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書名： Puppet 2.7 Cookbook
作者名： John Arundel
本章字數： 812字
更新時間： 2021-04-02 18:19:59

Testing your Puppet manifests

"If all else fails, immortality can always be assured by spectacular error."—J.K. Galbraith

Trouble has a way of sneaking up on you like a bug on a windshield. The standard checks provided by monitoring tools like Nagios don't always cover everything you want to monitor. While metrics such as load average and disk space can be useful problem indicators', I like to be able to get higher-level information about the applications and services my machines provide.

For example, if you are running a web application, it's not enough to know that the web server is listening to connections on port 80 and responding with an HTTP 200 OK status. It could just be returning the default Apache welcome page.

If your web application is an online store, for example, you might want to check the following:

Do we see expected text in the returned page (for example, "Welcome to FooStore")?
Can we log in as a user (if the application supports sessions)?
Can we search for a product and see the expected result?
Is the response time satisfactory?

This kind of monitoring—focusing on the behavior of the application, rather than operational metrics of the server itself—is sometimes called behavior-driven monitoring.

Just as developers often use behavior-driven tests to verify that the application does what it should when they make code changes, you can use behavior-driven monitoring to monitor it continuously in production.

In fact, thanks to a tool called cucumber-nagios, you can run the same tests the developers use. Lindsay Holmwood's wrapper for the popular Cucumber testing framework lets you run Cucumber-based tests under Nagios as though they were standard Nagios metrics.

Getting ready

To install cucumber-nagios, you will need a few dependencies first. If you are on Ubuntu or Debian, you will probably need to install RubyGems from source, as cucumber-nagios needs RubyGems 1.3.6 or higher. Download the tarball from the RubyGems site: http://rubygems.org/pages/download. Unpack it and run ruby setup.rb to build and install the package.
Next, you need to install a few more dependencies:
```
# apt-get install ruby1.8-dev libxml2-dev
```
Finally, you can install cucumber-nagios itself as follows:
```
# gem install cucumber-nagios
```

How to do it…

Once RubyGems and all its dependencies have been installed, you can start writing Cucumber tests. To do this, first use cucumber-nagios to help create a project directory with everything you will need:

# cucumber-nagios-gen project mytest
Generating with project generator:
 [ADDED] features/steps
 [ADDED] features/support
 [ADDED] .gitignore
 [ADDED] .bzrignore
 [ADDED] lib/generators/feature/%feature_name%.feature
 [ADDED] Gemfile
 [ADDED] bin/cucumber-nagios
 [ADDED] lib/generators/feature/%feature_name%_steps.rb
 [ADDED] README
Your new cucumber-nagios project can be found in /root/mytest.
Next, install the necessary RubyGems with:
 bundle install
Your project has been initialized as a git repository.

It's a good idea to run bundle install inside the project directory, as cucumber-nagios advises you to do. This will bundle all the dependencies for cucumber-nagios inside the directory. Then you can move the project directory to any machine and it will work.
```
# cd mytest
# bundle install
```

Now we can start writing a test. As an example, let's test the home page on Google:

# cucumber-nagios-gen feature www.google.com home 
Generating with feature generator: 
[ADDED] features/www.google.com/home.feature 
[ADDED] features/www.google.com/steps/home_steps.rb

If you edit the home.feature file, you will find that cucumber-nagios has generated a basic initial test for you:

Feature: www.google.com
  It should be up
  Scenario: Visiting home page
    When I go to "http://www.google.com"
    Then the request should succeed

You can run this from the project directory as follows:

# cucumber --require features features/www.google.com/home.feature 
Feature: www.google.com
 It should be up
 Scenario: Visiting home page # features/www.google.com/home.feature:4
 When I go to "http://www.google.com" # features/steps/http_steps.rb:11
 Then the request should succeed # features/steps/http_steps.rb:64
1 scenario (1 passed)
2 steps (2 passed)
0m0.176s

Assuming this works (if it doesn't, call Google), all you need to do to make this feature a Nagios check is to run it with cucumber-nagios instead of cucumber:

# bin/cucumber-nagios features/www.google.com/home.feature 
CUCUMBER OK - Critical: 0, Warning: 0, 2 okay | passed=2; failed=0; nosteps=0; total=2; time=0

How it works…

Any script can be a Nagios monitoring plugin; it just has to return the appropriate exit status (0 for OK, 1 for warning, and 2 for critical). cucumber-nagios wraps Cucumber tests to do this, and also prints out useful information which Nagios will report via the alert or the web interface.

There's more…

By itself, this doesn't do anything very useful. However, Cucumber lets you write quite sophisticated interaction scripts with websites: you can fill in form fields, search, click buttons, match text on the page, and so on. Whatever features of your web application or service you want to monitor; first figure out what a user would do in a web browser, then automate those steps with Cucumber to create the monitoring script.

You can find out more about how to write tests for cucumber-nagios on the Cucumber website: http://cukes.info/

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Puppet 2.7 Cookbook

Testing your Puppet manifests

Getting ready

How to do it…

How it works…

There's more…