Sometimes network components are compute node-specific. Sometimes such
components are replicated, almost identically, for multiple nodes
in the cluster.
One such example is the case of Kubernetes NodePort services which
translate (in the ovn-kubernetes case) to Load_Balancer
objects being applied to each and every node's logical gateway router.
These load balancers are almost identical, the main difference being
the fact that they use different VIPs (the node's IP).
With the current OVN load balancer design, this becomes a problem at
scale because the number of load balancers that must be configured is
N x M (N nodes times M services).
This series proposes a new concept in OVN: virtual network component
templates. The goal of the templates is to help reduce resource
consumption in the OVN central components in specific cases like the one
described above.
To achieve that, the CMS will instead configure a "templated" load
balancer for every service and apply that single template record to
the cluster-wide load balancer group. This template is then
instantiated differently on different compute nodes. This translation
is controlled through per-chassis "template variables" configured by
the CMS in the new NB.Template_Var table.
A syntetic benchmark simulating what an OpenShift router (using Node
Port services) scale test would do shows the following preliminary
results:
A. 120 node, 2K NodePort services:
- before:
- Southbound DB size on disk (compacted): ~385MB
- Southbound DB memory usage (RSS): ~3GB
- Southbound DB logical flows: 720K
- after:
- Southbound DB size on disk (compacted): ~100MB
- Southbound DB memory usage (RSS): ~250MB
- Southbound DB logical flows: 6K
B. 250 node, 2K NodePort services:
- after (didn't run the "before" test as it was taking way too long):
- Southbound DB size on disk (compacted): ~155MB
- Southbound DB memory usage (RSS): ~760MB
- Southbound DB logical flows: 6K
The series is sent as RFC because there's still the need to add
some template specific unit tests and the "ovn-nbctl lb-*" helper
utilities need to be adapted to support templated load balancers.
With these two items addressed the code is self can likely qualify
for acceptance as a new feature in the upcoming release.
There also exists a more extensive TODO list (also listed in the commit
log of every patch in the series for now) but these are mainly load
balancer related functionalities that are not yet implemented for
templated load balancers but can definitely be implemented as follow ups:
- No support for LB health check if the LB is templated.
- No support for VIP ARP responder if the LB is templated.
- No support for routed VIPs if the LB is templated.
- Figure out a way to deal with templates in ovn-trace
- Determine if we need to allow Template_Var to match against chassis
hostname or other IDs.
- Make ofctrl_inject_pkt() work with template_vars.
- Make test-ovn work with template_vars.
A basic example of how to configure a templated load balancer follows:
$ ovn-nbctl create load_balancer name=lb-test \
protocol=tcp options:template=true \
vips:\"^vip:4200\"="^backends"
$ ovn-nbctl ls-add ls
$ ovn-nbctl ls-lb-add ls lb-test
# Instantiate the load balancer on chassis-1
$ ovn-nbctl create template_var name=vip value=80.80.80.1 chassis=chassis-1
$ ovn-nbctl create template_var name=backends value='"42.42.42.1:1000"'
chassis=chassis-1
# Instantiate the load balancer on chassis-2
$ ovn-nbctl create template_var name=vip value=80.80.80.2 chassis=chassis-2
$ ovn-nbctl create template_var name=backends value='"42.42.42.2:1000"'
chassis=chassis-2
Dumitru Ceara (5):
Add NB and SB Template_Var tables.
controller: Add support for templated actions and matches.
controller: Make resource references more generic.
lb: Support using templates.
controller: Add Template_Var <- LB references.
controller/lflow.c | 248 ++++++++++++++++++++++++--------
controller/lflow.h | 98 +++++++------
controller/ofctrl.c | 9 +-
controller/ofctrl.h | 3 +-
controller/ovn-controller.c | 277 ++++++++++++++++++++++++++++++++++--
include/ovn/expr.h | 4 +-
include/ovn/lex.h | 14 +-
lib/actions.c | 9 +-
lib/expr.c | 14 +-
lib/lb.c | 201 ++++++++++++++++++++++----
lib/lb.h | 36 +++--
lib/lex.c | 55 +++++++
northd/northd.c | 64 +++++----
tests/ovn.at | 2 +-
tests/test-ovn.c | 16 ++-
utilities/ovn-trace.c | 26 +++-
16 files changed, 869 insertions(+), 207 deletions(-)
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