Kubespray: define the network-interface to use rather than each IP

[ant31]

To bind service we use :
the default order is :
ip | default_interface.ipv4

• ip: is manually set for each node, it is usually the private ip of the host
• default.ipv4: is gathered by ansible and it often the public ip.

Instead of setting an ip for each node we can set an interface and get the ip from ansible fact:

node_network_iface: eth1

and the new order would be :
ip | network[node_network_iface].ipv4 | default_interface.ipv4

[mattymo]

I'm in favor of a new fact for access_ip and ip to reduce lines like this:

{{ hostvars[host]['access_ip'] | default(hostvars[host]['ip'] | default(hostvars[host]['ansible_default_ipv4']['address'])) }}

Or do you intend to make it extended so that access_ip will look like this instead?

{{ hostvars[host]['access_ip'] | default(hostvars[host]['ip'] | default(hostvars[host]['node_network_iface']['address'] | default(hostvars[host]['ansible_default_ipv4']['address']))) }}

[apcension]

What's the background of having two facts, ip and access_ip?

Can we just use a singular entity that we pass in via the inventory?

[mattymo]

@apcension cloud instances often have an internal IP and a public IP. For example, node1 has ip 10.104.0.5, but its routable public IP is 44.11.22.3. This is optional for users, but I have a couple of use cases where it's necessary.

[bogdando]

The ip implies internal network, access_ip implies the public network endpoints and ansible_ssh_host stands for admin (ansible ssh access), correct? I liked this abstraction, why do we want to stick with direct interface names?

[ant31]

@bogdando it reduces the settings.
Most of the time the private interface is always the same.
Then instead of get to know/enter the private ip of all the nodes we can configure which interface to fetch the ip.

from :

node1 ansible_ssh_host=44.11.22.3 ip=10.92.4.5
node2 ansible_ssh_host=44.11.22.4 ip=10.91.13.48
node3 ansible_ssh_host=44.11.22.5 ip=10.92.49.138

to

node1 ansible_ssh_host=44.11.22.3
node2 ansible_ssh_host=44.11.22.4
node3 ansible_ssh_host=44.11.22.5
[all:vars]
network_interface=eth1

[ant31]

@apcension
ansible_ssh_host -> ip to connect the host
ip -> ip you want to use to bind services
access_ip -> in some cases (for example multi-az), you want to bind to the 'private_ip' but access via the public one.

[mattymo]

We can just set the default interface name to ansible_default_ipv4 and then let the user set it if he or she wishes.

[mattymo]

After some considerations, I decided that it is going to look incredibly ugly if we make a format that doesn't break fact caching. We should convert the host ip selection to a custom fact that we deploy on all hosts. Any thoughts?

[onixie]

hi @mattymo
Is there any progress on this issue?

I'm facing a similar case that I want to specify interface.
The default ansible_default_ipv4 points to the unexpected interface.

[ant31]

set the default interface name to ansible_default_ipv4

how to do that ?

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