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
This commit is contained in:
Anubhav Mishra
committed by
Robbie Zhang
Robbie Zhang
parent
5796be449b
commit
a46e1dd2ce
343
vendor/github.com/hashicorp/raft/configuration.go
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vendored
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343
vendor/github.com/hashicorp/raft/configuration.go
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package raft
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import "fmt"
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// ServerSuffrage determines whether a Server in a Configuration gets a vote.
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type ServerSuffrage int
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// Note: Don't renumber these, since the numbers are written into the log.
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const (
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// Voter is a server whose vote is counted in elections and whose match index
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// is used in advancing the leader's commit index.
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Voter ServerSuffrage = iota
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// Nonvoter is a server that receives log entries but is not considered for
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// elections or commitment purposes.
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Nonvoter
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// Staging is a server that acts like a nonvoter with one exception: once a
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// staging server receives enough log entries to be sufficiently caught up to
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// the leader's log, the leader will invoke a membership change to change
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// the Staging server to a Voter.
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Staging
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)
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func (s ServerSuffrage) String() string {
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switch s {
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case Voter:
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return "Voter"
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case Nonvoter:
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return "Nonvoter"
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case Staging:
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return "Staging"
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}
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return "ServerSuffrage"
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}
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// ServerID is a unique string identifying a server for all time.
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type ServerID string
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// ServerAddress is a network address for a server that a transport can contact.
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type ServerAddress string
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// Server tracks the information about a single server in a configuration.
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type Server struct {
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// Suffrage determines whether the server gets a vote.
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Suffrage ServerSuffrage
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// ID is a unique string identifying this server for all time.
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ID ServerID
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// Address is its network address that a transport can contact.
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Address ServerAddress
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}
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// Configuration tracks which servers are in the cluster, and whether they have
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// votes. This should include the local server, if it's a member of the cluster.
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// The servers are listed no particular order, but each should only appear once.
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// These entries are appended to the log during membership changes.
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type Configuration struct {
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Servers []Server
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}
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// Clone makes a deep copy of a Configuration.
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func (c *Configuration) Clone() (copy Configuration) {
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copy.Servers = append(copy.Servers, c.Servers...)
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return
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}
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// ConfigurationChangeCommand is the different ways to change the cluster
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// configuration.
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type ConfigurationChangeCommand uint8
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const (
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// AddStaging makes a server Staging unless its Voter.
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AddStaging ConfigurationChangeCommand = iota
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// AddNonvoter makes a server Nonvoter unless its Staging or Voter.
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AddNonvoter
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// DemoteVoter makes a server Nonvoter unless its absent.
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DemoteVoter
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// RemoveServer removes a server entirely from the cluster membership.
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RemoveServer
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// Promote is created automatically by a leader; it turns a Staging server
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// into a Voter.
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Promote
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)
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func (c ConfigurationChangeCommand) String() string {
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switch c {
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case AddStaging:
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return "AddStaging"
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case AddNonvoter:
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return "AddNonvoter"
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case DemoteVoter:
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return "DemoteVoter"
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case RemoveServer:
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return "RemoveServer"
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case Promote:
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return "Promote"
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}
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return "ConfigurationChangeCommand"
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}
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// configurationChangeRequest describes a change that a leader would like to
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// make to its current configuration. It's used only within a single server
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// (never serialized into the log), as part of `configurationChangeFuture`.
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type configurationChangeRequest struct {
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command ConfigurationChangeCommand
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serverID ServerID
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serverAddress ServerAddress // only present for AddStaging, AddNonvoter
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// prevIndex, if nonzero, is the index of the only configuration upon which
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// this change may be applied; if another configuration entry has been
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// added in the meantime, this request will fail.
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prevIndex uint64
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}
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// configurations is state tracked on every server about its Configurations.
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// Note that, per Diego's dissertation, there can be at most one uncommitted
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// configuration at a time (the next configuration may not be created until the
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// prior one has been committed).
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//
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// One downside to storing just two configurations is that if you try to take a
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// snahpsot when your state machine hasn't yet applied the committedIndex, we
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// have no record of the configuration that would logically fit into that
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// snapshot. We disallow snapshots in that case now. An alternative approach,
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// which LogCabin uses, is to track every configuration change in the
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// log.
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type configurations struct {
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// committed is the latest configuration in the log/snapshot that has been
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// committed (the one with the largest index).
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committed Configuration
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// committedIndex is the log index where 'committed' was written.
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committedIndex uint64
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// latest is the latest configuration in the log/snapshot (may be committed
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// or uncommitted)
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latest Configuration
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// latestIndex is the log index where 'latest' was written.
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latestIndex uint64
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}
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// Clone makes a deep copy of a configurations object.
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func (c *configurations) Clone() (copy configurations) {
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copy.committed = c.committed.Clone()
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copy.committedIndex = c.committedIndex
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copy.latest = c.latest.Clone()
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copy.latestIndex = c.latestIndex
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return
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}
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// hasVote returns true if the server identified by 'id' is a Voter in the
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// provided Configuration.
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func hasVote(configuration Configuration, id ServerID) bool {
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for _, server := range configuration.Servers {
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if server.ID == id {
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return server.Suffrage == Voter
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}
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}
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return false
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}
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// checkConfiguration tests a cluster membership configuration for common
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// errors.
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func checkConfiguration(configuration Configuration) error {
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idSet := make(map[ServerID]bool)
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addressSet := make(map[ServerAddress]bool)
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var voters int
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for _, server := range configuration.Servers {
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if server.ID == "" {
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return fmt.Errorf("Empty ID in configuration: %v", configuration)
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}
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if server.Address == "" {
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return fmt.Errorf("Empty address in configuration: %v", server)
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}
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if idSet[server.ID] {
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return fmt.Errorf("Found duplicate ID in configuration: %v", server.ID)
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}
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idSet[server.ID] = true
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if addressSet[server.Address] {
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return fmt.Errorf("Found duplicate address in configuration: %v", server.Address)
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}
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addressSet[server.Address] = true
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if server.Suffrage == Voter {
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voters++
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}
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}
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if voters == 0 {
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return fmt.Errorf("Need at least one voter in configuration: %v", configuration)
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}
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return nil
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}
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// nextConfiguration generates a new Configuration from the current one and a
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// configuration change request. It's split from appendConfigurationEntry so
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// that it can be unit tested easily.
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func nextConfiguration(current Configuration, currentIndex uint64, change configurationChangeRequest) (Configuration, error) {
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if change.prevIndex > 0 && change.prevIndex != currentIndex {
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return Configuration{}, fmt.Errorf("Configuration changed since %v (latest is %v)", change.prevIndex, currentIndex)
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}
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configuration := current.Clone()
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switch change.command {
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case AddStaging:
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// TODO: barf on new address?
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newServer := Server{
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// TODO: This should add the server as Staging, to be automatically
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// promoted to Voter later. However, the promoton to Voter is not yet
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// implemented, and doing so is not trivial with the way the leader loop
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// coordinates with the replication goroutines today. So, for now, the
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// server will have a vote right away, and the Promote case below is
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// unused.
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Suffrage: Voter,
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ID: change.serverID,
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Address: change.serverAddress,
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}
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found := false
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for i, server := range configuration.Servers {
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if server.ID == change.serverID {
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if server.Suffrage == Voter {
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configuration.Servers[i].Address = change.serverAddress
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} else {
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configuration.Servers[i] = newServer
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}
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found = true
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break
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}
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}
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if !found {
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configuration.Servers = append(configuration.Servers, newServer)
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}
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case AddNonvoter:
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newServer := Server{
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Suffrage: Nonvoter,
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ID: change.serverID,
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Address: change.serverAddress,
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}
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found := false
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for i, server := range configuration.Servers {
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if server.ID == change.serverID {
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if server.Suffrage != Nonvoter {
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configuration.Servers[i].Address = change.serverAddress
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} else {
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configuration.Servers[i] = newServer
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}
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found = true
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break
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}
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}
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if !found {
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configuration.Servers = append(configuration.Servers, newServer)
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}
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case DemoteVoter:
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for i, server := range configuration.Servers {
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if server.ID == change.serverID {
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configuration.Servers[i].Suffrage = Nonvoter
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break
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}
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}
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case RemoveServer:
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for i, server := range configuration.Servers {
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if server.ID == change.serverID {
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configuration.Servers = append(configuration.Servers[:i], configuration.Servers[i+1:]...)
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break
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}
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}
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case Promote:
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for i, server := range configuration.Servers {
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if server.ID == change.serverID && server.Suffrage == Staging {
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configuration.Servers[i].Suffrage = Voter
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break
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}
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}
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}
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// Make sure we didn't do something bad like remove the last voter
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if err := checkConfiguration(configuration); err != nil {
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return Configuration{}, err
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}
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return configuration, nil
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}
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// encodePeers is used to serialize a Configuration into the old peers format.
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// This is here for backwards compatibility when operating with a mix of old
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// servers and should be removed once we deprecate support for protocol version 1.
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func encodePeers(configuration Configuration, trans Transport) []byte {
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// Gather up all the voters, other suffrage types are not supported by
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// this data format.
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var encPeers [][]byte
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for _, server := range configuration.Servers {
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if server.Suffrage == Voter {
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encPeers = append(encPeers, trans.EncodePeer(server.ID, server.Address))
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}
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}
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// Encode the entire array.
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buf, err := encodeMsgPack(encPeers)
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if err != nil {
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panic(fmt.Errorf("failed to encode peers: %v", err))
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}
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return buf.Bytes()
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}
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// decodePeers is used to deserialize an old list of peers into a Configuration.
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// This is here for backwards compatibility with old log entries and snapshots;
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// it should be removed eventually.
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func decodePeers(buf []byte, trans Transport) Configuration {
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// Decode the buffer first.
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var encPeers [][]byte
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if err := decodeMsgPack(buf, &encPeers); err != nil {
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panic(fmt.Errorf("failed to decode peers: %v", err))
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}
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// Deserialize each peer.
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var servers []Server
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for _, enc := range encPeers {
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p := trans.DecodePeer(enc)
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servers = append(servers, Server{
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Suffrage: Voter,
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ID: ServerID(p),
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Address: ServerAddress(p),
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})
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}
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return Configuration{
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Servers: servers,
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}
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}
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// encodeConfiguration serializes a Configuration using MsgPack, or panics on
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// errors.
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func encodeConfiguration(configuration Configuration) []byte {
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buf, err := encodeMsgPack(configuration)
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if err != nil {
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panic(fmt.Errorf("failed to encode configuration: %v", err))
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}
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return buf.Bytes()
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}
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// decodeConfiguration deserializes a Configuration using MsgPack, or panics on
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// errors.
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func decodeConfiguration(buf []byte) Configuration {
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var configuration Configuration
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if err := decodeMsgPack(buf, &configuration); err != nil {
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panic(fmt.Errorf("failed to decode configuration: %v", err))
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}
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return configuration
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}
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