[frr] Reduce Calls to SONiC Cfggen

[tahmed-dev]

Calls to sonic-cfggen is CPU expensive. This PR reduces calls to
sonic-cfggen to two calls during startup when starting frr service.

singed-off-by: Tamer Ahmed tamer.ahmed@microsoft.com

- Why I did it
Reduce time required when invoking frr

- How I did it
Used template batch mode to batch together three calls into one call to sonic-cfggen

- How to verify it

root@str-s6000-acs-14:/# time ./docker_init_old.sh

real	0m12.873s
user	0m10.486s
sys	0m1.624s
root@str-s6000-acs-14:/# time ./docker_init_new.sh

real	0m3.572s
user	0m2.927s
sys	0m0.499s
root@str-s6000-acs-14:/# diff /etc/supervisor/conf.d/supervisord.conf.old /etc/supervisor/conf.d/supervisord.conf.new 
root@str-s6000-acs-14:/# diff /etc/frr/bgpd.conf.old /etc/frr/bgpd.conf.new 
root@str-s6000-acs-14:/# diff /etc/frr/zebra.conf.old /etc/frr/zebra.conf.new 
root@str-s6000-acs-14:/# diff /etc/frr/staticd.conf.old /etc/frr/staticd.conf.new 
root@str-s6000-acs-14:/# diff /usr/sbin/bgp-isolate.old /usr/sbin/bgp-isolate.new 
root@str-s6000-acs-14:/# diff /usr/sbin/bgp-unisolate.old /usr/sbin/bgp-unisolate.new 
root@str-s6000-acs-14:/# 

Update for the case when just once call is placed t sonic-cfggen:

root@str-s6000-acs-14:/# time ./docker_init_old.sh
CONFIG_TYPE=separated

real	0m12.117s
user	0m9.803s
sys	0m1.523s
root@str-s6000-acs-14:/# time ./docker_init_new.sh
CONFIG_TYPE=separated

real	0m2.598s
user	0m1.986s
sys	0m0.383s
root@str-s6000-acs-14:/# diff /etc/supervisor/conf.d/supervisord.conf.old /etc/supervisor/conf.d/supervisord.conf.new 
root@str-s6000-acs-14:/# diff /etc/frr/bgpd.conf.old /etc/frr/bgpd.conf.new 
root@str-s6000-acs-14:/# diff /etc/frr/zebra.conf.old /etc/frr/zebra.conf.new
root@str-s6000-acs-14:/# diff /etc/frr/staticd.conf.old /etc/frr/staticd.conf.new
root@str-s6000-acs-14:/# diff /usr/sbin/bgp-isolate.old /usr/sbin/bgp-isolate.new
root@str-s6000-acs-14:/# diff /usr/sbin/bgp-unisolate.old /usr/sbin/bgp-unisolate.new
root@str-s6000-acs-14:/# 

- Which release branch to backport (provide reason below if selected)

• 201811
• 201911
• 202006

[lguohan]

@pavel-shirshov to review

[pavel-shirshov]

I have couple questions

[pavel-shirshov]

Why do we need frr_vars?
Also why you have only source after -t?

[tahmed-dev]

the frr_vars is a template file that pulls information about the config_type. This variable later decides if BGP service is integrate into vtysh or not. The content of the frr_vars is retreiving single variable for now:
{{ DEVICE_METADATA["localhost"]["docker_routing_config_mode"] }}
Lack of destination after the first argument, means this template is going to be rendered to stdout.

In comparison, commit a5f2de does docker initialization with two calls to cfggen. The time difference between the two approaches is about 1sec.

[pavel-shirshov]

LGTM