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ೖ໳ Go ʕ ~ ؂ࢹϓϥάΠϯ੡࡞Ͱ֮͑Δ Go ~ YOSHIKAWA Ryota (@rrreeeyyy) hbstyle-2014-08-14

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Go lang?

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· Google ࣾʹΑͬͯ։ൃ · ੩తͷڧ͍ܕ෇͚ݴޠ (ܕ҆શͰ͋Δ) · GC ʹΑΔϝϞϦ؅ཧ · ฒߦ(Concurrency)ϓϩάϥϛϯάͷαϙʔτ · Cross Compile

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· Google ࣾʹΑͬͯ։ൃ · ੩తͷڧ͍ܕ෇͚ݴޠ (ܕ҆શͰ͋Δ) · GC ʹΑΔϝϞϦ؅ཧ · ฒߦ(Concurrency)ϓϩάϥϛϯάͷαϙʔτ · Cross Compile

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Go Tools

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· docker · flynn · etcd · consul, terraform · kubernetes

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Why serverengineer and Go?

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· (͋Δఔ౓) ΏΔ͘ॻ͚Δ · (͋Μ·Γ) ྫ֎ͱ͔Ͱࢮͳͳ͍ · Cross Compile ʹΑΔ഑෍ͷखܰ͞ · ॻ͍ͯ, ίϯύΠϧͯ͠, ഑ͬͯ, ಈ͘ · (ࣾ಺Ͱ) CentOS 4 32bit ͱ͔Ͱಈ͍ͨͱ͍͏ᷚ · ฒߦϓϩάϥϛϯά͕(ׂͱ)؆୯ · (※্ه͸શͯݸਓͷײ૝Ͱ͢)

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install Go

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Mac $ brew install go --cross-compile-all Linux ؤுͬͯϏϧυ͢Δ http://golang.org/doc/install

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։ൃ ͱͯ΋ศརͳͷͰ࢖͏ ଞʹ΋͋ΔͷͰؤுͬͯ୳͢ · gofmt · gocode · godoc · vim-go :

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Command-line application cli-init (tcnksm/cli-init) Λ࢖ͬͯΈΔ

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cli-init codegangsta/cli ༻ͷͻͳܗΛੜ੒ͯ͘͠ΕΔ (Go ͷ CLI tool Λ࡞ΔͷʹΑ͘࢖ΘΕ͍ͯΔ) $ go get -d github.com/tcnksm/cli-init $ cd $GOPATH/src/github.com/tcnksm/cli-init && make install $ cli-init -s subcmd,subcmd2,subcmd3 [app-name] ࠓճ͸ $ cli-init check_users

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package main import ( "github.com/codegangsta/cli" "os" ) func main() { app := cli.NewApp() app.Name = "check_users" app.Version = Version app.Usage = "" app.Author = "YOSHIKAWA Ryota" app.Email = "[email protected]" app.Action = doMain app.Run(os.Args) } func doMain(c *cli.Context) { }

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get flag, and print

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: app.Flags = []cli.Flag{ cli.IntFlag{ Name: "w, warning", Value: 5, Usage: "Set WARNING status if more than INTEGER users are logged in"}, cli.IntFlag{ Name: "c, critical", Value: 10, Usage: "Set CRITICAL status if more than INTEGER users are logged in"}, } app.Run(os.Args) } func doMain(c *cli.Context) { fmt.Println(c.Int("w")) }

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Compile $ go build Execute $ ./check_users 5 $ ./check_users -w 10 10 $ ./check_users --help : $ ./check_users -v 0.1.0

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Shell command

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: command_line := "/usr/bin/who" out, err := exec.Command("/bin/sh", "-c", command_line).Output() if err != nil { log.Fatal(err) } :

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loop

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: user_count := 0 : scanner := bufio.NewScanner(bytes.NewReader(out)) for scanner.Scan() { if err := scanner.Err(); err != nil { log.Fatal(err) } user_count += 1 } :

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switch

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: switch { case user_count > c.Int("c"): fmt.Printf("USERS CRITICAL - %v users currently logged in", user_count) os.Exit(2) case user_count <= c.Int("c") && user_count > c.Int("w"): fmt.Printf("USERS WARNING - %v users currently logged in", user_count) os.Exit(1) case user_count <= c.Int("w") && user_count >= 0: fmt.Printf("USERS OK - %v users currently logged in", user_count) os.Exit(0) } fmt.Printf("UNKNOWN State.") os.Exit(3) :

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https://gist.github.com/rrreeeyyy/ 50574284bc43a4e5fe97

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Cross Compile

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(͍͍ͩͨ)ͨͬͨ͜Ε͚ͩ $ GOOS=linux GOARGH=amd64 go build Linux/amd64 ͳόΠφϦ͕ग़དྷΔ ͳʹ͔Ͱૹ࣮ͬͯ͋͛ͯߦ͢Ε͹ಈ͘

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·ͱΊ · Go ͸ΠϯϑϥΤϯδχΞ޲͚ͷྑ͍ݴޠ · CLI πʔϧ࡞Δ࣌͸ cli-init ࢖͏ͱศར · Go ͷจ๏ͱ͔৭ʑ঺հ · goroutine ͱ͔ struct ͱ͔ channel ͱ͔... · select ͱ͔... ͷ࿩͸·͍͔ͨͭɻ

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΄͔ · ࣾ಺Ͱ nouka ͷ go ൛࡞ͬͯΔΑ · ͍ͬ͠ΐʹͦͩͯΑ͏