Merge lp:~hloeung/ubuntu-repository-cache/ipv4-over-ipv6 into lp:ubuntu-repository-cache

[Haw Loeung]

Allow overriding squid to prefer IPv4 over IPv6 for requests to upstream Ubuntu Archive servers/backend

In some cases, IPv4 results in lower latency, in others it can be an issue with connectivity.

Copied from https://code.launchpad.net/~cjwatson/charms/precise/squid-forwardproxy/dns-v4-first/+merge/354316

[🤖 Canonical IS Merge Bot (canonical-is-mergebot)]

This merge proposal is being monitored by mergebot. Change the status to Approved to merge.

[Haw Loeung (hloeung)]

See Ben's finding where there appears to be network related issues between an AWS region and us - https://pastebin.canonical.com/p/GB5rKBJjsm/

Also from a unit within that same region. IPv4:

| [hloeung@aerodent ~]$ ping -c 5 54.251.159.151
| PING 54.251.159.151 (54.251.159.151) 56(84) bytes of data.
| 64 bytes from 54.251.159.151: icmp_seq=1 ttl=49 time=153 ms
| 64 bytes from 54.251.159.151: icmp_seq=2 ttl=49 time=153 ms
| 64 bytes from 54.251.159.151: icmp_seq=3 ttl=49 time=153 ms
| 64 bytes from 54.251.159.151: icmp_seq=4 ttl=49 time=153 ms
| 64 bytes from 54.251.159.151: icmp_seq=5 ttl=49 time=153 ms
|
| --- 54.251.159.151 ping statistics ---
| 5 packets transmitted, 5 received, 0% packet loss, time 4000ms
| rtt min/avg/max/mdev = 153.173/153.239/153.318/0.354 ms

Now IPv6:

| [hloeung@aerodent ~]$ ping6 -c 5 2406:da18:395:c800:5609:e9e4:9c2d:c153
| PING 2406:da18:395:c800:5609:e9e4:9c2d:c153(2406:da18:395:c800:5609:e9e4:9c2d:c153) 56 data bytes
| 64 bytes from 2406:da18:395:c800:5609:e9e4:9c2d:c153: icmp_seq=1 ttl=240 time=174 ms
| 64 bytes from 2406:da18:395:c800:5609:e9e4:9c2d:c153: icmp_seq=2 ttl=240 time=171 ms
| 64 bytes from 2406:da18:395:c800:5609:e9e4:9c2d:c153: icmp_seq=3 ttl=240 time=171 ms
| 64 bytes from 2406:da18:395:c800:5609:e9e4:9c2d:c153: icmp_seq=4 ttl=240 time=172 ms
| 64 bytes from 2406:da18:395:c800:5609:e9e4:9c2d:c153: icmp_seq=5 ttl=240 time=174 ms
|
| --- 2406:da18:395:c800:5609:e9e4:9c2d:c153 ping statistics ---
| 5 packets transmitted, 5 received, 0% packet loss, time 4004ms
| rtt min/avg/max/mdev = 171.435/172.981/174.714/1.454 ms

That's ~20ms lower via IPv4.

[Barry Price (barryprice)]

LGTM +1

review: Approve

[🤖 Canonical IS Merge Bot (canonical-is-mergebot)]

Change successfully merged at revision 378

=== modified file 'config.yaml'
--- config.yaml	2022-08-04 00:42:20 +0000
+++ config.yaml	2022-08-22 02:16:14 +0000
@@ -179,6 +179,10 @@
     description: >
       Use daily extension like YYYMMDD instead of simply adding a number
     default: True
+  squid_dns_v4_first:
+    type: boolean
+    default: false
+    description: If true, prefer IPv4 addresses for dual-stack sites.
   squid_snmp:
     type: boolean
     description: >
 
=== modified file 'lib/ubuntu_repository_cache/squid.py'
--- lib/ubuntu_repository_cache/squid.py	2022-07-27 01:20:17 +0000
+++ lib/ubuntu_repository_cache/squid.py	2022-08-22 02:16:14 +0000
@@ -190,6 +190,8 @@
     LOG('Rendering squid configuration templates')
     config = hookenv.config()
     context = {}
+    context['DNS_v4_First'] = config.get('squid_dns_v4_first')
+
     # cache_mem() needs to be called before cache_dirs() as it sets
     # unitdata.kv().get('squid-cache-disk').
     context['Cache_Memory_Config'] = cache_mem()
 
=== modified file 'templates/squid-deb-proxy/squid-deb-proxy.conf'
--- templates/squid-deb-proxy/squid-deb-proxy.conf	2022-07-25 01:16:01 +0000
+++ templates/squid-deb-proxy/squid-deb-proxy.conf	2022-08-22 02:16:14 +0000
@@ -62,6 +62,10 @@
 
 collapsed_forwarding on
 
+{% if DNS_v4_First %}
+dns_v4_first on
+{%- endif %}
+
 # pid
 pid_filename /var/run/squid-deb-proxy.pid