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/raft/commands.go

@@ -0,0 +1,151 @@
+package raft
+
+// RPCHeader is a common sub-structure used to pass along protocol version and
+// other information about the cluster. For older Raft implementations before
+// versioning was added this will default to a zero-valued structure when read
+// by newer Raft versions.
+type RPCHeader struct {
+	// ProtocolVersion is the version of the protocol the sender is
+	// speaking.
+	ProtocolVersion ProtocolVersion
+}
+
+// WithRPCHeader is an interface that exposes the RPC header.
+type WithRPCHeader interface {
+	GetRPCHeader() RPCHeader
+}
+
+// AppendEntriesRequest is the command used to append entries to the
+// replicated log.
+type AppendEntriesRequest struct {
+	RPCHeader
+
+	// Provide the current term and leader
+	Term   uint64
+	Leader []byte
+
+	// Provide the previous entries for integrity checking
+	PrevLogEntry uint64
+	PrevLogTerm  uint64
+
+	// New entries to commit
+	Entries []*Log
+
+	// Commit index on the leader
+	LeaderCommitIndex uint64
+}
+
+// See WithRPCHeader.
+func (r *AppendEntriesRequest) GetRPCHeader() RPCHeader {
+	return r.RPCHeader
+}
+
+// AppendEntriesResponse is the response returned from an
+// AppendEntriesRequest.
+type AppendEntriesResponse struct {
+	RPCHeader
+
+	// Newer term if leader is out of date
+	Term uint64
+
+	// Last Log is a hint to help accelerate rebuilding slow nodes
+	LastLog uint64
+
+	// We may not succeed if we have a conflicting entry
+	Success bool
+
+	// There are scenarios where this request didn't succeed
+	// but there's no need to wait/back-off the next attempt.
+	NoRetryBackoff bool
+}
+
+// See WithRPCHeader.
+func (r *AppendEntriesResponse) GetRPCHeader() RPCHeader {
+	return r.RPCHeader
+}
+
+// RequestVoteRequest is the command used by a candidate to ask a Raft peer
+// for a vote in an election.
+type RequestVoteRequest struct {
+	RPCHeader
+
+	// Provide the term and our id
+	Term      uint64
+	Candidate []byte
+
+	// Used to ensure safety
+	LastLogIndex uint64
+	LastLogTerm  uint64
+}
+
+// See WithRPCHeader.
+func (r *RequestVoteRequest) GetRPCHeader() RPCHeader {
+	return r.RPCHeader
+}
+
+// RequestVoteResponse is the response returned from a RequestVoteRequest.
+type RequestVoteResponse struct {
+	RPCHeader
+
+	// Newer term if leader is out of date.
+	Term uint64
+
+	// Peers is deprecated, but required by servers that only understand
+	// protocol version 0. This is not populated in protocol version 2
+	// and later.
+	Peers []byte
+
+	// Is the vote granted.
+	Granted bool
+}
+
+// See WithRPCHeader.
+func (r *RequestVoteResponse) GetRPCHeader() RPCHeader {
+	return r.RPCHeader
+}
+
+// InstallSnapshotRequest is the command sent to a Raft peer to bootstrap its
+// log (and state machine) from a snapshot on another peer.
+type InstallSnapshotRequest struct {
+	RPCHeader
+	SnapshotVersion SnapshotVersion
+
+	Term   uint64
+	Leader []byte
+
+	// These are the last index/term included in the snapshot
+	LastLogIndex uint64
+	LastLogTerm  uint64
+
+	// Peer Set in the snapshot. This is deprecated in favor of Configuration
+	// but remains here in case we receive an InstallSnapshot from a leader
+	// that's running old code.
+	Peers []byte
+
+	// Cluster membership.
+	Configuration []byte
+	// Log index where 'Configuration' entry was originally written.
+	ConfigurationIndex uint64
+
+	// Size of the snapshot
+	Size int64
+}
+
+// See WithRPCHeader.
+func (r *InstallSnapshotRequest) GetRPCHeader() RPCHeader {
+	return r.RPCHeader
+}
+
+// InstallSnapshotResponse is the response returned from an
+// InstallSnapshotRequest.
+type InstallSnapshotResponse struct {
+	RPCHeader
+
+	Term    uint64
+	Success bool
+}
+
+// See WithRPCHeader.
+func (r *InstallSnapshotResponse) GetRPCHeader() RPCHeader {
+	return r.RPCHeader
+}