ipv6 static routes configured for eni are incorrect

[raphael.glon]

static routes rendered for eni configuration are not correct

example:

config:
    - mac_address: aa:12:bc:34:ee:ac
      name: eno3
      subnets:
      - address: fd00::12/64
        dns_nameservers: ['fd00:2::15']
        gateway: fd00::1
        ipv6: true
        routes:
        - netmask: '32'
          network: 'fd00:12::'
          gateway: fd00::2
        type: static
      type: physical
    version: 1

Cloud init renders:
"""
auto lo
iface lo inet loopback

auto eno3
iface eno3 inet6 static
    address fd00::12/64
    dns-nameservers fd00:2::15
    gateway fd00::1
    post-up route add -net fd00:12:: netmask 32 gw fd00::2 || true
    pre-down route del -net fd00:12:: netmask 32 gw fd00::2 || true
"""

but the post-up/pre-down commands are incorrect (tested, even when replacing the 32 netmask by ffff:ffff::)

One working version
"""
    post-up route add -A inet6 fd00:12::/32 gw fd00::2 || true
    pre-down route del -A inet6 fd00:12::/32 gw fd00::2 || true
"""

Fix proposal available here
https://code.launchpad.net/~raphael-glon/cloud-init/+git/cloud-init/+merge/363970

[Server Team CI bot (server-team-bot)]

This bug is fixed with commit 22e33293 to cloud-init on branch master.
To view that commit see the following URL:
https://git.launchpad.net/cloud-init/commit/?id=22e33293

[Chad Smith (chad.smith)]

This bug is believed to be fixed in cloud-init in version 19.1. If this is still a problem for you, please make a comment and set the state back to New

Thank you.

[James Falcon (falcojr)]

Tracked in Github Issues as https://github.com/canonical/cloud-init/issues/3348