Dear all,
We have been struggling with our Apache with mod-wsgi for a while now and
we finally managed to break the problem down to a minimum. We try to run a
Dash application that uses datashader, but it kept on crashing. The
following minimal example works fine on our server.
*myDashApp.py*
from flask import Flask
import dash
import dash_core_components as dcc
import dash_html_components as html
server = Flask('app')
app = dash.Dash('app', server=server)
colors = {
'background': '#111111',
'text': '#7FDBFF'
}
app.layout = html.Div(style={'backgroundColor': colors['background']},
children=[
html.H1(
children='Hello Dash',
style={
'textAlign': 'center',
'color': colors['text']
}
),
html.Div(children='Dash: A web application framework for Python.', style
={
'textAlign': 'center',
'color': colors['text']
}),
dcc.Graph(
id='Graph1',
figure={
'data': [
{'x': [1, 2, 3], 'y': [4, 1, 2], 'type': 'bar', 'name': 'SF'
},
{'x': [1, 2, 3], 'y': [2, 4, 5], 'type': 'bar', 'name': u
'Montréal'},
],
'layout': {
'plot_bgcolor': colors['background'],
'paper_bgcolor': colors['background'],
'font': {
'color': colors['text']
}
}
}
)
])
if __name__ == '__main__':
app.run_server()
(I copied that example from somewhere, but unfortunately forgot from where)
*wsgi.py*
sys.path.insert(0, "/data/website/myApp")
from myDashApp import server as application
*/etc/apache2/sites-enabled/default-ssl.conf*
<IfModule mod_ssl.c>
<VirtualHost _default_:443>
ServerName example.com
ServerAdmin [email protected]
# Flask application
WSGIProcessGroup myApp
WSGIApplicationGroup %{GLOBAL}
WSGIScriptAlias / /data/website/myApp/wsgi.py
WSGIDaemonProcess myApp
python-home=/usr/share/miniconda3/envs/my_env_36 \
threads=1 \
processes=4 \
display-name=%{GROUP} \
lang='en_US.UTF-8' \
locale='en_US.UTF-8' \
queue-timeout=45 \
socket-timeout=60 \
connect-timeout=15 \
request-timeout=60 \
inactivity-timeout=0 \
startup-timeout=15 \
deadlock-timeout=60 \
graceful-timeout=15 \
eviction-timeout=0 \
restart-interval=0 \
shutdown-timeout=5 \
maximum-requests=0
<Directory "/data/website/myApp/>
AllowOverride all
AuthType Basic
AuthUserFile /data/passwords/passwords.pwd
AuthName "myDemoApp"
<RequireAll>
Require valid-user
</RequireAll>
</Directory>
ErrorLog ${APACHE_LOG_DIR}/error.log
CustomLog ${APACHE_LOG_DIR}/access.log combined
SSLEngine on
SSLCertificateFile /etc/apache2/cert/host_name.crt.pem
SSLCertificateKeyFile /etc/apache2/cert/host_name.key
SSLProtocol all -SSLv2 -SSLv3 -TLSv1 -TLSv1.1
SSLHonorCipherOrder on
SSLCipherSuite
ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES256-GCM-SHA384:ECDHE-ECDSA-AES256-GCM-SHA384:DHE-RSA-AES128-GCM-SHA256:DHE-DSS-AES128-GCM-SHA256:kEDH+AESGCM:ECDHE-RSA-AES128-SHA256:ECDHE-ECDSA-AES128-SHA256:ECDHE-RSA-AES128-SHA:ECDHE-ECDSA-AES128-SHA:ECDHE-RSA-AES256-SHA384:ECDHE-ECDSA-AES256-SHA384:ECDHE-RSA-AES256-SHA:ECDHE-ECDSA-AES256-SHA:DHE-RSA-AES128-SHA256:DHE-RSA-AES128-SHA:DHE-DSS-AES128-SHA256:DHE-RSA-AES256-SHA256:DHE-DSS-AES256-SHA:DHE-RSA-AES256-SHA:AES128-GCM-SHA256:AES256-GCM-SHA384:AES128-SHA256:AES256-SHA256:AES128-SHA:AES256-SHA:AES:CAMELLIA:DES-CBC3-SHA:!aNULL:!eNULL:!EXPORT:!DES:!RC4:!MD5:!PSK:!aECDH:!EDH-DSS-DES-CBC3-SHA:!EDH-RSA-DES-CBC3-SHA:!KRB5-DES-CBC3-SHA
Header always set Strict-Transport-Security
"max-age=15552000; includeSubDomains"
<FilesMatch "\.(cgi|shtml|phtml|php)$">
SSLOptions +StdEnvVars
</FilesMatch>
<Directory /usr/lib/cgi-bin>
SSLOptions +StdEnvVars
</Directory>
</VirtualHost>
</IfModule>
Now, we can add the following lines to our myDashApp.py:
import ssl
foo = ssl.SSLContext()
Once we do that, we get the following error in the apache error log:
[Tue Mar 31 06:25:02.092936 2020] [core:notice] [pid 28668] AH00094: Command
line: '/usr/sbin/apache2'
[Tue Mar 31 09:31:37.336007 2020] [wsgi:error] [pid 30411] [remote 172.27.
1.200:55576] mod_wsgi (pid=30411): Failed to exec Python script file
'/data/website/myApp/wsgi.py'.
[Tue Mar 31 09:31:37.336081 2020] [wsgi:error] [pid 30411] [remote 172.27.
1.200:55576] mod_wsgi (pid=30411): Exception occurred processing WSGI
script '/data/website/myApp/wsgi.py'.
[Tue Mar 31 09:31:37.337969 2020] [wsgi:error] [pid 30411] [remote 172.27.
1.200:55576] Traceback (most recent call last):
[Tue Mar 31 09:31:37.338011 2020] [wsgi:error] [pid 30411] [remote 172.27.
1.200:55576] File "/data/website/myApp/wsgi.py", line 5, in <module>
[Tue Mar 31 09:31:37.338016 2020] [wsgi:error] [pid 30411] [remote 172.27.
1.200:55576] from myDashApp import server as application
[Tue Mar 31 09:31:37.338024 2020] [wsgi:error] [pid 30411] [remote 172.27.
1.200:55576] File "/data/website/myApp/myDashApp.py", line 7, in <module>
[Tue Mar 31 09:31:37.338028 2020] [wsgi:error] [pid 30411] [remote 172.27.
1.200:55576] bla = ssl.SSLContext()
[Tue Mar 31 09:31:37.338034 2020] [wsgi:error] [pid 30411] [remote 172.27.
1.200:55576] File
"/usr/share/miniconda3/envs/my_env_36/lib/python3.6/ssl.py", line 391, in
__new__
[Tue Mar 31 09:31:37.338038 2020] [wsgi:error] [pid 30411] [remote 172.27.
1.200:55576] self = _SSLContext.__new__(cls, protocol)
[Tue Mar 31 09:31:37.338059 2020] [wsgi:error] [pid 30411] [remote 172.27.
1.200:55576] ssl.SSLError: ('No cipher can be selected.',)
[Tue Mar 31 09:31:38.189212 2020] [wsgi:error] [pid 30409] [remote 172.27.
1.200:55575] mod_wsgi (pid=30409): Failed to exec Python script file
'/data/website/myApp/wsgi.py'.
[Tue Mar 31 09:31:38.189269 2020] [wsgi:error] [pid 30409] [remote 172.27.
1.200:55575] mod_wsgi (pid=30409): Exception occurred processing WSGI
script '/data/website/myApp/wsgi.py'.
[Tue Mar 31 09:31:38.189782 2020] [wsgi:error] [pid 30409] [remote 172.27.
1.200:55575] Traceback (most recent call last):
[Tue Mar 31 09:31:38.189810 2020] [wsgi:error] [pid 30409] [remote 172.27.
1.200:55575] File "/data/website/myApp/wsgi.py", line 5, in <module>
[Tue Mar 31 09:31:38.189813 2020] [wsgi:error] [pid 30409] [remote 172.27.
1.200:55575] from myDashApp import server as application
[Tue Mar 31 09:31:38.189818 2020] [wsgi:error] [pid 30409] [remote 172.27.
1.200:55575] File "/data/website/myApp/myDashApp.py", line 7, in <module>
[Tue Mar 31 09:31:38.189821 2020] [wsgi:error] [pid 30409] [remote 172.27.
1.200:55575] bla = ssl.SSLContext()
[Tue Mar 31 09:31:38.189825 2020] [wsgi:error] [pid 30409] [remote 172.27.
1.200:55575] File
"/usr/share/miniconda3/envs/my_env_36/lib/python3.6/ssl.py", line 391, in
__new__
[Tue Mar 31 09:31:38.189828 2020] [wsgi:error] [pid 30409] [remote 172.27.
1.200:55575] self = _SSLContext.__new__(cls, protocol)
[Tue Mar 31 09:31:38.189842 2020] [wsgi:error] [pid 30409] [remote 172.27.
1.200:55575] ssl.SSLError: ('No cipher can be selected.',)
Did anybody encounter a similar problem or does anybody have an idea on how
to fix that?
Just for a bit of context, we don't want to use SSL in our application, but
somehow datashader uses it for something and our goal is to get datashader to
work.
Thanks,
Raphael
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