This is a version of the script I use to generate changelogs for my projects.

changelog_generator.php

<?php
/**
 * composer.json:
 * {
 *   "require": {
 *     "zendframework/zend-http": "2.*"
 *   }
 * }
 */
require __DIR__ . '/vendor/autoload.php';
ini_set('display_errors', true);
error_reporting(E_ALL | E_STRICT);

$token     = '';    // Github API token
$user      = '';    // Your user or organization
$repo      = '';    // The repository you're getting the changelog for
$milestone = 0;     // The milestone ID

$client = new Zend\Http\Client();
$client->setOptions(array(
    'adapter' => 'Zend\Http\Client\Adapter\Curl',
));

$request = $client->getRequest();
$headers = $request->getHeaders();

$headers->addHeaderLine("Authorization", "token $token");

$client->setUri("https://api.github.com/repos/$user/$repo/issues?milestone=$milestone&state=closed&per_page=100");
$client->setMethod('GET');
$issues = array();
$done   = false;
$error  = false;
$i      = 0;
do {
    $response = $client->send();
    $json     = $response->getBody();
    $payload  = json_decode($json);
    if (!is_array($payload)) {
        $error = $payload;
    }
    if (is_array($payload)) {
        $issues = array_merge($issues, $payload);
        $linkHeader = $response->getHeaders()->get('Link');
        if (!$linkHeader) {
            $done = true;
        }
        if ($linkHeader) {
            $links = $linkHeader->getFieldValue();
            $links = explode(', ', $links);
            foreach ($links as $link) {
                $matches = array();
                if (preg_match('#<(?P<url>.*)>; rel="next"#', $link, $matches)) {
                    $client->setUri($matches['url']);
                }
            }
        }
    }
    $i += 1;
} while (!$done && !$error && ($i < 5));

if ($error) {
    var_export($error);
    exit(0);
}

echo "Total issues resolved: **" . count($issues) . "**\n";

foreach ($issues as $index => $issue) {
    $issues[$issue->number] = sprintf('- [%d: %s](%s)', $issue->number, $issue->title, $issue->html_url);
    unset($issues[$index]);
}
ksort($issues);
echo implode("\n", $issues) . "";

I've now created a repo for this to make it even easier: https://github.com/weierophinney/changelog_generator

Thanks to much for the link to repo! I would not find it otherwise

@TomasVotruba - two links:

• https://GitHub.com/weierophinney/changelog_generator
• https://GitHub.com/phly/keep-a-changelog (what I currently use)