Does "service mysql start" start the mysql server or client?
I have done as much searching on this topic as I can, and the answers do seem all over the place. Some sites state that the "service mysql start" starts the server, while others state that one must use "service mysqld start": e.g.: http://theos.in/desktop-linux/tip-that-matters/how-do-i-restart-mysql-server/
To elaborate some more - my understanding is that "mysql" is the process that represents the client interface that connects to a mysql server (either remote or local) and "mysqld" is the process for the server. I would assume that "service mysql start" would only start the mysql client (not the server) and I can use this client to connect to any mysql server. And if I haven't used "service mysqld start", no server would have been started on the local host and therefore I can't use the mysql client to connect to any local mysql server. Is my understanding correct?
Also, I am using a Red Hat server.
Any clarifications and explanations most appreciated - Thanks!
mysql client is never (AFAIK) run as a service, so
service mysql start
will start mysql server. To be precise, this will start service that is described in /etc/init.d/mysql script.
Some distributions name their init script differently, for example mysqld. So you should just check your /etc/init.d/
You can check what exactly that scipt is doing, even if you don't know bash.
First few lines should contain short description, in case of my ubuntu installation it is:
# cat /etc/init.d/mysql
#!/bin/bash
#
### BEGIN INIT INFO
# Provides: mysql
# Required-Start: $remote_fs $syslog
# Required-Stop: $remote_fs $syslog
# Should-Start: $network $time
# Should-Stop: $network $time
# Default-Start: 2 3 4 5
# Default-Stop: 0 1 6
# Short-Description: Start and stop the mysql database server daemon
# Description: Controls the main MySQL database server daemon "mysqld"
# and its wrapper script "mysqld_safe".
### END INIT INFO
So as you can see, mysql service script takes care of mysqld daemon (process). As opposed to mysql binary, found for example in /usr/bin which is client program and doesn't require any service to be running on your OS.
To sum everything up:
# service mysql start
will start server (daemon/service), then you can connect to it with
$ mysql -u root -p
If you are using the command "service mysqld start" this will start the mysql server in RHEL.
Actally the name "mysqld" depends on init.d scripts name. If it's mentioned as "mysql" in init.d scripts "mysql" will work. This variates from distro to distro.
in my case
systemctl restart rh-mysql57-mysqld.service
Related
I am creating a development/testing container that contains a number of elements including a mysql server that must run internally for code to access. To demonstrate the issue, I run the following Dockerfile with docker run -i -t demo_mysql_server:
FROM amazonlinux:2018.03
RUN yum -y update && yum -y install shadow-utils mysql-server
Unfortunately, after building the docker container I receive a common connection error (see 1, 2)
ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/var/lib/mysql/mysql.sock' (2)
which can be fixed by logging in as admin with docker run -i -u 0 -t demo_mysql_server
and executing:
echo "NETWORKING=yes" >/etc/sysconfig/network
service network restart
/etc/init.d/mysqld start
chkconfig mysqld on
which seems to turn everything on. However, incorporating these into RUN commands doesn't seem to keep the service on and logging in as admin requires restarting the service as above and adding a user and working as a non-admin and trying to start the service results in errors of the flavor:
bash: /etc/sysconfig/network: Permission denied
[testUser#544a938c44c1 /]$ service network restart
[testUser#544a938c44c1 /]$ /etc/init.d/mysqld start
/etc/init.d/mysqld: line 16: /etc/sysconfig/network: No such file or directory
[testUser#544a938c44c1 /]$ chkconfig mysqld on
You do not have enough privileges to perform this operation.
I this a normal error to see and how do I get the MySQL server instance to stay running?
i have "CentOS 6" VPS and i wanted to start mysql service automatically at Startup of Server when it is restarted. so i used this command in putty
chkconfig --level 345 mysqld on
this command is working and mysql starts on every startup automatically.
BUT how can i now stop this? what if i want to start Mysql manually on every startup, then what command should i use?
also what is the File where i can see the list of programs that are running automatically on every setup.
Thanks
You can turn off auto-start with this command:
chkconfig --level 345 mysqld off
To see what is configured for auto-start, you can run:
chkconfig --list
See more info on chkconfig here:
https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/6/html/Deployment_Guide/s2-services-chkconfig.html
I have installed Centos7 update, removed MariaDB and done a fresh install of MySQL - additionally I have removed it and reinstalled it but everytime I connect to mysql -u root -p I get the titled error. Additionally I have looked at other tickets associated with this but still not making progress. If I run service mysqld restart it says "Redirecting to /bin/systemctl restart mysqld.service" and then just hangs. Really not a linux expert so not sure what is causing this?
I had the same problem and found out a few things after digging around. MariaDB is a drop-in replacement for mysql. On the new system, mysql is the MariaDB client (although I'm not clear on what that means). I checked to see if the service was running:
service mysqld status
which indicated:
Redirecting to /bin/systemctl status mysqld.service
mysqld.service
Loaded: not-found (Reason: No such file or directory)
Active: inactive (dead)
In other words, the mysqld service is not running.
Starting the service worked for me:
`systemctl start mariadb.service`
Now all the mysql commands work as expected.
To tie the last knot, enable the service at boot:
`systemctl enable mariadb.service`
Check the 'socket=' entry in your /etc/my.cnf within the [mysqld] section:
[mysqld1]
socket = /tmp/mysql.sock1
An alternate method is to provide the '-hhost' & '-Pport' parameters to the 'mysqladmin' or 'mysql' commands, to avoid using the socket.
mysql -u user -hservername -P3006 -p -Dschema
mysqladmin -u user -p -hhostname -Pport
Removing the dir fixed it - deleted the dir (with rm -rf "dir name") and then unintalled mysql "yum remove mysql mysql-server" then reinstalled "yum install mysql-server" and ran "service mysqld start"
If you have this problem with the start mysql service hanging - check the logs /var/log/mysqld.log as suggested by Jeremiah.
If you look into the MariaDB log file, you may see that the issue is related to creating pid file. To solve it: create the PID directory then change its owner to mysql:mysql
To recover from a blackout I need to start the Galera cluster when the system boots and I can only do this with the following:
service mysql start --wsrep-new-cluster
"service mysql start" will get launched on boot but will fail because it is the only one in the cluster. How do I get the cluster to start from boot and not fail if it is the only one there?
EDIT
Looks like I have to leave gcomm:// blank for it to start but it is not the best solution as if another server came online first then it would fail.
#galera settings
wsrep_provider=/usr/lib/galera/libgalera_smm.so
wsrep_cluster_name="my_wsrep_cluster"
wsrep_cluster_address="gcomm://"
wsrep_sst_method=rsync
wsrep_provider_options="pc.bootstrap=true"
My solution is to edit init scripts - This is solution for debian - location my init script is /etc/init.d/mysql
then I found this line:
/usr/bin/mysqld_safe "${#:2}" > /dev/null 2>&1 &
and I added parameter --wsrep-new-cluster
/usr/bin/mysqld_safe --wsrep-new-cluster "${#:2}" > /dev/null 2>&1 &
and it is working after boot.
I've been through this before. The following is the procedure I documented for my co-workers:
First we will determine the node with the latest change
On each node go to /var/lib/mysql and examine the grastate.dat file
We are looking for the node with the highest seqno and a uuid that is not all zeros
On the node that captured the latest change startup the cluster in bootstrap mode
service mysql bootstrap
Startup the other nodes via the usual startup command
service mysql start
Check each node if they have the same DB list
mysql -u root -p
show databases;
On any node run the command to check for the status of the cluster and ensure you see something like the following
wsrep_local_state_comment | Synced <-- cluster is synced
wsrep_incoming_addresses | 10.0.0.9:3306,10.0.0.11:3306,10.0.0.13:3306 <-- all nodes are providers
wsrep_cluster_size | 3 <-- cluster consists of 3 nodes
wsrep_ready | ON <-- good :)
i am trying to setup mysql-proxy on ubuntu on amazon ec2
i have done following:
sudo apt-get install mysql-proxy --yes
vi /etc/default/mysql-proxy
i put following content on "/etc/default/mysql-proxy"
ENABLED="true"
OPTIONS="--proxy-lua-script=/usr/share/mysql-proxy/rw-splitting.lua
--proxy-address=127.0.0.1:3306
--proxy-backend-addresses=private_ip_of_another_ec2_db_server:3306,private_ip_of_another_ec2_db_server:3306"
also tied with "--proxy-address=private_ip_or_public_ip_of_proxy-server:3306 or 4040"
and "--proxy-backend-addresses=public_ip_of_another_ec2_db_server:3306,public_ip_of_another_ec2_db_server:3306"
after that i tried to connect proxy server from another pc using mysql like:
mysql -u some_user -pxxxxx -h proxy_server_ip
or
mysql -u some_user -pxxxxx -h proxy_server_ip -P 4040
but its not working
its showing error:
ERROR 2003 (HY000): Can't connect to MySQL server on 'ip' (10061)
i want to tell you can connect the db server remotely where i allowed remote connection to any host
i also tried /etc/init.d/mysql-proxy start or /etc/init.d/mysql-proxy restart but no result
just to inform you that /etc/init.d/mysql-proxy stop is showing failed
can anyone please help me to setup and configure mysql-proxy on ubuntu
===
Edit
i found some help from other question of stackoverflow and also according to a suggestion in the comments, have done following procedure. and it seems its working now.
i installed mysql-client and mysql-server locally(on proxy server)
then i tried to run mysql-proxy using following command:
mysql-proxy --proxy-backend-addresses=10.73.151.244:3306 --proxy-backend-addresses=10.73.198.7:3306 --proxy-address=:4040 --admin-username=root --admin-password=root --admin-lua-script=>/usr/lib/mysql-proxy/lua/admin.lua
then i tried to connect remotely to the proxy server and its working.
but it seems i need to run this command under screen because when i close the terminal proxy stops working.
Can you please tell me that do i need to run this command under screen or is there any other way to make it alive all time?
There is no need to install Mysql client or Mysql Server on your mysql-proxy.
Installing mysql-proxy does have "full daemon capabilities" compiled into it.
If your are running Ubuntu Server, you may wish to use an UPSTART service script.
This script can be copied into /etc/init/mysql-proxy.conf
# mysql-proxy.conf (Ubuntu 14.04.1) Upstart proxy configuration file for AWS RDS
# mysql-proxy - mysql-proxy job file
description "mysql-proxy upstart script"
author "shadowbq <shadowbq#gmail.com>"
# Stanzas
#
# Stanzas control when and how a process is started and stopped
# See a list of stanzas here: http://upstart.ubuntu.com/wiki/Stanzas#respawn
# When to start the service
start on runlevel [2345]
# When to stop the service
stop on runlevel [016]
# Automatically restart process if crashed
respawn
# Essentially lets upstart know the process will detach itself to the background
expect daemon
# Run before process
pre-start script
[ -d /var/run/mysql-proxy ] || mkdir -p /var/run/mysql-proxy
echo "starting mysql-proxy"
end script
# Start the process
exec /usr/bin/mysql-proxy --plugins=proxy --proxy-lua-script=/usr/share/mysql-proxy/rw-splitting.lua --log-level=debug --proxy-backend-addresses=private_ip_of_another_ec2_db_server:3306,private_ip_of_another_ec2_db_server:3306 --daemon --log-use-syslog --pid-file=/var/run/mysql-proxy/mysql-proxy.pid
In the above example I hard coded the AWS RDS server into script, instead of fiddling with defaults and config file
Install Upgraded version 0.8.5
Note:
apt repo does not have 0.8.5 so we need to download tar from mysql official site
Prerequisite :-
Create file /etc/default/mysql-proxy with following content
ENABLED="true"
OPTIONS="--defaults-file=/etc/mysql/mysql-proxy.cnf"
Installation Procedure :-
Download mysql-proxy 0.8.x
Untar in /usr/local
Update PATH environment with /usr/local/mysql-proxy-0.8.5-linux-debian6.0-x86-64bit/bin
vim /etc/environment (to update environment path)
cd /usr/local/mysql-proxy-0.8.5-linux-debian6.0-x86-64bit/bin
Run command sudo ./mysql-proxy --defaults-file=/etc/mysql/mysql-proxy.cnf
Sample mysql-proxy.cnf file
[mysql-proxy]
log-level=debug
log-file=/var/log/mysql-proxy.log
pid-file = /var/run/mysql-proxy.pid
daemon = true
--no-proxy = false
admin-username=ADMIN
admin-password=ADMIN
proxy-backend-addresses=RDS-ENDPOINT:RDS-PORT
admin-lua-script=/usr/lib/mysql-proxy/lua/admin.lua
proxy-address=0.0.0.0:4040
admin-address=localhost:4041
change host ip and port of RDS or mysql
connect to Mysql server via proxy with
mysql -h{proxy-host-ip} -P 4040 -u{mysql_username} -p