Louis Jones

Louis Jones

1567158649

Avoid Docker in Docker in Windows 10

Originally published by Thomas Suedbroecker at https://dzone.com

We defined a Dockerfile to create a Docker image for our Cloud-Native-Starter workshop especially for Windows 10 users. The users can now simply create a Docker image on the local Windows 10 machine and then follow the guided steps in the hands-on workshop documentation and use the bash scripts.

These are some challenges we had during the testing of the Dockerfile definition:

  • File sharing for Docker images on Windows
  • Docker port forwarding
  • Docker in Docker
  • Istio Virtual service configuration
  • Linux tools missing

Why Should We Use a Docker Image?

We wrote a lot of bash scripts to simplify the setup and steps inside the hands-on workshop. These bash scripts can’t be executed on a Windows console or in a Windows Powershell.

It is possible to install other environments like Cygwin on Windows to use bash scripts, but we notice with those solutions, other problems do appear, related to development tools installations.

We know that it is possible to install bash on Ubuntu on Windows 10, but we want to avoid such additional effort in a hands-on workshop for participants, who will maybe come unprepared to the workshop.

The Dockerfile Solution Decision

We decided to use a Docker image on Windows and define our own Dockerfile using Ubuntu as a starting point. The reason that we don’t build a Docker image and share it on Dockerhub is because we want to provide users the freedom of their own customization we can add the file with no effort to our GitHub project, and the users will always build an actual Docker image with the newest tools.

Use of The Docker Image

With the Docker command:

docker run -ti my-workshop-image:v1

we can start the Docker image in the interactive mode in a terminal session on our Windows 10 machine.

In the image below we see the start of the Docker image and the verification of the installed prerequisites of the workshop on the Docker image.

Docker image initialization

It seems that’s the best solution for our Windows 10 users to setup their machines in our workshop. They only need is to install Docker on Windows 10, which is effortless.

Installation of The Developer and Linux Tools

We need to install developer tools on our Docker image, as documented in our workshop, and some missing or useful Linux tools.

These are the developer tools we need to install into the Docker image:

  • Git
  • CURL
  • Docker (CLI online)
  • IBM Cloud CLI and two specific packages
  • kubectl from Kubernetes

In the Dockerfile definition, we see Ubuntu is our starting point for the Docker image and the needed/useful Linux tools:

FROM ubuntu
RUN apt-get update
RUN apt-get --assume-yes install curl
RUN apt-get --assume-yes install git-core
RUN apt-get --assume-yes install wget
# editor
RUN apt-get --assume-yes install nano
# setup network tools
RUN apt-get --assume-yes install apt-utils
RUN apt-get --assume-yes install net-tools
# zip
RUN apt-get --assume-yes install unzip
RUN apt-get --assume-yes install zip

File Sharing for Docker Images on Windows

It is challenging to share the local host filesystem on a Windows machine with a Docker image, because of the Windows Azure authorization. We search in the internet to get an easy solution, but the search ends with no easy solution. Here we see a long discussion in the Docker community about that topic.

With this in mind we decide just to clone our git repository into the Docker image, because that is the simplest way for our situation. Here we see how we clone our project.

# Cloud-Native-Starter -project 
# https://github.com/IBM/cloud-native-starter/blob/master/workshop/00-prerequisites.md                
# Install RUN mkdir usr/cns 
WORKDIR /usr/cns RUN 
git clone https://github.com/IBM/cloud-native-starter.git 
WORKDIR /usr/cns/cloud-native-starter

Docker in Docker

With the usage of the IBM Cloud Kubernetes service and the IBM Cloud Container Registry we don’t need to run the Docker daemon inside our Docker image. So we can move on with the Dockerfile solution for the workshop. Inside our bash scripts, we log on to IBM Cloud and we use the command ibmcloud cr build. Here we see the build command:

ibmcloud cr build -f Dockerfile --tag $REGISTRY/$REGISTRY_NAMESPACE/authors:1 .

In the following image, we see the difference between the usage of the IBM Cloud CLI and the Docker CLI.

Docker CLI

With Docker CLI we can’t build the Docker image and with the IBM Cloud CLI we can build a container image.

The reason why we can build the container image is because we are logged on to the IBM Cloud and we use the IBM Cloud CLI to upload the build context to the IBM Cloud Container Registry and we build the image inside the IBM Cloud Container Registry. With that situation, we are able to avoid Docker in Docker usage, but we need the Docker CLI to be installed. The image below shows a simplified view of how it works in our situation on Windows 10.

Windows container upload

Port Forwarding

The last remaining problem is how to do a port forwarding with Docker on Windows that uses Hyper-V?

Normally we do a local port forwarding on a PC from our IBM Cloud Kubernetes cluster to access the Kiali with a local browser. That is the command:

kubectl -n istio-system port-forward $(kubectl  -n istio-system get pod -l app=kiali -o jsonpath='{.items[0].metadata.-n istio-system get pod -l app=kiali -o jsonpath='{.items[0].metadata.name}') 20001:20001

But when we use this local port-forwarding inside the Docker image we can’t access the Kiali UI.

The reason is that we don’t have a browser inside our Docker image and even if we would install one, we can’t use command line and an open browser in our Docker image at the same time. Remember we are in an interactive terminal mode.

We must expose the port 20001 to our Docker image, to access Kiali in a browser on a local machine. That is the command, we use to start the Docker image and expose the port 20001.

docker run -ti -p 20001:20001 my-workshop-image:v1

But we notice that we are not able to access Kiali in a browser on the local Windows system. The reason for this is that Hyper-V runs our Docker Linux and we only have exposed the port to that Linux in the Hyper-V. If we want to access the port from the Windows host system, we need to expose the same port 20001 in Hyper-V. That’s too complex a configuration for our workshop and we decide to use Virtual Service configuration with Istio on our Kubernetes cluster in IBM Cloud.

The image below shows a simplified view of our needed port forwarding/exposing.

Docker portforwarding

Configuration of The Virtual Service for Istio

To solve the port forwarding challenge, we decide to configure the Istio Virtual Service. We map the Kiali port directly in the Istio Virtual Service and with that configuration it is possible to access Kiali from our Kubernetes Cluster directly.

Therefore we define a match for Kiali using: URI, port, and host information, as we see in the following YAML configuration.

apiVersion: networking.istio.io/v1alpha3
kind: VirtualService
metadata:
  name: virtualservice-ingress-web-api-web-app
spec:
  hosts:
  - "*"
  gateways:
  - default-gateway-ingress-http
  http:
  - match:
    - uri:
        prefix: /kiali
    route:
    - destination:
        port:
          number: 20001
        host: kiali.istio-system.svc.cluster.local

With that configuration we access easily the Kiali UI directly on our free Kubernetes Cluster on IBM Cloud.

Kiali access

I hope this was useful for you and let’s see what’s next.

Thanks for reading

If you liked this post, share it with all of your programming buddies!

Follow me on Facebook | Twitter

Further reading

Docker and Kubernetes: The Complete Guide

Docker Mastery: The Complete Toolset From a Docker Captain

Docker for the Absolute Beginner - Hands On - DevOps

Docker for Absolute Beginners

How to debug Node.js in a Docker container?

Docker Containers for Beginners

Deploy Docker Containers With AWS CodePipeline

Build Docker Images and Host a Docker Image Repository with GitLab

How to create a full stack React/Express/MongoDB app using Docker

#docker #kubernetes #devops

What is GEEK

Buddha Community

Avoid Docker in Docker in Windows 10
Iliana  Welch

Iliana Welch

1595249460

Docker Explained: Docker Architecture | Docker Registries

Following the second video about Docker basics, in this video, I explain Docker architecture and explain the different building blocks of the docker engine; docker client, API, Docker Daemon. I also explain what a docker registry is and I finish the video with a demo explaining and illustrating how to use Docker hub

In this video lesson you will learn:

  • What is Docker Host
  • What is Docker Engine
  • Learn about Docker Architecture
  • Learn about Docker client and Docker Daemon
  • Docker Hub and Registries
  • Simple demo to understand using images from registries

#docker #docker hub #docker host #docker engine #docker architecture #api

Alex Tyler

Alex Tyler

1594822290

Docker Installation on Windows 10

How to install docker on Windows 10.

Download docker desktop from Docker Hub

#docker #windows 10

Anil  Sakhiya

Anil Sakhiya

1599735120

Docker for Windows | What is Docker | Introduction To Docker on Windows

This live session on “Docker for Windows” will help you to cover all the basic concepts of Docker in windows. This session will start with topics such as What is Docker? Why do we need them? What are Containers? along with the concepts like Docker’s Engine, Image, and Architecture. And then we will learn how to install docker in windows and how to run some basic Docker commands that are necessary to know while working with Docker in windows. Once you are done learning all these concepts you will find yourself at a position where all your doubts regarding docker are being cleared and then you can move to more advanced Docker Concepts.

#docker #windows

How to Create Arrays in Python

In this tutorial, you'll know the basics of how to create arrays in Python using the array module. Learn how to use Python arrays. You'll see how to define them and the different methods commonly used for performing operations on them.

This tutorialvideo on 'Arrays in Python' will help you establish a strong hold on all the fundamentals in python programming language. Below are the topics covered in this video:  
1:15 What is an array?
2:53 Is python list same as an array?
3:48  How to create arrays in python?
7:19 Accessing array elements
9:59 Basic array operations
        - 10:33  Finding the length of an array
        - 11:44  Adding Elements
        - 15:06  Removing elements
        - 18:32  Array concatenation
       - 20:59  Slicing
       - 23:26  Looping  


Python Array Tutorial – Define, Index, Methods

In this article, you'll learn how to use Python arrays. You'll see how to define them and the different methods commonly used for performing operations on them.

The artcile covers arrays that you create by importing the array module. We won't cover NumPy arrays here.

Table of Contents

  1. Introduction to Arrays
    1. The differences between Lists and Arrays
    2. When to use arrays
  2. How to use arrays
    1. Define arrays
    2. Find the length of arrays
    3. Array indexing
    4. Search through arrays
    5. Loop through arrays
    6. Slice an array
  3. Array methods for performing operations
    1. Change an existing value
    2. Add a new value
    3. Remove a value
  4. Conclusion

Let's get started!

What are Python Arrays?

Arrays are a fundamental data structure, and an important part of most programming languages. In Python, they are containers which are able to store more than one item at the same time.

Specifically, they are an ordered collection of elements with every value being of the same data type. That is the most important thing to remember about Python arrays - the fact that they can only hold a sequence of multiple items that are of the same type.

What's the Difference between Python Lists and Python Arrays?

Lists are one of the most common data structures in Python, and a core part of the language.

Lists and arrays behave similarly.

Just like arrays, lists are an ordered sequence of elements.

They are also mutable and not fixed in size, which means they can grow and shrink throughout the life of the program. Items can be added and removed, making them very flexible to work with.

However, lists and arrays are not the same thing.

Lists store items that are of various data types. This means that a list can contain integers, floating point numbers, strings, or any other Python data type, at the same time. That is not the case with arrays.

As mentioned in the section above, arrays store only items that are of the same single data type. There are arrays that contain only integers, or only floating point numbers, or only any other Python data type you want to use.

When to Use Python Arrays

Lists are built into the Python programming language, whereas arrays aren't. Arrays are not a built-in data structure, and therefore need to be imported via the array module in order to be used.

Arrays of the array module are a thin wrapper over C arrays, and are useful when you want to work with homogeneous data.

They are also more compact and take up less memory and space which makes them more size efficient compared to lists.

If you want to perform mathematical calculations, then you should use NumPy arrays by importing the NumPy package. Besides that, you should just use Python arrays when you really need to, as lists work in a similar way and are more flexible to work with.

How to Use Arrays in Python

In order to create Python arrays, you'll first have to import the array module which contains all the necassary functions.

There are three ways you can import the array module:

  • By using import array at the top of the file. This includes the module array. You would then go on to create an array using array.array().
import array

#how you would create an array
array.array()
  • Instead of having to type array.array() all the time, you could use import array as arr at the top of the file, instead of import array alone. You would then create an array by typing arr.array(). The arr acts as an alias name, with the array constructor then immediately following it.
import array as arr

#how you would create an array
arr.array()
  • Lastly, you could also use from array import *, with * importing all the functionalities available. You would then create an array by writing the array() constructor alone.
from array import *

#how you would create an array
array()

How to Define Arrays in Python

Once you've imported the array module, you can then go on to define a Python array.

The general syntax for creating an array looks like this:

variable_name = array(typecode,[elements])

Let's break it down:

  • variable_name would be the name of the array.
  • The typecode specifies what kind of elements would be stored in the array. Whether it would be an array of integers, an array of floats or an array of any other Python data type. Remember that all elements should be of the same data type.
  • Inside square brackets you mention the elements that would be stored in the array, with each element being separated by a comma. You can also create an empty array by just writing variable_name = array(typecode) alone, without any elements.

Below is a typecode table, with the different typecodes that can be used with the different data types when defining Python arrays:

TYPECODEC TYPEPYTHON TYPESIZE
'b'signed charint1
'B'unsigned charint1
'u'wchar_tUnicode character2
'h'signed shortint2
'H'unsigned shortint2
'i'signed intint2
'I'unsigned intint2
'l'signed longint4
'L'unsigned longint4
'q'signed long longint8
'Q'unsigned long longint8
'f'floatfloat4
'd'doublefloat8

Tying everything together, here is an example of how you would define an array in Python:

import array as arr 

numbers = arr.array('i',[10,20,30])


print(numbers)

#output

#array('i', [10, 20, 30])

Let's break it down:

  • First we included the array module, in this case with import array as arr .
  • Then, we created a numbers array.
  • We used arr.array() because of import array as arr .
  • Inside the array() constructor, we first included i, for signed integer. Signed integer means that the array can include positive and negative values. Unsigned integer, with H for example, would mean that no negative values are allowed.
  • Lastly, we included the values to be stored in the array in square brackets.

Keep in mind that if you tried to include values that were not of i typecode, meaning they were not integer values, you would get an error:

import array as arr 

numbers = arr.array('i',[10.0,20,30])


print(numbers)

#output

#Traceback (most recent call last):
# File "/Users/dionysialemonaki/python_articles/demo.py", line 14, in <module>
#   numbers = arr.array('i',[10.0,20,30])
#TypeError: 'float' object cannot be interpreted as an integer

In the example above, I tried to include a floating point number in the array. I got an error because this is meant to be an integer array only.

Another way to create an array is the following:

from array import *

#an array of floating point values
numbers = array('d',[10.0,20.0,30.0])

print(numbers)

#output

#array('d', [10.0, 20.0, 30.0])

The example above imported the array module via from array import * and created an array numbers of float data type. This means that it holds only floating point numbers, which is specified with the 'd' typecode.

How to Find the Length of an Array in Python

To find out the exact number of elements contained in an array, use the built-in len() method.

It will return the integer number that is equal to the total number of elements in the array you specify.

import array as arr 

numbers = arr.array('i',[10,20,30])


print(len(numbers))

#output
# 3

In the example above, the array contained three elements – 10, 20, 30 – so the length of numbers is 3.

Array Indexing and How to Access Individual Items in an Array in Python

Each item in an array has a specific address. Individual items are accessed by referencing their index number.

Indexing in Python, and in all programming languages and computing in general, starts at 0. It is important to remember that counting starts at 0 and not at 1.

To access an element, you first write the name of the array followed by square brackets. Inside the square brackets you include the item's index number.

The general syntax would look something like this:

array_name[index_value_of_item]

Here is how you would access each individual element in an array:

import array as arr 

numbers = arr.array('i',[10,20,30])

print(numbers[0]) # gets the 1st element
print(numbers[1]) # gets the 2nd element
print(numbers[2]) # gets the 3rd element

#output

#10
#20
#30

Remember that the index value of the last element of an array is always one less than the length of the array. Where n is the length of the array, n - 1 will be the index value of the last item.

Note that you can also access each individual element using negative indexing.

With negative indexing, the last element would have an index of -1, the second to last element would have an index of -2, and so on.

Here is how you would get each item in an array using that method:

import array as arr 

numbers = arr.array('i',[10,20,30])

print(numbers[-1]) #gets last item
print(numbers[-2]) #gets second to last item
print(numbers[-3]) #gets first item
 
#output

#30
#20
#10

How to Search Through an Array in Python

You can find out an element's index number by using the index() method.

You pass the value of the element being searched as the argument to the method, and the element's index number is returned.

import array as arr 

numbers = arr.array('i',[10,20,30])

#search for the index of the value 10
print(numbers.index(10))

#output

#0

If there is more than one element with the same value, the index of the first instance of the value will be returned:

import array as arr 


numbers = arr.array('i',[10,20,30,10,20,30])

#search for the index of the value 10
#will return the index number of the first instance of the value 10
print(numbers.index(10))

#output

#0

How to Loop through an Array in Python

You've seen how to access each individual element in an array and print it out on its own.

You've also seen how to print the array, using the print() method. That method gives the following result:

import array as arr 

numbers = arr.array('i',[10,20,30])

print(numbers)

#output

#array('i', [10, 20, 30])

What if you want to print each value one by one?

This is where a loop comes in handy. You can loop through the array and print out each value, one-by-one, with each loop iteration.

For this you can use a simple for loop:

import array as arr 

numbers = arr.array('i',[10,20,30])

for number in numbers:
    print(number)
    
#output
#10
#20
#30

You could also use the range() function, and pass the len() method as its parameter. This would give the same result as above:

import array as arr  

values = arr.array('i',[10,20,30])

#prints each individual value in the array
for value in range(len(values)):
    print(values[value])

#output

#10
#20
#30

How to Slice an Array in Python

To access a specific range of values inside the array, use the slicing operator, which is a colon :.

When using the slicing operator and you only include one value, the counting starts from 0 by default. It gets the first item, and goes up to but not including the index number you specify.

import array as arr 

#original array
numbers = arr.array('i',[10,20,30])

#get the values 10 and 20 only
print(numbers[:2])  #first to second position

#output

#array('i', [10, 20])

When you pass two numbers as arguments, you specify a range of numbers. In this case, the counting starts at the position of the first number in the range, and up to but not including the second one:

import array as arr 

#original array
numbers = arr.array('i',[10,20,30])


#get the values 20 and 30 only
print(numbers[1:3]) #second to third position

#output

#rray('i', [20, 30])

Methods For Performing Operations on Arrays in Python

Arrays are mutable, which means they are changeable. You can change the value of the different items, add new ones, or remove any you don't want in your program anymore.

Let's see some of the most commonly used methods which are used for performing operations on arrays.

How to Change the Value of an Item in an Array

You can change the value of a specific element by speficying its position and assigning it a new value:

import array as arr 

#original array
numbers = arr.array('i',[10,20,30])

#change the first element
#change it from having a value of 10 to having a value of 40
numbers[0] = 40

print(numbers)

#output

#array('i', [40, 20, 30])

How to Add a New Value to an Array

To add one single value at the end of an array, use the append() method:

import array as arr 

#original array
numbers = arr.array('i',[10,20,30])

#add the integer 40 to the end of numbers
numbers.append(40)

print(numbers)

#output

#array('i', [10, 20, 30, 40])

Be aware that the new item you add needs to be the same data type as the rest of the items in the array.

Look what happens when I try to add a float to an array of integers:

import array as arr 

#original array
numbers = arr.array('i',[10,20,30])

#add the integer 40 to the end of numbers
numbers.append(40.0)

print(numbers)

#output

#Traceback (most recent call last):
#  File "/Users/dionysialemonaki/python_articles/demo.py", line 19, in <module>
#   numbers.append(40.0)
#TypeError: 'float' object cannot be interpreted as an integer

But what if you want to add more than one value to the end an array?

Use the extend() method, which takes an iterable (such as a list of items) as an argument. Again, make sure that the new items are all the same data type.

import array as arr 

#original array
numbers = arr.array('i',[10,20,30])

#add the integers 40,50,60 to the end of numbers
#The numbers need to be enclosed in square brackets

numbers.extend([40,50,60])

print(numbers)

#output

#array('i', [10, 20, 30, 40, 50, 60])

And what if you don't want to add an item to the end of an array? Use the insert() method, to add an item at a specific position.

The insert() function takes two arguments: the index number of the position the new element will be inserted, and the value of the new element.

import array as arr 

#original array
numbers = arr.array('i',[10,20,30])

#add the integer 40 in the first position
#remember indexing starts at 0

numbers.insert(0,40)

print(numbers)

#output

#array('i', [40, 10, 20, 30])

How to Remove a Value from an Array

To remove an element from an array, use the remove() method and include the value as an argument to the method.

import array as arr 

#original array
numbers = arr.array('i',[10,20,30])

numbers.remove(10)

print(numbers)

#output

#array('i', [20, 30])

With remove(), only the first instance of the value you pass as an argument will be removed.

See what happens when there are more than one identical values:

import array as arr 

#original array
numbers = arr.array('i',[10,20,30,10,20])

numbers.remove(10)

print(numbers)

#output

#array('i', [20, 30, 10, 20])

Only the first occurence of 10 is removed.

You can also use the pop() method, and specify the position of the element to be removed:

import array as arr 

#original array
numbers = arr.array('i',[10,20,30,10,20])

#remove the first instance of 10
numbers.pop(0)

print(numbers)

#output

#array('i', [20, 30, 10, 20])

Conclusion

And there you have it - you now know the basics of how to create arrays in Python using the array module. Hopefully you found this guide helpful.

Thanks for reading and happy coding!

#python #programming 

Try These Steps for Increasing Privacy and Security on Windows 10

Note: Some versions of Windows 10 may not show all the following settings.

Sure, Windows 10 comes with some built-in security features like Windows Defender. But this should not be seen as a cure-all for all the dangers of today’s internet. Instead, consider these tips for upping your Windows security even more.

1. Use a password rather than a PIN for local accounts.

Whether you use a local account or a Microsoft one, make sure you use a strong, alphanumeric password.

2. You don’t have to link your PC to a Microsoft account.

Create a local account instead. This prevents sharing data about local accounts, though at the expense of being able to share data across devices.

How: Settings > Accounts > Sign in with a local account instead

3. Randomize your hardware address on WiFi.

Enabling random hardware addresses reduces a user’s exposure to tracking across different WiFi networks. Note: not all devices support this function.

How: Settings > Network & Internet > Wi-Fi

#security #windows #cybersecurity #operating-systems #windows-security #privacy #hackernoon-top-story #windows-10