Chad Dotson

A small town Computer Scientist / Software Engineer. Chad enjoys writing Python and JavaScript as well as tinkering with his Raspberry Pi and Arduino. When not programming, he enjoys Photography (especially lightning) and Sci-Fi.

Aug

2017

Solar Eclipse 2017 From Sparta, TN

The August 21, 2017 Solar Eclipse as photographed from Sparta, TN (35.9727° N, 85.5638° W). This was about 3.2 miles from the center of Totality! These images do not convey the magnitude of the experience. Knowing what to expect in general does not prepare you. If I tried to find a single word to describe it, I would pick astonishing.

: Chad Dotson – 2017 Solar Eclipse – Sparta, Tennessee (35.9727° N, 85.5638° W) – 2m38.8s of Totality

: Chad Dotson – 2017 Solar Eclipse – Sparta, Tennessee (35.9727° N, 85.5638° W) – 2m38.8s of Totality

Location	Sparta, TN (35.9725° N, 85.5638° W)
Duration of Totality	2m38.8s
Magnitude	1.014
Obscuration	100.00%

Event	Date Time (UT)	Alt	Azi
Start of partial eclipse (C1)	2017/08/21 17:01:17	63.9°	154.8°
Start of total eclipse (C2)	2017/08/21 18:29:50.1	63.9°	205.4°
Maximum eclipse	2017/08/21 18:31:09.6	63.8°	206.1°
End of total eclipse (C3)	2017/08/21 18:32:28.9	63.6°	206.8°
End of partial eclipse (C4)	2017/08/21 19:56:17.0	51.9°	239.1°

Jul

2017

Thoughts On Team Communication

Awhile back I had some thoughts on communication. If you’ve ever played World of Tanks Blitz you’d know that basically its a team of tanks against another team of tanks. With the pick up, fast paced nature communication is minimal at best (sometimes limited to a single “<<<<<<<<<” or “>>>>>>>>>” indicating which direction to take the offense). I found that teams that could coordinate with minimal communication, play their tank roles (scouts, mediums, heavies, and destroyers), and move fast could achieve massive overwhelming victories. Something similar is probably true in an agile/teamwork environment. Know your stuff, know your role, take opportunities, work together, succeed.

Jun

2017

iPhone 5 / Verizon 4G – No Bars / 3g No Service Fix

Problem:

You’ve got a iPhone 5 that reports that it has 4g LTE service but 0 bars and, if you turn off LTE, it reports No Service under 3g.

Solution:

The fix, turn off all roaming . Settings > Cellular > Cellular Data Options > Roaming – Turn off all settings here.

Jan

2017

SSLError with Python 3.6.x on macOS Sierra

SSLError

Have you ran into trouble with SSLErrors after upgrading to Python 3.6 on macOS Sierra? For me, my first encounter was downloading the bokeh sample data (included here).

Python 3.6.0 (v3.6.0:41df79263a11, Dec 22 2016, 17:23:13) 
[GCC 4.2.1 (Apple Inc. build 5666) (dot 3)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import bokeh.sampledata
>>> bokeh.sampledata.download()
Using data directory: /Users/chad/.bokeh/data
Traceback (most recent call last):
  File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/urllib/request.py", line 1318, in do_open
    encode_chunked=req.has_header('Transfer-encoding'))
  File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/http/client.py", line 1239, in request
    self._send_request(method, url, body, headers, encode_chunked)
  File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/http/client.py", line 1285, in _send_request
    self.endheaders(body, encode_chunked=encode_chunked)
  File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/http/client.py", line 1234, in endheaders
    self._send_output(message_body, encode_chunked=encode_chunked)
  File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/http/client.py", line 1026, in _send_output
    self.send(msg)
  File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/http/client.py", line 964, in send
    self.connect()
  File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/http/client.py", line 1400, in connect
    server_hostname=server_hostname)
  File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/ssl.py", line 401, in wrap_socket
    _context=self, _session=session)
  File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/ssl.py", line 808, in __init__
    self.do_handshake()
  File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/ssl.py", line 1061, in do_handshake
    self._sslobj.do_handshake()
  File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/ssl.py", line 683, in do_handshake
    self._sslobj.do_handshake()
ssl.SSLError: [SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed (_ssl.c:749)

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/Users/chad/Library/Python/3.6/lib/python/site-packages/bokeh/sampledata/__init__.py", line 81, in download
    _getfile(base_url, file_name, data_dir, progress=progress)
  File "/Users/chad/Library/Python/3.6/lib/python/site-packages/bokeh/sampledata/__init__.py", line 87, in _getfile
    url = urlopen(file_url)
  File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/urllib/request.py", line 223, in urlopen
    return opener.open(url, data, timeout)
  File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/urllib/request.py", line 526, in open
    response = self._open(req, data)
  File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/urllib/request.py", line 544, in _open
    '_open', req)
  File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/urllib/request.py", line 504, in _call_chain
    result = func(*args)
  File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/urllib/request.py", line 1361, in https_open
    context=self._context, check_hostname=self._check_hostname)
  File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/urllib/request.py", line 1320, in do_open
    raise URLError(err)
urllib.error.URLError: <urlopen error [SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed (_ssl.c:749)>

Python 3.6.0 (v3.6.0:41df79263a11, Dec 22 2016, 17:23:13)

[GCC 4.2.1 (Apple Inc. build 5666) (dot 3)] on darwin

Type "help", "copyright", "credits" or "license" for more information.

>>> import bokeh.sampledata

>>> bokeh.sampledata.download()

Using data directory: /Users/chad/.bokeh/data

Traceback (most recent call last):

File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/urllib/request.py", line 1318, in do_open

encode_chunked=req.has_header('Transfer-encoding'))

File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/http/client.py", line 1239, in request

self._send_request(method, url, body, headers, encode_chunked)

File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/http/client.py", line 1285, in _send_request

self.endheaders(body, encode_chunked=encode_chunked)

File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/http/client.py", line 1234, in endheaders

self._send_output(message_body, encode_chunked=encode_chunked)

File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/http/client.py", line 1026, in _send_output

self.send(msg)

File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/http/client.py", line 964, in send

self.connect()

File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/http/client.py", line 1400, in connect

server_hostname=server_hostname)

File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/ssl.py", line 401, in wrap_socket

_context=self, _session=session)

File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/ssl.py", line 808, in __init__

self.do_handshake()

File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/ssl.py", line 1061, in do_handshake

self._sslobj.do_handshake()

File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/ssl.py", line 683, in do_handshake

self._sslobj.do_handshake()

ssl.SSLError: [SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed (_ssl.c:749)

During handling of the above exception, another exception occurred:

Traceback (most recent call last):

File "<stdin>", line 1, in <module>

File "/Users/chad/Library/Python/3.6/lib/python/site-packages/bokeh/sampledata/__init__.py", line 81, in download

_getfile(base_url, file_name, data_dir, progress=progress)

File "/Users/chad/Library/Python/3.6/lib/python/site-packages/bokeh/sampledata/__init__.py", line 87, in _getfile

url = urlopen(file_url)

File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/urllib/request.py", line 223, in urlopen

return opener.open(url, data, timeout)

File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/urllib/request.py", line 526, in open

response = self._open(req, data)

File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/urllib/request.py", line 544, in _open

'_open', req)

File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/urllib/request.py", line 504, in _call_chain

result = func(*args)

File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/urllib/request.py", line 1361, in https_open

context=self._context, check_hostname=self._check_hostname)

File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/urllib/request.py", line 1320, in do_open

raise URLError(err)

urllib.error.URLError: <urlopen error [SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed (_ssl.c:749)>

I finally got a chance to research exactly what was wrong. Given that Python 3.5 was working on my machine and 3.6 was working on several linux machines, I thought that it could have been an issue with Python 3.6, unlikely as it may be. After no bug fix version was released I realized that it must be my configuration.

Searching, I found one result related to this in the Python issue tracker: Issue 28150. One answerer points out that Python on macOS no longer relies on Apple’s version of OpenSSL, instead it is shipped with a new one. The gotcha: this new one does not have trust certificates installed. All this is detailed in the Readme.

The Installer Readme

So, as the Python issue tracker mentioned, there is an entry in the installer readme. Perhaps I should read these closer…

Certificate verification and OpenSSL

**NEW** This variant of Python 3.6 now includes its own private copy of OpenSSL 1.0.2. Unlike previous releases, the deprecated Apple-supplied OpenSSL libraries are no longer used. This also means that the trust certificates in system and user keychains managed by the Keychain Access application and the security command line utility are no longer used as defaults by the Python ssl module. For 3.6.0, a sample command script is included in /Applications/Python 3.6 to install a curated bundle of default root certificates from the third-party certifi package (https://pypi.python.org/pypi/certifi). If you choose to use certifi, you should consider subscribing to the project’s email update service to be notified when the certificate bundle is updated.

The bundled pip included with the Python 3.6 installer has its own default certificate store for verifying download connections.

Two Solutions

There are two solutions as mentioned:

Install the certifi package.
Run the download script provided with the installer – /Applications/Python 3.6/Install Certificates.command.

For myself, I ran the bundled script and everything seems to be functioning fine. It seems more than a little odd that this was not done on installation.

Jan

2017

Pip Installs From Github

Pip installs From github

Installing a package from github is fairly simple. The following are examples of installing packages from github.

# Install repo package from the url, master branch
pip3 install git+https://github.com/username/repo.git

@ Install repo from the specified branch
pip3 install git+https://github.com/username/repo.git@branch

# Install repo from the specified commit.
pip3 install git+https://github.com/username/repo.git@commit

# Install repo package from the url, master branch

pip3 install git+https://github.com/username/repo.git

@ Install repo from the specified branch

pip3 install git+https://github.com/username/repo.git@branch

# Install repo from the specified commit.

pip3 install git+https://github.com/username/repo.git@commit

requirements.txt

At some point, you will find yourself wanting to list a dependency in the requirements.txt file that resides on github. This is fairly straight forward If you only plan to use it in requirements.txt (not processed for usage in setup.py). Note that I’ve specified the master branch of repo and given it a version id.

https://github.com/username/repo/tarball/master#egg=repo-0.1.1

1	https://github.com/username/repo/tarball/master#egg=repo-0.1.1

setup.py and requirements.txt

Some people will process their requirements.txt files to generate the install_requires parameter for the setup function called in setup.py. This works fine until you have a repository on github. Setup will fail to find your dependencies if your requirements.txt has a line like the one above. To remedy this we must do two things.

Parse the line to create a named python dependency for install requires. Given the file above, install_requires would equal ["repo==0.0.1"] .
Specify the dependency_links argument to setup. ["https://github.com/chaddotson/repo/tarball/master#egg=repo-0.1.1"] for this example.

An Example

This is an example of a setup.py that properly processes requirements.txt dependencies that are located on github. It’s probably not complete, but it works for what I need. Feel free to take and adapt. See the repo here (python3).

from setuptools import setup

version = '0.1.0'

temp_install_reqs = []
install_reqs = []
dependency_links = []

with open("requirements.txt", "r") as f:
    temp_install_reqs = list(map(str.strip, f.readlines()))

for req in temp_install_reqs:
    # This if should be expanded with all the other possibilities that can exist.  However, this
    # simple version works for this program.
    if req.startswith("https://"):
        dependency_links.append(req)
        install_reqs.append(req[req.find("egg=") + 4:].replace("-", "==", 1))
    else:
        install_reqs.append(req)

setup(
    name='tweeter-repeater',
    version=version,
    packages=['bin'],
    url='',
    license='',
    author='Chad Dotson',
    author_email='chad@cdotson.com',
    description='',
    install_requires=install_reqs,
    dependency_links=dependency_links,
    entry_points={
        'console_scripts': [
            'tweeter-repeater = bin.main:main',
        ]
    },
)

from setuptools import setup

version = '0.1.0'

temp_install_reqs = []

install_reqs = []

dependency_links = []

with open("requirements.txt", "r") as f:

temp_install_reqs = list(map(str.strip, f.readlines()))

for req in temp_install_reqs:

# This if should be expanded with all the other possibilities that can exist. However, this

# simple version works for this program.

if req.startswith("https://"):

dependency_links.append(req)

install_reqs.append(req[req.find("egg=") + 4:].replace("-", "==", 1))

else:

install_reqs.append(req)

setup(

name='tweeter-repeater',

version=version,

packages=['bin'],

url='',

license='',

author='Chad Dotson',

author_email='chad@cdotson.com',

description='',

install_requires=install_reqs,

dependency_links=dependency_links,

entry_points={

'console_scripts': [

'tweeter-repeater = bin.main:main',

]

)

Jan

2017

Jack Daniels 2016 Barrel Tree in Lynchburg, TN

Jul

2016

July 8, 2016 Lightning

These are the first lightning photos in several months. It was a good electrical storm but the lightning wasn’t so photogenic.

Jun

2016

Raspberry Pi 3 Mini Cluster

I recently constructed a mini cluster consisting of 3 Raspberry Pi 3s. I am planning on using these machines for various little projects. I’ve installed some services on one of the nodes. Currently that node hosts Redis and RabbitMQ instances. I’m sure that I’ll have other services to install in the near future. I may even use it to tinker with clustering those services. Below are some pictures of the cluster as I was putting it together and a parts list.

: Initial node. RabbitMQ, Redis, etc

: First 2 nodes

: 2 nodes assembled

: All 3 nodes assembled

: Cluster wired up ready to go

: Final build. Wired lan removed until needed

Materials:

3x Raspberry Pi 3s – https://www.amazon.com/gp/product/B01CD5VC92/
3x 32GB Class 10 MicroSDs – https://www.amazon.com/gp/product/B00IVPU786/
3x Micro-USB to USB – https://www.amazon.com/gp/product/B00NH13O7K/
60W 6 port USB Charger- https://www.amazon.com/gp/product/B0115MVRO4/
GeauxRobot Enclosure – https://www.amazon.com/gp/product/B01D90TX1O/