Collect ip route change

[AllenXu93]

Add metrics for ip route change( add / del) count.
Better print detail change (dst ip and gateway) to log.

Here is bpftrace example:

bpftrace -e 'kprobe:fib_table_insert {printf("%s/%d via %s \n", ntop(((struct fib_config *)arg2)->fc_dst), ((struct fib_config *)arg2)->fc_dst_len, ntop(((struct fib_config *)arg2)->fc_gw4) )}'

bpftrace -e 'kprobe:fib_table_delete {printf("%s/%d  \n", ntop(((struct fib_config *)arg2)->fc_dst), ((struct fib_config *)arg2)->fc_dst_len )}'

[xianlubird]

就不能讲中文

[BSWANG]

可以考虑增加个route prober，在 metrics 中默认开启，在 events 中在有需要的时候动态开启