Category: Cloud

Kubernetes – from cluster reset to up and running

This is Step 2 in a series of Kubernetes blog posts

Step 1 covers the initial host creation and basic provisioning with Ansible: https://www.donaldsimpson.co.uk/2019/01/03/kubernetes-setting-up-the-hosts/

and Step 3 is where I set up Helm and Tiller and deploy an initial chart to the cluster: https://www.donaldsimpson.co.uk/2019/01/03/kubernetes-adding-helm-and-tiller-and-deploying-a-chart/

These are notes on going from a freshly reset kubernetes cluster to a running & healthy cluster with a pod network applied and worker nodes connected.

To get to this starting point I provisioned 4 Ubuntu hosts (1 master & 3 workers) on my VMWare server – a Dell Poweredge R710 with 128GB RAM.

I then used this Ansible project:

https://github.com/DonaldSimpson/ansible-kubeadm

to configure the hosts and prep for Kubernetes with kubeadm:

https://kubernetes.io/docs/setup/production-environment/tools/kubeadm/create-cluster-kubeadm/

I’ll write about this in more detail in another post…

Please note that none of this is production grade or recommended, it’s simply what I have done to suit my needs in my home lab. My focus is on automating Kubernetes processes and deployments, not creating highly available bullet-proof production systems.

To reset and restore a ‘new’ cluster, first on the master instance – reboot and as a normal user (I’m using an “ansible” user with sudo throughout):


sudo kubeadm reset
(y)
sudo swapoff -a
sudo kubeadm init --pod-network-cidr=10.244.0.0/16

I’m passing that CIDR address as I’m using Flannel for pod networking (details follow) – if you use something else you may not need that, but may well need something else.

That should be the MASTER started, with a message to add nodes with:


   kubeadm join 192.168.0.46:6443 --token 9w09pn.9i9uu1ht8gzv36od  --discovery-token-ca-cert-hash  sha256:4bb0bbb1033a96347c6dd888c769ec9c5f6caa1b699066a58720ffdb97a0f3d7

which all sounds good, but the first most basic check produces the following error:


ansible@umaster:~$ kubectl cluster-info
To further debug and diagnose cluster problems, use 'kubectl cluster-info dump'.
Unable to connect to the server: x509: certificate signed by unknown authority (possibly because of "crypto/rsa: verification error" while trying to verify candidate authority certificate "kubernetes")

which I think is due to the kubeadm reset cleaning up the previous config, but can be easily fixed with this:


mkdir -p $HOME/.kube
sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
sudo chown $(id -u):$(id -g) $HOME/.kube/config

then it works and MASTER is up and running ok:


ansible@umaster:~$ sudo kubectl cluster-info
Kubernetes master is running at https://192.168.0.46:6443
KubeDNS is running at https://192.168.0.46:6443/api/v1/namespaces/kube-system/services/kube-dns:dns/proxy
To further debug and diagnose cluster problems, use 'kubectl cluster-info dump'.

————- ADD NODES ——————

Use the command and token provided by the master on the worker node(s) (in my case that’s “ubuntu01” to “ubuntu04”). Again I’m running as the ansible user everywhere, and I’m disabling swap and doing a kubeadm reset first as I want this repeatable:

sudo swapoff -a
sudo kubeadm reset
sudo
  kubeadm join 192.168.0.46:6443 --token 9w09pn.9i9uu1ht8gzv36od 
--discovery-token-ca-cert-hash 
sha256:4bb0bbb1033a96347c6dd888c769ec9c5f6caa1b699066a58720ffdb97a0f3d7

I think the token expires after a few hours. If you want to get a new one you can query the Master using:

https://kubernetes.io/docs/reference/setup-tools/kubeadm/kubeadm-token/

Or, as I’ve just found out, the more recent versions ok k8s provide “kubeadm token create –print-join-command”, which provide output like the following example that you can save to a file/variable/whatever:

kubeadm join 192.168.0.46:6443 --token 8z5obf.2pwftdav48rri16o --discovery-token-ca-cert-hash sha256:2fabde5ad31a6f911785500730084a0e08472bdcb8cf935727c409b1e94daf44

I believe options to specify json or alternative output formatting is in the works too.

That’s all that is needed, if you’ve not used this node already it may take a while to pull things in but if you have it should be pretty much instant.

When ready, running a quick check on the MASTER shows the connected node (ubuntu01) and the Master (umaster) and their status:


ansible@umaster:~$ sudo kubectl get nodes --all-namespaces
NAME       STATUS     ROLES    AGE     VERSION
ubuntu01   NotReady   <none>   27s     v1.13.1
umaster    NotReady   master   8m26s   v1.13

The NotReady status is because there’s no pod network available – see here for details and options:

https://kubernetes.io/docs/setup/independent/create-cluster-kubeadm/#pod-network

so apply a pod network (I’m using flannel) like this on the Master only:


ansible@umaster:~$  sudo kubectl apply -f  https://raw.githubusercontent.com/coreos/flannel/bc79dd1505b0c8681ece4de4c0d86c5cd2643275/Documentation/kube-flannel.yml
clusterrole.rbac.authorization.k8s.io/flannel created
clusterrolebinding.rbac.authorization.k8s.io/flannel created
serviceaccount/flannel created
configmap/kube-flannel-cfg created
daemonset.extensions/kube-flannel-ds-amd64 created
daemonset.extensions/kube-flannel-ds-arm64 created
daemonset.extensions/kube-flannel-ds-arm created
daemonset.extensions/kube-flannel-ds-ppc64le created
daemonset.extensions/kube-flannel-ds-s390x created

Then check again and things should look better now they can communicate…


ansible@umaster:~$ sudo kubectl get nodes --all-namespaces
NAME       STATUS   ROLES    AGE     VERSION
ubuntu01   Ready    <none>   2m23s   v1.13.1
umaster    Ready    master   10m     v1.13.1
ansible@umaster:~$

Adding any number of subsequent nodes is very easy and exactly the same (the pod networking setup is a one-off step on the master only). I added all 4 of my worker vms and checked they were all Ready and “schedulable”. My server coped with this no problem at all. Note that by default you can’t schedule tasks on the Master, but this can be changed if you want to.

That’s the very basic “reset and restore” steps done. I plan to add this process to a Jenkins Pipeline, so that I can chain a complete cluster destroy/reprovision and application build, deploy and test process together.

The next steps I did were to:

  • install the Kubernetes Dashboard to the cluster
  • configure the Kubernetes Dashboard and fix permissions
  • deploy a sample application, replicaset & service and expose it to the network
  • configure Heapster

which I’ll post more on soonish… and I’ll add the precursor to this post on the host provisioning and kubeadm setup too.

Meetup – Deploying Openshift to AWS with HashiCorp Terraform and Ansible

 

Automated IT Solutions presented a talk on “Deploying Openshift to AWS with HashiCorp Terraform and Ansible”, by Liam Lavelle on 16th October 2018.

 

We would like to thank

 

  • Liam Lavelle for an interesting, informative and fun session
  • Everyone that came along to make it such a good event, with some great questions, helpful answers and interesting discussions
  • Hays for the beer, pizza, venue and help with everything

Hope to see you all at the next one soon!

The slides and all materials used in this session are available on our GitHub repo here:

 

Deploying Openshift to AWS with HashiCorp Terraform and Ansible

Tuesday, Oct 16, 2018, 6:15 PM

HAYS
7 Castle St, Edinburgh EH2 3AH Edinburgh, GB

30 Members Went

In this session we look at Infrastructure as Code and Configuration as Code, as we demonstrate how to use these approaches to deploy RedHat OpenShift to AWS with HashiCorp Terraform and Ansible. We start off with configuring AWS credentials, then use HashiCorp Terraform to create the AWS infrastructure needed to deploy and run our own RedHat OpenSh…

Check out this Meetup →

 

Here are the details:
When:
Tuesday, October 16th, 2018
6:15 PM to 9:00 PM

 

Where:
Hays office on the 2nd floor
7 Castle St, Edinburgh EH2 3AH · Edinburgh

 

What:
Deploying Openshift to AWS with HashiCorp Terraform and Ansible

 

Agenda:

In this session we look at Infrastructure as Code and Configuration as Code, as we demonstrate how to use these approaches to deploy RedHat OpenShift to AWS with HashiCorp Terraform and Ansible.

We start off with configuring AWS credentials, then use HashiCorp Terraform to create the AWS infrastructure needed to deploy and run our own RedHat OpenShift cluster.

We then go through using Ansible to deploy OpenShift to AWS, followed by a review of the Cluster, then take a quick look at troubleshooting any issues you may encounter.

There will be a break in the middle for beer & pizza courtesy of Hays, and we will wrap things up with a quick Q&A and feedback session.

If you would like to bring your own laptop and follow along, please do!

Who:
Intermediate Linux and some AWS knowledge is useful but not essential.

Getting started with Terraform and AWS

These are my notes from running through the Terraform getting started guide here:

https://www.terraform.io/intro/getting-started/install.html

to set up terraform (on a Mac) and provision a basic test instance in AWS.

Install process

This is very easy, simply download terraform for your platform (a single binary), extract it somewhere sensible and add that location to your PATH variable.

I set this up in my .profile, along the lines of:

export TFORM=/Users/donaldsimpson/TFORM
export PATH=$M2:$TFORM:$PATH

quick check that all looks ok:

Setup

As per the guide, the next steps are to get a note of your AWS access_key and secret_key from this AWS page, then create and edit a local “example.tf” file for your project, like this:

provider "aws" {
  access_key = "ACCESS_KEY_HERE"
  secret_key = "SECRET_KEY_HERE"
  region     = "us-east-1"
}

resource "aws_instance" "example" {
  ami           = "ami-2757f631"
  instance_type = "t2.micro"
}

I hit this issue: https://github.com/hashicorp/terraform/issues/4367 as my AWS account is pretty old, and had to change the values for

ami = "ami-2757f631"
instance_type = "t2.micro"

to be:

ami = "ami-408c7f28"
instance_type = "t1.micro"

Terraform init

You should now be able to run terraform init and see something positive…

Check the plan

Running “terraform plan” provides a dry run/sanity check of what would be done

Make it so

terraform apply: run the plan, and actually create the resources listed above:

Show it is so

Once that has completed, you can check your AWS console and see the newly created instance:

“terraform show” can confirm the same details in a less pointy-clickety way:

Next steps

This was all pretty simple, quick and straightforward.

The next steps are to manage the hosts in an Infrastructure as Code manner, adding in changes and deletions/reprovisioning, and to do something useful with them.

I’d also like to try using Terraform with Digital Ocean and VMWare providers.

 

Jenkins and Docker – Part 1 of 3

This post is the first in a series of 3 introducing the combined power of Jenkins, Docker, and the Jenkins DSL.

They should hopefully provide enough information to get to grips with both Docker and Jenkins – what they both do and how to use them – by showing some practical examples of them working together.

The first step, if you haven’t already, is to download and install Docker on your platform – the Docker website covers this in good detail for most platforms…

Docker for Mac

Docker for Windows

Docker for Linux

Once that’s done, you can try it out with the customary “Hello World” example…

I’m running Docker on an Ubuntu VM, but the commands and the results are the same regardless of platform – that’s one of the main Docker concepts.

You can then check which processes (docker containers) are running using the “docker ps” command – in my example you can see that there’s one Jenkins image running. If you run “docker ps -a” you will see all containers (including stopped ones, of which I have a few on this host):

and you can check your Docker version with:

root@ubuntud:~# docker --version
Docker version 1.13.0, build 49bf474

Now that the basic setup is done, we can move on to something a little more interesting – downloading and running a “Dockerised” Jenkins container.

I’m going to use my own Dockerised Jenkins Image, and there will be more detail on that in the next post – you’re welcome to try it out too, just run this command in your terminal:

docker run -d -p 8080:8080 donaldsimpson/dockerjenkins

if you don’t happen to have my docker image cached locally (like I do) then docker will automatically download it for you from Docker Hub then run it:

That command did a quite few important things, here’s a quick explanation of them all:

docker run -d

tells docker that we want to run the container in the background so that we can carry on and do other things while it runs. The alternative is -it, for an interactive/foreground session.

docker run -d -p 8080:8080

The -p 8080:8080 tells docker to map port 8080 on the local host to port 8080 in the running container. This means that when we visit localhost:8080 the request will be passed through to the container.

docker run -d -p 8080:8080 donaldsimpson/dockerjenkins

and finally, we have the namespace and name of the Docker image we want to run – my “donaldsimpson/dockerjenkins” one – more on this later!

You can now visit port 8080 on your Docker host and see that Jenkins is up and running….

 

That’s Jenkins up and running and being happily served from the Docker container that was just pulled from Docker Hub – how easy was that?!

And the best thing is, it’s entirely and reliably repeatable, it’s guaranteed to work the same on all platforms that can run Docker, and you can quickly and easily update, delete, replace, change or share it with others! Ok, that’s more than one thing, but the point is that there’s a lot to like here 🙂

That’s it for this post – in the next one we will look in to the various elements that came together to make this work – the code and configuration files in my Git repo, the automated build process on Docker Hub that builds and updates the Docker Image, and how the two are related.

Using ngrok to work around Carrier Grade NAT (CGNAT)

I wrote a while back about my troubles with Carrier Grade Nat (CGNAT), and described a solution that involved tunneling out of CGNAT using a combination of SSH and an AWS server – the full article is here.

That worked ok, but it was pretty fragile and not ideal – connections could be dropped, sessions expired, hosts rebooted etc etc. Passing data through my EC2 host is also not ideal.

My “new and improved” solution to this is to use a local tool like ngrok to create the tunnel for me. This is proving to be far simpler to manage, more reliable, and ngrok also provides a load of handy additional features too.

Here’s a very quick run through of getting it up and running on my Ubuntu VM, which sits behind CGNAT and hosts a webserver I’d like to be able to access from the outside occasionally. This is the front end to my ZoneMinder CCTV interface, but it could be anything you want to host and on any port.

First off, don’t use the default Ubuntu install, that will give you version 1.x which is out of date and didn’t work for me at all – it’s better, quicker and easier to get the latest binary for your platform directly from the ngrok website, extract that on your host and run it directly or add it to you PATH.

wget http://<YourDownloadURL>/ngrok-stable-linux-amd64.zip

unzip ngrok-stable-linux-amd64.zip

once that’s downloaded and extracted, you can (optionally) add your auth token, which you get when you register on the ngrok site. This is optional, but you get some worthwhile features from doing so.

./ngrok authtoken <YourAuthTokenFromTheNgrokWebsite>

Then you simply run ngrok like so:

./ngrok http 80

which should give you a console something like this:

from here you can get the Forwarding URL (http://<uniqueid>.eu.ngrok.io in this example) and your local port 80 should be available on that from anywhere on the internet.

Note I’m using this command:

screen ./ngrok http -region eu 80

to start up ngrok using screen, so I can CTRL+A+D out of that and resume it when I want using screen -r,

Here’s a pic of the console running, showing requests, and Apache being served by the ngrok URL:

That’s it – quick and easy, more stable, and far less faffing too.

 

There are tons of other options worth exploring, like specifying basic HTTP auth, saving your config to a local file, running other ports etc, all of them are explained in the documentation.

There’s a handy review of ngrok and several very similar tools here: http://john-sheehan.com/blog/a-survey-of-the-localhost-proxying-landscape

And some good tips & tricks with ngrok here:
https://developer.atlassian.com/blog/2015/05/secure-localhost-tunnels-with-ngrok/
as noted in the comments on that page: you obviously need to be safe and sensible when opening up ports to the internet…

Cheers,

Don

PS: Update to add the script I use to update the ngrok URL when it changes.

I have this in a local Jenkins job that runs every 30 mins or so, and it has been happily doing the job for a couple of years now – it’s far from perfect and it’s a lot to set up if you’re not used to these tools, but I’m adding it here just in case it helps anyone else….

#!/bin/bash

# Backup of the Jenkins job/script I put together to automatically update my home ngrok tunnel.
# When the tunnel dies, this script will (via Jenkins) create a new one and update a PHP redirect file on my
# AWS Host that allows me to connect to my CGNET'd home server via my AWS website using a dynamic ngrok end point
# Uses:
# - Jenkins
# - bash
# - ngrok
# - jq
# - grep and awk
# - PHP
# - Apache
# - AWS


# check if ngrok is running/not
pidof  ngrok >/dev/null
if [[ $? -ne 0 ]] ; then
		# A (re)start and update is required
    echo "Starting ngrok on $(date)"
    # Start up a new instance of ngrok
    BUILD_ID=dontKillMe nohup /root/ngrok/ngrok http -region eu 80 &
		# Give it a moment before testing it...
		echo "Sleeping for 15 seconds..."
    sleep 15
    # Get the updated publish_url value from the ngrok api
		export NGROKURL=`curl -s http://127.0.0.1:4040/api/tunnels | jq '.' | grep public_url | grep https | awk -F\" '{print $4}'`
    echo "NGROKURL is $NGROKURL"
    # add that to a one-line PHP redirect page
		echo "<?php header('Location: $NGROKURL/zm'); exit;?>" > ZoneMinder.php
    # upload that to my AWS host
    echo "scp'ing zm.php to AWS host..."
		scp -i /MY_AWS_KEY_FILE.pem ZoneMinder.php MY_AWS_USER@MY_AWS_HOST.amazonaws.com:/MY_HTDOCS_DIR/ZoneMinder.php
		echo "Transfer complete."
    # Send an update message via email
		echo "New ngrok url is $NGROKURL/zm" | mailx -s "ngrok zm url updated" MY_EMAIL@gmail.com
else
		# Nothing needed, carry on
		echo "ngrok is currently running, nothing to do"
fi

Tunneling out of Carrier Grade Nat (CGNAT) with SSH and AWS

Update: there’s a new & improved solution here too.
Intro

After switching to a 4G broadband provider, who shall (pretty much) remain nameless, I discovered they were using Carrier-Grade  NAT (aka CGNAT) on me.

There are more details on that here and here but in short, the ISP is ‘saving’ IPv4 addresses by sharing them out amongst several users and NAT’ing their connections – in much the same way as you do at home, when you port forward multiple devices using one external IP address: my home network is just one ‘device’ in a pool of their users, who are all sharing the same external IP address.

The impact of this for me is that I can no longer NAT my internal network services, as I have been given a shared pubic-facing IPv4 address. This approach may be practical for a bunch of mobile phone users wanting to check Twitter and Facebook, but it sucks big time for gamers or anyone else wanting to connect things from their home network to the internet. So, rather than having “Everything Everywhere” through my very expensive new 4G connection – with 12 months contract – it turns out I get “not much to anywhere“.

The Aim

Point being; I would like to be able to check my internal servers and websites when I’m away – especially my ZoneMinder CCTV setup – but my home broadband no longer has its own internet address. So an alternative solution had to be found…

The “TL; DR” summary

I basically use 2 servers, the one at home (unhelpfully now stuck behind my ISPs CGNAT) and one in the Amazon Cloud (my public facing AWS web server with DNS), and create a reverse SSH Tunnel between them. Plus a couple of essential tweaks you wont find out about if you don’t read any further 🙂

The Steps
Step 1 – create the reverse SSH tunnel:

This is initiated on the internal/home server, and connects outwards to the AWS host on the internet, like so.

ssh -N -R 8888:localhost:80 -i /home/don/DonKey.pem awsuser@ec2-xx-xx-xx-xx.compute-x.amazonaws.com

Here is an explanation of each part of this command:

-N (from the SSH man page) “Do not execute a remote command.  This is useful for just forwarding ports.”

-R (from the SSH man page)  “Specifies that connections to the given TCP port or Unix socket  on the remote (server) host are to be forwarded to the given host and port, or Unix socket, on the local side.”

8888:localhost:80 – means, create the reverse tunnel from localhost port 80 (my ZoneMinder web app) to port 8888 on the destination host. This doesn’t look right to me, but it’s what’s needed for a reverse tunnel

the -i and everything after it is just me connecting to my AWS host as my user with an identity file. YMMV, whatever you nornally do should be fine.

When you run this command you should not see any issues or warnings. You need to leave it running using whatever method you like – personally I like screen for this kind of thing, and will also be setting up Jenkins jobs later (below).

Step 2 – check on the AWS host

With that SSH command still running on your local server you should now be able to connect to the web app from your remote AWS Web Server, by reading from port 8888 with curl or wget.

This is a worthwhile check to perform at this point, before moving on to the next 2 steps – for example:

don@MyAWSHost:~$ wget -q -O- localhost:8888/zm | grep -i ZoneMinder
      <h1>ZoneMinder Login</h1>
don@MyAWSHost:~$

This shows that port 8888 on my AWS server is currently connected to the ZoneMinder application that’s running on port 80 of my home web server. A good sign.

Step 3 – configure AWS Security & Ports

Progress is being made, but in order to be able to hit that port with a browser and have things work as I’d like, I still need to configure AWS to allow incomming connections to the newly chosen port 8888.

This is done through the Amazon EC2 Management Console using the left hand menu item “Network & Security” then “Security Groups”:

awsmenuThis should load your current Security Groups, which you can click on to Edit. You may have a few to check.

Now select Add and configure a new Inbound rule something like so:

awsinboundruleIt’s the “Custom TCP Rule” second from the bottom, with port 8888 and “Anywhere” and “0.0.0.0/0” as the source in my picture. Don’t go for the HTTP option – unless you’re sure that’s what you want 🙂

Step 4 – configure SSH on AWS host

At this point I thought I was done… but it didn’t work and I couldn’t immediately see why, as the wget check was all good.

Some head scratching and checking of firewalls later, I realised it was most likely to be permissions on the port I was tunneling – it’s not very likely to be exposed and world readable by default, is it? Doh.

After a quick google I found a site that explained the changes I needed to make to my sshd_config file, so:

vim /etc/ssh/sshd_config

and add a new line that says:

GatewayPorts yes

to that file, checking that there’s no existing reference to GatewayPorts – edit this file carefully and at your own risk.

As I understand it – which may best be described as ‘loosely’ – the reason this worked when I tested with wget earlier is because I was connecting to the loopback interface; this change to sshd binds the port to all interfaces. See the detailed answer on this post for further detail, including ways to limit this to specific users.

Once that’s done, restart sshd with

service ssh restart

and you should now be able to connect by pointing a web browser at port 8888 (or whatever you set) of your AWS web server and see your app responding from the other end:

zmlogin
Step 5 – automate it with Jenkins

The final step for me is to wrap this (the ssh tunnel creation part) up in a Jenkins job running on my home server.

This is useful for a number of reasons, such as avoiding and resetting defunct/stale connections and enabling scheduling – i.e. I can have the port forwarded when I want it, and have it shutdown during the hours I don’t.

Extending Jenkins book

My new book, Extending Jenkins by Donald Simpson, has been published!

Extending Jenkins

There is a free sample chapter available here:
Chapter 8 – Testing and Debugging Jenkins Plugins

You can buy the full book in either electronic or paperback format direct from the publishers or through Amazon here in the UK or Amazon in the US

About This Book

  • Find out how to interact with Jenkins from within Eclipse, NetBeans, and IntelliJ IDEA
  • Develop custom solutions that act upon Jenkins information in real time
  • A step-by-step, practical guide to help you learn about extension points in existing plugins and how to build your own plugin

Who This Book Is For

This book is aimed primarily at developers and administrators who are interested in taking their interaction and usage of Jenkins to the next level.

The book assumes you have a working knowledge of Jenkins and programming in general, and an interest in learning about the different approaches to customizing and extending Jenkins so it fits your requirements and your environment perfectly.

Table of Contents

1: Preparatory Steps
2: Automating the Jenkins UI
3: Jenkins and the IDE
4: The API and the CLI
5: Extension Points
6: Developing Your Own Jenkins Plugin
7: Extending Jenkins Plugins
8: Testing and Debugging Jenkins Plugins
9: Putting Things Together

What You Will Learn

  • Retrieve and act upon Jenkins information in real time
  • Find out how to interact with Jenkins through a variety of IDEs
  • Develop your own Form and Input validation and customization
  • Explore how Extension points work, and develop your own Jenkins plugin
  • See how to use the Jenkins API and command-line interface
  • Get to know how to remotely update your Jenkins configuration
  • Design and develop your own Information Radiator
  • Discover how Jenkins customization can help improve quality and reduce costs

In Detail

Jenkins CI is the leading open source continuous integration server. It is written in Java and has a wealth of plugins to support the building and testing of virtually any project. Jenkins supports multiple Software Configuration Management tools such as Git, Subversion, and Mercurial.

This book explores and explains the many extension points and customizations that Jenkins offers its users, and teaches you how to develop your own Jenkins extensions and plugins.

First, you will learn how to adapt Jenkins and leverage its abilities to empower DevOps, Continuous Integration, Continuous Deployment, and Agile projects. Next, you will find out how to reduce the cost of modern software development, increase the quality of deliveries, and thereby reduce the time to market. We will also teach you how to create your own custom plugins using Extension points.

Finally, we will show you how to combine everything you learned over the course of the book into one real-world scenario.

Beginning Docker video course

Blog updates have been scarce recently as I have been busy working on a couple of publications… the first of which has just been released…

https://www.linuxjournal.com/node/1338951

This is a hands-on video course packed with practical examples to get you started with Docker.

Here is the course overview video:

And here is a free sample video from Section 2, “Docker Basics” where we take a look at running containers and the 3 different types of “containerized” commands:

and this final sample video is taken from Section 5 – “Running a Web Application with Docker“.

In this clip we build our own web application using Python, pip and Redis, which we will then “dockerize” and ship to “production”:

About This Video

  • Master Docker commands by creating and publishing a sample web application
  • Build and manage your own custom Docker Containers to set up data sources, filesystems, and networking
  • Build your own personal Heroku PaaS with Dokku

Who This Video Is For

If you’re a developer who wants to learn about Docker, a powerful tool to manage your applications effectively on various platforms, this course is perfect for you! It assumes basic knowledge of Linux but supplies everything you need to know to get your own Docker environment up and running.

What You Will Learn

  • Build new Docker containers and find and manage existing ones
  • Use the Docker Index, and create your own private one by using containers
  • Discover ways to automate Docker, and harness the power of containers!
  • Build your own Docker powered mini-Heroku Paas with Dokku
  • Set up Docker on your environment based on your application’s custom requirements
  • Master Docker patterns and enhancements using the Ambassador and Minimal containers

In Detail

One of the major challenges while creating an application is adapting your application to run smoothly on all of the plethora of operating systems available. Docker is an extremely efficient technology that allows you to wrap all your code along with its supporting files into a single bundle; it also guarantees that your application will behave in the same way on any host powered by Docker. You can also easily reuse existing Docker containers or create and publish your own. Unlike Virtual Machines, Docker containers are lightweight and more efficient.

Beginning Docker starts with the fundamentals of Docker—explaining how it works, how to set it up, and how to get started on leveraging the benefits of this technology. The course goes on to cover more advanced features and shows you how to create and share your own Docker images.

You will learn how to install Docker on your own machine, then how to manage it effectively, and then progress to creating and publishing your very own application. You will then learn a bit more about Docker Containers; built-in features and commands such as volumes, mounts, ports, and linking and constraining containers; before diving into running a web application.

Docker has functionality such as the Docker web API to handle complex automation processes which will be explained in detail. You will also learn how to use the Docker Hub to fetch and share containers, before running through the creation of your own Docker powered mini-Heroku

Beginning Docker covers everything required to get you up and running with Docker, with detailed real-world examples and helpful tips to make sure you get the most from it.

Style and Approach

An easy-to-follow and structured video tutorial with practical examples of Docker to help you get to grips with each and every aspect.

The course will take you on a journey from the basics to the advanced application of Docker containers, and includes several real-world scenarios to learn from.

Cheers,

Don

Jenkins and Docker – Part One

This post lists the steps taken to get started with Docker – the basic install and getting a Docker container up and running on Ubuntu.

There’s nothing new or unusual in this section, but it forms the background of the next post(s) where I plan to go in to detail on different approaches to using Docker with Jenkins (and vice versa).

If you’re unfamiliar with Docker here is a good introduction:

and you can try Docker out easily on the docker site: https://www.docker.com/tryit/

 

 

In my case the Ubuntu is a pretty ordinary “ubuntu 14.04.1 LTS (GNU/Linux 3.13.0-35-generic x86_64)” running as a guest VM on my Development VM Ware ESXi Server.

Installing docker on Ubuntu is trivial – here are the commands I found via a quick google, there were no issues…

apt-get -y install docker.io

(FYI it’s called docker.io as there’s a previous/existing package with the name docker)

fix path issues:

ln -sf /usr/bin/docker.io /usr/local/bin/docker
sed -i '$acomplete -F _docker docker' /etc/bash_completion.d/docker.io

have docker start up at boot:

update-rc.d docker.io defaults

and that’s that done – all very simple, quick and straightforward, now it’s time to pull down an Ubuntu image…

docker pull ubuntu

once that’s done, you are ready to run a command (bash in the case of this quick test I found suggested elsewhere) in a docker container like so:

docker run -i -t ubuntu /bin/bash

(-i attaches stdin & stdout and -t allocates a terminal)

That’s it for this post – the next will look at dynamic Jenkins Slave provisioning using Docker Containers, Jenkins plugins for Docker and ways to use Docker for a variety of Jenkins build, deployment and test tasks for Continuous Integration, Continuous Build and DevOps purposes.

Cheers,

Don

 

 

 

 

Extracting data from Jenkins

In Part I,  Information Radiators, I covered what they are, what the main benefits are, and the approach I usually use to set them up. This post goes in to more technical detail on how I extract this data from Jenkins.

My usual setup/architecture for Jenkins Information Radiators goes something along these lines:

  • TV screens running Mozilla Firefox or Google Chrome in Kiosk Mode, and Tab Mix Plus set up to rotate tabs (if required)
  • JSP Pages served via Tomcat on Linux server (which also runs the data extracting script described below)
  • MySQL database on Linux server – contains tables with data pulled from Jenkins and other sources, and the config data too (which URL’s to monitor)

And you’ll need some Jenkins instances/jobs to monitor too, obviously 🙂

The Jenkins XML API is very useful for automating tasks like this – if you simply append “/api/xml” to a
Jenkins job URL, it will serve up an XML version – note there is also a JSON API and a CLI and plenty of other options, but I’m using what suits me.

The Jenkins XML API

For example, if you go to one of your Jenkins jobs and add /api/xml like this:

“http://yourjenkinsserver:8080/job/yourjobname/api/xml”

you should get back some XML, possibly roughly like this example:

<?xml version="1.0"?>
<freeStyleBuild>
 <action>
 <parameter>
 <name>LOWER_ENV</name>
 <value>dev</value>
 </parameter>
 </action>
 <action>
 <cause>
 <shortDescription>Started by timer</shortDescription>
 </cause>
 </action>
 <building>false</building>
 <duration>61886</duration>
 <fullDisplayName>MyJob #580</fullDisplayName>
 <id>2014-04-01_10-01-50</id>
 <keepLog>false</keepLog>
 <number>580</number>
 <result>SUCCESS</result>
 <timestamp>1396342910088</timestamp>
 <url>http://jenkinsserver:8080/view/MyView/job/MyJob/580/</url>
 <builtOn/>
 <changeSet/>
</freeStyleBuild>

That XML contains loads of very useful information inside handy XML tag descriptions – you just need a way to get at that data and then you can present it as you like…

XPAth queries and the Jenkins XML API

so to automate that, I used to extend that approach a to query Jenkins via the XML API using XPAth queries to bring back just the data I actually wanted, quite like querying a database.

For example, wget’ing this URL would return just the current value of the <building> tag in the above XML:

http://yourjenkinsserver:8080/job/yourjobname/api/xml?xpath=//building/text()

e.g. “true” or “false” – this was very useful and easy to do, but the functionality was removed/disabled in recent versions of Jenkins for security reasons, meaning that my processes that used it needed rewritten 🙁

Extracting the data – Plan B…

So, here’s the new solution I went for – the real scripts/methods do some error handling and cleaning up etc but I’m just highlighting the main functions and the high level logic behind each of them here;

get_url’s method:

query a table in MySQL that contains a list of the job names and URL’s to monitor
for each $JOB_NAME found, it calls the get_file method, passing that the URL as a parameter.

get_file method:

this takes a URL param, and uses curl to fetch and save the XML data from that URL to a temporary file (“xmlfile”):

curl -sL "$1" | xmllint --format - > xmlfile

Note I’m using “xmllint –format” there to nicely format the XML data, which makes processing it later much easier.

get_data method:

this first calls “get_if_building” (see below) to see if the job is currently running or not, then it does:

TRUE_VAR="true"
 if [[ "$IS_BUILDING" == "$TRUE_VAR" ]]; then
 RESULT_TEXT="building..."
 else
 RESULT_TEXT=`grep "result>" xmlfile | awk -F\> '{print $2}' | awk -F\< '{print $1}'`
 fi

get_if_building method:

this simply checks and sets the IS_BUILDING var like so:

IS_BUILDING=`grep building xmlfile | awk -F\> '{print $2}' | awk -F\< '{print $1}'`

Putting it all together

My script then updates the MySQL database with the results from each check: success/failure, date, build number, user, change details etc

I then have JSP pages that read data from that table, and translate things like true/false in to HTML that sets the background colours (Red, Amber, Green), and shows the appropriate blocks and details per job.

If you have a few browsers/TV’s or Monitors showing these strategically placed around the office, developers get rapid feedback on the result of their code changes which speeds up development, increases quality and reduces development time and costs – and they can be fun to watch and set up too 🙂

Cheers,

Don

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