Re: Ridding unpredictable predictable interface names

Dear Nick,

Teh example polcy does not work for me, I have to find out how to work 
around 'with'.

So it boils down to the fact that I want to create, what you would call a 
dictionary in Pythonese.
Manually:
eth_map = { "eth1"  :  "52:54:00:40:13:98", "eth2" : "52:54:00:40:13:99", 
"eth5" : "52:54:00:40:13:9a" }
or automated:
keys_list = [ "eth1" ,  "eth2", "eth5"  ]
values_list = ["52:54:00:40:13:98", "52:54:00:40:13:99", 
"52:54:00:40:13:9a" ]
zip_iterator = zip(keys_list, values_list)
a_dictionary = dict(zip_iterator)
print(a_dictionary)

or in CFEngine if it were done manually in an array ( a data container 
would be possible too):
"eth_map[eth1]" string => "52:54:00:40:13:98";
"eth_map[eth2]" string => "52:54:00:40:13:99";
"eth_map[eth5]" string => "52:54:00:40:13:9a";

Any subsequent policy using an editing template would work.

> How do you know that mac 52:54:00:64:0d:0d should be mapped to eth2"

The policy is presented with the interface names in sorted order. 
The name of the role is 'oned', the  nics come from oned.nics_sort.

ip link fetches the mac addresses from the hypervisor.
Like this:
 "ip_link_all"                                  string => 
execresult("/usr/sbin/ip link | grep 'ether' ", useshell); 
 "ip_link_mac"                                   slist => 
string_split($(ip_link_all), "\n", 99);

So my solutions would be to build a python module to do the job. :-(

The entire policy set is below.

bundle agent test_link { 

vars: 

  "ip_link_all"                                  string => 
execresult("/usr/sbin/ip link | grep 'ether' ", useshell); 
 "ip_link_mac"                                   slist => 
string_split($(ip_link_all), "\n", 99); 
reports: 

 "$(this.bundle) nics_sort: $(oned.nics_sort)"; 
 "$(this.bundle) ip link all: $(ip_link_all)"; 
 "$(this.bundle) ip link: $(ip_link_mac)"; 

}

bundle agent oned { 
  
vars: 

 "nic[support]"                      string => "eth1"; 
 "nic[admin]"                        string => "eth2"; 
 "nic[life]"                         string => "eth5"; 

 "nics"                               slist => getvalues("nic"); 
 "nics_sort"                          slist => sort("nics", lex); 
 "nics_string"                       string => join(",", "nics_sort"); 

reports: 

  "$(this.bundle) nics_sort: $(nics_sort)"; 
  "$(this.bundle) nics: $(nics)"; 

}

body common control { 
 bundlesequence => { "oned", "test_link", }; 
 inputs         => { "/var/cfengine/inputs/lib/3.7/stdlib.cf", 
                     "/root/classify.cf", 
                     "/root/oned.cf", }; 
}
On Tuesday, 12 October 2021 at 17:09:55 UTC+2 Nick Anderson wrote:

> Martin Simons <[email protected]> writes: 
>
> I have two lists that I want to pair, like this: macs slist => { 
>> '52:54:00:64:0d:0c', '52:54:00:64:0d:0d ' }; Interfaces slist => { 'eth1', 
>> 'eth2' }; I want an array or container like this: persistent[eth1] string 
>> => '52:54:00:64:0d:0c'; persistent[eth2] string => '52:54:00:64:0d:0d'; I 
>> looked over the functions again and again but I do not get it right. How do 
>> I pair those into an array? 
>>
> I don't think that there are any native functions that deal with mapping 
> mac addresses to interface names, only interface names and IP addresses (
> iprange() 
> <https://docs.cfengine.com/docs/3.18/reference-functions-iprange.html>). 
> sys.hardware_mac 
> <https://docs.cfengine.com/docs/3.18/reference-special-variables-sys.html#sys-hardware_mac-interface_name> 
> maps mac addresses to interface names. 
> Listing 1: Example Policy
>
> bundle agent __main__{
>   reports:
>     "$(with)" with => storejson( "sys.hardware_mac" );}
>
>
> R: {
>   "docker0": "02:42:3f:46:7c:ce",
>   "enx5cff35c6864b": "5c:ff:35:c6:86:4b",
>   "tun0": "00:00:00:00:00:00",
>   "vboxnet0": "0a:00:27:00:00:00"
> }
>
> Are you able to use that directly? 
>
> If not, you need some way to link the mac address to the name, it's not 
> clear to me from above what that mapping data looks like. How do you know 
> that mac 52:54:00:64:0d:0d should be mapped to eth2? 
>

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