Error: can't connect to database server: Can't connect to MySQL server on '172.25.0.36' (111)

    in /var/www/html/martini-git/lib/mysql.php at line 614

#0 /var/www/html/martini-git/lib/mysql.php(487): DatabaseManager->connect('172.25.0.36')
#1 /var/www/html/martini-git/lib/mysql.php(680): DatabaseManager->assertMasterLink()
#2 /var/www/html/martini-git/lib/mysql.php(308): DatabaseManager->realQuery('DELETE FROM `ex...', Array, 'm6')
#3 /var/www/html/martini-git/lib/mysql.php(983): DatabaseManager->query('DELETE FROM `ex...', Array, 'm6')
#4 /var/www/html/martini-git/lib/mysql.php(1332): Database->query('DELETE FROM `ex...', Array)
#5 /var/www/html/martini-git/src/core/Martini.php(588): Database->deleteRecords('external_cache', Array)
#6 /var/www/html/martini-git/src/core/GeoInformationService/nhs/nhs.php(252): Martini->getRemoteFile('http://v1.syndi...', 1440, true)
#7 /var/www/html/martini-git/src/core/GeoInformationService/NhsServices.php(49): NhsServices::findNearestOrganisation('BH20 7EN', 'organisations/h...', Object(Martini))
#8 /var/www/html/martini-git/src/core/GeoInformationService/NhsServices.php(73): NhsInformationService->getList(Object(Location))
#9 /var/www/html/martini-git/src/modules/LocalInfoModule.php(1019): NhsInformationService->getHtmlList(Object(Location))
#10 /var/www/html/martini-git/src/modules/LocalInfoModule.php(107): LocalInfoModule->handleListRequest(Array)
#11 /var/www/html/martini-git/src/web.php(406): LocalInfoModule->handleDisplayRequest(Object(HttpRequest))
#12 /var/www/html/martini-git/src/web.php(60): RequestHandler->handleRequestInternal(Object(HttpRequest))
#13 /var/www/html/martini-git/lib/http.php(88): RequestHandler->handleRequest(Object(HttpRequest))
#14 /var/www/html/martini-git/htdocs/index.php(160): HttpApplication->run()
#15 {main}