added health check

The check runs the standard DokuWiki initialization, fatal errors should
get caught and be reported back to docker

Dockerfile

@@ -18,5 +18,8 @@ RUN /bin/bash /build-setup.sh
 VOLUME /storage
 EXPOSE 8080
 
+HEALTHCHECK --timeout=5s \
+    CMD curl --silent --fail-with-body http://localhost:8080/health.php || exit 1
+
 RUN chmod +x /dokuwiki-entrypoint.sh
 ENTRYPOINT ["/dokuwiki-entrypoint.sh"]

README.md

@@ -24,6 +24,7 @@ On first run, use DokuWiki's [installer](https://www.dokuwiki.org/installer) to
 * imagemagick installed and enabled
 * nice URLs via rewriting configured and enabled
 * farming support via the [farmer plugin](https://www.dokuwiki.org/plugin:farmer)
+* docker health check running basic DokuWiki checks (every 30 seconds, 3 retries)
 
 Note: This image does **not** include a mail server. You need to configure DokuWiki to use an external mail server, this
 is most easily achieved using the [SMTP plugin](https://www.dokuwiki.org/plugin:smtp).

root/var/www/html/health.php

@@ -0,0 +1,25 @@
+<?php
+
+define('DOKU_UNITTEST', 1);
+define('DOKU_INC', __DIR__ . '/');
+
+header('Content-Type: text/plain; charset=utf-8');
+try {
+    ob_start();
+    require DOKU_INC . 'inc/init.php';
+    ob_end_clean();
+    # if init didn't fail, DokuWiki should be generally okay
+    echo 'ok';
+} catch (\Exception $e) {
+    ob_end_clean();
+    header($_SERVER['SERVER_PROTOCOL'] . ' 500 Internal Server Error', true, 500);
+
+    // ensure we have a good status message on failure
+    $msg = $e->getMessage();
+    $msg = strip_tags($msg);
+    $msg = preg_replace('/^nice_die:/', '', $msg);
+    $msg = preg_replace('/\s+/', ' ', $msg);
+    $msg = trim($msg);
+    echo $msg;
+}
+