Golang 101 for IT-Pros - Cisco Live Orlando 2018 - DEVNET-1808
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The document covers an introduction to the Go programming language, explaining its features such as simplicity, composability, and built-in support for concurrency. It includes practical guidance on setting up a development environment, building and packaging applications using Docker, and creating command-line interfaces. Additionally, it highlights the growth of Go in various industries and offers resources for further learning and community contributions.
Golang 101 for IT-Pros - Cisco Live Orlando 2018 - DEVNET-1808
- 1. #CLUS Patrick Riel, Engineer Stève Sfartz, API Evangelist DEVNET-1808 #golang for ITPros
- 2. © 2018 Cisco and/or its affiliates. All rights reserved. Cisco Public#CLUS /Cisco/DevNet/SteveSfartz • API Evangelist @CiscoDevNet • API Design,Architecture and Operations • WebexTeams & Devices/xAPI developer • hosted @CiscoROI: Paris Innovation Center • Node.js mainly, a bit of #golang • Europe and all over the world • github: //ObjectIsAdvantag DEVNET-1808 “vision without execution is hallucination” -- Thomas Edison mailto: stsfartz@cisco.com twitter: @SteveSfartz
- 3. Agenda © 2018 Cisco and/or its affiliates. All rights reserved. Cisco Public#CLUS • Why go? • HelloWorld: install, code, compile, test • Multi-platform builds and packaging with docker • Setting up your development environment • Walkthrough: creating a command line interface • More advanced concepts: channels, go routines, … DEVNET-1808 3
- 4. © 2018 Cisco and/or its affiliates. All rights reserved. Cisco Public#CLUS Why Go? • Released by Google in 2009 • conceived in ‘07, popular since ‘15 • Designed to address software engineering issues faced in the construction of large server software • Influenced by: C, Python, Smalltalk,Alef, CSP, Modula, Pascal… • Focus on clarity, simplicity and composability, resulting in a productive, fun, expressive and powerful language • No class inheritance. ‘Embedding’ & ‘Interfaces’ to provide polymorphism • Built-in parallelism & asynchrony via ‘Channels’ & ‘goroutines’ • Includes a - debugging, profiling, formatting and testing - toolset 4DEVNET-1808
- 5. © 2018 Cisco and/or its affiliates. All rights reserved. Cisco Public#CLUS Software engineering guided the design of Go https://talks.golang.org/2012/splash.article • Clear dependencies • Clear syntax • Clear semantics • Composition over inheritance • Simplicity provided by the programming model (garbage collection, concurrency) • Easy tooling (the go tool, gofmt, godoc, gofix) • TRY IT: https://tour.golang.org 5DEVNET-1808
- 6. GoTour
- 7. © 2018 Cisco and/or its affiliates. All rights reserved. Cisco Public#CLUS 7DEVNET-1808 Variables https://tour.golang.org/basics
- 8. © 2018 Cisco and/or its affiliates. All rights reserved. Cisco Public#CLUS 8DEVNET-1808 Functions: mutiple results https://tour.golang.org/basics/6
- 9. © 2018 Cisco and/or its affiliates. All rights reserved. Cisco Public#CLUS 9DEVNET-1808 Functions: named results https://tour.golang.org/basics/7
- 10. Setting up Go on your machine
- 11. © 2018 Cisco and/or its affiliates. All rights reserved. Cisco Public#CLUS Installing Go https://golang.org/doc/install • Download the PKG on Mac (or MSI forWindows), and Install • by default installs in /usr/local/go (or c:Go forWindows). • adds the Go binary to your PATH environment variable • Set the GOROOT env variable if you install to a different location • Type ‘go version’ to check your installation is successful • Create a ‘go’ workspace directory • under $HOME/go on Mac (or %USERPROFILE%go forWindows) • Set a GOPATH environment variable is preferable (and mandatory if elsewhere) • Add the $GOPATH/bin directory to your path 11DEVNET-1808
- 12. © 2018 Cisco and/or its affiliates. All rights reserved. Cisco Public#CLUS HelloWorld (on a Mac) • Create a “src/hello” directory in your workspace • Create a file named hello.go • Build it with the go tool • Produces an executable named hello • Run go install to install the binary into your workspace's bin directory or go clean to remove it. 12DEVNET-1808 1 File: src/hello/hello.go 2 3
- 13. © 2018 Cisco and/or its affiliates. All rights reserved. Cisco Public#CLUS HelloWorld (on Windows) • Create a “src/hello” directory in your workspace • Create a file named hello.go • Build it with the go tool • Produces an executable named hello.exe • Run go install to install the binary into your workspace's bin directory or go clean to remove it. 13DEVNET-1808 1 2 File: src/hello/hello.go 3
- 14. © 2018 Cisco and/or its affiliates. All rights reserved. Cisco Public#CLUS Typical go folder structure https://golang.org/doc/code.html • go tooling requires to organize your code in a specific way • Go programmers typically keep all their Go code in a single workspace. • A workspace contains many version control repositories (managed by git, for example). • Each repository contains one or more packages. • Each package consists of one or more Go source files in a single directory. • The path to a package's directory determines its import path. 14DEVNET-1808 GOPATH = C:Localgowork mkdir ‘$GOPATH/src/github.com/<username>/hello’
- 15. © 2018 Cisco and/or its affiliates. All rights reserved. Cisco Public#CLUS Creating a Library https://golang.org/doc/code.html > mkdir $GOPATH/src/github.com/<user>/hello 15DEVNET-1808 filename: hello.go
- 16. © 2018 Cisco and/or its affiliates. All rights reserved. Cisco Public#CLUS Creating a Library https://golang.org/doc/code.html > mkdir $GOPATH/src/github.com/<user>/stringutil 16DEVNET-1808 filename: reverse.go
- 17. © 2018 Cisco and/or its affiliates. All rights reserved. Cisco Public#CLUS Creating a Library https://golang.org/doc/code.html > go install github.com/<user>/hello • the ‘stringutil’ package is automatically installed as well • go executables are statically linked 17DEVNET-1808
- 18. Setting up your development environment
- 19. © 2018 Cisco and/or its affiliates. All rights reserved. Cisco Public#CLUS Go Extension forVisual Studio Code 19DEVNET-1808 Installs automatically at launch or manually via go get –v: github.com/nsf/gocode github.com/uudashr/gopkgs/cmd/gopkgs github.com/ramya-rao-a/go-outline github.com/acroca/go-symbols golang.org/x/tools/cmd/guru golang.org/x/tools/cmd/gorename github.com/fatih/gomodifytags github.com/haya14busa/goplay/cmd/goplay github.com/josharian/impl github.com/rogpeppe/godef golang.org/x/tools/cmd/godoc sourcegraph.com/sqs/goreturns github.com/golang/lint/golint github.com/cweill/gotests github.com/derekparker/delve/cmd/dlv golang.org/x/tools/cmd/guru
- 20. Demo
- 21. © 2018 Cisco and/or its affiliates. All rights reserved. Cisco Public#CLUS VS Code golang extension: InstallationTips • If any go tools dependency is missing, install it manually • Make sure the $GOPATH/bin directory appears in your path • To install the Delve debugger, type > go get -u github.com/derekparker/delve/cmd/dlv • If having issue with the debugger on Mac: ‘lldb-server’ not found, type > xcode-select –install 21DEVNET-1808
- 23. © 2018 Cisco and/or its affiliates. All rights reserved. Cisco Public#CLUS Packaging for various platforms • The go toolchain natively cross-build executables for any Go-supported foreign platform • Example: > env GOOS=linuxGOARCH=amd64 go build -o dist/demo.linux -v main.go https://www.digitalocean.com/community/tutorials/how-to-build-go-executables- for-multiple-platforms-on-ubuntu-16-04 DEVNET-1808
- 24. © 2018 Cisco and/or its affiliates. All rights reserved. Cisco Public#CLUS DEVNET-1808 Dockerfile example https://github.com/ObjectIsAdvantag/CLEUR-1814/tree/master/8-docker
- 25. © 2018 Cisco and/or its affiliates. All rights reserved. Cisco Public#CLUS 25DEVNET-1808 Pointers https://tour.golang.org/moretypes/1
- 26. © 2018 Cisco and/or its affiliates. All rights reserved. Cisco Public#CLUS 26DEVNET-1808 readword.go
- 27. CLI with golang doing chatops
- 28. © 2018 Cisco and/or its affiliates. All rights reserved. Cisco Public#CLUS Methods and Interfaces • Remember: a method is just a function with a receiver argument • To implement an interface inGo • Implement all the methods in the interface 28DEVNET-1808 https://tour.golang.org/methods https://gobyexample.com/interfaces https://github.com/ObjectIsAdvantag/CLEUR-1814/blob/master/7-spark/main.go https://github.com/ObjectIsAdvantag/CLEUR-1814/blob/master/6-interfaces/main.go
- 29. CLI Demo
- 30. © 2018 Cisco and/or its affiliates. All rights reserved. Cisco Public#CLUS 30DEVNET-1808 Defer https://tour.golang.org/flowcontrol/12
- 31. © 2018 Cisco and/or its affiliates. All rights reserved. Cisco Public#CLUS Defer • defers the execution of a function until the surrounding function returns • deferred function calls are pushed onto a stack (executed in LIFO) 31DEVNET-1808 counting done 5 4 3 2 1 0
- 32. © 2018 Cisco and/or its affiliates. All rights reserved. Cisco Public#CLUS HTTP API Clients • simplify development • speed up development • clean code • abstraction https://www.scaledrone.com/blog/posts/creating-an-api-client-in-go 32DEVNET-1808
- 33. Advanced #golang
- 34. © 2018 Cisco and/or its affiliates. All rights reserved. Cisco Public#CLUS 34DEVNET-1808 Concurrency: channels & go routines
- 35. © 2018 Cisco and/or its affiliates. All rights reserved. Cisco Public#CLUS 35DEVNET-1808 Structures https://tour.golang.org/moretypes/2
- 36. © 2018 Cisco and/or its affiliates. All rights reserved. Cisco Public#CLUS 36DEVNET-1808 Arrays https://tour.golang.org/moretypes/6
- 37. © 2018 Cisco and/or its affiliates. All rights reserved. Cisco Public#CLUS 37DEVNET-1808 Slices https://tour.golang.org/moretypes/13
- 38. © 2018 Cisco and/or its affiliates. All rights reserved. Cisco Public#CLUS 38DEVNET-1808 Maps https://tour.golang.org/moretypes/22
- 39. © 2018 Cisco and/or its affiliates. All rights reserved. Cisco Public#CLUS 39DEVNET-1808 Closures https://tour.golang.org/moretypes/25
- 40. Wrapup
- 41. © 2018 Cisco and/or its affiliates. All rights reserved. Cisco Public#CLUS Wrapup… go for ITPros CLI Proxy Reverse Proxy Web API 41DEVNET-1808
- 42. © 2018 Cisco and/or its affiliates. All rights reserved. Cisco Public#CLUS State of go – 2017 user survey • Continued growth in the language • Enterprise-ready: for the first time, more Go at work than home • Top-uses of Go is now writingAPI/RPC services • 2016 was stillCLI. Now taking advantage of the distinguishing features of Go, key elements of cloud computing • Biggest challenges: lack of dependency management, generics • 64% responses use Go on Linux, 49% on MacOS, 18% onWindows • VSCode is now the most popular editor for Go developers • Finding answers:Go website, Stack Overflow, and reading code • Primary news sources: Go blog, Reddit, andTwitter 42DEVNET-1808
- 43. © 2018 Cisco and/or its affiliates. All rights reserved. Cisco Public#CLUS Cisco Community Contributions • golang samples • https://github.com/ObjectIsAdvantag/CLEUR-1814 • Cisco Spark REST API wrapper • https://github.com/jbogarin/go-cisco-spark • CiscoACI from golang • https://github.com/udhos/acigo • Answering Machine backed byTropo • https://github.com/ObjectIsAdvantag/answering-machine • Proxy incoming web hooks to established web sockets • https://github.com/sgrimee/whproxy 43DEVNET-1808
- 44. Complete your online session evaluation © 2018 Cisco and/or its affiliates. All rights reserved. Cisco Public#CLUS Give us your feedback to be entered into a Daily Survey Drawing. Complete your session surveys through the Cisco Live mobile app or on www.CiscoLive.com/us. Don’t forget: Cisco Live sessions will be available for viewing on demand after the event at www.CiscoLive.com/Online. DEVNET-1808
- 45. Q&A
- 46. Thank you #CLUS
- 47. #CLUS
Editor's Notes
- #4: Examples with what’s in the standard golang box Logs: https://github.com/sirupsen/logrus
- #5: https://talks.golang.org/2012/splash.article
- #13: Rather do ‘ $GOPATH/src/github.com/<username>/hello’
- #14: Rather do ‘ $GOPATH/src/github.com/<username>/hello’
- #25: https://cloud.google.com/appengine/docs/standard/go/tools/uploadinganapp
- #26: Pass by value is not ineficient in many cases, or mandates to create placeholders / shared variables, or even understand the context of the stack in JS
- #27: package main import ( "fmt" ) func readword() (word string) { fmt.Println("Type something") fmt.Scanf("%s", &word) return } func main() { w := readword() fmt.Println("You entered", w) }
- #31: Makes your code more elegant
- #35: package main import ( "fmt" "time" ) func timeout(t chan bool) { time.Sleep(5 * time.Second) t <- true } func readword(ch chan string) { fmt.Println("Type something and hit Enter") var word string fmt.Scanf("%s", &word) ch <- word } func main() { t := make(chan bool) go timeout(t) ch := make(chan string) go readword(ch) select { case word := <-ch: fmt.Println("Received", word) case <-t: fmt.Println("Timeout.") } }
- #40: For JS familiar developers