Microblog

Description

App allows to create text posts for logged in users, to follow & unfollow other users, to translate posts written in different languages, supports localization for 🇷🇺, 🇬🇧 & 🇫🇮.

Technology Stack

• Python
• Flask
• SQL Alchemy
• Bootstrap
• Babel
• Azure Translator
• MomentJS
• Elasticsearch
• Heroku
• Docker
• Redis

Deployment

Clone the repo and change directory to the cloned repo:

git clone https://github.com/hardkoro/flask_microblog.git

cd flask_microblog

Create and activate virtual environment:

python3 -m venv venv

. venv/bin/activate

Install requirements from file requirements.txt:

pip3 install -r requirements.txt

Provide flask environmen data via .flaskenv:

touch .flaskenv
cat >> .flaskenv

FLASK_APP=microblog.py  # name of the flask app
FLASK_ENV=production    # stage (e.g. 'production', 'development')

Provide sensitive data via .env file:

touch .env
cat >> .env

SECRET_KEY=paste_your_secret_key      # app's secret key
DATABASE_URL=paste_your_database_url  # database URL

MAIL_SERVER=paste_your_mail_server_host   # mail server host
MAIL_PORT=paste_your_mail_server_port     # mail server port
MAIL_USERNAME=paste_your_mail_username    # mail username
MAIL_PASSWORD=paste_your_mail_password    # mail password
MAIL_USE_TLS=paste_1_if_your_mail_server_uses_tls   # enable TLS

MS_TRANSLATOR_KEY=paste_your_key                  # Microsoft Azure Translator key
MS_TRANSLATOR_REGION_NAME=paste_your_region_name  # Microsoft Azure Translator region name

ELASTICSEARCH_URL=paste_your_elasticsearch_url    # Elasticsearch URL
REDIS_URL=paste_your_redis_url                    # Redis URL

LOG_TO_STDOUT=1   # specifies logging to stdout (e.g. for Heroku)

To emulate a mail server one might use another terminal window with the following command:

python -m smtpd -n -c DebuggingServer localhost:8025

Run app:

flask run

Information

Application based on Miguel Grinberg's tutorial on Flask web application

Translations

To provide more simpler way to add new translations one can use such commands:

• to add a new language:

  flask translate init LANG 

• to update all language repositories:

  flask translate update  

• to compile all language repositories:

  flask translate compile 

Translations are kept at: /app/translations folder.

Microsoft Translator API

To setup Microsoft Azure Translator, login to your Azure account, go to the Azure Portal & clcick on the "Create a resource" button. Find "Translator", select it & clieck the "Create" button.

Fill the form as follows:

Subscription: Pay-As-You-Go
Resource group: (New) your-microblog-resource-group-name
Resource group region: your-resource-group-region
Resource region: your-resource_region
Name: your-resource-name
Pricing tier: Free F0 (Up to 2M characters translated)

Click the "Review + create" button & then "Create", the translator API resource will be added to your account.

To obtain the key click the "Go to resource" button & then find the "Keys and Endpoint" option on the left sidebar. Copy one of the keys & the name of the region to your .env file as MS_TRANSLATOR_KEY and MS_TRANSLATOR_REGION_NAME respectively.

Elasticsearch

Setup the latest Elasticsearch version following the steps as described at Elasticsearch site: https://www.elastic.co/guide/en/elasticsearch/reference/current/install-elasticsearch.html

Add Elasticsearch URL to your .env file as ELASTICSEARCH_URL. Search engine may be switched to another technology by updating app/search.py module. The model may be included in search engine by providing inheritance from SearchableMixin mixin.

If the search is being added to the service with some existing posts, then posts should have to be indexed as follows:

flask shell

from app.search import add_to_index
from post in Post.query.all():
	add_to_index('post', post)

Heroku Deployment

Login to Heroku via Heroku CLI:

heroku login

Create an application:

heroku apps:create hk-flask-microblog

Add Heroku Postgres database:

heroku addons:add heroku-postgresql:hobby-dev

As Heroku requires logs to be outputted to stdout set an environment variable LOG_TO_STDOUT:

heroku config:set LOG_TO_STDOUT=`

Add Elasticsearch hosting via SearchBox add-on & Heroku Redis add-on:

heroku addons:create searchbox:starter
heroku addons:create heroku-redis:hobby-dev

Get SEARCHBOX_URL environment variable from Elasticsearch service & set the correspondent ELASTICSEARCH_URL variable*:

heroku config:get SEARCHBOX_URL
heroku config:set ELASTICSEARCH_URL=<your-elastic-search-url>

*don't forget to add port to the URL as the setup requires scheme, host & port (443 by default for SSH)

REDIS_URL is going to be added to your Heroku environment automatically.

Open SearchBox Elasticsearch resource panel and manually create an index for Post model via Dashboard > Indices > New index.

Set remaining .env & .flaskenv variables as follows:

heroku config:set ENV_VAR_NAME=env_var_value

Start the deployment:

git push heroku master

The corresponding Procfile should contain one web dyno & one worker:

web: flask db upgrade; flask translate compile; gunicorn microblog:app
worker: rq worker -u $REDIS_URL microblog-tasks

After deploying, one can start the worker with the following command:

heroku ps:scale worker=1

Docker Deployment

Install Docker & Docker-compose:

sudo apt-get remove docker docker-engine docker.io containerd runc
sudo apt-get update
sudo apt-get install \
  ca-certificates \
  curl \
  gnupg \
  lsb-release
curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo gpg --dearmor -o /usr/share/keyrings/docker-archive-keyring.gpg
echo \
  "deb [arch=$(dpkg --print-architecture) signed-by=/usr/share/keyrings/docker-archive-keyring.gpg] https://download.docker.com/linux/ubuntu \
  $(lsb_release -cs) stable" | sudo tee /etc/apt/sources.list.d/docker.list > /dev/null
sudo apt-get update
sudo apt-get install docker-ce docker-ce-cli containerd.io
sudo groupadd docker
sudo usermod -aG docker $USER
newgrp docker

sudo curl -L "https://github.com/docker/compose/releases/download/1.29.2/docker-compose-$(uname -s)-$(uname -m)" -o /usr/local/bin/docker-compose
sudo chmod +x /usr/local/bin/docker-compose

Create .env file & fill it with environment variables as follows (assuming PostgreSQL usage):

touch .env
cat >> .env

SECRET_KEY=paste_your_secret_key      # app's secret key
DATABASE_URL=postgresql://postgres_user:postgres_pwd@db/postgres_db   # Postgres DB URL (container db)
POSTGRES_USER=postgres_user     # Postgres user
POSTGRES_PASSWORD=postgres_pws  # Postgres password
POSTGRES_DB=postgres_db         # Postgres database name

MAIL_SERVER=paste_your_mail_server_host   # mail server host
MAIL_PORT=paste_your_mail_server_port     # mail server port
MAIL_USERNAME=paste_your_mail_username    # mail username
MAIL_PASSWORD=paste_your_mail_password    # mail password
MAIL_USE_TLS=paste_1_if_your_mail_server_uses_tls   # enable TLS

MS_TRANSLATOR_KEY=paste_your_key                  # Microsoft Azure Translator key
MS_TRANSLATOR_REGION_NAME=paste_your_region_name  # Microsoft Azure Translator region name

ELASTICSEARCH_URL=http://es:9200    # Elasticsearch URL (container es)
REDIS_URL=redis::/redis:6379        # Redis URL (container redis)

Run containers:

docker-compose up -d

The service will be running at http://localhost:8000/

Configuring Redis

Install Redis:

sudo apt update
sudo apt install redis-server

Change supervised directive to systemd to install Redis as a service in Ubuntu:

sudo nano /etc/redis/redis.conf

Restart service:

sudo systemctl restart redis.service

Test service:

sudo systemctl status redis

The output should contain words like active / running / enabled.