I was installing and setting up Cacti recently and faced following error:<\/p>\n\n\n\n
This post includes debugging steps and solution for the issue.<\/p>\n\n\n\n
Along with the Cacti’s web-interface, the poller.php was generating the same error as follows:<\/p>\n\n\n\n
root@ubuntu:\/var\/www\/cacti# php \/var\/www\/cacti\/poller.php\nFATAL: Cannot connect to MySQL server on 'localhost'. Please make sure you have specified a valid MySQL database name in 'include\/config.php'\n<\/pre>\n\n\n\n\n\n\n\nAlso the apache error log expressed following errors:<\/p>\n\n\n\n
tail -10f \/var\/log\/apache2\/error.log\n[Mon May 04 02:17:56 2015] [error] [client 127.0.0.1] PHP Warning: include_once(\/var\/www\/cacti-0.8.8c\/lib\/adodb\/adodb.inc.php): failed to open stream: Permission denied in \/var\/www\/cacti-0.8.8c\/include\/global.php on line 205\n[Mon May 04 02:17:56 2015] [error] [client 127.0.0.1] PHP Warning: include_once(): Failed opening '\/var\/www\/cacti-0.8.8c\/lib\/adodb\/adodb.inc.php' for inclusion (include_path='.:\/usr\/share\/php:\/usr\/share\/pear') in \/var\/www\/cacti-0.8.8c\/include\/global.php on line 205\n[Mon May 04 02:17:56 2015] [error] [client 127.0.0.1] PHP Warning: include_once(\/var\/www\/cacti-0.8.8c\/lib\/database.php): failed to open stream: Permission denied in \/var\/www\/cacti-0.8.8c\/include\/global.php on line 206\n[Mon May 04 02:17:56 2015] [error] [client 127.0.0.1] PHP Warning: include_once(): Failed opening '\/var\/www\/cacti-0.8.8c\/lib\/database.php' for inclusion (include_path='.:\/usr\/share\/php:\/usr\/share\/pear') in \/var\/www\/cacti-0.8.8c\/include\/global.php on line 206\n[Mon May 04 02:17:56 2015] [error] [client 127.0.0.1] PHP Fatal error: Call to undefined function db_connect_real() in \/var\/www\/cacti-0.8.8c\/include\/global.php on line 209\n[Mon May 04 02:18:42 2015] [error] [client 127.0.0.1] PHP Notice: Undefined variable: host in \/var\/www\/cacti-0.8.8c\/lib\/database.php on line 35\n[Mon May 04 02:18:42 2015] [error] [client 127.0.0.1] PHP Notice: Undefined variable: user in \/var\/www\/cacti-0.8.8c\/lib\/database.php on line 35\n[Mon May 04 02:18:42 2015] [error] [client 127.0.0.1] PHP Notice: Undefined variable: pass in \/var\/www\/cacti-0.8.8c\/lib\/database.php on line 35\n[Mon May 04 02:18:42 2015] [error] [client 127.0.0.1] PHP Notice: Undefined variable: db_name in \/var\/www\/cacti-0.8.8c\/lib\/database.php on line 35\n[Mon May 04 02:18:42 2015] [error] [client 127.0.0.1] PHP Notice: Undefined variable: db_type in \/var\/www\/cacti-0.8.8c\/lib\/database.php on line 35\n[Mon May 04 02:18:42 2015] [error] [client 127.0.0.1] PHP Notice: Undefined variable: port in \/var\/www\/cacti-0.8.8c\/lib\/database.php on line 35\n<\/pre>\n\n\n\nTroubleshooting steps:<\/h2>\n\n\n\n
\n
- Verified we have correct dir permisssions (Gave permissions: ugo+rx).<\/li>\n\n\n\n
- Verified ping to localhost (works). If you’re having other hostname check to see if it’s ping’able.<\/li>\n\n\n\n
- Confirmed that connectivity to mysql-server using mysql client using same parameters works.<\/li>\n\n\n\n
- There is no bind-address specified in MySQL config that may cause connectivity issues.<\/li>\n<\/ul>\n\n\n\n
<\/p>\n\n\n\n
After checking on above possibilities, the issue was still there. As said the Cacti’s web-interface on web-browser http:\/\/localhost\/cacti generated following errors:
FATAL: Cannot connect to MySQL server on ‘localhost’. Please make sure you have specified a valid MySQL database name in ‘include\/config.php’<\/em><\/p>\n\n\n\nI checked the global.php configurations and found db_connect_read function:<\/p>\n\n\n\n
# File: include\/global.php\n\n\/* connect to the database server *\/\ndb_connect_real($database_hostname, $database_username, $database_password, $database_default, $database_type, $database_port, $database_ssl);\n<\/pre>\n\n\n\nThe configuration in Cacti’s database config file is as follows:<\/p>\n\n\n\n
root@ubuntu:\/var\/www\/cacti# cat include\/config.php \n$database_type = \"mysql\";\n$database_default = \"cacti\";\n$database_hostname = \"localhost\";\n$database_username = \"cacti\";\n$database_password = \"xxxxx\";\n$database_port = \"3306\";\n$database_ssl = false;\n<\/pre>\n\n\n\nChanging $database_hostname to 127.0.0.1 in include\/config.php made the Cacti setup work!!<\/p>\n\n\n\n
$database_hostname = \"127.0.0.1\";\n<\/pre>\n\n\n\nThough I decided to resolve this keeping database_hostname to “localhost”. I looked at possible issues related to db_connect_real and php.ini details.<\/p>\n\n\n\n
Added doing following change in php configuration file:<\/p>\n\n\n\n
# vi \/etc\/php5\/apache2\/php.ini\nmysql.default_socket =\/var\/lib\/mysql\/mysqld.sock\n<\/pre>\n\n\n\nRestart apache and boom… Connectivity worked with hostname as “localhost”, the Cacti admin page loaded!!<\/p>\n\n\n\n
But why did that socket file change worked for hostname “localhost”!!! and why it was not concerned if I use hostname as IP (127.0.0.1)!<\/p>\n\n\n\n
I debugged further and created a softlink to MySQL socket-file at \/var\/run\/mysqld\/mysqld.sock and removed “mysql.default_socket =\/var\/lib\/mysql\/mysqld.sock ” from php.ini<\/p>\n\n\n\n
ln -s \/var\/lib\/mysql\/mysqld.sock \/var\/run\/mysqld\/mysqld.sock\n<\/pre>\n\n\n\ncat php.ini | grep default_socket\n## mysql.default_socket=\/var\/lib\/mysql\/mysqld.sock\n<\/pre>\n\n\n\nRestarted apache<\/p>\n\n\n\n
\/etc\/init.d\/apache2 restart\n<\/pre>\n\n\n\nand the Cacti worked for “localhost” database host!!<\/p>\n\n\n\n
So, for localhost as database_hostname, db_connect_real expect \/var\/run\/mysqld\/mysqld.sock as socket! I wonder if db_connect_real would like to buy a $database_socket variable in Cacti’s config.php?!!<\/p>\n\n\n\n
Anyways, there could be other issues that we checked earlier while “Troubleshooting Steps”, the issue here was MySQL’s socket file.<\/p>\n\n\n\n
\n
- If you’re using location other than \/var\/run\/mysqld\/mysqld.sock for mysql socket, specify it in “mysql.default_socket” in php.ini<\/li>\n\n\n\n
- If you can restart MySQL, change it to use socket=\/var\/run\/mysqld\/mysqld.sock.<\/li>\n<\/ul>\n\n\n\n
Do comment if you have more information on this behaviour!<\/p>\n","protected":false},"excerpt":{"rendered":"FATAL: Cannot connect to MySQL server on ‘localhost’: Cacti Error – Solution to the issue while setting-up.\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"om_disable_all_campaigns":false,"_monsterinsights_skip_tracking":false,"_monsterinsights_sitenote_active":false,"_monsterinsights_sitenote_note":"","_monsterinsights_sitenote_category":0,"footnotes":""},"categories":[8,6],"tags":[570,571,427,75],"class_list":{"0":"post-2198","1":"post","2":"type-post","3":"status-publish","4":"format-standard","6":"category-mysql","7":"category-technical","8":"tag-cacti-error","9":"tag-cannot-connect-to-mysql-on-localhost","10":"tag-mysql","11":"tag-mysql-server"},"aioseo_notices":[],"amp_enabled":true,"_links":{"self":[{"href":"https:\/\/kedar.nitty-witty.com\/blog\/wp-json\/wp\/v2\/posts\/2198","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/kedar.nitty-witty.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/kedar.nitty-witty.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/kedar.nitty-witty.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/kedar.nitty-witty.com\/blog\/wp-json\/wp\/v2\/comments?post=2198"}],"version-history":[{"count":7,"href":"https:\/\/kedar.nitty-witty.com\/blog\/wp-json\/wp\/v2\/posts\/2198\/revisions"}],"predecessor-version":[{"id":2863,"href":"https:\/\/kedar.nitty-witty.com\/blog\/wp-json\/wp\/v2\/posts\/2198\/revisions\/2863"}],"wp:attachment":[{"href":"https:\/\/kedar.nitty-witty.com\/blog\/wp-json\/wp\/v2\/media?parent=2198"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/kedar.nitty-witty.com\/blog\/wp-json\/wp\/v2\/categories?post=2198"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/kedar.nitty-witty.com\/blog\/wp-json\/wp\/v2\/tags?post=2198"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}