Adding GCEMetadataStream.

Fixes googleapis#8

src/Compute/Metadata/GCEMetadataStream.php

@@ -0,0 +1,173 @@
+<?php
+
+/**
+ * Copyright 2015 Google Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+namespace Google\Cloud\Compute\Metadata;
+
+use Google\Cloud\Compute\Metadata\Readers\StreamReader;
+
+/**
+ * A stream wrapper for GCE metadata.
+ *
+ * You can get the GCE metadata values very easily like:
+ *
+ * use Google\Cloud\Compute\Metadata\GCEMetadataStream;
+ *
+ * GCEMetadataStream::register();
+ * $val = file_get_contents('gce-metadata://project/mykey')
+ * or
+ * $val = file_get_contents('gce-metadata://instance/mykey')
+ */
+class GCEMetadataStream
+{
+    /**
+     * The base URL for the metadata.
+     */
+    const METADATA_BASE_URL = 'http://metadata.google.internal/computeMetadata/v1/';
+
+    /**
+     * The current seek position.
+     */
+    private $position;
+
+    /**
+     * The metadata value.
+     */
+    private $val;
+
+    /**
+     * The metadata reader.
+     */
+    private $reader;
+
+    /**
+     * A static method to register this stream wrapper.
+     */
+    public static function register()
+    {
+        stream_wrapper_register(
+            'gce-metadata',
+            '\Google\Cloud\Compute\Metadata\GCEMetadataStream'
+        )
+            or die('Failed to register GCEMetadataStream');
+    }
+
+    public function __construct()
+    {
+        $this->reader = new StreamReader();
+    }
+
+    /**
+     * A method to replace the reader implementation.
+     */
+    public function setReader($reader)
+    {
+        $this->reader = $reader;
+    }
+
+    // @codingStandardsIgnoreStart
+
+    // These methods are mandatory for implementing stream wrappers,
+    // so marking them with ignore tag.
+    //
+    // TODO: Find a way to just suppress certain types of errors with
+    // phpcs.
+    public function stream_open($path, $mode, $options, &$opened_path)
+    {
+        $url = parse_url($path);
+        if ($url['host'] != 'project' and $url['host'] != 'instance') {
+            return false;
+        }
+        $metadata_url = self::METADATA_BASE_URL.$url['host'].'/attributes'
+            .$url['path'];
+        $this->val = $this->reader->read($metadata_url);
+        $this->position = 0;
+
+        return true;
+    }
+
+    public function stream_stat()
+    {
+        return array();
+    }
+
+    public function stream_read($count)
+    {
+        $ret = substr($this->val, $this->position, $count);
+        $this->position += strlen($ret);
+
+        return $ret;
+    }
+
+    public function stream_write($data)
+    {
+        trigger_error('stream_write is not implemented.', E_WARNING);
+    }
+
+    public function stream_tell()
+    {
+        return $this->position;
+    }
+
+    public function stream_eof()
+    {
+        return $this->position >= strlen($this->val);
+    }
+
+    public function stream_seek($offset, $whence)
+    {
+        switch ($whence) {
+            case SEEK_SET:
+                if ($offset < strlen($this->val) && $offset >= 0) {
+                    $this->position = $offset;
+
+                    return true;
+                } else {
+                    return false;
+                }
+                break;
+
+            case SEEK_CUR:
+                if ($offset >= 0) {
+                    $this->position += $offset;
+
+                    return true;
+                } else {
+                    return false;
+                }
+                break;
+
+            case SEEK_END:
+                if (strlen($this->val) + $offset >= 0) {
+                    $this->position = strlen($this->val) + $offset;
+
+                    return true;
+                } else {
+                    return false;
+                }
+                break;
+
+            default:
+                return false;
+        }
+    }
+
+    public function stream_metadata($path, $option, $var)
+    {
+        return false;
+    }
+    // @codingStandardsIgnoreEnd
+}

src/Compute/Metadata/Readers/StreamReader.php

@@ -0,0 +1,44 @@
+<?php
+
+/**
+ * Copyright 2015 Google Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+namespace Google\Cloud\Compute\Metadata\Readers;
+
+/**
+ * A class only reading the metadata URL with an appropriate header.
+ *
+ * This class makes it easy to test the MetadataStream class.
+ */
+class StreamReader
+{
+    /**
+     * The header whose presence indicates GCE presence.
+     */
+    const FLAVOR_HEADER = 'Metadata-Flavor';
+
+    public function read($url)
+    {
+        $options = array(
+            'http' => array(
+                'method' => 'GET',
+                'header' => self::FLAVOR_HEADER.": Google\r\n",
+            ),
+        );
+        $context = stream_context_create($options);
+
+        return file_get_contents($url, false, $context);
+    }
+}

tests/ComputeMetadataTest.php

@@ -0,0 +1,80 @@
+<?php
+
+/**
+ * Copyright 2015 Google Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+namespace Google\Cloud\tests;
+
+use Google\Cloud\Compute\Metadata\GCEMetadataStream;
+
+class ComputeMetadataTest extends \PHPUnit_Framework_TestCase
+{
+    protected $mock;
+
+    public function setUp()
+    {
+        $this->stream = new GCEMetadataStream();
+        $this->mock = $this->getMockBuilder(
+            '\Google\Cloud\Compute\Metadata\StreamReader')
+            ->setMethods(array('read'))
+            ->getmock();
+        $this->stream->setReader($this->mock);
+    }
+
+    public function testProjectMetadata()
+    {
+        $expected_url = 'http://metadata.google.internal/computeMetadata/v1/'
+            .'project/attributes/mykey';
+        $expected_val = 'myval';
+        $this->mock->expects($this->once())
+            ->method('read')
+            ->with($this->equalTo($expected_url))
+            ->willReturn($expected_val);
+        $dummy = '';
+        $this->stream->stream_open('gce-metadata://project/mykey', null, null,
+                                   $dummy);
+        $val = $this->stream->stream_read(10);
+        $this->assertEquals($expected_val, $val);
+    }
+
+    public function testInstanceMetadata()
+    {
+        $expected_url = 'http://metadata.google.internal/computeMetadata/v1/'
+            .'instance/attributes/mykey';
+        $expected_val = 'myval';
+        $this->mock->expects($this->once())
+            ->method('read')
+            ->with($this->equalTo($expected_url))
+            ->willReturn($expected_val);
+        $dummy = '';
+        $this->stream->stream_open('gce-metadata://instance/mykey', null, null,
+                                   $dummy);
+        $val = $this->stream->stream_read(10);
+        $this->assertEquals($expected_val, $val);
+    }
+
+    public function testBogusMetadata()
+    {
+        $expected_val = false;
+        $this->mock->expects($this->never())
+            ->method('read')
+            ->with($this->anything());
+        $dummy = '';
+        $this->stream->stream_open('gce-metadata://bogus/mykey', null, null,
+                                   $dummy);
+        $val = $this->stream->stream_read(10);
+        $this->assertEquals($expected_val, $val);
+    }
+}