Book Review : First Ansible
The book "First Ansible" was released from O'Reilly Japan. I got the book, so I tried reading it.
Conclusion
From the conclusion, this book comes with "first time", but I think that it is a book to buy not only for the people who want to use it but also for those who are using it now.
I think that important points of using Ansible, how to use Ansible such as Playbook, Task, and Inventory are written in order from the beginning and I think that it will be able to understand immediately. For that reason it is for beginners.
And yet, quite annotations are many, not only for beginners, that it, caught easily grammatical problems and of YAML, localhost has written neatly to fine place like that is implicitly added to the inventory, the current I think that it is meaningful for people who are using it. Especially, I'm very thankful that it is written about things related to the design, such as writing the playbook by thinking this way and applying these rules.
In addition, translation is also done, there is no place to read and catch up.
2.0 compatible
I think that it is a place to worry about the correspondence situation to 2.0. This book is, Ansible: Up and Running is that the present translation. Since the Ansible 2.0 has not yet appeared when the original work was written, the content is naturally 1.9 compliant.
However, when translated into Japanese, it is said that all written Playbooks have confirmed the operation at 2.0.0.2. Well I would have not had much time, it's wonderful. So, there is nothing wrong with 1.9 compatible places.
In addition, "Ansible 2.0" is attached as an appendix, and new features such as blocks are explained.
Highlights of each chapter
From now on, I will talk about each chapter with arbitrariness and prejudice. I think that I do not know well even if I read this much, so please buy and read it if you are interested.
Chapter 1 : Introduction
Why you choose Ansible, things like installation method, etc. are written.
It is better that the Inventory file is still in the repository. Why default is /etc/ansible/hosts would be what.
Chapter 2 : Playbook : Getting started
It is the way to write Playbook and the definition of Ansible term such as task and Play. Particularly where you need YAML quotation marks, it is good to have something to do with it, so read it.
I regretly have not written much about cowsay. And to write a way to invalidate it!
Regarding handlers, I did not even think it was essential, so I agree. It is good that the task itself is simpler because it is better, but it is certainly addictive. By the way, --force-handlers but can be activated to force the handler by put options, it is what you do not notice things like that when you addictive.
Chapter 3 : Inventory : the server description
It is an inventory file. It is good to explain using Vagrant.
In particular, it is good to describe dynamic inventory with an example. I think that it is better to use dynamic inventory for more than 10 units. group_by is ... Hey is there is no thing that I also use .... Since it is used for installation of Ansible Tower etc., it may be good "at the time of this distribution collectively this".
Chapter 4 : Variables and Fact
Variables and facts. It is very important.
It is good that the local facts are properly written. This may be unnecessary because it requires one time to install, but it's pretty useful. Also, it was roughly summarized as the priority order "all methods not on this list", but it blew out a bit, but it is correct.
Chapter 5 : Mezzanine introduction of
It is quite purely an introduction of Mezzanine. Sorry, I did not know this.
Chapter 6 : Deployment of Mezzanine
Actual deployment using Vagrant. If you read this chapter, I think that you will be able to deal with real production environments as well. Well, since I am using it for django application, I think that it is necessary to make various changes in other cases, but the basic flow is fully understood.
xip.io did not know. It's a convenient service. Let's use it next time.
Chapter 7 : complex playbook
Explanation of functions not explained in Chapter 6. local_action , ` run_once , change_when/failed_when such, is an important feature is full. However, if you read chapters 6 and 7, you can do anything at all.
The highlight of this chapter is "Create your own filter" and "Create your own lookup plugin". I skip slowly, but it is good to have mention. As you can create filters and lookups yourself, what you can do with Ansible will dramatically increase. People who think that "YAML programming is complicated", I think that it is good to try creating filters oneself once.
By the way, in this chapter there is a complex loop after the lookup. This, in fact, with_hoge loop, such as is the is such because they are implemented as a look-up plug-in, it is good for is written neatly.
Chapter 8 : roll
It is a role. Roll is the most important function of Ansible. If you understand the roll exactly, you will be able to deal with complicated configurations with a concise playbook.
The difference between vars and defaults is quite troublesome. The author writes a story saying that the defaults may be overwritten and the usual variable is vars. It is correct, but sometimes you will want to overwrite it later. Personally I think that all defaults are OK.
By the way, although I mention a little about Ansible Galaxy, since the ansible-galaxy command can be specified outside the Ansible Galaxy site, keep the shared role in private git repository and share it with ansible-galaxy command within the organization, It is now possible to do.
In addition, -r in options, so can now be specified in the text file that from somewhere put any roll, just keep the one that file to the repository, you have to be able to initial setting . From this point of view, I think whether you can understand the importance of dividing into roles.
Chapter 9 : Ansible faster
It's like ssh multiplexing. In the case of such as EC2, too long for Unix domain socket of an error that has explains that there be returned looks good. It is good to have written about pipelining.
I have never used the fact cache. Collecting facts is not so time consuming (in proportion to other processing) if it is a regular machine, so I am concerned about cache mismatch. However, since there are cases where only truly a little task is executed, or in the case of a slow machine, it may be dramatically effective, so if you are "Ansible late," I think that you may try it.
Chapter 10 : Custom modules
Yes, it is a custom module. If you try to use Ansible slightly deeply, your own creation is the best. It is nonsense that I try my best trying to manage somehow at YAML.
In this chapter, in addition to how to make modules in Python, there is also a little bit how to create a module in bash. Module creation in Python has a fairly comprehensive helper function, so we can deal with many things, so if you make it in full swing it will be python optional. However, if a little operation is to be modularized, it is better for familiar language, so I think that it is very convenient that bash creation method is written.
Chapter 11 : Vagrant
A description of Vagrant and ansible provisioners. I did not know how to do parallel provision at Vagrant, so I learned a lot.
Chapter 12 : Amazon EC2
It is EC2. However, not only AWS but also security group and acquisition of AMI are listed up. In this chapter, it is better to keep in mind about the relationship between tag and group. Also, as there is a description about packer, it may be nice to try using it.
Note : P.230 of the footnote is left remaining that something editing stage?
Chapter 13 : Docker
It is Docker. In this chapter, it is written that there are two points concerning the relationship between Ansible and Docker.
- Used to ensure that multiple Dockers are activated in the specified order
- Use Ansible when creating Docker image
As for 1, I feel that docker-compose is better. About 2., there is a method to use a container containing Ansible. However, in Ansible 2.0, since docker connection plugin is attached as a standard, it is better to handle the image of docker directly. However, as I saw in 13.5.5, I have the idea that docker image creation is part of the build process, and Ansible does not build a Docker Image. I agree with this idea.
Chapter 14 : Playbook Debugging
A tips useful for debugging playbook is written. By the way, I have before Software DesignでAnsibleに関する記事を書かせて頂いた sometimes, I gained some debug module first and foremost. This is because the debug module is used for debugging without fail.
Summary
This book is recommended not only for those who use Ansible for the first time, but also for those who are actually using it. Let's buy by all means.