn-northd])
>
> AT_CLEANUP
> +
> +AT_SETUP([ovn -- ovn-northd pause and resume])
> +AT_SKIP_IF([test $HAVE_PYTHON = no])
> +ovn_start
> +
> +AT_CHECK([test xfalse = x`as northd ovs-appctl -t ovn-northd is-paused`])
> +
> +ovn-nbctl ls-add sw0
> +
> +OVS_WAIT_UNTIL([
> + ovn-sbctl lflow-list sw0
> + test 0 = $?])
> +
> +ovn-nbctl ls-del sw0
> +OVS_WAIT_UNTIL([
> + ovn-sbctl lflow-list sw0
> + test 1 = $?])
> +
> +# Now pause the ovn-northd
> +as northd ovs-appctl -t ovn-northd pause
> +AT_CHECK([test xtrue = x`as northd ovs-appctl -t ovn-northd is-paused`])
> +
> +ovn-nbctl ls-add sw0
> +
> +# There should be no logical flows for sw0 datapath.
> +OVS_WAIT_UNTIL([
> + ovn-sbctl lflow-list sw0
> + test 1 = $?])
> +
> +# Now resume ovn-northd
> +as northd ovs-appctl -t ovn-northd resume
> +AT_CHECK([test xfalse = x`as northd ovs-appctl -t ovn-northd is-paused`])
> +
> +OVS_WAIT_UNTIL([
> + ovn-sbctl lflow-list sw0
> + test 0 = $?])
> +
> +AT_CLEANUP
> --
> 2.21.0
>
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