Getting started with external scripts installation and configuration

Transcription

1 Getting started with external scripts installation and configuration

2 What are external scripts? External scripts are processes which run on the same hardware as Kognitio, via the operating system but outside of the Kognitio software These processes are invoked by Kognitio and can be run in various environments (i.e. bash and python) Click here for more details on Kognitio and external script RAM utilisation They typically receive data from Kognitio, do some processing on the data, then send data back to Kognitio. External scripts must share hardware resources, i.e. RAM and CPU cycles with Kognitio. If memory is required by external script processes then it is not available to Kognitio and vice versa

3 Requirements - overview The following conditions must be met in order to use external scripts: 1. Kognitio must be installed and operational. For details on how to install Kognitio click here 2. Kognitio must have a license which allows external scripts 3. Kognitio must be version 8 or higher 4. Every external script runs in an environment any environment to be utilised by external scripts must be identically installed on every node in the system. For example, if using bash, the bash executable must be installed on every node, in the same location. This is usually /usr/bin/bash and comes as part of the standard Linux OS installation 5. External scripts must be enabled in the Kognitio configuration file 6. (optional but very useful) Install Kognitio console Installation files and instructions can be found here These requirements are explained in subsequent slides.

4 Licenses To find out if you have a license which allows external scripts: on a Kognitio node, in a Linux shell, as user wxadmin, run the command: wxlicense -i grep external This should return the line external_scripts yes. If not you do not see this,please contact Kognitio to discuss licensing options. Note that external scripts can only be used on a system which has a RAM limitation in it s license.

5 Checking the version of Kognitio External scripts require Kognitio version 8 or higher to be installed. To find out which version is installed: On a Kognitio node, in a Linux shell, as wxadmin user, run the command: wxprobe This should return a line similar to: Kognitio WX2 Hardware Discovery Tool v rel OR In Kognitio console, connect to the database, and the version will be shown in the lower right corner If Version 7 or below is installed, contact Kognitio to discuss a Kognitio upgrade

6 Installing a script environment: the Python executable This section explains how to make sure the Python executable is installed on every node in Kognitio. You will need root access for the installation. 1) First open a command line interface and ssh into the Linux OS as root with ssh -A root@<hostname>

7 Installing the Python executable 2) Install Python. For SLES linux installations, with internet access type: zypper install python Note: other versions of Linux have different dependency management systems that can be used. For example for Ubuntu Linux use apt-get and for RedHat use yum. Both can be utilised to install python on a Kognitio node. For details on utilising yum click here

8 Installing the Python executable 3) Check that python is working, by running: python -c "help('modules')" head -n10 If Python is working, you should see a list of installed modules

9 Installing Python executable 4) Obtain IP addresses for each Kognitio node by running: /opt/kognitio/wx2/current/bin/wxprobe -i The output shows the ip address for every interface of every node on the system. This information is required in the next step.

10 Installing Python executable 5) Now that Python is installed on the first node, ssh to each other node in turn, as root, and run the same python install command. This includes the AP. Note: the IP addresses for ssh were found in the last step. Use the eth2 interface addresses highlighted. The Kognitio command line utility wxtool can also be used for the installation. Click here to find out how

11 Installing Python executable 6) To check that python is correctly installed run /opt/kognitio/wx2/current/bin/wxtool -S 'which python' The output should be the same for each node. In this example, the output is /usr/bin/python for every node. The installations were successful. If the output is different for one or more nodes ssh onto those nodes and re-install.

12 Installing Python executable 7) External scripts are run by the wxextern user by default, so wxextern needs to have execute permissions on the Python executable on all nodes. To check if this is the case, run: /opt/kognitio/wx2/current/bin/wx tool -S 'ls -la `which python`' The output from each node should show 3 x characters on the left hand side. If this is not the case, then run: /opt/kognitio/wx2/current/bin/wx tool -S 'chmod +x `which python`' Then run the first command again to check that it worked.

13 Editing the configuration file The Kognitio configuration file needs to specify that the external script functionality should be enabled. ssh to any Kognitio node as wxadmin and run wxviconf. This will open the Kognitio config file in a vi editor. Use the arrow keys to scroll down to the [boot options] section, and add the line: external_scripts=yes Note that external tables can also be enabled with external_tables=yes, but this is not related to external scripts. To save the file, type :wq and press return to exit the vi editor. If the operation was successful, you should see a message similar to the picture below left.

14 Restarting the database For the changes to take effect, Kognitio needs to be restarted. Run wxserver start This completes the configuration of Kognitio for external scripting For details on how to set up and run external scripts in Kognitio see Chapter 10 of the Kognitio Guide