silverstripe-environmentcheck/README.md

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# SilverStripe Environment Checker Module
Developed by Sam Minnée, thanks to Will Rossiter.
This module adds an API for running environment checks to your API.
* `dev/health` - A public URL that performs a quick check that this environment is functioning. This could be tied to a load balancer, for example.
* `dev/check` - An admin-only URL that performs a more comprehensive set of checks. This could be tied to a deployment system, for example.
## Aren't these just unit tests?
Almost, but not really. Environment checks differ from unit tests in two important ways:
* **They test environment specific settings.** Unit tests are designed to use dummy data and mock interfaces to external system. Environment checks check the real systems and data that the given environment is actually connected to.
* **They can't modify data.** Because these checks will run using production databases, they can't go modifying the data in there. This is the biggest reason why we haven't used the same base class as a unit test for writing environment checks - we wanted to make it impossible to accidentally plug a unit test into the environment checker!
## Installation
Register checks in your own `_config.php` - see the `_config.php` in this module for some defaults.
:::php
EnvironmentCheckSuite::register('health', 'DatabaseCheck', "Can we connect to the database?");
EnvironmentCheckSuite::register('check', 'URLCheck("")', "Is the homepage accessible?");
## Available checks
* `DatabaseCheck`: Check that the connection to the database is working, by ensuring that the table exists and that the table contain some records.
* `URLCheck`: Check that a given URL is functioning, by default, the homepage.
* `HasFunctionCheck`: Check that the given function exists.
This can be used to check that PHP modules or features are installed.
* `HasClassCheck`: Check that the given class exists.
This can be used to check that PHP modules or features are installed.
* `FileWriteableCheck`: Check that the given file is writeable.
* `FileAgeCheck`: Checks for the maximum age of one or more files or folders.
Useful for files which should be frequently auto-generated,
like static caches, as well as for backup files and folders.
* `ExternalURLCheck`: Checks that one or more URLs are reachable via HTTP.
* `SMTPConnectCheck`: Checks if the SMTP connection configured through PHP.ini works as expected.
## Adding more checks
To add more checks, you should put additional `EnvironmentCheckSuite::register` calls into your `_config.php`. See the `_config.php` file of this module for examples.
:::php
EnvironmentCheckSuite::register('check', 'HasFunctionCheck("curl_init")', "Does PHP have CURL support?");
EnvironmentCheckSuite::register('check', 'HasFunctionCheck("imagecreatetruecolor")', "Does PHP have GD2 support?");
The first argument is the name of the check suite. There are two built-in check suites, "health", and "check", corresponding to the `dev/health` and `dev/check` URLs. If you wish, you can create your own check suites and execute them on other URLs.
The module comes bundled with a few checks in `DefaultHealthChecks.php`. However, to test your own application, you probably want to write custom checks.
* Implement the `EnvironmentCheck` interface
* Define the `check()` function, which returns a 2 element array:
* The first element is one of `EnvironmentCheck::OK`, `EnvironmentCheck::WARNING`, `EnvironmentCheck::ERROR`, depending on the status of the check
* The second element is a string describing the response.
Here is a simple example of how you might create a check to test your own code. In this example, we are checking that an instance of the `MyGateway` class will return "foo" when `call()` is called on it. Testing interfaces with 3rd party systems is a common use case for custom environment checks.
:::php
class MyGatewayCheck implements EnvironmentCheck {
protected $checkTable;
function check() {
$g = new MyGateway;
$response = $g->call();
$expectedResponse = "foo";
if($response == null) {
return array(EnvironmentCheck::ERROR, "MyGateway didn't return a response");
} else if($response != $expectedResponse) {
return array(EnvironmentCheck::WARNING, "MyGateway returned unexpected response $response");
} else {
return array(EnvironmentCheck::OK, "");
}
}
}
Once you have created your custom check class, don't forget to register it in a check suite
:::php
EnvironmentCheckSuite::register('check', 'MyGatewayCheck', "Can I connect to the gateway?");
### Using other environment check suites
If you want to use the same UI as dev/health and dev/check, you can create an `EnvironmentChecker` object. This class is a `RequestHandler` and so can be returned from an action handler. The first argument to the `EnvironmentChecker` constructor is the suite name. For example:
class DevHealth extends Controller {
function index() {
$e = new EnvironmentChecker('health', 'Site health');
return $e;
}
}
If you wish to embed an environment check suite in another, you can use the following call.
$result = EnvironmentCheckSuite::inst("health")->run();
`$result` will contain a `EnvironmentCheckSuiteResult` object
* `$result->ShouldPass()`: Return a boolean of whether or not the tests passed.
* `$result->Status()`: The string "OK", "WARNING", or "ERROR", depending on the worst failure.
* `$result->Details()`: A `DataObjectSet` of details about the result of each check in the suite.
See `EnvironmentChecker.ss` to see how these can be used to build a UI.