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 !