Upgrade etcd to version 3.4

[lazzarello]

Changes the default version of etcd to 3.4 and forces API version 2 for Flanneld.

[ktsakalozos]

Thank you for this PR @lazzarello Please find some comments inline.

[lazzarello]

@ktsakalozos trying to build a version with changes to the install hook but I'm getting a false positive error. I'm new to the snapcraft build process so apologies in advance if I'm missing something obvious.

lee@henry:~/src/microk8s$ snapcraft --use-lxd --debug
The LXD provider is offered as a technology preview for early adopters.
The command line interface, container names or lifecycle handling may change in upcoming releases.
Launching a container.
/snap/snapcraft/3440/lib/python3.5/site-packages/pylxd/models/_model.py:116: UserWarning: Attempted to set unknown attribute "type" on instance of "Container"
  key, self.__class__.__name__
Waiting for cloud-init
...............
status: done
Skipping pull cluster-agent (already ran)
Skipping pull libnftnl (already ran)
Skipping pull iptables (already ran)
Skipping pull containerd (already ran)
Skipping pull libnvidia (already ran)
Skipping pull libnvidia-tools (already ran)
Skipping pull microk8s (already ran)
Skipping pull nvidia-runtime (already ran)
Skipping pull nvidia-runtime-hook (already ran)
Skipping build cluster-agent (already ran)
Skipping build libnftnl (already ran)
Skipping build iptables (already ran)
Skipping build containerd (already ran)
Skipping build libnvidia (already ran)
Skipping build libnvidia-tools (already ran)
Updating build step for microk8s ('pull' step changed)
Failed to copy '/root/parts/microk8s/src/.git/objects/48/61d635f0a34943090ffefea1a22efa41c9cd72': no such file or directory.
Check the path and try again.
snapcraft-microk8s # ls -l /root/parts/microk8s/src/.git/objects/48/61d635f0a34943090ffefea1a22efa41c9cd72
-r--r--r-- 1 root root 172 Jan  9 22:42 /root/parts/microk8s/src/.git/objects/48/61d635f0a34943090ffefea1a22efa41c9cd72

[balchua]

@lazzarello what i do if i get this is to do a clean first.
snapcraft clean after that you can do the normal build.
snapcraft --use-lxd
I tend to get this occasionally, i think when i switch branches.

[balchua]

The check ideally should be in the configure hook instead of install.

There are certain helper functions in the util.sh where you can add or remove options.
To add "options"

• refresh_opt_in_config <option name> <value> <file>

In your case it will look like this refresh_opt_in_config enable-v2 true etcd

Give it a try.

[lazzarello]

Thanks for the comments. I'll follow up on this but it's got a little lower in priority on my side.

update got some more time. I'll take this one over the finish line.

[lazzarello]

@ktsakalozos lemme know if you can get to a review. CI build tests pass now.

[ktsakalozos]

LGTM +1 Thank you @lazzarello