| Info |
|---|
review and discussion wished! |
Overview
First of all we split between critical- and non-critical services:
| Critical Services | Non Critical Services |
|---|---|
| All GUI related stuff
|
| Failover Possible | No Failover considerations at the time |
Failover Layers
1. NMS Prime GUI
no failover at the time
2. Apache
no failover at the time
3. Database
Normal MySQL / MariaDB failover cluster with N nodes. Possible Solutions:
- MaxScale
- MariaDB Galera Cluster (not tested)
4. NMS Prime Lower Layers
We differ between the master and N x slave NMS PRIME instances. The primary instance is also running the NMS PRIME GUI. Any changes in GUI will trigger realtime changes in any config, like DHCP, TFTP, ... via Laravel Observers or Jobs. The slaves are running on separate machines without a GUI. They are rebuilding DHCP, BIND, and TFTP configfiles on a regular base (e.g. 1 hour) via cronjob. The slaves are independent from Master and they are only connected towards MariaDB SQL cluster via a SQL read-only connection. So any changes in Master will be directly distributed towards SQL cluster and later automatically fetched from the slaves.
This concept offers:
- a Master with real-time changes towards all critical configs
- redundant slaves who is independent off Master
- a redundant database with load-sharing possibility
- Load-Sharing for either DHCP, DNS and TFTP for all Modems
5. Critical Services
ISC-DHCP
Normal ISC-DHCP failover with Master-Slave Concept:
Slaves rebuild their DHCP configs by them self after a defined time (see above).
DNS / BIND
Slaves rebuild their configs by them self after a defined time (see above).
More research required, but a good starting point could be here:
- https://www.lisenet.com/2018/configure-bind-dns-servers-with-failover-and-dynamic-updates-on-centos-7/
- https://serverfault.com/questions/236096/isc-dhcpbind-with-failover-and-dynamic-updates-can-the-secondary-bind-update-d
TFTP
Cronjob at slave will rebuild all configfiles on a recurring basis (e.g. every hour). In NMS Prime this could simply be done by running
Possible Cronjob for Slaves
| Code Block | ||
|---|---|---|
| ||
php artisan nms:dhcp && systemctl restart dhcp |
| Code Block | ||
|---|---|---|
| ||
php artisan nms:configfile |
| Info |
|---|
implementing this into Laravel scheduling framework (for slaves only!) will be a advance especially if building all config files could take longer than rebuild loop, since this could be easy avoided using ->withoutOverlapping(): See: https://github.com/nmsprime/nmsprime/blob/dev/app/Console/Kernel.php#L35 I would love to see a /etc/nmsprime/env statement for a possible slave configuration, like SLAVE_CONFIG_REBUILD_INTERVALL=3600 # time in seconds |
