1. In the implementation of health checks in Yii 2.0, a colleague had previously implemented a version, but I felt it was necessary to make some adjustments.
PHP
Yii::$app->db->open();
if(!Yii::$app->redis->ping()) {
throw new ServerErrorHttpException('error','Redis is unavailable.',500);
} elseif(!Yii::$app->db->getIsActive()) {
throw new ServerErrorHttpException('error','Database is unavailable.',500);
} else {
return 200;
}
2. Upon analyzing the code, I found that Yii::$app->db->getIsActive() is unnecessary. I reviewed the source code of the respective methods. The implementation related to $this->pdo in getIsActive() already exists in open().
PHP
/**
* Establishes a DB connection.
* It does nothing if a DB connection has already been established.
* @throws Exception if connection fails
*/
public function open()
{
if ($this->pdo !== null) {
return;
}
if (!empty($this->masters)) {
$db = $this->getMaster();
if ($db !== null) {
$this->pdo = $db->pdo;
return;
}
throw new InvalidConfigException('None of the master DB servers is available.');
}
if (empty($this->dsn)) {
throw new InvalidConfigException('Connection::dsn cannot be empty.');
}
$token = 'Opening DB connection: ' . $this->dsn;
$enableProfiling = $this->enableProfiling;
try {
if ($this->enableLogging) {
Yii::info($token, __METHOD__);
}
if ($enableProfiling) {
Yii::beginProfile($token, __METHOD__);
}
$this->pdo = $this->createPdoInstance();
$this->initConnection();
if ($enableProfiling) {
Yii::endProfile($token, __METHOD__);
}
} catch (\PDOException $e) {
if ($enableProfiling) {
Yii::endProfile($token, __METHOD__);
}
throw new Exception($e->getMessage(), $e->errorInfo, (int) $e->getCode(), $e);
}
}
/**
* Returns a value indicating whether the DB connection is established.
* @return bool whether the DB connection is established
*/
public function getIsActive()
{
return $this->pdo !== null;
}
3. Analyzing the code, I found that we can use commands directly. Redis has many useful commands that can be run directly from a connection. ping is among the available Redis commands. This command is often used to test whether a connection is still active or to measure connection latency. See Figure 1.
4. The adjusted version of the health check implementation in Yii 2.0.
PHP
Yii::$app->db->open();
Yii::$app->redis->open();
return 200;
5. After changing the database password to an incorrect one, the response is a 500 error as follows, which is expected. See Figure 2.
JSON
{
"name": "Database Exception",
"message": "SQLSTATE[HY000] [1045] Access denied for user 'pcs-api'@'localhost' (using password: YES)",
"code": 1045,
"type": "yii\\db\\Exception",
"file": "E:\\wwwroot\\pcs-api\\vendor\\yiisoft\\yii2\\db\\Connection.php",
"line": 637,
"stack-trace": [
"#0 E:\\wwwroot\\pcs-api\\api\\rests\\openconf\\CreateAction.php(58): yii\\db\\Connection->open()",
"#1 [internal function]: api\\rests\\openconf\\CreateAction->run()",
"#2 E:\\wwwroot\\pcs-api\\vendor\\yiisoft\\yii2\\base\\Action.php(94): call_user_func_array(Array, Array)",
"#3 E:\\wwwroot\\pcs-api\\vendor\\yiisoft\\yii2\\base\\Controller.php(157): yii\\base\\Action->runWithParams(Array)",
"#4 E:\\wwwroot\\pcs-api\\vendor\\yiisoft\\yii2\\base\\Module.php(528): yii\\base\\Controller->runAction('create', Array)",
"#5 E:\\wwwroot\\pcs-api\\vendor\\yiisoft\\yii2\\web\\Application.php(103): yii\\base\\Module->runAction('v1/openconf/cre...', Array)",
"#6 E:\\wwwroot\\pcs-api\\vendor\\yiisoft\\yii2\\base\\Application.php(386): yii\\web\\Application->handleRequest(Object(yii\\web\\Request))",
"#7 E:\\wwwroot\\pcs-api\\api\\web\\index.php(17): yii\\base\\Application->run()",
"#8 {main}"
],
"error-info": null,
"previous": {
"name": "Exception",
"message": "SQLSTATE[HY000] [1045] Access denied for user 'pcs-api'@'localhost' (using password: YES)",
"code": 1045,
"type": "PDOException",
"file": "E:\\wwwroot\\pcs-api\\vendor\\yiisoft\\yii2\\db\\Connection.php",
"line": 705,
"stack-trace": [
"#0 E:\\wwwroot\\pcs-api\\vendor\\yiisoft\\yii2\\db\\Connection.php(705): PDO->__construct('mysql:host=loca...', 'pcs-api', 'jwpuOHTSX5hOcuX...', NULL)",
"#1 E:\\wwwroot\\pcs-api\\vendor\\yiisoft\\yii2\\db\\Connection.php(626): yii\\db\\Connection->createPdoInstance()",
"#2 E:\\wwwroot\\pcs-api\\api\\rests\\openconf\\CreateAction.php(58): yii\\db\\Connection->open()",
"#3 [internal function]: api\\rests\\openconf\\CreateAction->run()",
"#4 E:\\wwwroot\\pcs-api\\vendor\\yiisoft\\yii2\\base\\Action.php(94): call_user_func_array(Array, Array)",
"#5 E:\\wwwroot\\pcs-api\\vendor\\yiisoft\\yii2\\base\\Controller.php(157): yii\\base\\Action->runWithParams(Array)",
"#6 E:\\wwwroot\\pcs-api\\vendor\\yiisoft\\yii2\\base\\Module.php(528): yii\\base\\Controller->runAction('create', Array)",
"#7 E:\\wwwroot\\pcs-api\\vendor\\yiisoft\\yii2\\web\\Application.php(103): yii\\base\\Module->runAction('v1/openconf/cre...', Array)",
"#8 E:\\wwwroot\\pcs-api\\vendor\\yiisoft\\yii2\\base\\Application.php(386): yii\\web\\Application->handleRequest(Object(yii\\web\\Request))",
"#9 E:\\wwwroot\\pcs-api\\api\\web\\index.php(17): yii\\base\\Application->run()",
"#10 {main}"
]
}
}
6. After changing the Redis password to an incorrect one, the response is a 500 error as follows, which is expected. Replacing Yii::$app->redis->open(); with Yii::$app->redis->ping() yields the same response, because open() must be executed before running the ping command. See Figure 3.
JSON
{
"name": "Database Exception",
"message": "Redis error: ERR Client sent AUTH, but no password is set\nRedis command was: AUTH 88888888",
"code": 0,
"type": "yii\\db\\Exception",
"file": "E:\\wwwroot\\pcs-api\\vendor\\yiisoft\\yii2-redis\\src\\Connection.php",
"line": 821,
"stack-trace": [
"#0 E:\\wwwroot\\pcs-api\\vendor\\yiisoft\\yii2-redis\\src\\Connection.php(789): yii\\redis\\Connection->parseResponse(Array, '*2\\r\\n$4\\r\\nAUTH\\r\\n$...')",
"#1 E:\\wwwroot\\pcs-api\\vendor\\yiisoft\\yii2-redis\\src\\Connection.php(772): yii\\redis\\Connection->sendCommandInternal('*2\\r\\n$4\\r\\nAUTH\\r\\n$...', Array)",
"#2 E:\\wwwroot\\pcs-api\\vendor\\yiisoft\\yii2-redis\\src\\Connection.php(634): yii\\redis\\Connection->executeCommand('AUTH', Array)",
"#3 E:\\wwwroot\\pcs-api\\vendor\\yiisoft\\yii2-redis\\src\\Connection.php(744): yii\\redis\\Connection->open()",
"#4 E:\\wwwroot\\pcs-api\\vendor\\yiisoft\\yii2-redis\\src\\Connection.php(709): yii\\redis\\Connection->executeCommand('PING', Array)",
"#5 E:\\wwwroot\\pcs-api\\api\\rests\\openconf\\CreateAction.php(57): yii\\redis\\Connection->__call('ping', Array)",
"#6 [internal function]: api\\rests\\openconf\\CreateAction->run()",
"#7 E:\\wwwroot\\pcs-api\\vendor\\yiisoft\\yii2\\base\\Action.php(94): call_user_func_array(Array, Array)",
"#8 E:\\wwwroot\\pcs-api\\vendor\\yiisoft\\yii2\\base\\Controller.php(157): yii\\base\\Action->runWithParams(Array)",
"#9 E:\\wwwroot\\pcs-api\\vendor\\yiisoft\\yii2\\base\\Module.php(528): yii\\base\\Controller->runAction('create', Array)",
"#10 E:\\wwwroot\\pcs-api\\vendor\\yiisoft\\yii2\\web\\Application.php(103): yii\\base\\Module->runAction('v1/openconf/cre...', Array)",
"#11 E:\\wwwroot\\pcs-api\\vendor\\yiisoft\\yii2\\base\\Application.php(386): yii\\web\\Application->handleRequest(Object(yii\\web\\Request))",
"#12 E:\\wwwroot\\pcs-api\\api\\web\\index.php(17): yii\\base\\Application->run()",
"#13 {main}"
],
"error-info": []
}
7. In summary, whether checking database or Redis connections, it is best to maintain a consistent detection method. Therefore, I uniformly adopted the open() method. Yii::$app->db->getIsActive() is unnecessary and a redundant implementation.