Create a Couchbase cluster in less than a minute with Ansible

TL;DR: Look at the Couchbase Ansible Playbook on my Github.

Introduction  

When I was looking for a more effective way to create my cluster I asked some sysadmins which tools I should use to do it. The answer I got during OSDC was not Puppet, nor Chef, but was Ansible.

This article shows you how you can easily configure and create a Couchbase cluster deployed and many linux boxes...and the only thing you need on these boxes is an SSH Server!

Thanks to Jan-Piet Mens that was one of the person that convinced me to use Ansible and answered questions I had about Ansible.

You can watch the demonstration below, and/or look at all the details in the next paragraph.

Ansible

Ansible is an open-source software that allows administrator to configure and manage many computers over SSH.

I won't go in all the details about the installation, just follow the steps documented in the Getting Started Guide. As you can see from this guide, you just need Python and few other libraries and clone Ansible project from Github. So I am expecting that you have Ansible working with your various servers on which you want to deploy Couchbase.

Also for this first scripts I am using root on my server to do all the operations. So be sure you have register the root ssh keys to your administration server, from where you are running the Ansible scripts.

Create a Couchbase Cluster

So before going into the details of the Ansible script it is interesting to explain how you create a Couchbase Cluster. So here are the 5 steps to create and configure a cluster:

1. Install Couchbase on each nodes of the cluster, as documented here.
2. Take one of the node and "initialize" the cluster,  using cluster-init command.
3. Add the other nodes to the cluster, using server-add command.
4. Rebalance, using rebalance command. 
5. Create a Bucket, using bucket-create command.   

So the goal now is to create an Ansible Playbook that does these steps for you.

Ansible Playbook for Couchbase

The first think you need is to have the list of hosts you want to target, so I have create a hosts file that contains all my server organized in 2 groups:

[couchbase-main]
vm1.grallandco.com

[couchbase-nodes]
vm2.grallandco.com
vm3.grallandco.com

The group [couchbase-main] group is just one of the node that will drive the installation and configuration, as you probably already know, Couchbase does not have any master... All nodes in the cluster are identical.

To ease the configuration of the cluster, I have create another file that contains all parameters that must be sent to all the various commands. This file is located in the group_vars/all see the section Splitting Out Host and Group Specific Data in the documentation.

# Adminisrator user and password
admin_user: Administrator
admin_password: password

# ram quota for the cluster
cluster_ram_quota: 1024

# bucket and replicas
bucket_name: ansible
bucket_ram_quota: 512
num_replicas: 2

Use this file to configure your cluster.

Let's describe the playbook file :

- name: Couchbase Installation
  hosts: all
  user: root
   
  tasks:

  - name: download Couchbase package
    get_url: url=http://packages.couchbase.com/releases/2.0.1/couchbase-server-enterprise_x86_64_2.0.1.deb dest=~/.
 
  - name: Install dependencies
    apt: pkg=libssl0.9.8 state=present

  - name: Install Couchbase .deb file on all machines
    shell: dpkg -i ~/couchbase-server-enterprise_x86_64_2.0.1.deb

As expected, the installation has to be done on all servers as root then we need to execute 3 tasks:

1. Download the product, the get_url command will only download the file if not already present
2. Install the dependencies with the apt command, the state=present allows the system to only install this package if not already present
3. Install Couchbase with a simple shell command. (here I am not checking if Couchbase is already installed)

So we have now installed Couchbase on all the nodes. Let's now configure the first node and add the others:

- name: Initialize the cluster and add the nodes to the cluster
  hosts: couchbase-main
  user: root 

  tasks:
  - name: Configure main node
    shell: /opt/couchbase/bin/couchbase-cli cluster-init -c 127.0.0.1:8091  --cluster-init-username=${admin_user} --cluster-init-password=${admin_password} --cluster-init-port=8091 --cluster-init-ramsize=${cluster_ram_quota} 

  - name: Create shell script for configuring main node
    action: template src=couchbase-add-node.j2 dest=/tmp/addnodes.sh mode=750
  
  - name: Launch config script
    action: shell /tmp/addnodes.sh
  
  - name: Rebalance the cluster
    shell: /opt/couchbase/bin/couchbase-cli rebalance -c 127.0.0.1:8091 -u ${admin_user} -p ${admin_password}      
  
  - name: create bucket ${bucket_name} with ${num_replicas} replicas
    shell: /opt/couchbase/bin/couchbase-cli bucket-create -c 127.0.0.1:8091 --bucket=${bucket_name} --bucket-type=couchbase --bucket-port=11211 --bucket-ramsize=${bucket_ram_quota}  --bucket-replica=${num_replicas} -u ${admin_user} -p ${admin_password}

Now we need to execute specific taks on the "main" server:

• Initialization of the cluster using the Couchbase CLI, on line 06 and 07

Then the system needs to ask all other server to join the cluster. For this the system needs to get the various IP and for each IP address execute the add-server command with the IP address. As far as I know it is not possible to get the IP address from the main playbook YAML file, so I ask the system to generate a shell script to add each node and execute the script.
This is done from the line 09 to 13.

To generate the shell script, I use Ansible Template, the template is available in the couchbase-add-node.j2 file. 

{% for host in groups['couchbase-nodes'] %}
/opt/couchbase/bin/couchbase-cli server-add -c 127.0.0.1:8091 -u ${admin_user} -p ${admin_password} --server-add={{ hostvars[host]['ansible_eth0']['ipv4']['address'] }}:8091 --server-add-username=${admin_user} --server-add-password=${admin_password}   
{% endfor %}

As you can see this script loop on each server in the [couchbase-nodes] group and use its IP address to add the node to the cluster.

Finally the script rebalance the cluster (line 16) and add a new bucket (line 19).

You are now ready to execute the playbook using the following command :

./bin/ansible-playbook -i ./couchbase/hosts ./couchbase/couchbase.yml -vv

I am adding the -vv parameter to allow you to see more information about what's happening during the execution of the script.

This will execute all the commands described in the playbook, and after few seconds you will have a new cluster ready to be used! You can for example open a browser and go to the Couchase Administration Console and check that your cluster is configured as expected.

As you can see it is really easy and fast to create a new cluster using Ansible.

I have also create a script to uninstall properly the cluster.. just launch

./bin/ansible-playbook -i ./couchbase/hosts ./couchbase/couchbase-uninstall.yml 

Six months as Technical Evangelist at Couchbase

Already 6 months! Already 6 months that I have joined Couchbase as Technical Evangelist. This is a good opportunity to take some time to look back.

So first of all what is a Developer/Technical Evangelist?
Hmm it depends of each company/product, but let me tell you what it is for me, inside Couchbase. This is one of the most exciting job I ever had. And I think it is the best job you can have when you are passionate about technology, and you like to share this passion with others. So my role as Technical Evangelist is to help the developers to adopt NoSQL technologies in general, and as you can guess Couchbase in particular.

Let's now see in more details what I have done during these past six months and why I am so happy about it. I have organized the different activities in three types:

• Outbound activities : meet the developers
• Online activities : reach even more developers
• Inbound Activities : make the product better !

Outbound activities : meet the developers !

A large part of my activities for this first semester was made of conferences and meetups. All these events are great opportunities for me to talk about NoSQL and get more people to use Couchbase Server 2.0, here a short list of what I have done:

• participated to many Couchbase Developer Days in various cities (Portland, Seattle, Vancouver, Oslo, Copenhagen, Stockholm, Munich, Amsterdam, Barcelona, Paris, ...), these are one day workshops where I am helping developers to get their hands dirty on Couchbase
• participated to Couchconf Berlin and Couchbase [UK] our main European events where I met many Customer and key members of the community
• submitted talks to conferences and adapt them to the conference, then spoken in various conferences about NoSQL and Couchbase (33Degree Warsaw,  NoSQL & Big Data Israel, Devoxx France, NoSQL Matters, and many others).
• met many developers during user groups and meetups. I have to say that I have been very active there, and quite happy to see that NoSQL is a very hot topic for developers, and this in all languages.
• delivered BrowBagLunches to various technical teams in companies 

Yes! Be a Technical Evangelist means, at least for me, be on the road. It is very nice to meet developers from various countries, different cultures, languages, and… this also means tasting many different types of food!

Another interesting thing when you work on a database/infrastructure layer is the fact that it is technology agnostic; you can access Couchbase with multiple programming languages: Java, .Net,Javascript/Node, Ruby, PHP, Python, C, … and even Go. So with this job I met developers with different backgrounds and views about application development. So yes when I am at a conference or meetup, I am suppose to "teach" something to people, but I have also learned a lot of things, and still doing it.

Online activities : reach even more developers!

Meeting developers during conferences is great but it, it is also very important to produce content to reach even more people, so I have :

• written blog post about Couchbase usage, most of them based on feedback/questions from the community
• created sample code to show how it works
• monitored and answered questions on various sites and mailing lists, from Couchbase discussion forums, mailing lists, Stack Overflow, Quora and others...

This task is quite interesting because it is the moment where you can reach many developers and also get feedback from users, and understand how they are using the product. I have to say that I was not as productive as I was expected, mainly because I was traveling a lot during this period.

Another important thing about online activities, is the "Couchbase Community" itself, many users of Couchbase are creating content : blog posts, samples, new applications, or features - for example I am talking with a person that is developing a Dart Client for Couchbase, so as Technical Evangelist I am also working closely with the most active contributor.

Inbound Activities : make the product better !

So the ultimate goal of a Technical Evangelist at Couchbase is to "convert" developers to NoSQL/Couchbase and get them to talk about Couchbase. Meeting them online or during events is a way of achieving this; but it is also great to do it directly with the product. This means participating to the "development" of the product or its ecosystem. Here some of the things that I have done on this topic:

• talked a lot with the development team, core developers, product managers, architects, … Quite exciting to work with so much smart people and have access to them. During this discussions I was able to comment the roadmap, influence features, but also it is all the time an opportunity to learn new things about Couchbase - and many other things around architecture, programming languages, take a look for example to this nice post from Damien Katz .
• contributed some code, yes remember Couchbase is an open source project and it is quite easy to participate to the development. Obviously based on my skills I have only help a little bit with the Java and the Javascript SDK. So if like me you are interested to contribute to the project, take a look to this page: "Contributing Changes"
• but the biggest contributions to the products are such like doc reviews, testing and writing bug reports, and this is very important and interesting, since once again it helps a lot with the product adoption by the developers.

So what?

As you can see the Technical Evangelist job is a quite exciting job, and one of the reason I really love it, it is simply because it allows me to do many different things, that are all related to the technology. Six months is still a very short period, I still have many things to learn and to with the team to be successful, such as be more present online (blog, sample code, technical article, screencast, ..), be accepted in more conferences, and code a little more (I have to finish for example the Couchbase Data Provider for Hibernate OGM, and many other ideas around application development experience) 

Finally, Couchbase needs you ! This is a good opportunity to say that Couchbase is always looking for talents, especially in the Technical/Developer Evangelist team, so do not hesitate to look at the different job openings and join the team !

Screencast : Fun with Couchbase, MapReduce and Twitter

I have created this simple screencast to show how you can, using Couchbase do some realtime analysis based on Twitter feed.

The key steps of this demonstration are

1. Inject Tweets using a simple program available on my Github Couchbase-Twitter-Injector
2. Create views to index and query the Tweets by
• User name
• Tags
• Date

The views that I used in this demonstration are available at the bottom of this post.

Views:

Easy application development with Couchbase, Angular and Node

A friend of mine wants to build a simple system to capture ideas, and votes. Even if you can find many online services to do that, I think it is a good opportunity to show how easy it is to develop new application using a Couchbase and Node.js.

So how to start?
Some of us will start with the UI, other with the data, in this example I am starting with the model. The basics steps are :

1. Model your documents
2. Create Views
3. Create Services
4. Create the UI
5. Improve your application by iteration

The sources of this sample application are available in Gihub :
https://github.com/tgrall/couchbase-node-ideas

Use the following command to clone the project locally :

git clone https://github.com/tgrall/couchbase-node-ideas.git

Note: my goal is not to provide a complete application, but to describe the key steps to develop an application.

How to get the latest document by date/time field?

I read this question on Twitter, let me answer the question in this short article.

First of all you need to be sure your documents have an attribute that contains a date ;), something like :

To get the "latest hired employee" you need to create a view, and emit the hire date as key. The important part is to check that this date is emitted in a format that is sorted properly, for example an array of value using dateToArray function, or the time as numerical value. In the following view I am using the date as an array like that I will be able to do some grouping but this is another topic. The view looks like the following:



Now that you have a view. You can now query it using the parameters:

• descending = true
• limit = 1

If you use Java SDK the code will look like the following :

Finally it is important when you work with views to understand how the index are managed by the server so be sure your read the chapter "Index Updates and the stale Parameter".

Introduction to Collated Views with Couchbase 2.0

Most of the applications have to deal with "master/detail" type of data:

• breweries and beer
• department and employees
• invoices and items 
• ...

This is necessary for example to create application view like the following:

With Couchbase, and many of the document oriented databases you have different ways to deal with this, you can:

• Create a single document for each master and embed all the children in it
• Create a master and child documents and link them using an attribute.

In the first case when all the information are stored in a single document it is quite easy to use the entire set of data and for example create a screen that shows all the information, but what about the second case?

In this post I am explaining how it is possible to use Couchbase views to deal with that an make it easy to create master/detail views.

As an ex-Oracle employee, I am using the infamous SCOTT schema with the DEPT and EMP tables, as the first example. Then at the end I will extend this to the beer sample data provided with Couchbase.

The Data

Couchbase is a schema-less database, and you can store “anything you want” into it, but for this you need to use JSON documents and create 2 types of document : “department” and “employee”.

The way we usually do that is using a technical attribute to type the document. So the employee and department document will look as follow :

Department

{
  "type": "dept",
  "id": 10,
  "name": "Accounting",
  "city": "New York"
}

Employee

{
  "type": "emp",
  "id": 7782,
  "name": "Blake",
  "job": "Clark",
  "manager": 7839,
  "salary": 2450,
  "dept_id": "dept__10"
}

This shows just the document, in Couchbase you have to associate a document to a key. For this example I am using a simple pattern : type__id , for these documents the keys will look like the following:

• dept__10
• emp__20

You can use any pattern to create a key, for example for the employee you could chose to put an email.  

Note the “dept_id” attribute in the employee document. This is the key of the department; you can see that as the “foreign key”. But remember, the relationship between the department and employee documents are managed entirely by the application, Couchbase Server does not enforce it.

I have created a Zip file that contains all the data, you can download it from here; and import the data into Couchbase using the cbdocloader utility. To import the data run the following command from a terminal window:

./cbdocloader -n 127.0.0.1:8091 -u Administrator -p password -b default ~/Downloads/emp-dept.zip 

You can learn more about the cbdocloader tool in the documentation.

The View

Queries inside Couchbase are based on views; and views build indexes, so we have to create a view, a "collated view" to be exact.

The idea behing a collated view is to produce an index where the keys are ordered so that a parent id appears first followed by its children.  So we are generating an index that will look like:

DEPT_10, Accounting
DEPT_10, Blake
DEPT_10, Miller
DEPT_20, Research
DEPT_20, Adams
DEPT_20, Ford
...


This is in fact quite easy to do with Couchbase views. The only trick here is to control the order and be sure the master is always the first one, just before its children.

So to control this we can create an compound key that contains the department id, a "sorting" element and the name (beer or brewery)

So the map function of the view looks like the following:

The key is composed of:

• the department id extracted from the department document itself or from the employee document depending of the type of document
• an arbitrary number that is used to control the ordering. I put 0 for the department, 1 for the employee
• the name of the department or the employee, this also allows to sort the result by name

In addition to the key, this view is used to emit some information about the salary of the employees. The salary is simply the sum of the salary plus the commission when exists. The result of the view looks like:

With this view you can now use the result of the view to build report for your application. It is also possible to use parameters in your query to see only a part of the data, for example by departement, using for example startkey=["dept__20",0]&endkey=["dept__20",2] to view only the data -Department and Employees- of the deparment 20-Research.

The Beer Sample Application

You can create an equivalent view for the beer sample application where you print all the breweries and beers in the same report. The view is called "all_with_beers" in the design document "brewery". The view looks like:

Once you have publish it in production you can use it in the Beer Sample application, for this example I have modified the Java sample application.

Create a servlet to handle user request and on the /all URI.

The "BreweryAndBeerServlet" that calls the view using the following code :


The result of the query is set into the HttpRequest and the all.jsp page is executed. The JSP uses JSTL to print the information using the following code:

The JSP gets the items from the HTTP Request and loops on each items, then based on the type of the item the information is printed. The final result looks like :

This extension to the Beer Sample application is available here : https://github.com/tgrall/beersample-java/tree/BreweriesAndBeers

Getting started with Couchbase and node.js on Windows

In a previous post I have explained how to use Couchbase and Node.js on OS X. Since it is quite different on Windows here another article about it.

Install Couchbase Server 2.0

If you have not installed Couchbase Server already, do the following :

1. Download Couchbase Server from here
2. Run the installer
3. Configure the database at http://localhost:8091 (if you have issue take a look to this article)

These steps are documented in the Couchbase Server Manual.

Install Node 

Install latest version of node

It is quite easy to install Node.js using the Windows installer provided at http://nodejs.org.

Once you have installed node, you can test is using the command line interface:

c:\Users\tgrall>node
> console.log(process.version);
v0.8.16

Node is installed. So far so good !

Install Couchnode

Couchnode, the Couchbase Client Library for Node.js, is a native module. The tool used to install native modules is node-gyp.  So to install couchnode you need to install :

• node-gyp
• python
• Visual Studio to have access to a C/C++ compiler

Install node-gyp

The node-gyp module is easy to install and you can install it using npm using the following command:

npm install -g node-gyp

The -g parameter indicates that this module will be installed globally and added to your %PATH%.

Install Python

GYP uses Python to generate the project, so you need to install it on your environment. I have installed Python 2.7.3 using the Windows installer.

Install Visual Studio

Finally you need a C/C++ compiler, the best way to get it is to install Visual Studio. As you probably know I am not a Windows expert and I do not know a lot about Microsoft development tools. I have downloaded Visual Studio Express the free development tools from here; it was sufficient.

Install Libcouchbase for Windows

Couchnode uses libcouchbase the C client library, so before running the npm install for Couchbase, you need to install libcouchbase itself.

You can download it from Couchbase site. The Windows versions are located in the left menu of the page. Download the zip file, that matches your environment. I have downloaded the "Windows, 64-bit MSVC 10".

Node-gyp will look for all the dependencies (DLL, library headers) into c:\couchbase directory, so you need to unzip the file in this folder. This location comes from the binding.gyp file of the couchnode project.

Install and Test Couchnode itself!

Let's check what we have done so far; we have installed:

• Node
• node-gyp
• Python
• Visual Studio
• Libcouchbase

We are now ready to install and use couchnode itself. For this we can create a new node project.

mkdir my-app
cd my-app
npm install couchbase

The install command will:

• Create a node_modules folder and put couchbase client library in it
• When installing/building couchnode on Windows I had the following warning :

C:\Program Files (x86)\MSBuild\Microsoft.Cpp\v4.0\V110\Microsoft.CppBuild.targets(1138,5): warning MSB8012: TargetExt(.dll) does not match the Linker's Output

File property value (.node). This may cause your project to build incorrectly.

To correct this, please make sure that $(OutDir), $(TargetName) and $(TargetExt) property values match the value specified in %(Link.OutputFile).

[C:\Users\tgrall\node\node_modules\couchbase\build\couchbase_impl.vcxproj]

This is only a warning and as far as I know, it is not a blocker. At the end of the log you should see:

couchbase@0.0.10 node_modules\couchbase
├── bindings@1.0.0
└── request@2.11.4


You have successfully installed couchnode.

Let's now write a small test. Create a test.js file with the following content:

var  driver = require('couchbase');

driver.connect({
  "username": "",
  "password": "",
  "hostname": "localhost:8091",
  "bucket": "default"}, 
  function(err, cb) {
    if (err) {
      throw (err)
    }
 
 var key = 'foo';
 cb.set(key, '{"server" : "couchbase", "version" : 2 }' , function (err, meta) {
  if (err) { console.log(err); }
        cb.get(key, function(err, doc) {
   if (err){ console.log(err);}
   console.log(doc);
        });  
 });
});

Run this with the command:

node test.js

You should see the following text in your console :

{ server: 'couchbase', version: 2 }

Conclusion

In this article you have learned how to:

• Install Couchbase
• Install Node
• Install and configure node-gyp
• Install and use Couchbase and Node

all this on Windows 7.