0e8e8f0f31
Allows for a plugin type that can be used to scrape metrics. This is useful because metrics are not neccessarily at a standard location... `--metrics-addr` must be set, and must currently be a TCP socket. Even if metrics are done via a unix socket, there's no guarentee where the socket may be located on the system, making bind-mounting such a socket into a container difficult (and racey, failure-prone on daemon restart). Metrics plugins side-step this issue by always listening on a unix socket and then bind-mounting that into a known path in the plugin container. Note there has been similar work in the past (and ultimately punted at the time) for consistent access to the Docker API from within a container. Why not add metrics to the Docker API and just provide a plugin with access to the Docker API? Certainly this can be useful, but gives a lot of control/access to a plugin that may only need the metrics. We can look at supporting API plugins separately for this reason. Signed-off-by: Brian Goff <cpuguy83@gmail.com>
86 lines
2.4 KiB
Go
86 lines
2.4 KiB
Go
// +build !windows
|
|
|
|
package daemon
|
|
|
|
import (
|
|
"net"
|
|
"net/http"
|
|
"os"
|
|
"path/filepath"
|
|
"syscall"
|
|
|
|
"github.com/Sirupsen/logrus"
|
|
"github.com/docker/docker/pkg/mount"
|
|
"github.com/docker/docker/pkg/plugingetter"
|
|
"github.com/docker/docker/pkg/plugins"
|
|
metrics "github.com/docker/go-metrics"
|
|
"github.com/pkg/errors"
|
|
)
|
|
|
|
func (daemon *Daemon) listenMetricsSock() (string, error) {
|
|
path := filepath.Join(daemon.configStore.ExecRoot, "metrics.sock")
|
|
syscall.Unlink(path)
|
|
l, err := net.Listen("unix", path)
|
|
if err != nil {
|
|
return "", errors.Wrap(err, "error setting up metrics plugin listener")
|
|
}
|
|
|
|
mux := http.NewServeMux()
|
|
mux.Handle("/metrics", metrics.Handler())
|
|
go func() {
|
|
http.Serve(l, mux)
|
|
}()
|
|
daemon.metricsPluginListener = l
|
|
return path, nil
|
|
}
|
|
|
|
func registerMetricsPluginCallback(getter plugingetter.PluginGetter, sockPath string) {
|
|
getter.Handle(metricsPluginType, func(name string, client *plugins.Client) {
|
|
// Use lookup since nothing in the system can really reference it, no need
|
|
// to protect against removal
|
|
p, err := getter.Get(name, metricsPluginType, plugingetter.Lookup)
|
|
if err != nil {
|
|
return
|
|
}
|
|
|
|
mp := metricsPlugin{p}
|
|
sockBase := mp.sockBase()
|
|
if err := os.MkdirAll(sockBase, 0755); err != nil {
|
|
logrus.WithError(err).WithField("name", name).WithField("path", sockBase).Error("error creating metrics plugin base path")
|
|
return
|
|
}
|
|
|
|
defer func() {
|
|
if err != nil {
|
|
os.RemoveAll(sockBase)
|
|
}
|
|
}()
|
|
|
|
pluginSockPath := filepath.Join(sockBase, mp.sock())
|
|
_, err = os.Stat(pluginSockPath)
|
|
if err == nil {
|
|
mount.Unmount(pluginSockPath)
|
|
} else {
|
|
logrus.WithField("path", pluginSockPath).Debugf("creating plugin socket")
|
|
f, err := os.OpenFile(pluginSockPath, os.O_CREATE, 0600)
|
|
if err != nil {
|
|
return
|
|
}
|
|
f.Close()
|
|
}
|
|
|
|
if err := mount.Mount(sockPath, pluginSockPath, "none", "bind,ro"); err != nil {
|
|
logrus.WithError(err).WithField("name", name).Error("could not mount metrics socket to plugin")
|
|
return
|
|
}
|
|
|
|
if err := pluginStartMetricsCollection(p); err != nil {
|
|
if err := mount.Unmount(pluginSockPath); err != nil {
|
|
if mounted, _ := mount.Mounted(pluginSockPath); mounted {
|
|
logrus.WithError(err).WithField("sock_path", pluginSockPath).Error("error unmounting metrics socket from plugin during cleanup")
|
|
}
|
|
}
|
|
logrus.WithError(err).WithField("name", name).Error("error while initializing metrics plugin")
|
|
}
|
|
})
|
|
}
|