Tag: flask

Python migration with Alembic

$ pip install alembic
$ alembic init --template generic alembic

edit alembic.ini

sqlalchemy.url = mysql://root:@localhost/database_name
$ alembic current
$ alembic revision -m "Init"
$ alembic upgrade head
INFO [alembic.migration] Context impl MySQLImpl. INFO [alembic.migration] Will assume non-transactional DDL. INFO [alembic.migration] Running upgrade None -> 174f01a0ar12, Init

Setup python app in centos from scratch (centos 6.9+uwsgi+nginx+flask+mysql)

Initial setup

$ sudo yum update
$ sudo yum install epel-release
$ sudo yum groupinstall "Development tools"
$ sudo yum install zlib-devel bzip2-devel openssl-devel ncurses-devel sqlite-devel telnet htop
$ sudo yum install python-devel python-virtualenv
$ sudo yum install mysql-connector-python mysql-devel mysql-server

Install Python

Download and install Python : https://www.python.org/

./configure && make && make altinstall

Install uWSGI

$ wget https://bootstrap.pypa.io/get-pip.py
$ which python2.7
$ sudo /usr/local/bin/python2.7 get-pip.py
$ which pip2.7
$ sudo /usr/local/bin/pip2.7 install uWSGI
$ which uwsgi
$ uwsgi --version

Setup vassels

$ sudo mkdir -p /etc/uwsgi/vassels

Setup Emperor service

$ sudo vim /etc/init.d/emperor
#!/bin/sh
# chkconfig: 2345 99 10
# Description: Starts and stops the emperor-uwsgi
# See how we were called.
RUNEMPEROR="/usr/local/bin/uwsgi --emperor=/etc/uwsgi/vassels"
PIDFILE=/var/run/emperor-uwsgi.pid
LOGFILE=/var/log/uwsgi/emperor.log
start() {
if [ -f /var/run/$PIDNAME ] && kill -0 $(cat /var/run/$PIDNAME); then
echo 'Service emperor-uwsgi already running' >&2
return 1
fi
echo 'Starting Emperor...' >&2
local CMD="$RUNEMPEROR &> \"$LOGFILE\" & echo \$!"
su -c "$CMD" > "$PIDFILE"
echo 'Service started' >&2
}
stop() {
if [ ! -f "$PIDFILE" ] || ! kill -0 $(cat "$PIDFILE"); then
echo 'Service emperor-uwsgi not running' >&2
return 1
fi
echo 'Stopping emperor-uwsgi' >&2
kill -7 $(cat "$PIDFILE") && rm -f "$PIDFILE"
echo 'Service stopped' >&2
}
status() {
if [ ! -f "$PIDFILE" ]; then
echo "Emperor is not running." >&2
return 1
else
echo "Emperor (pid  `cat ${PIDFILE}`) is running..."
ps -ef |grep `cat $PIDFILE`| grep -v grep
fi
}
case "$1" in
start)
start
;;
stop)
stop
;;
status)
status
;;
restart)
stop
start
;;
*)
echo "Usage: emperor {start|stop|restart}"
exit 1
esac

 Setup app user & environment

$ useradd foobar
$ usermod -md /srv/foobar foobar
$ chmod 755 /srv/foobar
$ sudo su - foobar
foobar@local~$ virtualenv --python=python2.7 ~/venv
foobar@local~$ mkdir www
foobar@local~$ mkdir logs
foobar@local~$ touch logs/uwsgi.log
foobar@local~$ touch uwsgi.ini
foobar@local~$ echo "source ~/venv/bin/activate" >> ~/.bashrc
foobar@local~$ source ~/venv/bin/activate
(venv)foobar@local~$ vim uwsgi.ini

[uwsgi]
master = true
processes = 2
socket = /tmp/foobar.sock
chdir = /srv/foobar/www
virtualenv = /srv/foobar/venv
module = app:app
uid = foobar
chown-socket = foobar:nginx
chmod-socket = 660
vacuum = true
die-on-term = true
python-autoreload = 3
py-autoreload = 1
logger = file:/srv/foobar/logs/uwsgi.log

Exit from foobar user & create uwsgi symlink

(venv)foobar@local~$ exit
$ sudo ln -s /srv/foobar/uwsgi.ini /etc/uwsgi/vassels/foobar.ini

Start emperor service & setup set the startup

$ sudo service emperor start
$ sudo chkconfig emperor on