Add support for late binding to IP addresses using go-sockaddr/template

command/agent/config.go

@@ -2,6 +2,7 @@ package agent
 
 import (
 	"encoding/base64"
+	"errors"
 	"fmt"
 	"io"
 	"net"
@@ -13,6 +14,8 @@ import (
 	"strings"
 	"time"
 
+	"github.com/hashicorp/go-sockaddr/template"
+
 	client "github.com/hashicorp/nomad/client/config"
 	"github.com/hashicorp/nomad/helper"
 	"github.com/hashicorp/nomad/nomad"
@@ -692,22 +695,45 @@ func (c *Config) Merge(b *Config) *Config {
 // normalizeAddrs normalizes Addresses and AdvertiseAddrs to always be
 // initialized and have sane defaults.
 func (c *Config) normalizeAddrs() error {
-	c.Addresses.HTTP = normalizeBind(c.Addresses.HTTP, c.BindAddr)
-	c.Addresses.RPC = normalizeBind(c.Addresses.RPC, c.BindAddr)
-	c.Addresses.Serf = normalizeBind(c.Addresses.Serf, c.BindAddr)
+	if c.BindAddr != "" {
+		ipStr, err := parseSingleIPTemplate(c.BindAddr)
+		if err != nil {
+			return fmt.Errorf("Bind address resolution failed: %v", err)
+		}
+		c.BindAddr = ipStr
+	}
+
+	addr, err := normalizeBind(c.Addresses.HTTP, c.BindAddr)
+	if err != nil {
+		return fmt.Errorf("Failed to parse HTTP address: %v", err)
+	}
+	c.Addresses.HTTP = addr
+
+	addr, err = normalizeBind(c.Addresses.RPC, c.BindAddr)
+	if err != nil {
+		return fmt.Errorf("Failed to parse RPC address: %v", err)
+	}
+	c.Addresses.RPC = addr
+
+	addr, err = normalizeBind(c.Addresses.Serf, c.BindAddr)
+	if err != nil {
+		return fmt.Errorf("Failed to parse Serf address: %v", err)
+	}
+	c.Addresses.Serf = addr
+
 	c.normalizedAddrs = &Addresses{
 		HTTP: net.JoinHostPort(c.Addresses.HTTP, strconv.Itoa(c.Ports.HTTP)),
 		RPC:  net.JoinHostPort(c.Addresses.RPC, strconv.Itoa(c.Ports.RPC)),
 		Serf: net.JoinHostPort(c.Addresses.Serf, strconv.Itoa(c.Ports.Serf)),
 	}
 
-	addr, err := normalizeAdvertise(c.AdvertiseAddrs.HTTP, c.Addresses.HTTP, c.Ports.HTTP, c.DevMode)
+	addr, err = normalizeAdvertise(c.AdvertiseAddrs.HTTP, c.Addresses.HTTP, c.Ports.HTTP)
 	if err != nil {
 		return fmt.Errorf("Failed to parse HTTP advertise address: %v", err)
 	}
 	c.AdvertiseAddrs.HTTP = addr
 
-	addr, err = normalizeAdvertise(c.AdvertiseAddrs.RPC, c.Addresses.RPC, c.Ports.RPC, c.DevMode)
+	addr, err = normalizeAdvertise(c.AdvertiseAddrs.RPC, c.Addresses.RPC, c.Ports.RPC)
 	if err != nil {
 		return fmt.Errorf("Failed to parse RPC advertise address: %v", err)
 	}
@@ -715,7 +741,7 @@ func (c *Config) normalizeAddrs() error {
 
 	// Skip serf if server is disabled
 	if c.Server != nil && c.Server.Enabled {
-		addr, err = normalizeAdvertise(c.AdvertiseAddrs.Serf, c.Addresses.Serf, c.Ports.Serf, c.DevMode)
+		addr, err = normalizeAdvertise(c.AdvertiseAddrs.Serf, c.Addresses.Serf, c.Ports.Serf)
 		if err != nil {
 			return fmt.Errorf("Failed to parse Serf advertise address: %v", err)
 		}
@@ -725,14 +751,34 @@ func (c *Config) normalizeAddrs() error {
 	return nil
 }
 
+// parseSingleIPTemplate is used as a helper function to parse out a single IP
+// address from a config parameter.
+func parseSingleIPTemplate(ipTmpl string) (string, error) {
+	out, err := template.Parse(ipTmpl)
+	if err != nil {
+		return "", fmt.Errorf("Unable to parse address template %q: %v", ipTmpl, err)
+	}
+
+	ips := strings.Split(out, " ")
+	switch len(ips) {
+	case 0:
+		return "", errors.New("No addresses found, please configure one.")
+	case 1:
+		return ips[0], nil
+	default:
+		return "", fmt.Errorf("Multiple addresses found (%q), please configure one.", out)
+	}
+}
+
 // normalizeBind returns a normalized bind address.
 //
 // If addr is set it is used, if not the default bind address is used.
-func normalizeBind(addr, bind string) string {
+func normalizeBind(addr, bind string) (string, error) {
 	if addr == "" {
-		return bind
+		return bind, nil
+	} else {
+		return parseSingleIPTemplate(addr)
 	}
-	return addr
 }
 
 // normalizeAdvertise returns a normalized advertise address.
@@ -747,61 +793,28 @@ func normalizeBind(addr, bind string) string {
 // is resolved and returned with the port.
 //
 // Loopback is only considered a valid advertise address in dev mode.
-func normalizeAdvertise(addr string, bind string, defport int, dev bool) (string, error) {
+func normalizeAdvertise(addr string, bind string, defport int) (string, error) {
 	if addr != "" {
 		// Default to using manually configured address
-		_, _, err := net.SplitHostPort(addr)
+		host, port, err := net.SplitHostPort(addr)
 		if err != nil {
 			if !isMissingPort(err) {
 				return "", fmt.Errorf("Error parsing advertise address %q: %v", addr, err)
 			}
-
-			// missing port, append the default
-			return net.JoinHostPort(addr, strconv.Itoa(defport)), nil
-		}
-		return addr, nil
+			host = addr
+			port = strconv.Itoa(defport)
 		}
 
-	// Fallback to bind address first, and then try resolving the local hostname
-	ips, err := net.LookupIP(bind)
+		ipStr, err := parseSingleIPTemplate(host)
 		if err != nil {
-		return "", fmt.Errorf("Error resolving bind address %q: %v", bind, err)
+			return "", fmt.Errorf("Error parsing advertise address template: %v", err)
 		}
 
-	// Return the first unicast address
-	for _, ip := range ips {
-		if ip.IsLinkLocalUnicast() || ip.IsGlobalUnicast() {
-			return net.JoinHostPort(ip.String(), strconv.Itoa(defport)), nil
-		}
-		if ip.IsLoopback() && dev {
-			// loopback is fine for dev mode
-			return net.JoinHostPort(ip.String(), strconv.Itoa(defport)), nil
-		}
+		return net.JoinHostPort(ipStr, port), nil
 	}
 
-	// As a last resort resolve the hostname and use it if it's not
-	// localhost (as localhost is never a sensible default)
-	host, err := os.Hostname()
-	if err != nil {
-		return "", fmt.Errorf("Unable to get hostname to set advertise address: %v", err)
-	}
-
-	ips, err = net.LookupIP(host)
-	if err != nil {
-		return "", fmt.Errorf("Error resolving hostname %q for advertise address: %v", host, err)
-	}
-
-	// Return the first unicast address
-	for _, ip := range ips {
-		if ip.IsLinkLocalUnicast() || ip.IsGlobalUnicast() {
-			return net.JoinHostPort(ip.String(), strconv.Itoa(defport)), nil
-		}
-		if ip.IsLoopback() && dev {
-			// loopback is fine for dev mode
-			return net.JoinHostPort(ip.String(), strconv.Itoa(defport)), nil
-		}
-	}
-	return "", fmt.Errorf("No valid advertise addresses, please set `advertise` manually")
+	// Fallback to bind address, as it has been resolved before.
+	return net.JoinHostPort(bind, strconv.Itoa(defport)), nil
 }
 
 // isMissingPort returns true if an error is a "missing port" error from

command/agent/config_test.go

@@ -1,6 +1,7 @@
 package agent
 
 import (
+	"fmt"
 	"io/ioutil"
 	"net"
 	"os"
@@ -520,6 +521,121 @@ func TestConfig_Listener(t *testing.T) {
 	}
 }
 
+func TestConfig_normalizeAddrs(t *testing.T) {
+	c := &Config{
+		BindAddr: "127.0.0.1",
+		Ports: &Ports{
+			HTTP: 4646,
+			RPC:  4647,
+			Serf: 4648,
+		},
+		Addresses:      &Addresses{},
+		AdvertiseAddrs: &AdvertiseAddrs{},
+		DevMode:        true,
+	}
+
+	if err := c.normalizeAddrs(); err != nil {
+		t.Fatalf("unable to normalize addresses: %s", err)
+	}
+
+	if c.BindAddr != "127.0.0.1" {
+		t.Fatalf("expected BindAddr 127.0.0.1, got %s", c.BindAddr)
+	}
+
+	if c.normalizedAddrs.HTTP != "127.0.0.1:4646" {
+		t.Fatalf("expected HTTP address 127.0.0.1:4646, got %s", c.normalizedAddrs.HTTP)
+	}
+
+	if c.normalizedAddrs.RPC != "127.0.0.1:4647" {
+		t.Fatalf("expected RPC address 127.0.0.1:4647, got %s", c.normalizedAddrs.RPC)
+	}
+
+	if c.normalizedAddrs.Serf != "127.0.0.1:4648" {
+		t.Fatalf("expected Serf address 127.0.0.1:4648, got %s", c.normalizedAddrs.Serf)
+	}
+
+	if c.AdvertiseAddrs.HTTP != "127.0.0.1:4646" {
+		t.Fatalf("expected HTTP advertise address 127.0.0.1:4646, got %s", c.AdvertiseAddrs.HTTP)
+	}
+
+	if c.AdvertiseAddrs.RPC != "127.0.0.1:4647" {
+		t.Fatalf("expected RPC advertise address 127.0.0.1:4647, got %s", c.AdvertiseAddrs.RPC)
+	}
+
+	// Client mode, no Serf address defined
+	if c.AdvertiseAddrs.Serf != "" {
+		t.Fatalf("expected unset Serf advertise address, got %s", c.AdvertiseAddrs.Serf)
+	}
+
+	c = &Config{
+		BindAddr: "169.254.1.5",
+		Ports: &Ports{
+			HTTP: 4646,
+			RPC:  4647,
+			Serf: 4648,
+		},
+		Addresses: &Addresses{
+			HTTP: "169.254.1.10",
+		},
+		AdvertiseAddrs: &AdvertiseAddrs{
+			RPC: "169.254.1.40",
+		},
+		Server: &ServerConfig{
+			Enabled: true,
+		},
+	}
+
+	if err := c.normalizeAddrs(); err != nil {
+		t.Fatalf("unable to normalize addresses: %s", err)
+	}
+
+	if c.BindAddr != "169.254.1.5" {
+		t.Fatalf("expected BindAddr 169.254.1.5, got %s", c.BindAddr)
+	}
+
+	if c.AdvertiseAddrs.HTTP != "169.254.1.10:4646" {
+		t.Fatalf("expected HTTP advertise address 169.254.1.10:4646, got %s", c.AdvertiseAddrs.HTTP)
+	}
+
+	if c.AdvertiseAddrs.RPC != "169.254.1.40:4647" {
+		t.Fatalf("expected RPC advertise address 169.254.1.40:4647, got %s", c.AdvertiseAddrs.RPC)
+	}
+
+	if c.AdvertiseAddrs.Serf != "169.254.1.5:4648" {
+		t.Fatalf("expected Serf advertise address 169.254.1.5:4648, got %s", c.AdvertiseAddrs.Serf)
+	}
+
+	c = &Config{
+		BindAddr: "{{ GetPrivateIP }}",
+		Ports: &Ports{
+			HTTP: 4646,
+			RPC:  4647,
+			Serf: 4648,
+		},
+		Addresses:      &Addresses{},
+		AdvertiseAddrs: &AdvertiseAddrs{},
+		Server: &ServerConfig{
+			Enabled: true,
+		},
+	}
+
+	if err := c.normalizeAddrs(); err != nil {
+		t.Fatalf("unable to normalize addresses: %s", err)
+	}
+
+	if c.AdvertiseAddrs.HTTP != fmt.Sprintf("%s:4646", c.BindAddr) {
+		t.Fatalf("expected HTTP advertise address %s:4646, got %s", c.BindAddr, c.AdvertiseAddrs.HTTP)
+	}
+
+	if c.AdvertiseAddrs.RPC != fmt.Sprintf("%s:4647", c.BindAddr) {
+		t.Fatalf("expected RPC advertise address %s:4647, got %s", c.BindAddr, c.AdvertiseAddrs.RPC)
+	}
+
+	if c.AdvertiseAddrs.Serf != fmt.Sprintf("%s:4648", c.BindAddr) {
+		t.Fatalf("expected Serf advertise address %s:4648, got %s", c.BindAddr, c.AdvertiseAddrs.Serf)
+	}
+}
+
 func TestResources_ParseReserved(t *testing.T) {
 	cases := []struct {
 		Input  string

vendor/github.com/hashicorp/go-sockaddr/template/Makefile

@@ -0,0 +1,2 @@
+test::
+	go test

vendor/github.com/hashicorp/go-sockaddr/template/README.md

@@ -0,0 +1,6 @@
+# sockaddr/template
+
+sockaddr's template library.  See
+the
+[sockaddr/template](https://godoc.org/github.com/hashicorp/go-sockaddr/template)
+docs for details on how to use this template.

vendor/github.com/hashicorp/go-sockaddr/template/doc.go

@@ -0,0 +1,239 @@
+/*
+
+Package sockaddr/template provides a text/template interface the SockAddr helper
+functions.  The primary entry point into the sockaddr/template package is
+through its Parse() call.  For example:
+
+    import (
+      "fmt"
+
+      template "github.com/hashicorp/go-sockaddr/template"
+    )
+
+    results, err := template.Parse(`{{ GetPrivateIP }}`)
+    if err != nil {
+      fmt.Errorf("Unable to find a private IP address: %v", err)
+    }
+    fmt.Printf("My Private IP address is: %s\n", results)
+
+Below is a list of builtin template functions and details re: their usage.  It
+is possible to add additional functions by calling ParseIfAddrsTemplate
+directly.
+
+In general, the calling convention for this template library is to seed a list
+of initial interfaces via one of the Get*Interfaces() calls, then filter, sort,
+and extract the necessary attributes for use as string input.  This template
+interface is primarily geared toward resolving specific values that are only
+available at runtime, but can be defined as a heuristic for execution when a
+config file is parsed.
+
+All functions, unless noted otherwise, return an array of IfAddr structs making
+it possible to `sort`, `filter`, `limit`, seek (via the `offset` function), or
+`unique` the list.  To extract useful string information, the `attr` and `join`
+functions return a single string value.  See below for details.
+
+Important note: see the
+https://github.com/hashicorp/go-sockaddr/tree/master/cmd/sockaddr utility for
+more examples and for a CLI utility to experiment with the template syntax.
+
+`GetAllInterfaces` - Returns an exhaustive set of IfAddr structs available on
+the host.  `GetAllInterfaces` is the initial input and accessible as the initial
+"dot" in the pipeline.
+
+Example:
+
+    {{ GetAllInterfaces }}
+
+
+`GetDefaultInterfaces` - Returns one IfAddr for every IP that is on the
+interface containing the default route for the host.
+
+Example:
+
+    {{ GetDefaultInterfaces }}
+
+`GetPrivateInterfaces` - Returns one IfAddr for every forwardable IP address
+that is included in RFC 6890, is attached to the interface with the default
+route, and whose interface is marked as up.  NOTE: RFC 6890 is a more exhaustive
+version of RFC1918 because it spans IPv4 and IPv6, however it does permit the
+inclusion of likely undesired addresses such as multicast, therefore our version
+of "private" also filters out non-forwardable addresses.
+
+Example:
+
+    {{ GetPrivateInterfaces | include "flags" "up" }}
+
+
+`GetPublicInterfaces` - Returns a list of IfAddr that do not match RFC 6890, is
+attached to the default route, and whose interface is marked as up.
+
+Example:
+
+    {{ GetPublicInterfaces | include "flags" "up" }}
+
+
+`GetPrivateIP` - Helper function that returns a string of the first IP address
+from GetPrivateInterfaces.
+
+Example:
+
+    {{ GetPrivateIP }}
+
+
+`GetPublicIP` - Helper function that returns a string of the first IP from
+GetPublicInterfaces.
+
+Example:
+
+    {{ GetPublicIP }}
+
+`GetInterfaceIP` - Helper function that returns a string of the first IP from
+the named interface.
+
+Example:
+
+    {{ GetInterfaceIP }}
+
+
+`sort` - Sorts the IfAddrs result based on its arguments.  `sort` takes one
+argument, a list of ways to sort its IfAddrs argument.  The list of sort
+criteria is comma separated (`,`):
+  - `address`, `+address`: Ascending sort of IfAddrs by Address
+  - `-address`: Descending sort of IfAddrs by Address
+  - `name`, `+name`: Ascending sort of IfAddrs by lexical ordering of interface name
+  - `-name`: Descending sort of IfAddrs by lexical ordering of interface name
+  - `port`, `+port`: Ascending sort of IfAddrs by port number
+  - `-port`: Descending sort of IfAddrs by port number
+  - `private`, `+private`: Ascending sort of IfAddrs with private addresses first
+  - `-private`: Descending sort IfAddrs with private addresses last
+  - `size`, `+size`: Ascending sort of IfAddrs by their network size as determined
+    by their netmask (larger networks first)
+  - `-size`: Descending sort of IfAddrs by their network size as determined by their
+    netmask (smaller networks first)
+  - `type`, `+type`: Ascending sort of IfAddrs by the type of the IfAddr (Unix,
+    IPv4, then IPv6)
+  - `-type`: Descending sort of IfAddrs by the type of the IfAddr (IPv6, IPv4, Unix)
+
+Example:
+
+    {{ GetPrivateInterfaces | sort "type,size,address" }}
+
+
+`exclude` and `include`: Filters IfAddrs based on the selector criteria and its
+arguments.  Both `exclude` and `include` take two arguments.  The list of
+available filtering criteria is:
+  - "address": Filter IfAddrs based on a regexp matching the string representation
+    of the address
+  - "flag","flags": Filter IfAddrs based on the list of flags specified.  Multiple
+    flags can be passed together using the pipe character (`|`) to create an inclusive
+    bitmask of flags.  The list of flags is included below.
+  - "name": Filter IfAddrs based on a regexp matching the interface name.
+  - "network": Filter IfAddrs based on whether a netowkr is included in a given
+    CIDR.  More than one CIDR can be passed in if each network is separated by
+    the pipe character (`|`).
+  - "port": Filter IfAddrs based on an exact match of the port number (number must
+    be expressed as a string)
+  - "rfc", "rfcs": Filter IfAddrs based on the matching RFC.  If more than one RFC
+    is specified, the list of RFCs can be joined together using the pipe character (`|`).
+  - "size": Filter IfAddrs based on the exact match of the mask size.
+  - "type": Filter IfAddrs based on their SockAddr type.  Multiple types can be
+    specified together by using the pipe character (`|`).  Valid types include:
+    `ip`, `ipv4`, `ipv6`, and `unix`.
+
+Example:
+
+    {{ GetPrivateInterfaces | exclude "type" "IPv6" | include "flag" "up|forwardable" }}
+
+
+`unique`: Removes duplicate entries from the IfAddrs list, assuming the list has
+already been sorted.  `unique` only takes one argument:
+  - "address": Removes duplicates with the same address
+  - "name": Removes duplicates with the same interface names
+
+Example:
+
+    {{ GetPrivateInterfaces | sort "type,address" | unique "name" }}
+
+
+`limit`: Reduces the size of the list to the specified value.
+
+Example:
+
+    {{ GetPrivateInterfaces | include "flags" "forwardable|up" | limit 1 }}
+
+
+`offset`: Seeks into the list by the specified value.  A negative value can be
+used to seek from the end of the list.
+
+Example:
+
+    {{ GetPrivateInterfaces | include "flags" "forwardable|up" | offset "-2" | limit 1 }}
+
+
+`attr`: Extracts a single attribute of the first member of the list and returns
+it as a string.  `attr` takes a single attribute name.  The list of available
+attributes is type-specific and shared between `join`.  See below for a list of
+supported attributes.
+
+Example:
+
+    {{ GetPrivateInterfaces | include "flags" "forwardable|up" | attr "address" }}
+
+
+`join`: Similar to `attr`, `join` extracts all matching attributes of the list
+and returns them as a string joined by the separator, the second argument to
+`join`.  The list of available attributes is type-specific and shared between
+`join`.
+
+Example:
+
+    {{ GetPrivateInterfaces | include "flags" "forwardable|up" | join "address" " " }}
+
+
+`exclude` and `include` flags:
+  - `broadcast`
+  - `down`: Is the interface down?
+  - `forwardable`: Is the IP forwardable?
+  - `global unicast`
+  - `interface-local multicast`
+  - `link-local multicast`
+  - `link-local unicast`
+  - `loopback`
+  - `multicast`
+  - `point-to-point`
+  - `unspecified`: Is the IfAddr the IPv6 unspecified address?
+  - `up`: Is the interface up?
+
+
+Attributes for `attr` and `join`:
+
+SockAddr Type:
+  - `string`
+  - `type`
+
+IPAddr Type:
+  - `address`
+  - `binary`
+  - `first_usable`
+  - `hex`
+  - `host`
+  - `last_usable`
+  - `mask_bits`
+  - `netmask`
+  - `network`
+  - `octets`: Decimal values per byte
+  - `port`
+  - `size`: Number of hosts in the network
+
+IPv4Addr Type:
+  - `broadcast`
+  - `uint32`: unsigned integer representation of the value
+
+IPv6Addr Type:
+  - `uint128`: unsigned integer representation of the value
+
+UnixSock Type:
+  - `path`
+
+*/
+package template

vendor/github.com/hashicorp/go-sockaddr/template/template.go

@@ -0,0 +1,125 @@
+package template
+
+import (
+	"bytes"
+	"fmt"
+	"text/template"
+
+	"github.com/hashicorp/errwrap"
+	sockaddr "github.com/hashicorp/go-sockaddr"
+)
+
+var (
+	// SourceFuncs is a map of all top-level functions that generate
+	// sockaddr data types.
+	SourceFuncs template.FuncMap
+
+	// SortFuncs is a map of all functions used in sorting
+	SortFuncs template.FuncMap
+
+	// FilterFuncs is a map of all functions used in sorting
+	FilterFuncs template.FuncMap
+
+	// HelperFuncs is a map of all functions used in sorting
+	HelperFuncs template.FuncMap
+)
+
+func init() {
+	SourceFuncs = template.FuncMap{
+		// GetAllInterfaces - Returns an exhaustive set of IfAddr
+		// structs available on the host.  `GetAllInterfaces` is the
+		// initial input and accessible as the initial "dot" in the
+		// pipeline.
+		"GetAllInterfaces": sockaddr.GetAllInterfaces,
+
+		// GetDefaultInterfaces - Returns one IfAddr for every IP that
+		// is on the interface containing the default route for the
+		// host.
+		"GetDefaultInterfaces": sockaddr.GetDefaultInterfaces,
+
+		// GetPrivateInterfaces - Returns one IfAddr for every IP that
+		// matches RFC 6890, are attached to the interface with the
+		// default route, and are forwardable IP addresses.  NOTE: RFC
+		// 6890 is a more exhaustive version of RFC1918 because it spans
+		// IPv4 and IPv6, however it doespermit the inclusion of likely
+		// undesired addresses such as multicast, therefore our
+		// definition of a "private" address also excludes
+		// non-forwardable IP addresses (as defined by the IETF).
+		"GetPrivateInterfaces": sockaddr.GetPrivateInterfaces,
+
+		// GetPublicInterfaces - Returns a list of IfAddr that do not
+		// match RFC 6890, are attached to the default route, and are
+		// forwardable.
+		"GetPublicInterfaces": sockaddr.GetPublicInterfaces,
+	}
+
+	SortFuncs = template.FuncMap{
+		"sort": sockaddr.SortIfBy,
+	}
+
+	FilterFuncs = template.FuncMap{
+		"exclude": sockaddr.ExcludeIfs,
+		"include": sockaddr.IncludeIfs,
+	}
+
+	HelperFuncs = template.FuncMap{
+		// Misc functions that operate on IfAddrs inputs
+		"attr":   sockaddr.IfAttr,
+		"join":   sockaddr.JoinIfAddrs,
+		"limit":  sockaddr.LimitIfAddrs,
+		"offset": sockaddr.OffsetIfAddrs,
+		"unique": sockaddr.UniqueIfAddrsBy,
+
+		// Return a Private RFC 6890 IP address string that is attached
+		// to the default route and a forwardable address.
+		"GetPrivateIP": sockaddr.GetPrivateIP,
+
+		// Return a Public RFC 6890 IP address string that is attached
+		// to the default route and a forwardable address.
+		"GetPublicIP": sockaddr.GetPublicIP,
+
+		// Return the first IP address of the named interface, sorted by
+		// the largest network size.
+		"GetInterfaceIP": sockaddr.GetInterfaceIP,
+	}
+}
+
+// Parse parses input as template input using the addresses available on the
+// host, then returns the string output if there are no errors.
+func Parse(input string) (string, error) {
+	addrs, err := sockaddr.GetAllInterfaces()
+	if err != nil {
+		return "", errwrap.Wrapf("unable to query interface addresses: {{err}}", err)
+	}
+
+	return ParseIfAddrs(input, addrs)
+}
+
+// ParseIfAddrs parses input as template input using the IfAddrs inputs, then
+// returns the string output if there are no errors.
+func ParseIfAddrs(input string, ifAddrs sockaddr.IfAddrs) (string, error) {
+	return ParseIfAddrsTemplate(input, ifAddrs, template.New("sockaddr.Parse"))
+}
+
+// ParseIfAddrsTemplate parses input as template input using the IfAddrs inputs,
+// then returns the string output if there are no errors.
+func ParseIfAddrsTemplate(input string, ifAddrs sockaddr.IfAddrs, tmplIn *template.Template) (string, error) {
+	// Create a template, add the function map, and parse the text.
+	tmpl, err := tmplIn.Option("missingkey=error").
+		Funcs(SourceFuncs).
+		Funcs(SortFuncs).
+		Funcs(FilterFuncs).
+		Funcs(HelperFuncs).
+		Parse(input)
+	if err != nil {
+		return "", errwrap.Wrapf(fmt.Sprintf("unable to parse template %+q: {{err}}", input), err)
+	}
+
+	var outWriter bytes.Buffer
+	err = tmpl.Execute(&outWriter, ifAddrs)
+	if err != nil {
+		return "", errwrap.Wrapf(fmt.Sprintf("unable to execute sockaddr input %+q: {{err}}", input), err)
+	}
+
+	return outWriter.String(), nil
+}

vendor/vendor.json

@@ -793,6 +793,12 @@
 			"revision": "f910dd83c2052566cad78352c33af714358d1372",
 			"revisionTime": "2017-02-08T07:30:35Z"
 		},
+		{
+			"checksumSHA1": "lPzwetgfMBtpHqdTPolgejMctVQ=",
+			"path": "github.com/hashicorp/go-sockaddr/template",
+			"revision": "f910dd83c2052566cad78352c33af714358d1372",
+			"revisionTime": "2017-02-08T07:30:35Z"
+		},
 		{
 			"path": "github.com/hashicorp/go-syslog",
 			"revision": "42a2b573b664dbf281bd48c3cc12c086b17a39ba"