Documented Python and module installation process.

This commit is contained in:
Kristjan Komlosi
2019-06-22 11:29:13 +02:00
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# TeraHz build guide
The recommended way of getting TeraHz is the official SD card image provided
under the releases tab in the GitHub repository. Installing TeraHz from source
is a time consuming and painful process, even more so if you don't know what
you're doing, and whatever you end up building __will not be officially
The recommended way of getting TeraHz is the official Raspberry Pi SD card image
provided under the releases tab in the GitHub repository. Installing TeraHz from
source is a time consuming and painful process, even more so if you don't know
what you're doing, and whatever you end up building __will not be officially
supported__ (unless you're a core developer).
With this warning out of the way, let's begin.
## Getting the latest sources
The most reliable way to get working source code is by cloning the official GitHub
repository and checking out the `development-working` tag. This tag marks the latest
confirmed working commit. Building from the master branch is somewhat risky, and
building from development branches is straight up stupid if you're not a developer.
The most reliable way to get working source code is by cloning the official
GitHub repository and checking out the `development-stable` tag. This tag marks
the latest confirmed working commit. Building from the master branch is somewhat
risky, and building from development branches is straight up stupid if you're
not a developer.
After cloning and checking out, check the documentation for module dependencies
and the required version of python in the `docs/dependencies.md` file.
@@ -20,15 +21,66 @@ and the required version of python in the `docs/dependencies.md` file.
This step depends a lot on the platform you're using. TeraHz was developed with
Raspberry Pi and Raspbian in mind. If you're familiar with Raspbian enough,
you'll know that the latest version of Python available is `3.5`, which is too
obsolete to run TeraHz and the required modules consistently.
obsolete to run TeraHz and the required modules consistently. This leaves us
with compiling Python from source. __This step is guaranteed to be slow,
overnight compiling with something like tmux is recommended.__
After messing with Debian arm64 packages in the early development days I determined
that the most reliable way of getting Python on Raspbian is compiling it from source.
This part of the installation will take the largest portion of time, as compiling
anything complex on the Raspberry is painfully slow.
### Pre-requirements
Installing python without most C libraries will lead to a rather minimalistic
Python install, missing a lot of important modules. To prevent this, update
the system packages. After that, reboot.
If you're running an OS that provides a recent version of Python, great! You won't
have to waste so much time waiting for the build process to finish.
```
sudo apt update
sudo apt full-upgrade
sudo reboot
```
The Python version TeraHz works best on is `3.6.8`. To install it, download the
gzipped tarball from the official Python website, and decompress it.
Install the required build tools, libraries and their headers.
```
sudo apt-get install build-essential tk-dev libncurses5-dev libncursesw5-dev libreadline6-dev libdb5.3-dev libgdbm-dev libsqlite3-dev libssl-dev libbz2-dev libexpat1-dev liblzma-dev zlib1g-dev
```
### Compiling
Compiling Python from source is, in fact pretty easy, just time-consuming. I'll
advise you again to use a terminal multiplexer like `tmux` to start the build
process, detach the terminal session overnight and reattach it some time later
to check on it.
Python 3.6.8 can be downloaded in many forms, but you'll be using the most basic
of them all: a gzipped tarball. Download and decompress it, the cd into its
directory.
```
wget https://www.python.org/ftp/python/3.6.8/Python-3.6.8.tgz
tar -xzf Python-3.6.8.tgz
cd Python-3.6.8
```
Python's build process is pretty classic, a `.configure` script and a Makefile.
Using the `-j` option with Make can reduce the compile time significantly. Go
with as many threads as you have cores: `-j 4` works great on the Pi 3 B/B+.
```
./configure
make -j4
```
When the compilation ends, install your freshly built version of python.
```
sudo make altinstall
```
Altinstall means that the new version of Python will be installed beside the
existing version, and all related commands will use the full naming scheme:
think `python3.6` or `pip3.6` instead of the shorter `python3` or `pip3`.
### Modules
Another painfully slow part is the installation of all the required modules needed
by TeraHz. Luckily, `pip3.6` takes care of the entire installation process. You might also want to run this command through a terminal multiplexer overnight, as it takes a few hours to complete.
```
pip3.6 install smbus pyserial flask pandas
```