Add new DEFAULT_NIC_CONFIG configuration parameter

This can be used to define an action for the default NIC that
Ganeti will attach to an instance if none of the --net and --no-nics
input arguments are defined on the instance creation command.

This resolves #90

docs/configuration.rst

@@ -123,6 +123,20 @@ some external programs in ``/etc/default/snf-image``:
   # card's NETWORK_TAGS variable.
   # STATELESS_DHCPV6_TAGS="nfdhcpd stateless_dhcpv6"
 
+  # DEFAULT_NIC_CONFIG: This option defines the network configuration to be
+  # performed if there is a default NIC attached to the instance with no further
+  # information associated with it. This will happen if the user creates an
+  # instance and does not define any of the --net and --no-nics input arguments.
+  # In this case Ganeti will create a NIC with a random MAC and set up according
+  # to the cluster level NIC parameters. The user may want to leave this NIC
+  # unconfigured (by leaving this option empty), perform "dhcp" or use one of the
+  # various IPv6 auto configuration methods. The supported IPv6 methods are:
+  # "dhcpv6" (Stateful DHCPv6), "slaac_dhcp" (Stateless DHCPv6) and "slaac"
+  # (Stateless Autoconfiguration). IPv4 and IPv6 configuration methods can be
+  # defined in conjunction using the plus (`+') sign. IPv4 must precede (e.g.:
+  # "dhcp+slaac_dhcp").
+  # DEFAULT_NIC_CONFIG="dhcp"
+
   # UNATTEND: This variable overwrites the unattend.xml file used when deploying
   # a Windows image. snf-image-helper will use its own unattend.xml file if this
   # variable is empty.
@@ -167,6 +181,9 @@ The most common configuration parameters the user may need to overwrite are:
  * **PROGRESS_MONITOR**: To specify an executable that will handle the
    monitoring messages exported by *snf-image*
  * **DHCP_TAGS**: To specify which Ganeti networks support DHCP
+ * **DEFAULT_NIC_CONFIG**: To specify a configuration method for the default
+   NIC Ganeti will attach on instances that were created without using the
+   *--net* or *--no-nics* input arguments.
  * **STATELESS_DHCPV6_TAGS**: To specify which Ganeti networks support SLAAC
    and stateless DHCPv6
  * **STATEFUL_DHCPV6_TAGS**: To specify which Ganeti networks support DHCPv6

snf-image-helper/tasks/50ConfigureNetwork.in

@@ -112,28 +112,47 @@ for index in $(seq 0 $((SNF_IMAGE_NIC_COUNT-1))); do
         ipv6=yes
     fi
 
-    ARGS="-n $index"
+    ARGS=("-n" "$index")
 
     if [ "$ipv4" = yes ]; then
         if [ "$dhcp" = yes ]; then
-            ARGS+=" -4 dhcp"
+            ARGS+=("-4" "dhcp")
         else
-            ARGS+=" -4 static"
+            ARGS+=("-4" "static")
         fi
     fi
 
     if [ "$ipv6" = yes ]; then
         if [ "$dhcp6" = stateful ]; then
-            ARGS+=" -6 dhcp"
+            ARGS+=("-6" "dhcp")
         elif [ "$dhcp6" = stateless ]; then
-            ARGS+=" -6 slaac_dhcp"
+            ARGS+=("-6" "slaac_dhcp")
         else
-            ARGS+=" -6 slaac"
+            ARGS+=("-6" "slaac")
         fi
     fi
 
-    echo "Running: $networking_tool $ARGS"
-    "$networking_tool" $ARGS
+    if [ $SNF_IMAGE_NIC_COUNT -eq 1 -a "$ipv4" = "no" -a "$ipv6" = "no" ]; then
+        # This looks like being the default NIC.
+        keys=(dhcp {dhcp+,}{dhcpv6,slaac,slaac_dhcp})
+        values=("-4 dhcp" {"-4 dhcp ",}{"-6 dhcp","-6 slaac","-6 slaac_dhcp"})
+        declare -A default_nic_action
+        for((i=0; i<${#keys[@]}; i++)); do
+            default_nic_action["${keys[$i]}"]="${values[$i]}"
+        done
+
+        warn "Detected a default NIC with no further info associated with it."
+
+        if [ -z "$SNF_IMAGE_DEFAULT_NIC_CONFIG" ]; then
+            warn "No configuration for default NIC is defined"
+        else
+            warn "Performing configuration for default NIC: $SNF_IMAGE_DEFAULT_NIC_CONFIG"
+            ARGS+=(${default_nic_action["$SNF_IMAGE_DEFAULT_NIC_CONFIG"]})
+        fi
+    fi
+
+    echo "Running: $networking_tool ${ARGS[@]}"
+    "$networking_tool" "${ARGS[@]}"
 
 done
 

snf-image-host/common.sh.in

@@ -562,6 +562,21 @@ fi
 : ${DHCP_TAGS:="auto dhcp nfdhcpd"}
 : ${STATEFUL_DHCPV6_TAGS:="dhcpv6 stateful_dhcpv6"}
 : ${STATELESS_DHCPV6_TAGS:="nfdhcpd stateless_dhcpv6"}
+: ${DEFAULT_NIC_CONFIG:="dhcp"}
+
+found=no
+for val in "" dhcp {dhcp+,}{dhcpv6,slaac,slaac_dhcp}; do
+    if [ "$DEFAULT_NIC_CONFIG" = "$val" ]; then
+        found=yes
+        break
+    fi
+done
+
+if [ "$found" = "no" ]; then
+    log_error "DEFAULT_NIC_CONFIG (=\`$DEFAULT_NIC_CONFIG') has invalid value."
+    log_error "Valid values are: \`'" dhcp {dhcp+,}{dhcpv6,slaac,slaac_dhcp}
+    exit 1
+fi
 
 SCRIPT_NAME=$(basename $0)
 

snf-image-host/create

@@ -185,6 +185,7 @@ snf_export_HOSTNAME="$instance"
 snf_export_DHCP_TAGS="$DHCP_TAGS"
 snf_export_STATEFUL_DHCPV6_TAGS="$STATEFUL_DHCPV6_TAGS"
 snf_export_STATELESS_DHCPV6_TAGS="$STATELESS_DHCPV6_TAGS"
+snf_export_DEFAULT_NIC_CONFIG="$DEFAULT_NIC_CONFIG"
 
 if [ -n "${IMG_PASSWD+dummy}" ]; then
     snf_export_PASSWD="$IMG_PASSWD"

snf-image-host/defaults.in

@@ -114,6 +114,20 @@
 # card's NETWORK_TAGS variable.
 # STATELESS_DHCPV6_TAGS="nfdhcpd stateless_dhcpv6"
 
+# DEFAULT_NIC_CONFIG: This option defines the network configuration to be
+# performed if there is a default NIC attached to the instance with no further
+# information associated with it. This will happen if the user creates an
+# instance and does not define any of the --net and --no-nics input arguments.
+# In this case Ganeti will create a NIC with a random MAC and set up according
+# to the cluster level NIC parameters. The user may want to leave this NIC
+# unconfigured (by leaving this option empty), perform "dhcp" or use one of the
+# various IPv6 auto configuration methods. The supported IPv6 methods are:
+# "dhcpv6" (Stateful DHCPv6), "slaac_dhcp" (Stateless DHCPv6) and "slaac"
+# (Stateless Autoconfiguration). IPv4 and IPv6 configuration methods can be
+# defined in conjunction using the plus (`+') sign. IPv4 must precede (e.g.:
+# "dhcp+slaac_dhcp").
+# DEFAULT_NIC_CONFIG="dhcp"
+
 # UNATTEND: This variable overwrites the unattend.xml file used when deploying
 # a Windows image. snf-image-helper will use its own unattend.xml file if this
 # variable is empty.