open-consul/agent/metadata/server.go
R.B. Boyer a7fb26f50f
wan federation via mesh gateways (#6884)
This is like a Möbius strip of code due to the fact that low-level components (serf/memberlist) are connected to high-level components (the catalog and mesh-gateways) in a twisty maze of references which make it hard to dive into. With that in mind here's a high level summary of what you'll find in the patch:

There are several distinct chunks of code that are affected:

* new flags and config options for the server

* retry join WAN is slightly different

* retry join code is shared to discover primary mesh gateways from secondary datacenters

* because retry join logic runs in the *agent* and the results of that
  operation for primary mesh gateways are needed in the *server* there are
  some methods like `RefreshPrimaryGatewayFallbackAddresses` that must occur
  at multiple layers of abstraction just to pass the data down to the right
  layer.

* new cache type `FederationStateListMeshGatewaysName` for use in `proxycfg/xds` layers

* the function signature for RPC dialing picked up a new required field (the
  node name of the destination)

* several new RPCs for manipulating a FederationState object:
  `FederationState:{Apply,Get,List,ListMeshGateways}`

* 3 read-only internal APIs for debugging use to invoke those RPCs from curl

* raft and fsm changes to persist these FederationStates

* replication for FederationStates as they are canonically stored in the
  Primary and replicated to the Secondaries.

* a special derivative of anti-entropy that runs in secondaries to snapshot
  their local mesh gateway `CheckServiceNodes` and sync them into their upstream
  FederationState in the primary (this works in conjunction with the
  replication to distribute addresses for all mesh gateways in all DCs to all
  other DCs)

* a "gateway locator" convenience object to make use of this data to choose
  the addresses of gateways to use for any given RPC or gossip operation to a
  remote DC. This gets data from the "retry join" logic in the agent and also
  directly calls into the FSM.

* RPC (`:8300`) on the server sniffs the first byte of a new connection to
  determine if it's actually doing native TLS. If so it checks the ALPN header
  for protocol determination (just like how the existing system uses the
  type-byte marker).

* 2 new kinds of protocols are exclusively decoded via this native TLS
  mechanism: one for ferrying "packet" operations (udp-like) from the gossip
  layer and one for "stream" operations (tcp-like). The packet operations
  re-use sockets (using length-prefixing) to cut down on TLS re-negotiation
  overhead.

* the server instances specially wrap the `memberlist.NetTransport` when running
  with gateway federation enabled (in a `wanfed.Transport`). The general gist is
  that if it tries to dial a node in the SAME datacenter (deduced by looking
  at the suffix of the node name) there is no change. If dialing a DIFFERENT
  datacenter it is wrapped up in a TLS+ALPN blob and sent through some mesh
  gateways to eventually end up in a server's :8300 port.

* a new flag when launching a mesh gateway via `consul connect envoy` to
  indicate that the servers are to be exposed. This sets a special service
  meta when registering the gateway into the catalog.

* `proxycfg/xds` notice this metadata blob to activate additional watches for
  the FederationState objects as well as the location of all of the consul
  servers in that datacenter.

* `xds:` if the extra metadata is in place additional clusters are defined in a
  DC to bulk sink all traffic to another DC's gateways. For the current
  datacenter we listen on a wildcard name (`server.<dc>.consul`) that load
  balances all servers as well as one mini-cluster per node
  (`<node>.server.<dc>.consul`)

* the `consul tls cert create` command got a new flag (`-node`) to help create
  an additional SAN in certs that can be used with this flavor of federation.
2020-03-09 15:59:02 -05:00

191 lines
4.1 KiB
Go

package metadata
import (
"fmt"
"net"
"regexp"
"strconv"
"strings"
"github.com/hashicorp/consul/agent/structs"
"github.com/hashicorp/go-version"
"github.com/hashicorp/serf/serf"
)
// Key is used in maps and for equality tests. A key is based on endpoints.
type Key struct {
name string
}
// Equal compares two Key objects
func (k *Key) Equal(x *Key) bool {
return k.name == x.name
}
// Server is used to return details of a consul server
type Server struct {
Name string // <node>.<dc>
ShortName string // <node>
ID string
Datacenter string
Segment string
Port int
SegmentAddrs map[string]string
SegmentPorts map[string]int
WanJoinPort int
Bootstrap bool
Expect int
Build version.Version
Version int
RaftVersion int
Addr net.Addr
Status serf.MemberStatus
NonVoter bool
ACLs structs.ACLMode
FeatureFlags map[string]int
// If true, use TLS when connecting to this server
UseTLS bool
}
// Key returns the corresponding Key
func (s *Server) Key() *Key {
return &Key{
name: s.Name,
}
}
// String returns a string representation of Server
func (s *Server) String() string {
var addrStr, networkStr string
if s.Addr != nil {
addrStr = s.Addr.String()
networkStr = s.Addr.Network()
}
return fmt.Sprintf("%s (Addr: %s/%s) (DC: %s)", s.Name, networkStr, addrStr, s.Datacenter)
}
var versionFormat = regexp.MustCompile(`\d+\.\d+\.\d+`)
// IsConsulServer returns true if a serf member is a consul server
// agent. Returns a bool and a pointer to the Server.
func IsConsulServer(m serf.Member) (bool, *Server) {
if m.Tags["role"] != "consul" {
return false, nil
}
datacenter := m.Tags["dc"]
segment := m.Tags["segment"]
_, bootstrap := m.Tags["bootstrap"]
_, useTLS := m.Tags["use_tls"]
expect := 0
expectStr, ok := m.Tags["expect"]
var err error
if ok {
expect, err = strconv.Atoi(expectStr)
if err != nil {
return false, nil
}
}
portStr := m.Tags["port"]
port, err := strconv.Atoi(portStr)
if err != nil {
return false, nil
}
var acls structs.ACLMode
if aclMode, ok := m.Tags["acls"]; ok {
acls = structs.ACLMode(aclMode)
} else {
acls = structs.ACLModeUnknown
}
segmentAddrs := make(map[string]string)
segmentPorts := make(map[string]int)
featureFlags := make(map[string]int)
for name, value := range m.Tags {
if strings.HasPrefix(name, "sl_") {
addr, port, err := net.SplitHostPort(value)
if err != nil {
return false, nil
}
segmentPort, err := strconv.Atoi(port)
if err != nil {
return false, nil
}
segmentName := strings.TrimPrefix(name, "sl_")
segmentAddrs[segmentName] = addr
segmentPorts[segmentName] = segmentPort
} else if strings.HasPrefix(name, "ft_") {
featureName := strings.TrimPrefix(name, "ft_")
featureState, err := strconv.Atoi(value)
if err != nil {
return false, nil
}
featureFlags[featureName] = featureState
}
}
buildVersion, err := Build(&m)
if err != nil {
return false, nil
}
wanJoinPort := 0
wanJoinPortStr, ok := m.Tags["wan_join_port"]
if ok {
wanJoinPort, err = strconv.Atoi(wanJoinPortStr)
if err != nil {
return false, nil
}
}
vsnStr := m.Tags["vsn"]
vsn, err := strconv.Atoi(vsnStr)
if err != nil {
return false, nil
}
raftVsn := 0
raftVsnStr, ok := m.Tags["raft_vsn"]
if ok {
raftVsn, err = strconv.Atoi(raftVsnStr)
if err != nil {
return false, nil
}
}
// Check if the server is a non voter
_, nonVoter := m.Tags["nonvoter"]
addr := &net.TCPAddr{IP: m.Addr, Port: port}
parts := &Server{
Name: m.Name,
ShortName: strings.TrimSuffix(m.Name, "."+datacenter),
ID: m.Tags["id"],
Datacenter: datacenter,
Segment: segment,
Port: port,
SegmentAddrs: segmentAddrs,
SegmentPorts: segmentPorts,
WanJoinPort: wanJoinPort,
Bootstrap: bootstrap,
Expect: expect,
Addr: addr,
Build: *buildVersion,
Version: vsn,
RaftVersion: raftVsn,
Status: m.Status,
UseTLS: useTLS,
NonVoter: nonVoter,
ACLs: acls,
FeatureFlags: featureFlags,
}
return true, parts
}