open-consul/agent/consul/util.go

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package consul
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import (
"runtime"
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"strconv"
"github.com/hashicorp/go-version"
"github.com/hashicorp/serf/serf"
"github.com/hashicorp/consul/agent/metadata"
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)
// CanServersUnderstandProtocol checks to see if all the servers in the given
// list understand the given protocol version. If there are no servers in the
// list then this will return false.
func CanServersUnderstandProtocol(members []serf.Member, version uint8) (bool, error) {
numServers, numWhoGrok := 0, 0
for _, m := range members {
if m.Tags["role"] != "consul" {
continue
}
numServers++
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vsnMin, err := strconv.Atoi(m.Tags["vsn_min"])
if err != nil {
return false, err
}
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vsnMax, err := strconv.Atoi(m.Tags["vsn_max"])
if err != nil {
return false, err
}
v := int(version)
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if (v >= vsnMin) && (v <= vsnMax) {
numWhoGrok++
}
}
return (numServers > 0) && (numWhoGrok == numServers), nil
}
// Returns if a member is a consul node. Returns a bool,
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// and the datacenter.
func isConsulNode(m serf.Member) (bool, string) {
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if m.Tags["role"] != "node" {
return false, ""
}
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return true, m.Tags["dc"]
}
// runtimeStats is used to return various runtime information
func runtimeStats() map[string]string {
return map[string]string{
"os": runtime.GOOS,
"arch": runtime.GOARCH,
"version": runtime.Version(),
"max_procs": strconv.FormatInt(int64(runtime.GOMAXPROCS(0)), 10),
"goroutines": strconv.FormatInt(int64(runtime.NumGoroutine()), 10),
"cpu_count": strconv.FormatInt(int64(runtime.NumCPU()), 10),
}
}
// checkServersProvider exists so that we can unit tests the requirements checking functions
// without having to spin up a whole agent/server.
type checkServersProvider interface {
CheckServers(datacenter string, fn func(*metadata.Server) bool)
}
// serverRequirementsFn should inspect the given metadata.Server struct
// and return two booleans. The first indicates whether the given requirements
// are met. The second indicates whether this server should be considered filtered.
//
// The reason for the two booleans is so that a requirement function could "filter"
// out the left server members if we only want to consider things which are still
// around or likely to come back (failed state).
type serverRequirementFn func(*metadata.Server) (ok bool, filtered bool)
type serversMeetRequirementsState struct {
// meetsRequirements is the callback to actual check for some specific requirement
meetsRequirements serverRequirementFn
// ok indicates whether all unfiltered servers meet the desired requirements
ok bool
// found is a boolean indicating that the meetsRequirement function accepted at
// least one unfiltered server.
found bool
}
func (s *serversMeetRequirementsState) update(srv *metadata.Server) bool {
ok, filtered := s.meetsRequirements(srv)
if filtered {
// keep going but don't update any of the internal state as this server
// was filtered by the requirements function
return true
}
// mark that at least one server processed was not filtered
s.found = true
if !ok {
// mark that at least one server does not meet the requirements
s.ok = false
// prevent continuing server evaluation
return false
}
// this should already be set but this will prevent accidentally reusing
// the state object from causing false-negatives.
s.ok = true
// continue evaluating servers
return true
}
// ServersInDCMeetRequirements returns whether the given server members meet the requirements as defined by the
// callback function and whether at least one server remains unfiltered by the requirements function.
func ServersInDCMeetRequirements(provider checkServersProvider, datacenter string, meetsRequirements serverRequirementFn) (ok bool, found bool) {
state := serversMeetRequirementsState{meetsRequirements: meetsRequirements, found: false, ok: true}
provider.CheckServers(datacenter, state.update)
return state.ok, state.found
}
// ServersInDCMeetMinimumVersion returns whether the given alive servers from a particular
// datacenter are at least on the given Consul version. This also returns whether any
// alive or failed servers are known in that datacenter (ignoring left and leaving ones)
func ServersInDCMeetMinimumVersion(provider checkServersProvider, datacenter string, minVersion *version.Version) (ok bool, found bool) {
return ServersInDCMeetRequirements(provider, datacenter, func(srv *metadata.Server) (bool, bool) {
if srv.Status != serf.StatusAlive && srv.Status != serf.StatusFailed {
// filter out the left servers as those should not be factored into our requirements
return true, true
}
return !srv.Build.LessThan(minVersion), false
})
}
// CheckServers implements the checkServersProvider interface for the Server
func (s *Server) CheckServers(datacenter string, fn func(*metadata.Server) bool) {
if datacenter == s.config.Datacenter {
// use the ServerLookup type for the local DC
s.serverLookup.CheckServers(fn)
} else {
// use the router for all non-local DCs
s.router.CheckServers(datacenter, fn)
}
}
// CheckServers implements the checkServersProvider interface for the Client
func (c *Client) CheckServers(datacenter string, fn func(*metadata.Server) bool) {
if datacenter != c.config.Datacenter {
return
}
c.router.CheckServers(datacenter, fn)
}