Containerd Server学习 Part 1

【编者的话】containerd v1.0.0的源码分析，以docker-containerd --config /var/run/docker/containerd/containerd.toml为入口，看大神们如何组织Go语言代码

containerd.io
github: containerd v1.0.0

准备:

go get -v github.com/containerd/containerd
cd $GOPATH/src/github.com/containerd/containerd
git checkout v1.0.0 -b v1.0.0

分析

命令行

• 位置：cmd/containerd/main.go
• 作用：定义containerd 命令行相关参数与配置文件
• 依赖：github.com/urfave/cli

package main

import (
    "fmt"
    "os"

    "github.com/containerd/containerd/version"
    "github.com/urfave/cli"
)

const usage = `
                    __        _                     __
  _________  ____  / /_____ _(_)___  ___  _________/ /
 / ___/ __ \/ __ \/ __/ __ ` + "`" + `/ / __ \/ _ \/ ___/ __  /
/ /__/ /_/ / / / / /_/ /_/ / / / / /  __/ /  / /_/ /
\___/\____/_/ /_/\__/\__,_/_/_/ /_/\___/_/   \__,_/

high performance container runtime
`

func main() {
    app := cli.NewApp()
    app.Name = "containerd"
    app.Version = version.Version
    app.Usage = usage
    app.Flags = []cli.Flag{
        cli.StringFlag{
            Name:  "config,c",
            Usage: "path to the configuration file",
            Value: defaultConfigPath,
        },
    }
    app.Commands = []cli.Command{}
    app.Action = func(context *cli.Context) error {
        return nil
    }
    if err := app.Run(os.Args); err != nil {
        fmt.Fprintf(os.Stderr, "containerd: %s\n", err)
        os.Exit(1)
    }
}

配置文件解析

• 位置：server/config.go
• 作用：解析配置文件相关参数
• 依赖：
  github.com/BurntSushi/toml
  github.com/pkg/errors

// LoadConfig loads the containerd server config from the provided path
func LoadConfig(path string, v *Config) error {
    if v == nil {
        return errors.Wrapf(errdefs.ErrInvalidArgument, "argument v must not be nil")
    }
    md, err := toml.DecodeFile(path, v)
    if err != nil {
        return err
    }
    v.md = md
    return nil
}

添加参数

• 位置：cmd/containerd/main.go
• 作用：应用参数到相关配置

func applyFlags(context *cli.Context, config *server.Config) error {
    // the order for config vs flag values is that flags will always override
    // the config values if they are set
    if err := setLevel(context, config); err != nil {
        return err
    }
    for _, v := range []struct {
        name string
        d    *string
    }{
        {
            name: "root",
            d:    &config.Root,
        },
        {
            name: "state",
            d:    &config.State,
        },
        {
            name: "address",
            d:    &config.GRPC.Address,
        },
    } {
        if s := context.GlobalString(v.name); s != "" {
            *v.d = s
        }
    }
    return nil
}

日志

• 位置：log/context.go
• 作用：应用日志
• 依赖： github.com/sirupsen/logrus

...
var ctx    = log.WithModule(gocontext.Background(), "containerd")
...
log.G(ctx).WithFields(logrus.Fields{
            "version":  version.Version,
            "revision": version.Revision,
        }).Info("starting containerd")
...

# log/context.go
func WithModule(ctx context.Context, module string) context.Context {
    parent := GetModulePath(ctx)
    if parent != "" {
        if path.Base(parent) == module {
            return ctx
        }
        module = path.Join(parent, module)
    }

    ctx = WithLogger(ctx, GetLogger(ctx).WithField("module", module))
    return context.WithValue(ctx, moduleKey{}, module)
}

整理：

https://github.com/llitfkitfk/containerd/tree/part-1