Category: Unknown Code Ramblings

A Really Quick Introduction to Minikube

There’s likely a million introductions to Minikube, but I wanted one of my own. Thus, here you go!  Minikube is basically Kubernetes light that runs on your own machine. Albeit, it does this similarly to how Docker used to do it, via a virtual machine. Thus, you can do some things with it but if you want to get serious you’ll still need to spool up a proper cluster somewhere as it will start to bog down your machine with any heavy workloads.

1: Minikube – Installing

Linux Direct:

 curl -LO https://storage.googleapis.com/minikube/releases/latest/minikube-linux-amd64 \
   && sudo install minikube-linux-amd64 /usr/local/bin/minikube

Linux Debian:

 curl -LO https://storage.googleapis.com/minikube/releases/latest/minikube-linux-amd64 \
   && sudo install minikube-linux-amd64 /usr/local/bin/minikube

Linux Red Hat:

curl -LO https://storage.googleapis.com/minikube/releases/latest/minikube-1.4.0.rpm \
 && sudo rpm -ivh minikube-1.4.0.rpm

2: Starting Minikube

minikube start will start a minikube instance, pulling images, resources, kubelets, kubeadm, dashboard, and all those resources.

00-starting

3: Stopping Minikube

minikube stop brings the minikube service to a stop, allowing for restart later.

09-stopping-minikube

4. Deleting Minikube

minikube delete will delete the minikube. This will delete any of the content or related collateral that was running in the minikube.

01-delete

5. Restarting after Delete

minikube start this is the way to restart a minikube instance after you’ve stopped the instance. It’s also the way start a minikube, as shown above.

03-restarting-after-delete

6. Starting a Named Minikube

If you want a named minikube instance, use the -p switch, with a command like minikube start -p adrons-minikube.

04-minikube-with-name

7. Starting & Using the Dashboard

To check out the dashboard, that pretty Google dashboard for Kubernetes, run minikube dashboard to bring that up.

05-starting-dashboard

06-minikube-dashboard.png

8. Status!

To get a quick update on the current state of the minikube instance just run minikube status.

07-other-minikube-commands

9. Starting Minikube sans a Virtual Machine

This is, albeit I may be mistaken, this is a Linux only feature. Run minikube start --vm-driver=none and it’ll kick off a minikube right there on your local machine.

09-minikube-no-vm-started.png

References:

Learning Go Episode 4 – Composite Types, Slices, Arrays, Etc.

Episode Post & Video Links:  1, 2, 3, 4 (this post), 5, 6, 7, and 8. Non-linked are in the works! Videos available now on Youtube however, so check em’ out!

If you’d like to go through this material too in book form, I highly suggest “The Go Programming Language” by Alan A.A. Donovan & Brian W. Kernighan. I use it throughout these sessions to provide a guideline. I however add a bunch of other material about IDE’s, development tips n’ tricks and other material.

8:00 Starting the core content with some notes. Composite types, arrays, slices, etc.
11:40 Announcement of my first reload – http://compositecode.blog/2019/02/11/… – second successful time blogged here) of the XPS 15 I have, which – https://youtu.be/f0z1chi4v1Q – actually ended in catastrophe the first time!
14:08 Starting the project for this session.
16:48 Setting up arrays, the things that could be confusing, and setup of our first code for the day. I work through assignment, creation, new vs. comparison, and various other characteristics of working with arrays during this time.


fmt.Println("Hello, let's talk composite types.")
basketOfStuff := [3]string{"The first string","second","This string."}
var zeeValues [2]int
for i, v := range basketOfStuff {
fmt.Printf("Value %d: %s\n", i, v)
}
fmt.Println(zeeValues)
if zeeValues[0] == zeeValues[1] {
fmt.Println("The values are the same, this doesn't instantiate like the `new` keyword.")
} else {
fmt.Println("The way go appears to instantiate unset variable values, such as in this array is like the `new` keyword instantiation.")
}
zeeValues[0] = 1 + 52 * 3
zeeValues[1] = 9
fmt.Println(zeeValues[len(zeeValues) – 1])

view raw

testing-out-composite-types.go

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29:36 Creation of a type, called Currency, of type int, setting up constants, and using this kind of like an enumerator to work with code that reads cleaner. Plus of course, all the various things that you might want to, or need for a setup of types, ints, and related composite types like this.


type Currency int
const (
USD Currency = iota
CAN
EUR
GBP
JPY
NOK
SEK
DKK
)
symbol := […]string{USD: "$", CAN: "$", EUR: "€", GBP: "£", JPY:"¥", NOK:"kr", SEK:"kr",DKK:"kr"}
fmt.Println(EUR, symbol[EUR])
fmt.Println(JPY, symbol[JPY])
r := […]int{99: -1}
r[36] = 425
r[42] = 42
fmt.Println(r[36] + r[42])
fmt.Println(strconv.Itoa(r[36]))

view raw

currency.go

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43:48 Creating an example directly from the aforementioned book enumerating the months of the year. This is a great example I just had to work through it a bit for an example.


months := […]string{1: "January", 2:"February", 3: "March", 4:"April", 12:"December"}
for _, s := range months {
fmt.Printf("The month: %s\n", s)
}
var runes []rune
for _, r := range "Language: 走" {
runes = append(runes, r)
}
fmt.Printf("%q \n", runes)
var x, y []int
for i := 0; i < 10; i++ {
y = appendInt(x, i)
fmt.Printf("%d cap=%d\t%v\n", i, cap(y), y)
x = y
}

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the_months.go

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52:40 Here I start showing, and in the process, doing some learning of my own about runes. I wasn’t really familiar with them before digging in just now!


… the rest of the main.go file is here…
var runes []rune
for _, r := range "Language: 走" {
runes = append(runes, r)
}
fmt.Printf("%q \n", runes)
var x, y []int
for i := 0; i < 10; i++ {
y = appendInt(x, i)
fmt.Printf("%d cap=%d\t%v\n", i, cap(y), y)
x = y
}
}
func appendInt(x []int, i int) []int {
var z []int
zlen := len(x) + 1
if zlen <= cap(x) {
z = x[:zlen]
} else {
zcap := zlen
if zcap < 2* len(x) {
zcap = 2 * len(x)
}
z = make([]int, zlen, zcap)
copy(z, x)
}
return z
}

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main.go

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1:09:40 Here I break things down and start a new branch for some additional examples. I also derail off into some other things about meetups and such for a short bit. Skip to the next code bits at the next time point.
1:23:58 From here on to the remainder of the video I work through a few examples of how to setup maps, how make works, and related coding around how to retrieve, set, and otherwise manipulate the maps one you’ve got them.


package main
import "fmt"
func main() {
ages := map[string]int{
"Peterson": 52,
"Sally": 22,
"Javovia": 15,
"Ben": 42,
}
jobAssociation := make(map[string]string)
jobAssociation["Peterson"] = "Engineer"
jobAssociation["Sally"] = "CEO"
jobAssociation["Jovovia"] = "Gamer"
jobAssociation["Ben"] = "Programmer"
printAges(ages)
printJobAssociations(jobAssociation)
fmt.Println(ages)
fmt.Println(jobAssociation)
fmt.Println(jobAssociation["Jovovia"])
fmt.Println(jobAssociation["Frank"]) // Blank! 😮
fmt.Println(ages["Sally"])
delete(ages, "Sally")
fmt.Println(ages)
fmt.Println(ages["Sally"])
delete(jobAssociation, "Jovovia")
fmt.Println(jobAssociation)
fmt.Println(jobAssociation["Jovovia"]) // Blank.
ages2 := map[string]int{
"Frank": 52,
"Johnson": 22,
"Smith": 15,
"Jezebelle": 42,
}
ages3 := map[string]int{
"Frank": 52,
"Johnson": 22,
"Smith": 15,
"Jezebelle": 42,
}
if equal(ages, ages2) {
fmt.Println("Naw, not really equal.")
} else {
fmt.Println("This is correct, not equal.")
}
if equal(ages2, ages3) {
fmt.Println("True, these are effectively the same map values and keys.")
}
}
func printJobAssociations(associations map[string]string) {
for name, job := range associations {
fmt.Printf("%s\t%s\n", name, job)
}
}
func printAges(ages map[string]int) {
for name, age := range ages {
fmt.Printf("%s\t%d\n", name, age)
}
}
func equal(x, y map[string]int) bool {
if len(x) != len(y) {
return false
}
for k, xv := range x {
if yv, ok := y[k]; !ok || yv != xv {
return false
}
}
return true
}

view raw

map_types.go

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That’s it for this synopsis. Until next episode, happy code thrashing and go coding!

Thrashing Metal Monday for Week of the 13th of May.

A new band I just learned about this last week is Bloody Hammers. Listen to those vocals, traditional dark prodding rhythms and melody. It’s eerie in the best of ways and provides that melancholy horror movie feel so well! Beautiful!

You can check out their website which has good details and information, but their material is of course out there on Bandcamp too so check that out and pick up some tunes!

Not new for regular readers of Composite Code or viewers of Thrashing Code listening sessions, but I felt another Spoil Engine tune showing some of their range would be a good kick to Monday. May it light your mind up for the week!

To wrap up the trigonous edges of metal for today, part one of the new Amon Amarth saga!

It’s Monday, So Here’s Your Metal Dose

A quick list, devoid of details, cuz I’m already into the thick of it today. A mix of new, a mix of old, some Japanese lyrics, and a few English ones.

If you’re up for some listening sessions and getting introduced to even more metal and various musical variety, check out these two past listening sessions on my Thrashing Code Channel!

Listening Sessions Episode 1 – Bands List

Listening Sessions Episode 2

In Flight to Apache Cassandra Days

Another flight down to the bay area. Today it was Alaska Air Flight 330 from Seattle to San Jose. It was mostly a clear day at start, with a solid layer of bright cloud cover exiting Washington on the way down to Oregon. As we crossed over that arbitrary human defined line of Oregon and California, nature presented us with even more perfectly glowing bright cloud cover. This is Cascadia after all and it’s basically covered in clouds the majority of the time. On departure I also noted Bremerton has three aircraft carriers in dock along with a normal plethora of other naval vessels. The amount of naval power in the area is always pretty awe inspiring.

Why was I in flight once again? I am heading down to teach with Jeff Carpenter (@jscarp) at the South Bay Cassandra User Group‘s Cassandra Day events. These are single day events, where we cover an introduction to Apache Cassandra, concepts of data-modeling for Apache Cassandra, and then a wrap up of application development with the respective drivers. Now if you aren’t in Santa Clara – or ya know Menlo Park, San Jose, Oakland, San Francisco, or well, the surrounding area – there are other days scheduled! We also have days scheduled that aren’t even located in the Bay, so check out the full list of events:

https://www.datastax.com/company/events

NOTE: If you’re interested in Seattle, Portland, or Vancouver BC area events, scroll all the way down to the end of this blog entry I’ve got more details for you!

Introduction to Apache Cassandra

In the introduction to Apache Cassandra we cover an overview of the architecture and features of the distributed database. Starting off with a definition of a distributed hash ring and how this is used in Apache Cassandra to provide data storage across the nodes that make up the Apache Cassandra Database. Moving on we’ll get into the other capabilities, trade offs of data replication between nodes, configuration settings, and a lot more.

Data Modeling

For data modeling we start off with a short review of relational database data modeling to provide something that is more familiar for many people. From this, we then build off of many concepts around denormalization, breaking apart various levels of normalization forms, and then get into the thinking and approach behind modeling an application in a distributed database and go deeper with details around Apache Cassandra.

Application Development

For application development, focusing around the Java language and technology stack, we’ll start with some concepts around how the drivers connect to and work with Apache Cassandra. We’ll open up some code too, get into some code changes and additions, to get more familiar with how the driver works and some of the capabilities of the driver itself.

Most of the code, concepts, and related material in use around Java and the tech stack are directly usable on C#, JavaScript, and even using the community open source Go CQL Library.

Coming soon…

In the coming weeks (ok, maybe a month or two) we’ll be updating this material for Apache Cassandra v4 and additionally, I’m aiming to line up some half day and probably some full day workshops in the Cascadian region: Portland, Seattle, and Vancouver BC. They’ll be almost identical except for a few tweaks, but you’ll have to RSVP to find out the details!

Also, if you’re in between any of those cities and have a stop on the Amtrak Cascades, let me know and we’ll get an RSVP list started for your city and see if we can get the required attendee count to make it official!