Docker Inside -- Client-Server Architecture --

株式会社 CA リワードの社内で開催している Go 勉強会の資料です。

Docker の採用しているクライアントサーバアーキテクチャについて、 Docker daemon 側と Docker client 側の実装をそれぞれ解説した資料です。

Transcript

1. Docker Inside -- Client-Server Architecture -- Soshi Katsuta (CA Reward) Go 勉強会 #4 Sep 28, 2015
2. Agenda Docker’s architecture Docker server (Docker daemon) Docker client (Docker command) Misc
3. Docker’s architecture docker pull docker run docker ... unix socket TCP
4. Docker’s architecture docker pull docker run docker ... unix socket TCP
5. Docker server (Docker daemon)
6. Docker’s architecture ? unix socket TCP
7. Docker Remote API v1.20
8. Docker Remote API を直接使ってみる $ docker images REPOSITORY TAG IMAGE ID CREATED VIRTUAL SIZE golang latest e7bca7669626 10 days ago 709.5 MB $ export DOCKER_IP=$(docker-machine ip demo) $ wget --server-response --no-check-certificate --certificate $DOCKER_CERT_PATH/cert. pem --private-key $DOCKER_CERT_PATH/key.pem "https://$DOCKER_IP:2376/images/json" -O - -q | jq . HTTP/1.1 200 OK Content-Type: application/json Server: Docker/1.8.2 (linux) Date: Sun, 27 Sep 2015 15:33:47 GMT Content-Length: 568 [ { "Id": "e7bca7669626deae3a1d4bdf66bae5ee8d02f5f5130f090a4895a8cd9fce4921", "ParentId": "62df3617331c53ec328a2ae479b275f2ed1aa6fe4a0eacf5f5967e090b666a42", "RepoTags": [ "golang:latest" ], "RepoDigests": [], "Created": 1442507466, "Size": 2481, "VirtualSize": 709470237, "Labels": {} } ]
9. DOCKER_* 環境変数は Docker デーモンへの接続情報 $ docker-machine env demo export DOCKER_TLS_VERIFY="1" export DOCKER_HOST="tcp://192.168.99.101:2376" export DOCKER_CERT_PATH="/Users/soshi/.docker/machine/machines/demo" export DOCKER_MACHINE_NAME="demo" # Run this command to configure your shell: # eval "$(docker-machine env demo)" $ docker-machine config demo --tlsverify --tlscacert="/Users/soshi/.docker/machine/machines/demo/ca.pem" -- tlscert="/Users/soshi/.docker/machine/machines/demo/cert.pem" --tlskey=" /Users/soshi/.docker/machine/machines/demo/key.pem" -H=tcp://192.168.99.101:2376 $ docker $(docker-machine config demo) images REPOSITORY TAG IMAGE ID CREATED VIRTUAL SIZE golang latest e7bca7669626 10 days ago 709.5 MB
10. POST /build https://docs.docker.com/reference/api/docker_remote_api_v1. 20/#build-image-from-a-dockerfile Dockerfile は tar に 固められてサーバに送られる
11. ルーティング定義: docker/docker/api/server/server.go#L321-L414 func createRouter(s *Server) *mux.Router { r := mux.NewRouter() if os.Getenv("DEBUG") != "" { profilerSetup(r, "/debug/") } m := map[string]map[string]HTTPAPIFunc{ ... "GET": { ... "/info": s.getInfo, "/version": s.getVersion, "/images/json": s.getImagesJSON, ... }, "POST": { ... "/build": s.postBuild, "/images/create": s.postImagesCreate, ... "/containers/create": s.postContainersCreate, ... "/containers/{name:.*}/restart": s.postContainersRestart, "/containers/{name:.*}/start": s.postContainersStart, "/containers/{name:.*}/stop": s.postContainersStop, ... ...
12. イメージ情報一覧を返す: docker/docker/api/server/image.go#L361- L373 func (s *Server) getImagesJSON(ctx context.Context, w http.ResponseWriter, r *http. Request, vars map[string]string) error { if err := parseForm(r); err != nil { return err } // FIXME: The filter parameter could just be a match filter images, err := s.daemon.Repositories().Images( r.Form.Get("filters"), r.Form.Get("filter"), boolValue(r, "all")) if err != nil { return err } return writeJSON(w, http.StatusOK, images) }
13. OS X 版のバイナリには daemon コマンドがない $ uname -a Darwin MacBookPro.local 14.5.0 Darwin Kernel Version 14.5.0: Wed Jul 29 02:26:53 PDT 2015; root: xnu-2782.40.9~1/RELEASE_X86_64 x86_64 $ docker daemon --help docker: 'daemon' is not a docker command. See 'docker --help'. $ docker-machine ssh demo docker@demo:~$ uname -a Linux demo 4.0.9-boot2docker #1 SMP Thu Sep 10 20:39:20 UTC 2015 x86_64 GNU/Linux docker@demo:~$ docker daemon --help Usage: docker daemon [OPTIONS] Enable daemon mode --api-cors-header= Set CORS headers in the remote API -b, --bridge= Attach containers to a network bridge ... docker@dome:~$ ps aux | grep docker root 2385 0.1 3.5 432244 35980 ? Sl 08:22 1:07 /usr/local/bin/docker daemon -D -g /var/lib/docker -H unix:// -H tcp://0.0.0.0:2376 --label provider=virtualbox --tlsverify -- tlscacert=/var/lib/boot2docker/ca.pem --tlscert=/var/lib/boot2docker/server.pem -- tlskey=/var/lib/boot2docker/server-key.pem -s aufs Linux 版には当然ある
14. daemon コマンドをサポートしていないアーキテクチャ用: docker/docker/daemon/daemon_unsupported.go // +build !linux,!freebsd,!windows package daemon const platformSupported = false // +build linux freebsd package daemon import ... const ( // See https://git.kernel.org/cgit/linux/kernel/git/tip/tip.git/tree/kernel/sched/sched.h? id=8cd9234c64c584432f6992fe944ca9e46ca8ea76#n269 linuxMinCPUShares = 2 linuxMaxCPUShares = 262144 platformSupported = true ) ... daemon コマンドをサポートしているアーキテクチャ用: (Unix) docker/docker/daemon/daemon_unix.go
15. Docker’s architecture docker pull docker run docker ... unix socket TCP
16. Docker client
17. docker images # イメージ一覧を表示する $ docker images REPOSITORY TAG IMAGE ID CREATED VIRTUAL SIZE golang latest e7bca7669626 10 days ago 709.5 MB # 中間イメージも表示する $ docker images -a REPOSITORY TAG IMAGE ID CREATED VIRTUAL SIZE golang latest e7bca7669626 10 days ago 709.5 MB <none> <none> 62df3617331c 10 days ago 709.5 MB <none> <none> a2e423ce2323 10 days ago 709.5 MB <none> <none> 3947c44d1a74 10 days ago 709.5 MB <none> <none> 0719eb1f7878 10 days ago 709.5 MB <none> <none> d5d9aea02377 10 days ago 709.5 MB <none> <none> c24b809cc565 10 days ago 425.8 MB <none> <none> a35079f01662 10 days ago 425.8 MB <none> <none> a3b158f2d1df 10 days ago 425.8 MB <none> <none> aba657f6bfe7 10 days ago 425.8 MB <none> <none> 20b348f4d568 2 weeks ago 291.8 MB <none> <none> 8b49fe88b40b 2 weeks ago 169.5 MB <none> <none> 8c00acfb0175 2 weeks ago 125.2 MB <none> <none> 843e2bded498 2 weeks ago 125.2 MB
18. docker/docker/api/client/images.go // CmdImages lists the images in a specified repository, or all top-level images if no repository is specified. func (cli *DockerCli) CmdImages(args ...string) error { cmd := Cli.Subcmd("images", []string{"[REPOSITORY[:TAG]]"}, "List images", true) ... all := cmd.Bool([]string{"a", "-all"}, false, "Show all images (default hides intermediate images)") ... v := url.Values{} ... if *all { v.Set("all", "1") } serverResp, err := cli.call("GET", "/images/json?"+v.Encode(), nil, nil) if err != nil { return err } defer serverResp.body.Close() images := []types.Image{} if err := json.NewDecoder(serverResp.body).Decode(&images); err != nil { return err } w := tabwriter.NewWriter(cli.out, 20, 1, 3, ' ', 0) ... fmt.Fprintln(w, "REPOSITORY\tTAG\tIMAGE ID\tCREATED\tVIRTUAL SIZE") ... for _, image := range images { ... fmt.Fprintf(w, "%s\t%s\t%s\t%s ago\t%s\n", repo, tag, ID, units.HumanDuration(time.Now().UTC().Sub (time.Unix(int64(image.Created), 0))), units.HumanSize(float64(image.VirtualSize))) ... } if !*quiet { w.Flush() } return nil }
19. Misc container names https://github.com/docker/docker/blob/master/pkg/namesgenerator/names-generator.go https://github.com/docker/docker/pull/4902 internal container files $ docker info ... Storage Driver: aufs Root Dir: /mnt/sda1/var/lib/docker/aufs ... $ docker-machine ssh demo docker@demo:~$ sudo ls -al /mnt/sda1/var/lib/docker/aufs/diff/**