For what I know, there're two way to limit bandwidth with k8s.

First, configure the CNI with

{
   "type": "bandwidth",
   "capabilities": {"bandwidth": true},
   "ingressRate": 10000000,
   "ingressBurst": 10000000,
   "egressRate": 10000000,
   "egressBurst": 10000000
}

And second, annotate a pod with:

annotations:
  kubernetes.io/ingress-bandwidth: 8M
  kubernetes.io/egress-bandwidth: 8M

I read through the documentations but didn't find any way to configure burst for a pod.

But the default burst is too large to make the limitation useful:

qdisc tbf 1: dev calia2333445823 root refcnt 2 rate 8Mbit burst 256Mb lat 25.0ms

And it seems when the CNI is configured with bandwidth limit, then pod annotations will not override the CNI's configure and take effect.

So how can I set a burst for just a pod?

iperf output to illustrate the burst:

server:

Accepted connection from 192.168.0.34, port 49470
[  5] local 192.168.203.129 port 1234 connected to 192.168.0.34 port 49472
[ ID] Interval           Transfer     Bandwidth
[  5]   0.00-1.00   sec   246 MBytes  2060541 Kbits/sec                  (omitted)
[  5]   1.00-2.00   sec   935 KBytes  7657 Kbits/sec                  (omitted)
[  5]   2.00-3.00   sec   933 KBytes  7645 Kbits/sec                  (omitted)
[  5]   0.00-1.00   sec   935 KBytes  7655 Kbits/sec
[  5]   1.00-2.00   sec   935 KBytes  7659 Kbits/sec
[  5]   2.00-3.00   sec   935 KBytes  7655 Kbits/sec
[  5]   3.00-4.00   sec   933 KBytes  7645 Kbits/sec
[  5]   4.00-5.00   sec   932 KBytes  7637 Kbits/sec
[  5]   5.00-6.00   sec   935 KBytes  7657 Kbits/sec
[  5]   6.00-7.00   sec   936 KBytes  7667 Kbits/sec
[  5]   7.00-8.00   sec   932 KBytes  7632 Kbits/sec
[  5]   8.00-9.00   sec   935 KBytes  7659 Kbits/sec
[  5]   9.00-10.00  sec   933 KBytes  7647 Kbits/sec
[  5]  10.00-11.00  sec   935 KBytes  7654 Kbits/sec
[  5]  11.00-11.15  sec   141 KBytes  7582 Kbits/sec
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval           Transfer     Bandwidth
[  5]   0.00-11.15  sec  0.00 Bytes  0.00 Kbits/sec                  sender
[  5]   0.00-11.15  sec  10.2 MBytes  7650 Kbits/sec                  receiver

client:

[  4] local 192.168.0.34 port 49472 connected to 192.168.203.129 port 1234
[ ID] Interval           Transfer     Bandwidth       Retr  Cwnd
[  4]   0.00-1.00   sec   247 MBytes  2073202 Kbits/sec    0    324 KBytes       (omitted)
[  4]   1.00-2.00   sec   700 KBytes  5732 Kbits/sec    0    366 KBytes       (omitted)
[  4]   2.00-3.00   sec  1.55 MBytes  13037 Kbits/sec    0    407 KBytes       (omitted)
[  4]   0.00-1.00   sec   891 KBytes  7291 Kbits/sec    0    448 KBytes
[  4]   1.00-2.00   sec   954 KBytes  7821 Kbits/sec    0    491 KBytes
[  4]   2.00-3.00   sec  1018 KBytes  8344 Kbits/sec    0    532 KBytes
[  4]   3.00-4.00   sec  1.06 MBytes  8858 Kbits/sec    0    573 KBytes
[  4]   4.00-5.00   sec  1.18 MBytes  9897 Kbits/sec    0    615 KBytes
[  4]   5.00-6.00   sec  1.24 MBytes  10433 Kbits/sec    0    656 KBytes
[  4]   6.00-7.00   sec  1.25 MBytes  10487 Kbits/sec    0    697 KBytes
[  4]   7.00-8.00   sec  1.25 MBytes  10488 Kbits/sec    0    766 KBytes
[  4]   8.00-9.00   sec  0.00 Bytes  0.00 Kbits/sec    0    899 KBytes
[  4]   9.00-10.00  sec  1.25 MBytes  10485 Kbits/sec    0   1.03 MBytes
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval           Transfer     Bandwidth       Retr
[  4]   0.00-10.00  sec  10.0 MBytes  8410 Kbits/sec    0             sender
[  4]   0.00-10.00  sec  10.2 MBytes  8532 Kbits/sec                  receiver

Environment:

• Kubernetes 1.15.7
• Calico v3.11.1
• bandwidth plugin v0.8.0
• tc iproute 4.11.0-14.el7