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feat: check product name file on linux for gce #469

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merged 4 commits into from
Aug 22, 2023
Merged

feat: check product name file on linux for gce #469

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b163b42
feat: check product name file on linux for gce
bshaffer Aug 15, 2023
5bef54d
fix lint errors
bshaffer Aug 15, 2023
482e644
add residency test on GCE
bshaffer Aug 22, 2023
af4460f
mock the exception
bshaffer Aug 22, 2023
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21 changes: 21 additions & 0 deletions src/Credentials/GCECredentials.php
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Original file line number Diff line number Diff line change
Expand Up @@ -100,6 +100,11 @@ class GCECredentials extends CredentialsLoader implements
*/
const FLAVOR_HEADER = 'Metadata-Flavor';

/**
* The Linux file which contains the product name.
*/
private const GKE_PRODUCT_NAME_FILE = '/sys/class/dmi/id/product_name';

/**
* Note: the explicit `timeout` and `tries` below is a workaround. The underlying
* issue is that resolving an unknown host on some networks will take
Expand Down Expand Up @@ -340,6 +345,22 @@ public static function onGce(callable $httpHandler = null)
} catch (ConnectException $e) {
}
}

if (PHP_OS === 'Windows') {
// @TODO: implement GCE residency detection on Windows
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return false;
}

// Detect GCE residency on Linux
return self::detectResidencyLinux(self::GKE_PRODUCT_NAME_FILE);
}

private static function detectResidencyLinux(string $productNameFile): bool
{
if (file_exists($productNameFile)) {
$productName = trim((string) file_get_contents($productNameFile));
return 0 === strpos($productName, 'Google');
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Maybe lowercase is better?

Suggested change
return 0 === strpos($productName, 'Google');
return 0 === strpos($productName, 'google');

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@bshaffer bshaffer Aug 22, 2023 •
edited
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The is determined by the Operating system, and the string is uppercase (literally, Google). So making it lowercase would fail the check.

Why do you think lowercase is better?

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My only question is: Should we normalize the contents (e.g. force lowercase) in order to avoid any sort of subtle issues with string matching/discrepancies in this file's contents?

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@bshaffer bshaffer Aug 22, 2023 •
edited
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The Product Name is either Google or Google Compute Engine. The lowercase name google is not valid (or at least, there are no known Operating Systems which use that). So there's no reason to add a check for the lowercase value.

To my knowledge, other language implementations have not included such a normalization

}
return false;
}

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32 changes: 32 additions & 0 deletions tests/Credentials/GCECredentialsTest.php
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Expand Up @@ -73,6 +73,38 @@ public function testOnGCEIsFalseOnServerErrorStatus()
$this->assertFalse(GCECredentials::onGCE($httpHandler));
}

public function testCheckProductNameFile()
{
$tmpFile = tempnam(sys_get_temp_dir(), 'gce-test-product-name');

$method = (new \ReflectionClass(GCECredentials::class))
->getMethod('detectResidencyLinux');
$method->setAccessible(true);

$this->assertFalse($method->invoke(null, '/nonexistant/file'));

file_put_contents($tmpFile, 'Google');
$this->assertTrue($method->invoke(null, $tmpFile));

file_put_contents($tmpFile, 'Not Google');
$this->assertFalse($method->invoke(null, $tmpFile));
}

public function testOnGceWithResidency()
{
if (!GCECredentials::onGCE()) {
$this->markTestSkipped('This test only works while running on GCE');
}

// If calling metadata server fails, this will check the residency file.
$httpHandler = function () {
// Mock an exception, such as a ping timeout
throw $this->prophesize(ClientException::class)->reveal();
};

$this->assertTrue(GCECredentials::onGCE($httpHandler));
}

public function testOnGCEIsFalseOnOkStatusWithoutExpectedHeader()
{
$httpHandler = getHandler([
Expand Down