common: Support MySQL through socket

Unlike PostgreSQL, MySQL’s DSN needs a separate option for UNIX sockets.
It also cannot handle ports with socket.

This will be useful for running tests with internal MySQL instance.

NEWS.md

@@ -13,6 +13,7 @@
 - Data directory can be configured ([#1043](https://github.com/fossar/selfoss/pull/1043))
 - New spout for searching Twitter (e.g. following hashtags) was added. ([#1213](https://github.com/fossar/selfoss/pull/1213))
 - Added option `reading_speed_wpm` for showing estimated reading time. ([#1232](https://github.com/fossar/selfoss/pull/1232))
+- Added option `db_socket` for connecting to MySQL database through UNIX domain. ([#1284](https://github.com/fossar/selfoss/pull/1284))
 - Search query is now part of URL. ([#1216](https://github.com/fossar/selfoss/pull/1216))
 - Search will be carried out using regular expressions when the search query is wrapped in forward slashes, e.g. `/regex/`. The expression syntax is database specific. ([#1205](https://github.com/fossar/selfoss/pull/1205))
 - YouTube spout now supports following playlists. ([#1260](https://github.com/fossar/selfoss/pull/1260))

docs/content/docs/administration/options.md

@@ -53,6 +53,12 @@ Table prefix for MySQL/SQLite databases. This is useful to avoid conflicts when
 Port for database connections. By default `3306` will be used for MySQL and `5432` for PostgreSQL.
 </div>
 
+### `db_socket`
+<div class="config-option">
+
+A UNIX domain socket used for connecting to the MySQL database server. Usually, you want to use `db_host=localhost`, which should use the default socket path (typically `/run/mysqld/mysqld.sock` for MySQL or `/run/postgresql` for PostgreSQL) but if you need to specify a different location, you can. This is orthogonal to `db_host` option.
+</div>
+
 ### `logger_destination`
 <div class="config-option">
 

src/common.php

@@ -84,6 +84,11 @@
 $dice->addRule(daos\SourcesInterface::class, $shared);
 $dice->addRule(daos\TagsInterface::class, $shared);
 
+if ($configuration->isChanged('dbSocket') && $configuration->isChanged('dbHost')) {
+    echo 'You cannot set both `db_socket` and `db_host` options.' . PHP_EOL;
+    exit;
+}
+
 // Database connection
 if ($configuration->dbType === 'sqlite') {
     $db_file = $configuration->dbFile;
@@ -93,16 +98,21 @@
         touch($db_file);
     }
 
+    // https://www.php.net/manual/en/ref.pdo-sqlite.connection.php
     $dsn = 'sqlite:' . $db_file;
     $dbParams = [
         $dsn,
     ];
 } elseif ($configuration->dbType === 'mysql') {
+    $socket = $configuration->dbSocket;
     $host = $configuration->dbHost;
     $port = $configuration->dbPort;
     $database = $configuration->dbDatabase;
 
-    if ($port !== null) {
+    // https://www.php.net/manual/en/ref.pdo-mysql.connection.php
+    if ($socket !== null) {
+        $dsn = "mysql:unix_socket=$socket; dbname=$database";
+    } elseif ($port !== null) {
         $dsn = "mysql:host=$host; port=$port; dbname=$database";
     } else {
         $dsn = "mysql:host=$host; dbname=$database";
@@ -115,10 +125,13 @@
         [PDO::MYSQL_ATTR_INIT_COMMAND => 'SET NAMES utf8mb4;'],
     ];
 } elseif ($configuration->dbType === 'pgsql') {
-    $host = $configuration->dbHost;
+    $socket = $configuration->dbSocket;
+    // PostgreSQL uses host key for socket.
+    $host = $configuration->dbSocket !== null ? $configuration->dbSocket : $configuration->dbHost;
     $port = $configuration->dbPort;
     $database = $configuration->dbDatabase;
 
+    // https://www.php.net/manual/en/ref.pdo-pgsql.connection.php
     if ($port !== null) {
         $dsn = "pgsql:host=$host; port=$port; dbname=$database";
     } else {

src/helpers/Configuration.php

@@ -19,6 +19,9 @@ class Configuration {
         'ftrssCustomDataDir',
     ];
 
+    /** @var array<string, bool> Keeps track of options that have been changed. */
+    private $modifiedOptions = [];
+
     // Internal but overridable values.
 
     /** @var int debugging level @internal */
@@ -56,6 +59,9 @@ class Configuration {
     /** @var ?int */
     public $dbPort = null;
 
+    /** @var ?string */
+    public $dbSocket = null;
+
     /** @var string */
     public $dbPrefix = '';
 
@@ -217,6 +223,7 @@ public function __construct($configPath = null, $environment = []) {
             }
 
             $this->{$propertyName} = $value;
+            $this->modifiedOptions[$propertyName] = true;
         }
 
         // Interpolate variables in the config values.
@@ -226,4 +233,15 @@ public function __construct($configPath = null, $environment = []) {
             $this->{$property} = str_replace('%datadir%', $datadir, $value);
         }
     }
+
+    /**
+     * Checks whether given configuration option has been changed.
+     *
+     * @param string $key
+     *
+     * @return bool
+     */
+    public function isChanged($key) {
+        return isset($this->modifiedOptions[$key]);
+    }
 }