iptables-legacy for Raspian Buster

Fixes #24: Add more clarity around inventory file creation.

Fixes #26: Ignore failure in service task in reset playbook so it can run.

Fixes #17: Fix is changed check so reboot task doesn't fail.

Fixes #22: Set proper file mode using an octal.

Fixes #16: Add nocows = true.

Fixes #15: Update default k3s version.

Add /usr/local/bin to secure_path, Add br_netfilter on centos

Signed-off-by: Julien DOCHE <julien.doche@gmail.com>

Fix systemd TimeoutStartSec

Fixes #3: Fix linting issues, add ansible-lint and yamllint configuration.

fix typo for master_ip

Fixes #11: Add Apache 2.0 LICENSE file.

Fixes #4: Use k3s_cluster (no dashes) for inventory name.

Fixes #5: Use Ansible's reboot module instead of reboot command.

Fixes #9: Make sure both iptables and ip6tables are configured correctly.

Signed-off-by: Julien DOCHE <julien.doche@gmail.com>

[systemd] Add value to LimitNOFILE due to performance problems

Fixes #1729: Use 'is changed' instead of non-existent changed filter.

When k3s is installed on an OS with default high ulimits, performance
issues can be observed. This was discovered on CoreOS where the default
value is 1073741816. Symptoms include very slow file operations such
as installing a Rook/Ceph cluster will take ~6 hours instead of ~10 minutes.

A google search for 'container LimitNOFILE' will show that most major
projects set this already, including the (unused) containerd systemd unit
found in this repository at /vendor/github.com/containerd/containerd/containerd.service

k3OS is not affected becuasse the default there is already 1048576.

See description in coreos/fedora-coreos-tracker#329

Signed-off-by: Julien DOCHE <julien.doche@gmail.com>