[cfggen] Allow sku with no alias mapping and minigraph with no png

[taoyl-ms]

No description provided.

[lguohan]

                neighbors[endport] = {'name': startdevice, 'port': startport}

this name is not mapped to alias, it seems it is not consistent.

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Refers to: src/sonic-config-engine/minigraph.py:68 in e4319eb. [](commit_id = e4319eb, deletion_comment = False)

[lguohan]

I do not know if it worth to do port alias mapping in the minigraph, another way to do is to do it in the template, it is like only doing this port alias mapping when needed. @jleveque , any thoughts on this?

[taoyl-ms]

I think it makes more sense to do port mapping in minigraph since it is a pure minigraph concept and sonic components shouldn't really care about it.
After minigraph.py finished the mapping, everything on the machine (except snmp and CLI tools) will only need to deal with sonic interfaces name, which is a neater contract.

[jleveque]

I know we discussed making the alias mapping an extra layer, outside the minigraph, but I'm still a bit too junior on the project to know all of the potential needs for aliases throughout SONiC. I think it makes sense to be a function of sonic-config-engine nevertheless, whether it's done as part of the minigraph parsing or as another layer afterward.

[lguohan]

so, let's do more consistently and fix the neighbor port name as well?

[lguohan]

is this really about no png or only for the console, mgmt information in the device section? should we modify the title accordingly?

[taoyl-ms]

It's really about no png. In the previous version if there is no png session sonic-cfggen will crash upon reading minigraph. In the new version it won't crash, but just ignore the corresponding data. (So if your template does not depend on png data it can still work with a minigraph without png)

[taoyl-ms]

I'll take a look on the neighbor port part.

[taoyl-ms]

@lguohan Please review commit 2.