Add HashiCorp Nomad provider (#483)

* provider: adding Nomad provider

* updating CONTRIBUTING.md with Nomad provider

* updated README.md by adding the Nomad provider

* fix typo

* adding nomad/api and nomad/testutil deps

* adding Nomad binary dependency for provider tests

* fixed the nomad binary download command step and added tolerations to the nomad provider.

* adding nomad provider demo gif

* adding my name to authors

* adding two missing go-rootcerts files after dep ensure

* delete pod comment

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

@@ -0,0 +1,135 @@
+package sockaddr
+
+import (
+	"fmt"
+	"strings"
+)
+
+type UnixSock struct {
+	SockAddr
+	path string
+}
+type UnixSocks []*UnixSock
+
+// unixAttrMap is a map of the UnixSockAddr type-specific attributes.
+var unixAttrMap map[AttrName]func(UnixSock) string
+var unixAttrs []AttrName
+
+func init() {
+	unixAttrInit()
+}
+
+// NewUnixSock creates an UnixSock from a string path.  String can be in the
+// form of either URI-based string (e.g. `file:///etc/passwd`), an absolute
+// path (e.g. `/etc/passwd`), or a relative path (e.g. `./foo`).
+func NewUnixSock(s string) (ret UnixSock, err error) {
+	ret.path = s
+	return ret, nil
+}
+
+// CmpAddress follows the Cmp() standard protocol and returns:
+//
+// - -1 If the receiver should sort first because its name lexically sorts before arg
+// - 0 if the SockAddr arg is not a UnixSock, or is a UnixSock with the same path.
+// - 1 If the argument should sort first.
+func (us UnixSock) CmpAddress(sa SockAddr) int {
+	usb, ok := sa.(UnixSock)
+	if !ok {
+		return sortDeferDecision
+	}
+
+	return strings.Compare(us.Path(), usb.Path())
+}
+
+// DialPacketArgs returns the arguments required to be passed to net.DialUnix()
+// with the `unixgram` network type.
+func (us UnixSock) DialPacketArgs() (network, dialArgs string) {
+	return "unixgram", us.path
+}
+
+// DialStreamArgs returns the arguments required to be passed to net.DialUnix()
+// with the `unix` network type.
+func (us UnixSock) DialStreamArgs() (network, dialArgs string) {
+	return "unix", us.path
+}
+
+// Equal returns true if a SockAddr is equal to the receiving UnixSock.
+func (us UnixSock) Equal(sa SockAddr) bool {
+	usb, ok := sa.(UnixSock)
+	if !ok {
+		return false
+	}
+
+	if us.Path() != usb.Path() {
+		return false
+	}
+
+	return true
+}
+
+// ListenPacketArgs returns the arguments required to be passed to
+// net.ListenUnixgram() with the `unixgram` network type.
+func (us UnixSock) ListenPacketArgs() (network, dialArgs string) {
+	return "unixgram", us.path
+}
+
+// ListenStreamArgs returns the arguments required to be passed to
+// net.ListenUnix() with the `unix` network type.
+func (us UnixSock) ListenStreamArgs() (network, dialArgs string) {
+	return "unix", us.path
+}
+
+// MustUnixSock is a helper method that must return an UnixSock or panic on
+// invalid input.
+func MustUnixSock(addr string) UnixSock {
+	us, err := NewUnixSock(addr)
+	if err != nil {
+		panic(fmt.Sprintf("Unable to create a UnixSock from %+q: %v", addr, err))
+	}
+	return us
+}
+
+// Path returns the given path of the UnixSock
+func (us UnixSock) Path() string {
+	return us.path
+}
+
+// String returns the path of the UnixSock
+func (us UnixSock) String() string {
+	return fmt.Sprintf("%+q", us.path)
+}
+
+// Type is used as a type switch and returns TypeUnix
+func (UnixSock) Type() SockAddrType {
+	return TypeUnix
+}
+
+// UnixSockAttrs returns a list of attributes supported by the UnixSockAddr type
+func UnixSockAttrs() []AttrName {
+	return unixAttrs
+}
+
+// UnixSockAttr returns a string representation of an attribute for the given
+// UnixSock.
+func UnixSockAttr(us UnixSock, attrName AttrName) string {
+	fn, found := unixAttrMap[attrName]
+	if !found {
+		return ""
+	}
+
+	return fn(us)
+}
+
+// unixAttrInit is called once at init()
+func unixAttrInit() {
+	// Sorted for human readability
+	unixAttrs = []AttrName{
+		"path",
+	}
+
+	unixAttrMap = map[AttrName]func(us UnixSock) string{
+		"path": func(us UnixSock) string {
+			return us.Path()
+		},
+	}
+}