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table.go
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table.go
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package route
import (
"errors"
"fmt"
"log"
"net/http"
"net/url"
"sort"
"strings"
"sync"
"sync/atomic"
"github.com/eBay/fabio/metrics"
)
var errInvalidPrefix = errors.New("route: prefix must not be empty")
var errInvalidTarget = errors.New("route: target must not be empty")
var errNoMatch = errors.New("route: no target match")
// table stores the active routing table. Must never be nil.
var table atomic.Value
// ServiceRegistry stores the metrics for the services.
var ServiceRegistry metrics.Registry = metrics.NoopRegistry{}
// init initializes the routing table.
func init() {
table.Store(make(Table))
}
// GetTable returns the active routing table. The function
// is safe to be called from multiple goroutines and the
// value is never nil.
func GetTable() Table {
return table.Load().(Table)
}
// mu guards table and registry in SetTable.
var mu sync.Mutex
// SetTable sets the active routing table. A nil value
// logs a warning and is ignored. The function is safe
// to be called from multiple goroutines.
func SetTable(t Table) {
if t == nil {
log.Print("[WARN] Ignoring nil routing table")
return
}
mu.Lock()
table.Store(t)
syncRegistry(t)
mu.Unlock()
}
// syncRegistry unregisters all inactive timers.
// It assumes that all timers of the table have
// already been registered.
func syncRegistry(t Table) {
timers := map[string]bool{}
// get all registered timers
for _, name := range ServiceRegistry.Names() {
timers[name] = false
}
// mark the ones from this table as active.
// this can also add new entries but we do not
// really care since we are only interested in the
// inactive ones.
for _, routes := range t {
for _, r := range routes {
for _, tg := range r.Targets {
timers[tg.timerName] = true
}
}
}
// unregister inactive timers
for name, active := range timers {
if !active {
ServiceRegistry.Unregister(name)
log.Printf("[INFO] Unregistered timer %s", name)
}
}
}
// Table contains a set of routes grouped by host.
// The host routes are sorted from most to least specific
// by sorting the routes in reverse order by path.
type Table map[string]Routes
// hostpath splits a host/path prefix into a host and a path.
// The path always starts with a slash
func hostpath(prefix string) (host string, path string) {
p := strings.SplitN(prefix, "/", 2)
host, path = p[0], ""
if len(p) == 1 {
return p[0], "/"
}
return p[0], "/" + p[1]
}
func NewTable(s string) (t Table, err error) {
defs, err := Parse(s)
if err != nil {
return nil, err
}
t = make(Table)
for _, d := range defs {
switch d.Cmd {
case RouteAddCmd:
err = t.addRoute(d)
case RouteDelCmd:
err = t.delRoute(d)
case RouteWeightCmd:
err = t.weighRoute(d)
default:
err = fmt.Errorf("route: invalid command: %s", d.Cmd)
}
if err != nil {
return nil, err
}
}
return t, nil
}
// addRoute adds a new route prefix -> target for the given service.
func (t Table) addRoute(d *RouteDef) error {
host, path := hostpath(d.Src)
if d.Src == "" {
return errInvalidPrefix
}
if d.Dst == "" {
return errInvalidTarget
}
targetURL, err := url.Parse(d.Dst)
if err != nil {
return fmt.Errorf("route: invalid target. %s", err)
}
switch {
// add new host
case t[host] == nil:
r := &Route{Host: host, Path: path, Opts: d.Opts}
r.addTarget(d.Service, targetURL, d.Weight, d.Tags)
t[host] = Routes{r}
// add new route to existing host
case t[host].find(path) == nil:
r := &Route{Host: host, Path: path, Opts: d.Opts}
r.addTarget(d.Service, targetURL, d.Weight, d.Tags)
t[host] = append(t[host], r)
sort.Sort(t[host])
// add new target to existing route
default:
t[host].find(path).addTarget(d.Service, targetURL, d.Weight, d.Tags)
}
return nil
}
func (t Table) weighRoute(d *RouteDef) error {
host, path := hostpath(d.Src)
if d.Src == "" {
return errInvalidPrefix
}
if t[host] == nil || t[host].find(path) == nil {
return errNoMatch
}
if n := t[host].find(path).setWeight(d.Service, d.Weight, d.Tags); n == 0 {
return errNoMatch
}
return nil
}
// delRoute removes one or more routes depending on the arguments.
// If service, prefix and target are provided then only this route
// is removed. Are only service and prefix provided then all routes
// for this service and prefix are removed. This removes all active
// instances of the service from the route. If only the service is
// provided then all routes for this service are removed. The service
// will no longer receive traffic. Routes with no targets are removed.
func (t Table) delRoute(d *RouteDef) error {
switch {
case len(d.Tags) > 0:
for _, routes := range t {
for _, r := range routes {
r.filter(func(tg *Target) bool {
return (d.Service == "" || tg.Service == d.Service) && contains(tg.Tags, d.Tags)
})
}
}
case d.Src == "" && d.Dst == "":
for _, routes := range t {
for _, r := range routes {
r.filter(func(tg *Target) bool {
return tg.Service == d.Service
})
}
}
case d.Dst == "":
r := t.route(hostpath(d.Src))
if r == nil {
return nil
}
r.filter(func(tg *Target) bool {
return tg.Service == d.Service
})
default:
targetURL, err := url.Parse(d.Dst)
if err != nil {
return fmt.Errorf("route: invalid target. %s", err)
}
r := t.route(hostpath(d.Src))
if r == nil {
return nil
}
r.filter(func(tg *Target) bool {
return tg.Service == d.Service && tg.URL.String() == targetURL.String()
})
}
// remove all routes without targets
for host, routes := range t {
var clone Routes
for _, r := range routes {
if len(r.Targets) == 0 {
continue
}
clone = append(clone, r)
}
t[host] = clone
}
// remove all hosts without routes
for host, routes := range t {
if len(routes) == 0 {
delete(t, host)
}
}
return nil
}
// route finds the route for host/path or returns nil if none exists.
func (t Table) route(host, path string) *Route {
routes := t[host]
if routes == nil {
return nil
}
return routes.find(path)
}
// normalizeHost returns the hostname from the request
// and removes the default port if present.
func normalizeHost(req *http.Request) string {
host := strings.ToLower(req.Host)
if req.TLS == nil && strings.HasSuffix(host, ":80") {
return host[:len(host)-len(":80")]
}
if req.TLS != nil && strings.HasSuffix(host, ":443") {
return host[:len(host)-len(":443")]
}
return host
}
// Lookup finds a target url based on the current matcher and picker
// or nil if there is none. It first checks the routes for the host
// and if none matches then it falls back to generic routes without
// a host. This is useful for a catch-all '/' rule.
func (t Table) Lookup(req *http.Request, trace string) *Target {
path := req.URL.Path
if trace != "" {
if len(trace) > 16 {
trace = trace[:15]
}
log.Printf("[TRACE] %s Tracing %s%s", trace, req.Host, path)
}
target := t.lookup(normalizeHost(req), path, trace)
if target == nil {
target = t.lookup("", path, trace)
}
if target != nil && trace != "" {
log.Printf("[TRACE] %s Routing to service %s on %s", trace, target.Service, target.URL)
}
return target
}
func (t Table) LookupHost(host string) *Target {
return t.lookup(host, "/", "")
}
func (t Table) lookup(host, path, trace string) *Target {
for _, r := range t[host] {
if match(path, r) {
n := len(r.Targets)
if n == 0 {
return nil
}
var target *Target
if n == 1 {
target = r.Targets[0]
} else {
target = pick(r)
}
if trace != "" {
log.Printf("[TRACE] %s Match %s%s", trace, r.Host, r.Path)
}
return target
}
if trace != "" {
log.Printf("[TRACE] %s No match %s%s", trace, r.Host, r.Path)
}
}
return nil
}
func (t Table) config(addWeight bool) []string {
var hosts []string
for host := range t {
if host != "" {
hosts = append(hosts, host)
}
}
sort.Strings(hosts)
// entries without host come last
hosts = append(hosts, "")
var cfg []string
for _, host := range hosts {
for _, routes := range t[host] {
cfg = append(cfg, routes.config(addWeight)...)
}
}
return cfg
}
// String returns the routing table as config file which can
// be read by Parse() again.
func (t Table) String() string {
return strings.Join(t.config(false), "\n")
}