From a6ce10abfbff7698293d06f714a29959c035c706 Mon Sep 17 00:00:00 2001 From: Cameron Spear Date: Wed, 10 Feb 2016 23:43:57 -0800 Subject: [PATCH] Use a file to save the state so you don't need the Docker daemon to start This allows this plugin to come back online correctly after a system reboot. --- driver.go | 134 ++++++++++++++++++++++++++++++------------- init/systemd.service | 5 +- 2 files changed, 96 insertions(+), 43 deletions(-) diff --git a/driver.go b/driver.go index 2cdc56b..cb9d34e 100644 --- a/driver.go +++ b/driver.go @@ -5,6 +5,9 @@ import ( "sync" "os" "strconv" + "io/ioutil" + "path" + "encoding/json" "github.com/docker/go-plugins-helpers/volume" "github.com/docker/engine-api/client" @@ -22,6 +25,11 @@ var ( white = color.New(color.FgWhite).SprintfFunc() ) +const ( + stateDir = "/var/lib/docker/plugin-data/" + stateFile = "local-persist.json" +) + type localPersistDriver struct { volumes map[string]string mutex *sync.Mutex @@ -29,6 +37,10 @@ type localPersistDriver struct { name string } +type saveData struct { + State map[string]string `json:"state"` +} + func newLocalPersistDriver() localPersistDriver { fmt.Printf(white("%-18s", "Starting... ")) @@ -39,47 +51,9 @@ func newLocalPersistDriver() localPersistDriver { name : "local-persist", } - if os.Getenv("GO_ENV") != "test" { - // some systems delete /run/docker/plugins for some reason, so we want to make sure this directory exists! - // otherwise, our plugin will silently fail to be found by docker and it will not work - err := os.MkdirAll("/run/docker/plugins/", 0700) - if err != nil { - // we want full-on exits here if we have failed already! - panic(err) - } - } - - // set up the ability to make API calls to the daemon - defaultHeaders := map[string]string{"User-Agent": "engine-api-cli-1.0"} - // need at least Docker 1.9 for named Volume support - cli, err := client.NewClient("unix:///var/run/docker.sock", "v1.21", nil, defaultHeaders) - if err != nil { - // we want full-on exits here if we have failed already! - panic(err) - } - - // grab ALL containers... - options := types.ContainerListOptions{All: true} - containers, err := cli.ContainerList(options) - - // ...and check to see if any of them belong to this driver and recreate their references - for _, container := range containers { - info, err := cli.ContainerInspect(container.ID) - if err != nil { - // we want full-on exits here if we have failed already! - panic(err) - } - - for _, mount := range info.Mounts { - if mount.Driver == driver.name { - // @TODO there could be multiple volumes (mounts) with this { name: source } combo, and while that's okay - // what if they is the same name with a different source? could that happen? if it could, - // it'd be bad, so maybe we want to panic here? - driver.volumes[mount.Name] = mount.Source - } - } - } + os.Mkdir(stateDir, 0700) + _, driver.volumes = driver.findExistingVolumesFromStateFile() fmt.Printf("Found %s volumes on startup\n", yellow(strconv.Itoa(len(driver.volumes)))) return driver @@ -141,6 +115,10 @@ func (driver localPersistDriver) Create(req volume.Request) volume.Response { } driver.volumes[req.Name] = mountpoint + e := driver.saveState(driver.volumes) + if e != nil { + fmt.Println(e.Error()) + } fmt.Printf("%17s Created volume %s with mountpoint %s\n", " ", cyan(req.Name), magenta(mountpoint)) @@ -154,6 +132,11 @@ func (driver localPersistDriver) Remove(req volume.Request) volume.Response { delete(driver.volumes, req.Name) + err := driver.saveState(driver.volumes) + if err != nil { + fmt.Println(err.Error()) + } + fmt.Printf("Removed %s\n", cyan(req.Name)) return volume.Response{} @@ -194,3 +177,74 @@ func (driver localPersistDriver) volume(name string) *volume.Volume { Mountpoint: driver.volumes[name], } } + +func (driver localPersistDriver) findExistingVolumesFromDockerDaemon() (error, map[string]string) { + // set up the ability to make API calls to the daemon + defaultHeaders := map[string]string{"User-Agent": "engine-api-cli-1.0"} + // need at least Docker 1.9 for named Volume support + cli, err := client.NewClient("unix:///var/run/docker.sock", "v1.21", nil, defaultHeaders) + if err != nil { + return err, map[string]string{} + } + + // grab ALL containers... + options := types.ContainerListOptions{All: true} + containers, err := cli.ContainerList(options) + + // ...and check to see if any of them belong to this driver and recreate their references + var volumes = map[string]string{} + for _, container := range containers { + info, err := cli.ContainerInspect(container.ID) + if err != nil { + // something really weird happened here... PANIC + panic(err) + } + + for _, mount := range info.Mounts { + if mount.Driver == driver.name { + // @TODO there could be multiple volumes (mounts) with this { name: source } combo, and while that's okay + // what if they is the same name with a different source? could that happen? if it could, + // it'd be bad, so maybe we want to panic here? + volumes[mount.Name] = mount.Source + } + } + } + + if err != nil || len(volumes) == 0 { + fmt.Print("Attempting to load from file state... ") + + return driver.findExistingVolumesFromStateFile() + } + + return nil, volumes +} + +func (driver localPersistDriver) findExistingVolumesFromStateFile() (error, map[string]string) { + path := path.Join(stateDir, stateFile) + fileData, err := ioutil.ReadFile(path) + if err != nil { + return err, map[string]string{} + } + + var data saveData + e := json.Unmarshal(fileData, &data) + if e != nil { + return e, map[string]string{} + } + + return nil, data.State +} + +func (driver localPersistDriver) saveState(volumes map[string]string) error { + data := saveData{ + State: volumes, + } + + fileData, err := json.Marshal(data) + if err != nil { + return err + } + + path := path.Join(stateDir, stateFile) + return ioutil.WriteFile(path, fileData, 0600) +} diff --git a/init/systemd.service b/init/systemd.service index 09b22fe..6979124 100644 --- a/init/systemd.service +++ b/init/systemd.service @@ -1,11 +1,10 @@ [Unit] Description=docker-volume-local-persist -After=docker.service -Requires=docker.service +Before=docker.service +Wants=docker.service [Service] TimeoutStartSec=0 -ExecStartPre=-/usr/bin/pkill docker-volume-local-persist ExecStart=/usr/bin/docker-volume-local-persist [Install]