[WIP] provider: add boot check-in on azure and packet

[lucab]

DO NOT MERGE: neither providers have been tested on the field.

---

This adds a phone-home feature via the --check-in flag, in order to
support reporting back readiness state to the hosting infrastructure.
Initial implementation supports azure and packet.

Closes: #120

[dustymabe]

@lucab - let us know when this is ready for some eyes

[dustymabe]

FYI I found the lease files that we might be able to use to look at dhcp options if we need that information.

in intramfs:

pre-pivot:/# cat /tmp/dhclient.eth0.lease
default-duid "\000\004\326\367\325\377\250\006B\223\230\247\351\347\013\352\354\264";
lease {
  interface "eth0";
  fixed-address 10.0.2.15;
  option subnet-mask 255.255.255.0;
  option dhcp-lease-time 86400;
  option routers 10.0.2.2;
  option dhcp-message-type 5;
  option domain-name-servers 10.0.2.3;
  option dhcp-server-identifier 10.0.2.2;
  option host-name "coreos";
  renew 5 2019/01/04 04:31:00;
  rebind 5 2019/01/04 14:54:43;
  expire 5 2019/01/04 17:54:43;
}

after system bootup:

[root@coreos ~]# cat dhclient-1a3418d7-44ff-3df4-9859-acacdf110662-enp4s0.lease
...
default-duid "\000\004\204\320\313\221vI@\362\214\201\334|\310\037\013\202";
lease {
  interface "enp4s0";
  fixed-address 192.168.200.101;
  option subnet-mask 255.255.255.0;
  option routers 192.168.200.1;
  option dhcp-lease-time 86400;
  option dhcp-message-type 5;
  option domain-name-servers 192.168.200.1;
  option dhcp-server-identifier 192.168.200.1;
  option dhcp-renewal-time 39655;
  option broadcast-address 192.168.200.255;
  option dhcp-rebinding-time 72055;
  option host-name "foo";
  option domain-name "foo.net";
  renew 3 2018/12/26 14:32:39;
  rebind 4 2018/12/27 00:37:10;
  expire 4 2018/12/27 04:36:15;
}

[arithx]

I had previously played around with modifying the dhclient options in the fedora-coreos-base.yaml postprocess section (specifically /usr/lib/dracut/modules.d/40network/dhclient.conf so it happened inside dracut) to grab all options by adding request; and it did also capture option-245.

[jlebon]

OK, split out option-245 support for RHCOS/FCOS into #146.

[jlebon]

Opened a respin of this in #147. (I don't have write access so I'm not able to directly push to this same PR).

[lucab]

Closing in favor of #147.