DigitalOcean: use meta-data for network configruation

On DigitalOcean, Network information is provided via Meta-data.
It changes the datasource to be a local datasource, meaning it
will run before fallback networking is configured.

The advantage of that is that before networking is configured it
can bring up a network device with ipv4 link-local and hit the
metadata service that lives at 169.254.169.254 to find its networking
configuration.  It then takes down the link local address and lets
cloud-init configure networking.

The configuring of a network device to go looking for a metadata
service is gated by a check of data in the smbios.  This guarantees
that the code will not run on another system.

1 files changed, 218 insertions, 0 deletions

diff --git a/cloudinit/sources/helpers/digitalocean.py b/cloudinit/sources/helpers/digitalocean.py
new file mode 100644
index 00000000..b0a721c2
--- /dev/null
+++ b/cloudinit/sources/helpers/digitalocean.py
@@ -0,0 +1,218 @@
+# vi: ts=4 expandtab
+#
+#    Author: Ben Howard  <bh@digitalocean.com>
+
+#    This program is free software: you can redistribute it and/or modify
+#    it under the terms of the GNU General Public License version 3, as
+#    published by the Free Software Foundation.
+#
+#    This program is distributed in the hope that it will be useful,
+#    but WITHOUT ANY WARRANTY; without even the implied warranty of
+#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+#    GNU General Public License for more details.
+#
+#    You should have received a copy of the GNU General Public License
+#    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+import json
+import random
+
+from cloudinit import log as logging
+from cloudinit import net as cloudnet
+from cloudinit import url_helper
+from cloudinit import util
+
+NIC_MAP = {'public': 'eth0', 'private': 'eth1'}
+
+LOG = logging.getLogger(__name__)
+
+
+def assign_ipv4_link_local(nic=None):
+    """Bring up NIC using an address using link-local (ip4LL) IPs. On
+       DigitalOcean, the link-local domain is per-droplet routed, so there
+       is no risk of collisions. However, to be more safe, the ip4LL
+       address is random.
+    """
+
+    if not nic:
+        for cdev in sorted(cloudnet.get_devicelist()):
+            if cloudnet.is_physical(cdev):
+                nic = cdev
+                LOG.debug("assigned nic '%s' for link-local discovery", nic)
+                break
+
+    if not nic:
+        raise RuntimeError("unable to find interfaces to access the"
+                           "meta-data server. This droplet is broken.")
+
+    addr = "169.254.{0}.{1}/16".format(random.randint(1, 168),
+                                       random.randint(0, 255))
+
+    ip_addr_cmd = ['ip', 'addr', 'add', addr, 'dev', nic]
+    ip_link_cmd = ['ip', 'link', 'set', 'dev', nic, 'up']
+
+    if not util.which('ip'):
+        raise RuntimeError("No 'ip' command available to configure ip4LL "
+                           "address")
+
+    try:
+        (result, _err) = util.subp(ip_addr_cmd)
+        LOG.debug("assigned ip4LL address '%s' to '%s'", addr, nic)
+
+        (result, _err) = util.subp(ip_link_cmd)
+        LOG.debug("brought device '%s' up", nic)
+    except Exception:
+        util.logexc(LOG, "ip4LL address assignment of '%s' to '%s' failed."
+                         " Droplet networking will be broken", addr, nic)
+        raise
+
+    return nic
+
+
+def del_ipv4_link_local(nic=None):
+    """Remove the ip4LL address. While this is not necessary, the ip4LL
+       address is extraneous and confusing to users.
+    """
+    if not nic:
+        LOG.debug("no link_local address interface defined, skipping link "
+                  "local address cleanup")
+        return
+
+    LOG.debug("cleaning up ipv4LL address")
+
+    ip_addr_cmd = ['ip', 'addr', 'flush', 'dev', nic]
+
+    try:
+        (result, _err) = util.subp(ip_addr_cmd)
+        LOG.debug("removed ip4LL addresses from %s", nic)
+
+    except Exception as e:
+        util.logexc(LOG, "failed to remove ip4LL address from '%s'.", nic, e)
+
+
+def convert_network_configuration(config, dns_servers):
+    """Convert the DigitalOcean Network description into Cloud-init's netconfig
+       format.
+
+       Example JSON:
+        {'public': [
+              {'mac': '04:01:58:27:7f:01',
+               'ipv4': {'gateway': '45.55.32.1',
+                        'netmask': '255.255.224.0',
+                        'ip_address': '45.55.50.93'},
+               'anchor_ipv4': {
+                        'gateway': '10.17.0.1',
+                        'netmask': '255.255.0.0',
+                        'ip_address': '10.17.0.9'},
+               'type': 'public',
+               'ipv6': {'gateway': '....',
+                        'ip_address': '....',
+                        'cidr': 64}}
+           ],
+          'private': [
+              {'mac': '04:01:58:27:7f:02',
+               'ipv4': {'gateway': '10.132.0.1',
+                        'netmask': '255.255.0.0',
+                        'ip_address': '10.132.75.35'},
+               'type': 'private'}
+           ]
+        }
+    """
+
+    def _get_subnet_part(pcfg, nameservers=None):
+        subpart = {'type': 'static',
+                   'control': 'auto',
+                   'address': pcfg.get('ip_address'),
+                   'gateway': pcfg.get('gateway')}
+
+        if nameservers:
+            subpart['dns_nameservers'] = nameservers
+
+        if ":" in pcfg.get('ip_address'):
+            subpart['address'] = "{0}/{1}".format(pcfg.get('ip_address'),
+                                                  pcfg.get('cidr'))
+        else:
+            subpart['netmask'] = pcfg.get('netmask')
+
+        return subpart
+
+    all_nics = []
+    for k in ('public', 'private'):
+        if k in config:
+            all_nics.extend(config[k])
+
+    macs_to_nics = cloudnet.get_interfaces_by_mac()
+    nic_configs = []
+
+    for nic in all_nics:
+
+        mac_address = nic.get('mac')
+        sysfs_name = macs_to_nics.get(mac_address)
+        nic_type = nic.get('type', 'unknown')
+        # Note: the entry 'public' above contains a list, but
+        # the list will only ever have one nic inside it per digital ocean.
+        # If it ever had more than one nic, then this code would
+        # assign all 'public' the same name.
+        if_name = NIC_MAP.get(nic_type, sysfs_name)
+
+        LOG.debug("mapped %s interface to %s, assigning name of %s",
+                  mac_address, sysfs_name, if_name)
+
+        ncfg = {'type': 'physical',
+                'mac_address': mac_address,
+                'name': if_name}
+
+        subnets = []
+        for netdef in ('ipv4', 'ipv6', 'anchor_ipv4', 'anchor_ipv6'):
+            raw_subnet = nic.get(netdef, None)
+            if not raw_subnet:
+                continue
+
+            sub_part = _get_subnet_part(raw_subnet)
+            if nic_type == 'public' and 'anchor' not in netdef:
+                # add DNS resolvers to the public interfaces only
+                sub_part = _get_subnet_part(raw_subnet, dns_servers)
+            else:
+                # remove the gateway any non-public interfaces
+                if 'gateway' in sub_part:
+                    del sub_part['gateway']
+
+            subnets.append(sub_part)
+
+        ncfg['subnets'] = subnets
+        nic_configs.append(ncfg)
+        LOG.debug("nic '%s' configuration: %s", if_name, ncfg)
+
+    return {'version': 1, 'config': nic_configs}
+
+
+def read_metadata(url, timeout=2, sec_between=2, retries=30):
+    response = url_helper.readurl(url, timeout=timeout,
+                                  sec_between=sec_between, retries=retries)
+    if not response.ok():
+        raise RuntimeError("unable to read metadata at %s" % url)
+    return json.loads(response.contents.decode())
+
+
+def read_sysinfo():
+    # DigitalOcean embeds vendor ID and instance/droplet_id in the
+    # SMBIOS information
+
+    # Detect if we are on DigitalOcean and return the Droplet's ID
+    vendor_name = util.read_dmi_data("system-manufacturer")
+    if vendor_name != "DigitalOcean":
+        return (False, None)
+
+    droplet_id = util.read_dmi_data("system-serial-number")
+    if droplet_id:
+        LOG.debug("system identified via SMBIOS as DigitalOcean Droplet: %s",
+                  droplet_id)
+    else:
+        msg = ("system identified via SMBIOS as a DigitalOcean "
+               "Droplet, but did not provide an ID. Please file a "
+               "support ticket at: "
+               "https://cloud.digitalocean.com/support/tickets/new")
+        LOG.critical(msg)
+        raise RuntimeError(msg)
+
+    return (True, droplet_id)