Creating Recipes for non-available python apps

Since influxdb-python and pynmea2 are not available as standard python recipes, I began by creating recipes for them using devtool.

Steps

use devtool to add the influxdb-python

devtool add influxdb-python https://github.com/influxdata/influxdb-python/archive/v5.2.0.tar.gz
use devtool to add the pynmea2

devtool add pynmea2 https://github.com/Knio/pynmea2/archive/1.7.1.tar.gz

The above mentioned steps creates a folder workspace in your $BUILD_DIR and created auto-generated recipes for the repos.

Edit the recipes

devtool edit-recipe influxdb-python
add or check DEPEND_${PN} and RDEPENDS_${PN} to your recipes accordingly. I added all the requirements.txt for influxdb-python to RDEPENDS_${PN} viz.

RDEPEND_${PN} += "${PYTHON_PN}-modules ${PYTHON_PN}-requests ${PYTHON_PN}-dateutil ${PYTHON_PN}-pytz ${PYTHON_PN}-six"

NOTE: I have not added pandas or numpy as they aren't relevant for my application.
I added DEPENDS_${PN} = "${PYTHON_PN}-modules also.

NOTE: Perform the same for pynmea2 but since it does not have any requirements.txt I added RDEPENDS_${PN} = "${PYTHON_PN}-modules" so all major things are available on the target.

Recipe Structure

GitHub Gist for Recipes

I followed the meta-python folder's structure where each of the recipes consists of :

recipe.inc
recipe_version_number.bb

In the influxdb_python.inc keep all the stuff generated from devtool viz.

# Recipe created by recipetool
# This is the basis of a recipe and may need further editing in order to be fully functional.
# (Feel free to remove these comments when editing.)
#
# WARNING: the following LICENSE and LIC_FILES_CHKSUM values are best guesses - it is
# your responsibility to verify that the values are complete and correct.
LICENSE = "MIT"
LIC_FILES_CHKSUM = "file://LICENSE;md5=046523829184aac3703a4c60c0ae2104"

HOMEPAGE = "https://github.com/influxdb/influxdb-python"
SUMMARY = "InfluxDB client"

SRC_URI = "https://github.com/influxdata/influxdb-python/archive/v${PV}.tar.gz"
SRC_URI[md5sum] = "105d88695151e241523b31dd1375096e"
SRC_URI[sha256sum] = "620de85bcca5207b06ec1565884b6d10b4be01d579a78e08b1e922f453fdac05"

DEPENDS_${PN} = "${PYTHON_PN}-modules"
RDEPENDS_${PN} = "${PYTHON_PN}-modules ${PYTHON_PN}-requests ${PYTHON_PN}-dateutil ${PYTHON_PN}-pytz ${PYTHON_PN}-six"

In the influxdb_python_5.2.0.bb I added the following lines:

inherit setuptools3 pypi                              
require influxdb-python.inc

NOTE: I added setuptools3 since I want my app to be run on python3.5. For python2.7 use setuptools.

Similarly, I did the same for pynmea2.inc:

# Recipe created by recipetool
# This is the basis of a recipe and may need further editing in order to be fully functional.
# (Feel free to remove these comments when editing.)
#
# WARNING: the following LICENSE and LIC_FILES_CHKSUM values are best guesses - it is
# your responsibility to verify that the values are complete and correct.
LICENSE = "MIT"
LIC_FILES_CHKSUM = "file://LICENSE;md5=bb5e173bc54080cb25079199959ba6b6"

HOMEPAGE = "https://github.com/Knio/pynmea2"
SUMMARY = "Python library for the NMEA 0183 protcol"

SRC_URI = "https://github.com/Knio/pynmea2/archive/${PV}.tar.gz"
SRC_URI[md5sum] = "a90baf61f4e676bef76099e4bd7c0581"
SRC_URI[sha256sum] = "8f8f68623bd2d5dab7f04a9c31813a3f4aa15467db0373cbce6b9b0ae44ca48e"

#DEPENDS_${PN} = "${PYTHON_PN}-datetime ${PYTHON_PN}-threading ${PYTHON_PN}-io"
DEPENDS_${PN} = "${PYTHON_PN}-modules"
# WARNING: the following rdepends are determined through basic analysis of the
# python sources, and might not be 100% accurate.
RDEPENDS_${PN} = "${PYTHON_PN}-modules"

For pynmea2_1.7.1.bb:

inherit setuptools3 pypi
require pynmea2.inc

Baking the recipes

You could test them with bitbake -k influxdb-python and bitbake -k pynmea2 or with devtool build influxdb-python and devtool build pynmea2

If you have no errors then you can deploy it on target using:

devtool deploy-target influxdb-python user@machineIP:dest_folder

Checks

You can check by firing the python shell

# python3 

 >> import influxdb-python
 >> import pyserial

if the import is throws no missing modules error then it is success!!

Final steps

You can undeploy the modules: devtool undeploy-target recipe_name [address of target]
send the recipes to you custom meta layer devtool finish recipe_name ../meta-custom

NOTE: If you are using krogoth or lower the you will have to move your recipes to you meta layer manually

Now include these recipes in your conf/local.conf with IMAGE_INSTALL_append = " influxdb-python pynmea2" and bitbake -k your-image-name

Custom Application

Not tested yet.

But I think I will simple add my app like mentioned in YoctoCookBook Repository for hello-world with my meta layer.

NUGGETS

${PYTHON_PN}-modules is a saviour really. I tried manually added runtime deps and everytime i deployed it on the board there were always some dependencies missing. But adding the modules solved all the missing deps issue in an instance.
I am not sure when to use DEPENDS_${PN} but I assume most python applications depend on the basic python-modules hence I added them.
NOT A YOCTO EXPERT but this is just my finding in the last 2 weeks. There is a lack of proper examples for Python in Yocto. hope this helps someone.