azure dhclient-hook cleanups

This adds some function to the generator to maintain the presense of a
flag file '/run/cloud-init/enabled' indicating that cloud-init is enabled.

Then, only run the dhclient hooks if on Azure and cloud-init is enabled.
The test for is_azure currently only checks to see that the board vendor
is Microsoft, not actually that we are on azure.  Running should not be
harmful anywhere, other than slowing down dhclient.

The value of this additional code is that then dhclient having run
does not task the system with the load of cloud-init.

Additionally, some changes to config are done here.
 * rename 'dhclient_leases' to 'dhclient_lease_file'
 * move that to the datasource config (datasource/Azure/dhclient_lease_file)

Also, it removes the config in config/cloud.cfg that set agent_command
to __builtin__.  This means that by default cloud-init still needs
the agent installed.  The suggested follow-on improvement is to
use __builtin__ if there is no walinux-agent installed.

8 files changed, 71 insertions, 28 deletions

diff --git a/cloudinit/sources/DataSourceAzure.py b/cloudinit/sources/DataSourceAzure.py
index a251fe01..dbc2bb68 100644
--- a/cloudinit/sources/DataSourceAzure.py
+++ b/cloudinit/sources/DataSourceAzure.py
@@ -54,6 +54,7 @@ BUILTIN_DS_CONFIG = {
         'hostname_command': 'hostname',
     },
     'disk_aliases': {'ephemeral0': '/dev/sdb'},
+    'dhclient_lease_file': '/var/lib/dhcp/dhclient.eth0.leases',
 }
 
 BUILTIN_CLOUD_CONFIG = {
@@ -106,8 +107,6 @@ def temporary_hostname(temp_hostname, cfg, hostname_command='hostname'):
 
 
 class DataSourceAzureNet(sources.DataSource):
-    FALLBACK_LEASE = '/var/lib/dhcp/dhclient.eth0.leases'
-
     def __init__(self, sys_cfg, distro, paths):
         sources.DataSource.__init__(self, sys_cfg, distro, paths)
         self.seed_dir = os.path.join(paths.seed_dir, 'azure')
@@ -116,8 +115,7 @@ class DataSourceAzureNet(sources.DataSource):
         self.ds_cfg = util.mergemanydict([
             util.get_cfg_by_path(sys_cfg, DS_CFG_PATH, {}),
             BUILTIN_DS_CONFIG])
-        self.dhclient_lease_file = self.paths.cfgs.get('dhclient_lease',
-                                                       self.FALLBACK_LEASE)
+        self.dhclient_lease_file = self.ds_cfg.get('dhclient_lease_file')
 
     def __str__(self):
         root = sources.DataSource.__str__(self)
@@ -126,6 +124,9 @@ class DataSourceAzureNet(sources.DataSource):
     def get_metadata_from_agent(self):
         temp_hostname = self.metadata.get('local-hostname')
         hostname_command = self.ds_cfg['hostname_bounce']['hostname_command']
+        agent_cmd = self.ds_cfg['agent_command']
+        LOG.debug("Getting metadata via agent.  hostname=%s cmd=%s",
+                  temp_hostname, agent_cmd)
         with temporary_hostname(temp_hostname, self.ds_cfg,
                                 hostname_command=hostname_command) \
                 as previous_hostname:
@@ -141,7 +142,7 @@ class DataSourceAzureNet(sources.DataSource):
                     util.logexc(LOG, "handling set_hostname failed")
 
             try:
-                invoke_agent(self.ds_cfg['agent_command'])
+                invoke_agent(agent_cmd)
             except util.ProcessExecutionError:
                 # claim the datasource even if the command failed
                 util.logexc(LOG, "agent command '%s' failed.",
@@ -234,13 +235,13 @@ class DataSourceAzureNet(sources.DataSource):
                                     dhclient_lease_file)
         else:
             metadata_func = self.get_metadata_from_agent
+
         try:
             fabric_data = metadata_func()
         except Exception as exc:
             LOG.info("Error communicating with Azure fabric; assume we aren't"
                      " on Azure.", exc_info=True)
             return False
-
         self.metadata['instance-id'] = util.read_dmi_data('system-uuid')
         self.metadata.update(fabric_data)
 
diff --git a/cloudinit/sources/helpers/azure.py b/cloudinit/sources/helpers/azure.py
index 6e43440f..689ed4cc 100644
--- a/cloudinit/sources/helpers/azure.py
+++ b/cloudinit/sources/helpers/azure.py
@@ -190,7 +190,8 @@ class WALinuxAgentShim(object):
         '</Health>'])
 
     def __init__(self, fallback_lease_file=None):
-        LOG.debug('WALinuxAgentShim instantiated...')
+        LOG.debug('WALinuxAgentShim instantiated, fallback_lease_file=%s',
+                  fallback_lease_file)
         self.dhcpoptions = None
         self._endpoint = None
         self.openssl_manager = None
diff --git a/config/cloud.cfg b/config/cloud.cfg
index 93ef3423..2d7fb473 100644
--- a/config/cloud.cfg
+++ b/config/cloud.cfg
@@ -98,7 +98,6 @@ system_info:
       cloud_dir: /var/lib/cloud/
       templates_dir: /etc/cloud/templates/
       upstart_dir: /etc/init/
-      dhclient_lease: 
    package_mirrors:
      - arches: [i386, amd64]
        failsafe:
@@ -115,8 +114,3 @@ system_info:
          primary: http://ports.ubuntu.com/ubuntu-ports
          security: http://ports.ubuntu.com/ubuntu-ports
    ssh_svcname: ssh
-datasource:
-  Azure:
-    set_hostname: False
-    agent_command: __builtin__
-
diff --git a/doc/sources/azure/README.rst b/doc/sources/azure/README.rst
index 48f3cc7a..ec7d9e84 100644
--- a/doc/sources/azure/README.rst
+++ b/doc/sources/azure/README.rst
@@ -30,13 +30,10 @@ datasource:
 If those files are not available, the fallback is to check the leases file
 for the endpoint server (again option 245).
 
-You can define the path to the lease file with the 'dhclient_lease' configuration
-value under system_info: and paths:.  For example:
+You can define the path to the lease file with the 'dhclient_lease_file'
+configuration.  The default value is /var/lib/dhcp/dhclient.eth0.leases.
 
-      dhclient_lease: /var/lib/dhcp/dhclient.eth0.leases
-
-If no configuration value is provided, the dhclient_lease value will fallback to
-/var/lib/dhcp/dhclient.eth0.leases.
+    dhclient_lease_file: /var/lib/dhcp/dhclient.eth0.leases
 
 walinuxagent
 ------------
diff --git a/systemd/cloud-init-generator b/systemd/cloud-init-generator
index 2d319695..fedb6309 100755
--- a/systemd/cloud-init-generator
+++ b/systemd/cloud-init-generator
@@ -6,6 +6,7 @@ DEBUG_LEVEL=1
 LOG_D="/run/cloud-init"
 ENABLE="enabled"
 DISABLE="disabled"
+RUN_ENABLED_FILE="$LOG_D/$ENABLE"
 CLOUD_SYSTEM_TARGET="/lib/systemd/system/cloud-init.target"
 CLOUD_TARGET_NAME="cloud-init.target"
 # lxc sets 'container', but lets make that explicitly a global
@@ -107,6 +108,7 @@ main() {
                     "ln $CLOUD_SYSTEM_TARGET $link_path"
             fi
         fi
+        : > "$RUN_ENABLED_FILE"
     elif [ "$result" = "$DISABLE" ]; then
         if [ -f "$link_path" ]; then
             if rm -f "$link_path"; then
@@ -118,6 +120,9 @@ main() {
         else
             debug 1 "already disabled: no change needed [no $link_path]"
         fi
+        if [ -e "$RUN_ENABLED_FILE" ]; then
+            rm -f "$RUN_ENABLED_FILE"
+        fi
     else
         debug 0 "unexpected result '$result'"
         ret=3
diff --git a/tools/hook-dhclient b/tools/hook-dhclient
index d099979a..6a4626c6 100755
--- a/tools/hook-dhclient
+++ b/tools/hook-dhclient
@@ -1,9 +1,24 @@
 #!/bin/sh
 # This script writes DHCP lease information into the cloud-init run directory
 # It is sourced, not executed.  For more information see dhclient-script(8).
+is_azure() {
+    local dmi_path="/sys/class/dmi/id/board_vendor" vendor=""
+    if [ -e "$dmi_path" ] && read vendor < "$dmi_path"; then
+        [ "$vendor" = "Microsoft Corporation" ] && return 0
+    fi
+    return 1
+}
 
-case "$reason" in
-   BOUND) cloud-init dhclient-hook up "$interface";;
-   DOWN|RELEASE|REBOOT|STOP|EXPIRE)
-      cloud-init dhclient-hook down "$interface";;
-esac
+is_enabled() {
+    # only execute hooks if cloud-init is enabled and on azure
+    [ -e /run/cloud-init/enabled ] || return 1
+    is_azure
+}
+
+if is_enabled; then
+   case "$reason" in
+      BOUND) cloud-init dhclient-hook up "$interface";;
+      DOWN|RELEASE|REBOOT|STOP|EXPIRE)
+         cloud-init dhclient-hook down "$interface";;
+   esac
+fi
diff --git a/tools/hook-network-manager b/tools/hook-network-manager
index 447b134e..98a36c8a 100755
--- a/tools/hook-network-manager
+++ b/tools/hook-network-manager
@@ -2,8 +2,23 @@
 # This script hooks into NetworkManager(8) via its scripts
 # arguments are 'interface-name' and 'action'
 #
+is_azure() {
+    local dmi_path="/sys/class/dmi/id/board_vendor" vendor=""
+    if [ -e "$dmi_path" ] && read vendor < "$dmi_path"; then
+        [ "$vendor" = "Microsoft Corporation" ] && return 0
+    fi
+    return 1
+}
 
-case "$1:$2" in
-   *:up) exec cloud-init dhclient-hook up "$1";;
-   *:down) exec cloud-init dhclient-hook down "$1";;
-esac
+is_enabled() {
+    # only execute hooks if cloud-init is enabled and on azure
+    [ -e /run/cloud-init/enabled ] || return 1
+    is_azure
+}
+
+if is_enabled; then
+    case "$1:$2" in
+        *:up) exec cloud-init dhclient-hook up "$1";;
+        *:down) exec cloud-init dhclient-hook down "$1";;
+    esac
+fi
diff --git a/tools/hook-rhel.sh b/tools/hook-rhel.sh
index 5e963a89..8232414c 100755
--- a/tools/hook-rhel.sh
+++ b/tools/hook-rhel.sh
@@ -2,11 +2,26 @@
 # Current versions of RHEL and CentOS do not honor the directory
 # /etc/dhcp/dhclient-exit-hooks.d so this file can be placed in
 # /etc/dhcp/dhclient.d instead
+is_azure() {
+    local dmi_path="/sys/class/dmi/id/board_vendor" vendor=""
+    if [ -e "$dmi_path" ] && read vendor < "$dmi_path"; then
+        [ "$vendor" = "Microsoft Corporation" ] && return 0
+    fi
+    return 1
+}
+
+is_enabled() {
+    # only execute hooks if cloud-init is enabled and on azure
+    [ -e /run/cloud-init/enabled ] || return 1
+    is_azure
+}
 
 hook-rhel_config(){
+    is_enabled || return 0
     cloud-init dhclient-hook up "$interface"
 }
 
 hook-rhel_restore(){
+    is_enabled || return 0
     cloud-init dhclient-hook down "$interface"
 }