Wednesday, August 10, 2016

Installing MariaDB MaxScale the hard way

If you are like me (let's for everyones sake hope you are not, though) you like to do things the hard way, in particular when it comes to testing things. For example when installing things on your Linux box, just to try them out, you might not want to do a yum install an rpm -ivh or an apt-get to have some files spread all over your system, instead you want to tar xvf some tarball and possibly, if you are in a good mood or you want to be a nice so you get some gifts for christmas or maybe because it is just that day, you unpack that tarball in /usr/local instead of in /home/bofh/junk. And this will usually get you in some trouble, but as we have already determined that we are truly bad (maybe we should get a tattoo or two also, or is the right to death-metal antics reserved for IT security personel only? Sure seems so) we can ignore that and get to work.

Here I will show you how to install MariaDB MaxScale from a tar-ball and get it running, without touching any system directories or anything if you want to test it or if you, even in production, want to install it in some non-standard location (like /usr/local. I actually like to have stuff there, I don't know what's so wrong with that. I'm a rebel, I know).

To begin with, let's download MariaDB MaxScale tarball (rpm's are for wussies), for example from where you should register and then go to "my portal"->"Downloads"->"MariaDB MaxScale" and download an appropriate .tar.gz for your operating system of choice. In my case I download it for CentOS 6 / RHEL 6 and as the current MariaDB MaxScale version is 1.4.3 I issue the command in my home directory (/home2/anders):
$ wget<my tag>/mariadb-maxscale/1.4.3/rhel/6/x86_64/maxscale-1.4.3-1.rhel.6.x86_64.tar.gz
With <my tag> replaced by a generated tag on Following this we are stuck with a tarball named maxscale-1.4.3-1.rhel.6.x86_64.tar.gz and we unpack that as usual and then create a more readable link to the created directory:
$ tar xvfz maxscale-1.4.3-1.rhel.6.x86_64.tar.gz
$ ln -s maxscale-1.4.3-1.rhel.6.x86_64 maxscale143
So far nothing magic has happened. The next step is to create a few directories in our new maxscale143 directory where MariaDB MaxScale will keep temporary, stuff, logs etc:
$ cd maxscale143
$ mkdir cache data log

The next step after this is to create a MariaDB MaxScale configuration file. There is a template for this in the etc subdirectory so we just have to copy that:
$ cp etc/maxscale.cnf.template etc/maxscale.cnf
The supplied config file will start MariaDB MaxScale with just 1 server defined, and unless you have this server running on a non-standard port or on another machine than the one where MariaDB MaxScale itself is running, you can leave this configuration file alone, and if not you have to edit the [server1] section appropriately.

Another thing to look for is iptables / firewalld settings, but this you already know about I guess. You might want to turn them off (which is not recommended at all) or configure it appropriately. As per the default configuration with MariaDB MaxScale 1.4.3, ports 4006, 4008 and 6603 will be listened to, so you configure iptables / firewalld appropriately. And don't turn them of, do this the right way for once. I turned iptables off by the way, just to annoy you.

Now, MariaDB MaxScale will connect to the server we defined in the configuration file above, and we need to allow it to connect and execute a few commands. There are two users that MariaDB MaxScale can use, one to connect and get authentication data, like usernames and passwords, and another separate one to monitor the state of the server. In the supplied configuration template these two users use the same account, namely myuser using mypwd as the password, and this is what I use in the following where are set up the appropriate user and grant in the MariaDB server I am connecting to, and also note that I am assuming that MariaDB MaxScale and the MariaDB server on question run on the same node. So connect to MariaDB and issue the following commands:
MariaDB> CREATE USER 'myuser'@'localhost'  IDENTIFIED BY 'mypwd';
MariaDB> GRANT SELECT ON mysql.user TO 'myuser'@'localhost';
MariaDB> GRANT SELECT ON mysql.db TO 'myuser'@'localhost';
MariaDB> GRANT SELECT ON mysql.tables_priv TO 'myuser'@'localhost';
MariaDB> GRANT SHOW DATABASES ON *.*TO 'myuser'@'localhost';
MariaDB> GRANT REPLICATION SLAVE ON *.* TO 'myuser'@'localhost';
MariaDB> GRANT REPLICATION CLIENT ON *.* TO 'myuser'@'localhost';

With this in place we are ready to start MariaDB MaxScale, but this is an itsy bitsy more complex than you think. The issue is that the default locations for a lot of stuff that MariaDB MaxScale wants to use is somewhere in the global file system, and they are also not relative to some basedir as is conveniently the case with MariaDB server itself. to support this, instead of putting all this in the global section in the MariaDB MaxScale config file I'll instead put any necessary arguments to get MaxScale going on the command line, and for that I have created three scripts, 1 to set up the environment, one to start MariaDB MaxScale and one to stop it. Let's start with the environment one. This is places in the MariaDB MaxScale home directory (maxscale143) is called and has the following contents:
MAXSCALE_HOME=$(cd $(dirname $BASH_SOURCE) ; pwd)
export LD_LIBRARY_PATH=$MAXSCALE_HOME/usr/lib64/maxscale

The next file to create is the script to start MariaDB MaxScale, this is called, is again placed in the MariaDB MaxScale root directory and has this content:
. `dirname $0`/

$MAXSCALE_HOME/usr/bin/maxscale \
  --config=$MAXSCALE_HOME/etc/maxscale.cnf \
  --logdir=$MAXSCALE_HOME/log \
  --language=$MAXSCALE_HOME/var/lib/maxscale \
  --datadir=$MAXSCALE_HOME/data \
  --libdir=$MAXSCALE_HOME/usr/lib64/maxscale \
  --piddir=$MAXSCALE_HOME --syslog=no \

As you can see this invokes before going on to start MariaDB MaxScale. The only parameter that I really don't have to set here, but which I set anyway, again  just to be annoying to the world in general, is --syslog=no as we are only testing things here and logging to syslog is then not really appropriate (but it is the default).

All we need now is script to stop MariaDB MaxScale, and for this create a file called in the MariaDB MaxScale home directory with this content:
. `dirname $0`/

if [ -e "$MAXSCALE_HOME/" ]; then
   kill -term `cat $MAXSCALE_HOME/`

Following this, the one thing that remains to be done is to make the scripts we just created executable:
$ chmod +x

Now we are ready to try things, let's start MariaDB MaxScale first:
$ ./
And then let's see if we can connect to the MariaDB server through MariaDB MaxScale:
$ mysql -h -P 4006 -u myuser -pmypwd
Welcome to the MariaDB monitor.  Commands end with ; or \g.
Your MySQL connection id is 6950
Server version: 10.0.0 1.4.3-maxscale MariaDB Server

Copyright (c) 2000, 2016, Oracle, MariaDB Corporation Ab and others.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

MySQL [(none)]>

As you can see, I am not connecting as root here, as this is not allowed by MariaDB MaxScale by default. Also, I am not connecting to localhost as that assumes I am connecting using a socket, which is not what we want to do here.

This is all for today, now I'll need to start my Harley-Davidson and head down town to hang with the other tough guys (OK, I'm really taking my beaten-up Ford and pick up the kids from Kindergarten, I admit it).

Keep on SQL'ing

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