Full example of nginx+flask+postgres multi-container setup

.gitignore

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+__pycache__

Dockerfile

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+FROM python:3
+MAINTAINER Ameya Lokare <[email protected]>
+
+ENV PYTHONUNBUFFERED 1
+RUN mkdir -p /opt/services/flaskapp/src
+#VOLUME ["/opt/services/flaskapp/src"]
+# We copy the requirements.txt file first to avoid cache invalidations
+COPY requirements.txt /opt/services/flaskapp/src/
+WORKDIR /opt/services/flaskapp/src
+RUN pip install -r requirements.txt
+COPY . /opt/services/flaskapp/src
+EXPOSE 5090
+CMD ["python", "app.py"]

app.py

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+import datetime
+import os
+
+from flask import Flask, render_template, redirect, url_for
+from forms import SignupForm
+
+from models import Signups
+from database import db_session
+
+app = Flask(__name__)
+app.secret_key = os.environ['APP_SECRET_KEY']
+
+@app.route("/", methods=('GET', 'POST'))
+def signup():
+    form = SignupForm()
+    if form.validate_on_submit():
+        signup = Signups(name=form.name.data, email=form.email.data, date_signed_up=datetime.datetime.now())
+        db_session.add(signup)
+        db_session.commit()
+        return redirect(url_for('success'))
+    return render_template('signup.html', form=form)
+
+@app.route("/success")
+def success():
+    return "Thank you for signing up!"
+
+if __name__ == '__main__':
+    app.run(host='0.0.0.0', port=5090, debug=True)

conf.d/flaskapp.conf

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+server {
+    listen 80;
+    server_name localhost;
+
+    location / {
+        proxy_set_header   Host                 $host;
+        proxy_set_header   X-Real-IP            $remote_addr;
+        proxy_set_header   X-Forwarded-For      $proxy_add_x_forwarded_for;
+        proxy_set_header   X-Forwarded-Proto    $scheme;
+        proxy_set_header Host $http_host;
+
+        proxy_pass http://flaskapp:5090;
+    }
+}

database.py

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+import os
+from sqlalchemy import create_engine
+from sqlalchemy.orm import scoped_session, sessionmaker
+from sqlalchemy.ext.declarative import declarative_base
+
+user = os.environ['POSTGRES_USER']
+pwd = os.environ['POSTGRES_PASSWORD']
+db = os.environ['POSTGRES_DB']
+host = 'db'
+port = '5432'
+engine = create_engine('postgres://%s:%s@%s:%s/%s' % (user, pwd, host, port, db)) 
+
+db_session = scoped_session(sessionmaker(autocommit=False,
+                                         autoflush=False,
+                                         bind=engine))
+Base = declarative_base()
+Base.query = db_session.query_property()
+
+def init_db():
+    # import all modules here that might define models so that
+    # they will be registered properly on the metadata.  Otherwise
+    # you will have to import them first before calling init_db()
+    import models
+    Base.metadata.create_all(bind=engine)

docker-compose.yml

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+version: '3'
+services:
+  db:
+    image: "postgres:9.6.5"
+    volumes:
+      - "dbdata:/var/lib/postgresql/data"
+    env_file:
+      - env_file
+    networks:
+      - db_nw
+  flaskapp:
+    build: .
+    env_file:
+      - env_file
+    volumes:
+      - .:/opt/services/flaskapp/src
+    networks:
+      - db_nw
+      - web_nw
+    depends_on:
+      - db
+  nginx:
+    image: "nginx:1.13.5"
+    ports:
+      - "8080:80"
+    volumes:
+      - ./conf.d:/etc/nginx/conf.d
+    networks:
+      - web_nw
+    depends_on: 
+      - flaskapp
+networks:
+  db_nw:
+    driver: bridge
+  web_nw:
+    driver: bridge
+volumes:
+  dbdata:

env_file

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+POSTGRES_USER=postgres
+POSTGRES_PASSWORD=USE_YOUR_PASSWORD
+POSTGRES_DB=flaskapp_db
+APP_SECRET_KEY=USE_YOUR_SECRET_KEY

forms.py

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+from flask_wtf import FlaskForm
+from wtforms import StringField
+from wtforms.validators import DataRequired
+
+class SignupForm(FlaskForm):
+    name = StringField('name', validators=[DataRequired()])
+    email = StringField('email', validators=[DataRequired()])
+

models.py

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+from database import Base
+from sqlalchemy import Column, Integer, String
+from sqlalchemy.types import DateTime
+
+class Signups(Base):
+    """
+    Example Signups table
+    """
+    __tablename__ = 'signups'
+    id = Column(Integer, primary_key=True)
+    name = Column(String(256))
+    email = Column(String(256), unique=True)
+    date_signed_up = Column(DateTime())

requirements.txt

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+Flask
+psycopg2
+SQLAlchemy
+Flask-WTF

templates/signup.html

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+<!DOCTYPE html>
+<html lang="en">
+    <body>
+        <h1> Hello, please sign up! </h1>
+        <form method="POST" action="/">
+            {{ form.csrf_token }}
+            {{ form.name.label }} {{ form.name(size=20) }}
+            {{ form.email.label }} {{ form.email(size=20) }}
+            <input type="submit" value="Go">
+        </form>
+    </body>
+</html>