/
swarm.go
284 lines (230 loc) · 6.47 KB
/
swarm.go
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package swarm
import (
"context"
"fmt"
"io/ioutil"
"net"
"net/http"
"net/url"
"sync"
"time"
"github.com/docker/docker/api/types"
"github.com/docker/docker/api/types/swarm"
"github.com/docker/docker/client"
consul "github.com/hashicorp/consul/api"
"github.com/ngalayko/p2p/instance/peers"
"github.com/ngalayko/p2p/logger"
)
const consulHealthy = "passing"
// Swarm can create a new peer service in the docker swarm.
type Swarm struct {
logger *logger.Logger
swarmCli *client.Client
consulCli *consul.Client
peerServiceName string
peersGuard *sync.RWMutex
knownPeers map[string]bool
}
// New is a swarm creator constructor.
func New(
ctx context.Context,
log *logger.Logger,
peerServiceName string,
consulAddr string,
) *Swarm {
log = log.Prefix("swarm")
swarmCli, err := client.NewEnvClient()
if err != nil {
log.Panic("failed to create docker client: %s", err)
}
consulCfg := consul.DefaultConfig()
consulCfg.Address = consulAddr
consulCli, err := consul.NewClient(consulCfg)
if err != nil {
log.Panic("failed to create consul client: %s", err)
}
if _, err := consulCli.Status().Leader(); err != nil {
log.Panic("can't connect to consul: %s", err)
}
return &Swarm{
logger: log,
swarmCli: swarmCli,
consulCli: consulCli,
peerServiceName: peerServiceName,
peersGuard: &sync.RWMutex{},
knownPeers: map[string]bool{},
}
}
// Create implements Creator.
// creates a new docker service in a swarm cluster.
func (s *Swarm) Create(ctx context.Context) (*peers.Peer, *url.URL, error) {
if err := s.createPeer(ctx); err != nil {
return nil, nil, fmt.Errorf("error creating peer: %s", err)
}
start := time.Now()
newPeer, u, err := s.waitForNewPeer(ctx)
if err != nil {
return nil, nil, fmt.Errorf("error while waiting for a new peer: %s", err)
}
s.logger.Info("peer %s took %s to start", newPeer.ID, time.Since(start))
return newPeer, u, nil
}
func (s *Swarm) createPeer(ctx context.Context) error {
s.peersGuard.RLock()
s.logger.Debug("looking for unused peers")
for _, inUse := range s.knownPeers {
if inUse {
continue
}
s.logger.Debug("found unused peer")
s.peersGuard.RUnlock()
return nil
}
s.peersGuard.RUnlock()
s.logger.Debug("no unused peers")
peerService, err := s.getPeersService(ctx)
if err != nil {
return fmt.Errorf("can't get peer service: %s", err)
}
before := *peerService.Spec.Mode.Replicated.Replicas
after := before + 1
s.logger.Info("scaling %s from %d to %d", s.peerServiceName, before, after)
*peerService.Spec.Mode.Replicated.Replicas++
resp, err := s.swarmCli.ServiceUpdate(
ctx,
peerService.ID,
swarm.Version{
Index: peerService.Version.Index,
},
peerService.Spec,
types.ServiceUpdateOptions{},
)
if err != nil {
return fmt.Errorf("failed to update service %s: %s", s.peerServiceName, err)
}
for _, w := range resp.Warnings {
s.logger.Warning(w)
}
return nil
}
func (s *Swarm) waitForNewPeer(ctx context.Context) (*peers.Peer, *url.URL, error) {
s.logger.Info("waiting for a new peer")
getNew := func(ctx context.Context) (*peers.Peer, *url.URL, error) {
services, err := s.consulCli.Agent().Services()
if err != nil {
return nil, nil, fmt.Errorf("failed to list consul services: %s", err)
}
for _, service := range services {
p, u, err := s.processPeer(service)
if err != nil {
s.logger.Error("%s: %s", service.ID, err)
continue
}
return p, u, nil
}
return nil, nil, fmt.Errorf("no valid peers found")
}
if p, u, err := getNew(ctx); err == nil {
return p, u, nil
}
for {
select {
case <-ctx.Done():
return nil, nil, fmt.Errorf("cancelled")
case <-time.Tick(time.Second):
p, u, err := getNew(ctx)
if err == nil {
return p, u, nil
}
s.logger.Error("failed to get new peer: %s", err)
}
}
}
func (s *Swarm) processPeer(service *consul.AgentService) (*peers.Peer, *url.URL, error) {
s.peersGuard.Lock()
defer s.peersGuard.Unlock()
if s.knownPeers[service.ID] {
return nil, nil, fmt.Errorf("already in use")
}
peer, u, err := s.parsePeer(service)
if err != nil {
return nil, nil, fmt.Errorf("error parsing peer %s: %s", service.ID, err)
}
s.knownPeers[service.ID] = true
return peer, u, nil
}
func (s *Swarm) queryServices(ctx context.Context) (map[string]*consul.AgentService, error) {
ss, err := s.consulCli.Agent().Services()
if err == nil {
return ss, nil
}
s.logger.Info("waiting for consul")
for {
select {
case <-ctx.Done():
return nil, fmt.Errorf("cancelled")
case <-time.Tick(time.Second):
ss, err := s.consulCli.Agent().Services()
if err == nil {
return ss, nil
}
s.logger.Error("failed to list consul services: %s", err)
}
}
}
func (s *Swarm) parsePeer(service *consul.AgentService) (*peers.Peer, *url.URL, error) {
health, _, err := s.consulCli.Agent().AgentHealthServiceByID(service.ID)
if health != consulHealthy {
return nil, nil, fmt.Errorf("service %s status is %s", service.ID, health)
}
host := fmt.Sprintf("http://%s:%d", service.Address, service.Port)
response, err := http.Get(fmt.Sprintf("%s/healthcheck", host))
if err != nil {
return nil, nil, fmt.Errorf("can't get healthcheck response from %s: %s", service.ID, err)
}
bytes, err := ioutil.ReadAll(response.Body)
if err != nil {
return nil, nil, fmt.Errorf("error reading %s response: %s", service.ID, err)
}
defer response.Body.Close()
newPeer := &peers.Peer{}
if err := newPeer.Unmarshal(bytes); err != nil {
return nil, nil, fmt.Errorf("can't unmarshal response from %s: %s", service.ID, err)
}
newPeer.Addrs.Add(net.IP(service.Address))
u, err := url.Parse(host)
if err != nil {
return nil, nil, fmt.Errorf("can't parse url: %s", err)
}
return newPeer, u, nil
}
func (s *Swarm) getPeersService(ctx context.Context) (*swarm.Service, error) {
get := func(ctx context.Context) (*swarm.Service, error) {
services, err := s.swarmCli.ServiceList(ctx, types.ServiceListOptions{})
if err != nil {
return nil, fmt.Errorf("failed to list services: %s", err)
}
for _, service := range services {
if service.Spec.Name == s.peerServiceName {
return &service, nil
}
}
return nil, fmt.Errorf("service %s not found", s.peerServiceName)
}
if s, err := get(ctx); err == nil {
return s, nil
}
for {
select {
case <-ctx.Done():
return nil, fmt.Errorf("cancelled")
case <-time.Tick(time.Second):
service, err := get(ctx)
if err != nil {
s.logger.Error("failed to get service: %s", s.peerServiceName)
continue
}
return service, nil
}
}
}