go | rael.io

Extending the Kubernetes API with Custom Resources, Controllers and Operators

Wed, 18 Sep 2019 18:30:00 +0200

What is the controller pattern? And the operator pattern? How we can use custom controllers to extend the Kubernetes API? How we can build our own custom resources, controllers and operators?

Join at meetup.com/Cloud-Native-Barcelona

Slides at go.rael.dev/cnbcn-extending-k8s The talk will be streamed live at https://glovoapp.zoom.us/j/364754734.

Agenda

18:30 Welcome

Introduction to the Cloud Native community and Glovo!

18:45 Kubernetes Architecture

Introduction to the core principles an components of the Kubernetes architecture. We will start a Kubernetes cluster from scratch, component by component learning how each piece fits into the puzzle.

github.com/raelga/kubernetes-talks/tree/master/k8s-from-scratch

19:40 Break

19:45 Kubernetes Custom Controllers and Operators in action

Introduction to the Operator concept. We will deploy some operators in a Google Kubernetes Engine cluster step by step and build our own Operator without (almost) writing any code.

20:30 Pizza and drinks from Glovo!

Speakers

Nacho Alonso

SRE at CAPSiDE, contributor at Kubernetes and co-organizer at Cloud Native Barcelona

Rael Garcia

SRE at CAPSiDE, contributor at Kubernetes and organizer at Cloud Native Barcelona

Roi Vázquez

SRE at CAPSiDE and contributor at Kubernetes @lominorama

Sergio López

SRE at Red Hat @slopezz

yodo

Mon, 26 Aug 2019 11:23:56 +0200

Simple GoLang TODO application

This application is just a playground to learn:

TDD with GoLang
github.com/spf13/cobra
github.com/spf13/viper
gopkg.in/yaml.v2
GitHub Actions
```
$ go build
```

$ ./yodo get
default:
Empty list

$ ./yodo add Add verbose mode
add task "Add verbose mode" (false) to file$

$ ./yodo get
default:
- [0] "Add verbose mode" (false)

$ ./yodo do 0
Task 0 done.

$ ./yodo get
default:
- [0] "Add verbose mode" (true)

$ cat ~/.yodo/default.yaml
id: 0
name: default
tasks:
- id: 0
status: true
description: Add verbose mode

Notes

Gopher art from ashleymcnamara/gophers.

rael.io

Thu, 15 Aug 2019 11:23:56 +0200

Static site for rael.io using:

Kubernetes

Wed, 01 Aug 2018 11:23:56 +0200

Contributing to the Kubernetes project in different special interest groups, mainly focused on community engagement, documentation and user/contributor experience.

Gubernator PR Dashboard

sig-docs

Lead and approver for the Spanish content at kubernetes.io in sig-docs.

sig-contribex

Contributor in sig-contribex by organizing events like talks, workshops or the New Contributors Summits during KubeCon. Also working on initiatives to improve the Kubernetes community and the contributor experience.

Contributor Summits

sig-usability

Contributor in sig-usability to ensure that the Kubernetes project is maximally usable by users of a variety of different backgrounds and abilities.

Usability Special Interest Group

sig-cli

Contributor in sig-cli adding Spanish support to kubectl.

Go Playground

Mon, 12 Feb 2018 11:23:56 +0200

Features

Compiles to Machine Code
Design for concurrence
Statically typed
Garbage collected

Language

Variables

https://blog.golang.org/gos-declaration-syntax

Definition

var foo string;
foo = "bar" // OK, new value for foo
foo = 5 // compile error, expected string, found int
newfoo = "bar" // compile error, foo is not defined
bar := "foo" // implicit var

Basic Types

https://golang.org/pkg/go/types/ or go doc types

 Invalid: {Invalid, 0, "invalid type"},
Bool: {Bool, IsBoolean, "bool"},
Int: {Int, IsInteger, "int"},
Int8: {Int8, IsInteger, "int8"},
Int16: {Int16, IsInteger, "int16"},
Int32: {Int32, IsInteger, "int32"},
Int64: {Int64, IsInteger, "int64"},
Uint: {Uint, IsInteger | IsUnsigned, "uint"},
Uint8: {Uint8, IsInteger | IsUnsigned, "uint8"},
Uint16: {Uint16, IsInteger | IsUnsigned, "uint16"},
Uint32: {Uint32, IsInteger | IsUnsigned, "uint32"},
Uint64: {Uint64, IsInteger | IsUnsigned, "uint64"},
Uintptr: {Uintptr, IsInteger | IsUnsigned, "uintptr"},
Float32: {Float32, IsFloat, "float32"},
Float64: {Float64, IsFloat, "float64"},
Complex64: {Complex64, IsComplex, "complex64"},
Complex128: {Complex128, IsComplex, "complex128"},
String: {String, IsString, "string"},
UnsafePointer: {UnsafePointer, 0, "Pointer"},
UntypedBool: {UntypedBool, IsBoolean | IsUntyped, "untyped bool"},
UntypedInt: {UntypedInt, IsInteger | IsUntyped, "untyped int"},
UntypedRune: {UntypedRune, IsInteger | IsUntyped, "untyped rune"},
UntypedFloat: {UntypedFloat, IsFloat | IsUntyped, "untyped float"},
UntypedComplex: {UntypedComplex, IsComplex | IsUntyped, "untyped complex"},
UntypedString: {UntypedString, IsString | IsUntyped, "untyped string"},
UntypedNil: {UntypedNil, IsUntyped, "untyped nil"},

var x byte = 255 // byte alias for uint8
var y byte = x + 5 // overflow to 4
x++ // overflow to 0
var y byte = 0
y = y - 1 // underflow to 255

var foo byte = 2
var foo int32 = 260
sum = foo + bar // compilation error different types
foo = bar // compilation error different types
var conv uint8 = uint8(260) // 4

Arrays

var a [2]int
a[0] = 1
a[1] = "foo" // compile error, wrong type
a[1] = 2 // OK
a[2] = 3 // compile error, out of bounds
index := 2
a[index] = 3 // runtime error, out of bounds
n := 5
var b [n]int // compile error, array size must be constant
var c [2]int // OK
c = a // OK, copy all values
var d [4]int
d = a // compile error, wrong type [2]int vs [4]int

Go will put the array values contiguous in memory adding padding if needed to align with ⁴⁄₈ bytes.

var a [2][2][2]int
0x00 a[0][0][0]
0x01 a[0][0][1]
0x02 a[0][1][0]
0x03 a[0][1][1]
0x04 a[1][0][0]
0x05 a[1][0][1]
0x06 a[1][1][0]
0x07 a[1][1][1]

Slices

TODO

### Structs

type Person struct {
Name string
Age string
Gender string
Children []Person // OK, can be empty, is a slice
Mother Person // compile error, invalid recurse type
Father Person // Type Person contains a Person, infinite references
Parents []Person // OK, can be empty, is a slice
}

### Pointer

var x int = 42
var y *int // pointer to integrer
y = &x // &x returns the pointer to x (address of x)
z := *y // *y derreferences y, gets 42, the value of x
x = 24 // updates x value
z = *y // *y returns the new value of x, 24

Maps

TODO

Definition scope

x := 0
if condition {
x := 42
}
y := x // y is 0
if condition {
y = 21
}
z := y // z is 21

Functions

func foo(x, y int, z bool) int {
if z {
return x + y
} else {
return "bar" // compile error, wrong return type
}
}
func bar() (string, int) {
return "The answer is", 42
}
func main() {
var x int = foo(1, 2, true) // OK
var y int = foo(1, 2) // compile error, wrong number of arguments
var z int = foo(1, 2, "bar") // compile error, last argument not a bool
var v bool = foo(1, 2, true) // compile error, wrong return type
a := 1
b := 2
s := foo(a, b, true) + a // OK, compiler knows that a, b and foo are int
str, num := bar() // OK
}

Syntax

Semicolons are inserted by the compiler

func foo(x int) int {
x++
return x
}
foo(1)

The compiler will put the ;:

func foo(x int) int {
x++;
return x;
};
foo(1);

### Loops

abc := [3]string{"a", "b", "c"}
for i, v := rang abc {
// i is the index or key if abc is a map
// v is the value
}

Range

Resources

Notes

Gopher art from ashleymcnamara/gophers.

tgfwdbot

Sun, 09 Jul 2017 11:23:56 +0200

Bot to forward messages between supergroups and private chats, to allow talking in Telegram supergroups when banned.

Why

Sometimes, due to trolls reporters, users can be banned from any Telegram supergroup, not only the one where reported. With this bot, users will be able to participate in specific groups through the bot.

This bot can be added to the group, identified by TELEGRAM_GROUP_ID, and will:

Forward any message from the Group to the private conversation with the banned user
Forward any message from the private conversation with the banned user to the Group

The admins of the groups where the bot is a member will decide if the allows the banned users to participate or not.

Disclaimer

This bot is not intended to be a tool for spammers and malicious users to bypass Telegram bans. The purpose is to allow users to interact in the groups with the authorization of the group admins when globally banned from supergroups due to troll reportings.

Notes

Gopher art from ashleymcnamara/gophers.