frr: T4020: add option to define number of open file descriptors

[c-po]

Change Summary

This allows the operator to control the number of open file descriptors each daemon is allowed to start with. The current assumed value on most operating systems is 1024.

If the operator plans to run bgp with several thousands of peers then this is where we would modify FRR to allow this to happen.

set system frr descriptors <n>

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Code style update (formatting, renaming)
• Refactoring (no functional changes)
• Migration from an old Vyatta component to vyos-1x, please link to related PR inside obsoleted component
• Other (please describe):

Related Task(s)

• https://vyos.dev/T4020

Related PR(s)

• frr: T4020: document multiple per daemon config knobs vyos-documentation#1184

Component(s) name

FRR, system startup

Proposed changes

How to test

Smoketest result

[email protected]:~$ /usr/libexec/vyos/tests/smoke/cli/test_system_frr.py
test_frr_bmp (__main__.TestSystemFRR.test_frr_bmp) ... ok
test_frr_bmp_and_snmp (__main__.TestSystemFRR.test_frr_bmp_and_snmp) ... ok
test_frr_file_descriptors (__main__.TestSystemFRR.test_01frr_file_descriptors) ... ok
test_frr_irdp (__main__.TestSystemFRR.test_frr_irdp) ... ok
test_frr_snmp_add_remove (__main__.TestSystemFRR.test_frr_snmp_add_remove) ... ok
test_frr_snmp_empty (__main__.TestSystemFRR.test_frr_snmp_empty) ... ok
test_frr_snmp_multipledaemons (__main__.TestSystemFRR.test_frr_snmp_multipledaemons) ... ok

----------------------------------------------------------------------
Ran 7 tests in 21.114s

OK

Checklist:

• I have read the CONTRIBUTING document
• I have linked this PR to one or more Phabricator Task(s)
• I have run the components SMOKETESTS if applicable
• My commit headlines contain a valid Task id
• My change requires a change to the documentation
• I have updated the documentation accordingly

[c-po]

@Mergifyio backport sagitta

[mergify]

backport sagitta

✅ Backports have been created

• #2640 frr: T4020: add option to define number of open file descriptors (backport #2639) has been created for branch sagitta