We introduced Python plug-ins for EPL in this post. The full community installation provides a Python installation, but users of the community core package will need to provide their own. Today we’re going to explore how to do this on various common operating systems.
Configuring Apama to use an external Python
By default, Apama will look inside the installation to locate a copy of the Python library when loading Python plug-ins. In order to load one in another location, you can set the AP_PYTHONHOME environment variable. It should be set to the location in which you installed Python.
Note that you will need to install exactly Python 3.6. Apama does not support other versions of Python.
#linux
export AP_PYTHONHOME=/opt/python36
correlator --python
#Windows
set AP_PYTHONHOME=c:\python36
correlator --python
If you have correctly installed and configured Python you will see in the correlator log that it has loaded the correct version of Python:
2018-09-03 09:44:06.257 INFO [15484] - <correlator.python> Initialized python interpreter version 3.6.6 (v3.6.6:4cf1f54eb7, Jun 27 2018, 03:37:03) [MSC v.1900 64 bit (AMD64)]
Installation of Python on common operating systems
On the latest release of each of the major Linux distributions, Python 3.6 can be installed using the system package manager.
UBUNTU LINUX BIONIC (18.04 LTS)
Python 3.6 is available in the standard repository and can be installed simply with:#
apt-get install python3.6 libpython3.6
export AP_PYTHONHOME=/usr
This will enable support for running both the Pysys test framework and other Python-based tools included in the Apama distribution, and also Python EPL plug-ins.
UBUNTU LINUX XENIAL (16.04 LTS)
For the Xenial 16.04 release of Ubuntu, Python 3.6 is not available in the main repository, but can be accessed via a PPA:
apt-add-repository ppa:deadsnakes/ppa
apt-get update
apt-get install python3.6 libpython3.6
export AP_PYTHONHOME=/usr
This will enable support for running both the Pysys test framework and other Python-based tools included in the Apama distribution, and also Python EPL plug-ins.
DEBIAN BUSTER (10 TESTING)
Python 3.6 is available in the standard repository and can be installed simply with:
apt-get install python3.6 libpython3.6
export AP_PYTHONHOME=/usr
This will enable support for running both the Pysys test framework and other Python-based tools included in the Apama distribution, and also Python EPL plug-ins.
CENTOS 7 / RHEL 7
RHEL 7, and therefore CentOS, does not include Python3.6 in the standard repository. Instead it is accessible from the EPEL repositories. In addition, the Python 3.6 packages in those repositories don’t by default provide Python via the python3 name, but only via python3.6 .
yum install epel-release
yum install python36
alternatives --install /usr/bin/python3 python36 /usr/bin/python3.6 1
export AP_PYTHONHOME=/usr
This will enable support for running both the Pysys test framework and other Python-based tools included in the Apama distribution, and also Python EPL plug-ins.
OPENSUSE LEAP 15.0 / SLES 15.0
Python 3.6 is available in the standard repository and can be installed simply with:
zypper install python3
export AP_PYTHONHOME=/usr
This will enable support for running both the Pysys test framework and other Python-based tools included in the Apama distribution, and also Python EPL plug-ins.
WINDOWS
To install Python on Windows we recommend downloading the installation package from Python Releases for Windows | Python.org. You need to download the Python 3.6.6 x86-64 executable installer.
Run the Python installer with the default options but also select ‘Add to PATH’.
You will also need to install the PyWin32 extensions. Once you’ve installed Python, start a command prompt and run:
pip install pywin32
Finally, configure Apama to use the installation. If you installed to a non-default location you will need to change the path you use:
set AP_PYTHONHOME=%LOCALAPPDATA%\Programs\Python\Python36
This will enable support for running both the Pysys test framework and other Python-based tools included in the Apama distribution, and also Python EPL plug-ins.
OLDER/OTHER LINUX DISTRIBUTIONS
Other Linux distributions based on the appropriate versions above of the major distributions should be able to install packages in the standard fashion listed above. If you’re using a non-standard distribution first consult your distribution packaging to see whether you can install it via their packages. If you can then it’s likely that after you do so you can run the correlator just by using:
export AP_PYTHONHOME=/usr
If Python is not available packaged, or you are using an older release of the distribution which only has an older version of Python available, then you may need to build from source. This definitely applies to Debian Stretch (9, the latest stable release at time of writing), Debian Jessie (8), Ubuntu Trusty (14.04 LTS), OpenSuse Leap 42.3, SLES 12.3 and versions of Raspian based on Debian Jessie or Stretch.
On these distributions, you will first need to install the dependencies necessary to build Python, then get the Python sources, build and install it.
On Debian, Ubuntu, or Raspian systems you can install the dependencies with:
apt-get install libssl-dev zlib1g-dev libncurses5-dev libncursesw5-dev libreadline-dev libsqlite3-dev libgdbm-dev libdb5.3-dev libbz2-dev libexpat1-dev liblzma-dev tk-dev build-essential wget
On OpenSuse Leap or SLES systems you can install the dependencies with:
zypper install readline-devel sqlite3-devel libbz2-devel zlib-devel libopenssl-devel wget tar gcc make
On other systems you will need to consult your package manager documentation for how to install the dependencies.
Once you have the dependencies the instructions are the same on all operating systems.
wget https://www.python.org/ftp/python/3.6.6/Python-3.6.6.tar.xz
tar xf Python-3.6.6.tar.xz
cd Python-3.6.6
./configure --enable-optimizations --enable-shared
make -j 8 build_all
make altinstall
export AP_PYTHONHOME=/usr/local
export PATH=/usr/local/bin:$PATH
This will enable support for running both the Pysys test framework and other Python-based tools included in the Apama distribution, and also Python EPL plug-ins.
Installing in Docker
Dockerfiles for all of the above Linux distributions can be found on GitHub - mjj29/linux-python-apama-docker: Dockerfiles to demonstrate installing Python on different operating systems and using them with Apama which demonstrate adding Python to the base operating system, adding an installation of Apama Core and adding a trivial Apama project to demonstrate that Python can be loaded and run.
For further information on how to use Python plug-ins from EPL please check out our other blog posts, the documentation available on https://www.apamacommunity.com/ or post with the “apama” tag on Newest 'apama' Questions - Stack Overflow. See you next time.