Python/Django + Postgres database example (#86)

* Remove --pi hack in favour of pi@HOST.

* Properly deploy systemd startup in bootstrap.

Fixes #71.

* piku-bootstrap using separate ansible playbooks.

* Prefer built-in playbooks in piku-bootstrap.

* Document new piku-bootstrap options.

* Doc piku-bootstrap built-in playbooks usage.

* Move 'using' doc to top.

* Typos + doc fixes in piku-bootstrap.

* Improved built-in playbook detection.

* Added node playbook.

* Documentation tweaks.

* Documentation tweaks.

* Built-in playbook for installing postgres.

* Example Python/Django + Postgres app.

examples/python-postgres/.gitignore

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+db.sqlite3
+__pycache__
+virtualenv

examples/python-postgres/.python-version

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+3.6.6

examples/python-postgres/ENV

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+NGINX_STATIC_PATHS=/static:static

examples/python-postgres/Procfile

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+release: ./bin/provision-database
+wsgi: pikudjango.wsgi:application

examples/python-postgres/README.md

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+# Postgres backed Python + Django app
+
+This is a simple Piku app to demonstrate deploying a Postgres backed Django app.
+
+During the `release` worker phase this app creates a Postgres database, as well as running the Django `collectstatic` and `migrate` tasks. The `release` worker will use the domain name (`NGINX_SERVER_NAME`) for the database name and the Django app assumes this in [settings.py](pikudjango/settings.py), so make sure you set the config variable to specify a domain name. See below for instructions.
+
+In order for this to work you will first need to install `postgresql` on your Piku server. You can do this with the bootstrap script:
+
+```shell
+piku-bootstrap root@myserver.net postgres.yml
+```
+
+To publish this app to `piku`, make a copy of this folder and run the following commands inside the copy:
+
+```bash
+git init .
+git remote add piku piku@your_server:pypostgres
+git add .
+git commit -a -m "initial commit"
+git push piku master
+```
+
+Then you can connect a domain, set up an SSL cert, and create a database, by setting the `NGINX_SERVER_NAME` config variable.
+
+```bash
+piku config:set NGINX_SERVER_NAME=your_domain_name.com NGINX_HTTPS_ONLY=1
+```
+
+You can also create a super user and set a password like this:
+
+```bash
+piku run -- ./manage.py createsuperuser --email your@email.com --username admin --no-input
+piku run -- ./manage.py changepassword admin
+```
+
+You will not see a prompt after the second command but you can type a new password anyway and hit enter.

examples/python-postgres/bin/provision-database

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+#!/bin/sh
+
+echo "Db/server name: [${NGINX_SERVER_NAME}]"
+
+if [ "${NGINX_SERVER_NAME}" = "" ]
+then
+  echo "Skipping db creation as NGINX_SERVER_NAME is not set."
+else
+  psql "${NGINX_SERVER_NAME}" -c ";" 2>/dev/null && echo "Database ${NGINX_SERVER_NAME} already exists" || createdb "${NGINX_SERVER_NAME}"
+fi
+
+./manage.py migrate --no-input
+./manage.py collectstatic --no-input

examples/python-postgres/manage.py

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+#!/usr/bin/env python
+"""Django's command-line utility for administrative tasks."""
+import os
+import sys
+
+
+def main():
+    os.environ.setdefault('DJANGO_SETTINGS_MODULE', 'pikudjango.settings')
+    try:
+        from django.core.management import execute_from_command_line
+    except ImportError as exc:
+        raise ImportError(
+            "Couldn't import Django. Are you sure it's installed and "
+            "available on your PYTHONPATH environment variable? Did you "
+            "forget to activate a virtual environment?"
+        ) from exc
+    execute_from_command_line(sys.argv)
+
+
+if __name__ == '__main__':
+    main()

examples/python-postgres/pikudjango/settings.py

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+"""
+Django settings for pikudjango project.
+
+Generated by 'django-admin startproject' using Django 2.2.2.
+
+For more information on this file, see
+https://docs.djangoproject.com/en/2.2/topics/settings/
+
+For the full list of settings and their values, see
+https://docs.djangoproject.com/en/2.2/ref/settings/
+"""
+
+import os
+
+# Build paths inside the project like this: os.path.join(BASE_DIR, ...)
+BASE_DIR = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
+
+
+# Quick-start development settings - unsuitable for production
+# See https://docs.djangoproject.com/en/2.2/howto/deployment/checklist/
+
+# SECURITY WARNING: keep the secret key used in production secret!
+SECRET_KEY = 'eu0^r0ilw-vkeh&n6%4mdkz0b+#e@tw1orypf)lcw5=#!z(6j1'
+
+# SECURITY WARNING: don't run with debug turned on in production!
+DEBUG = True
+
+ALLOWED_HOSTS = [os.environ.get("NGINX_SERVER_NAME", "")]
+
+
+# Application definition
+
+INSTALLED_APPS = [
+    'django.contrib.admin',
+    'django.contrib.auth',
+    'django.contrib.contenttypes',
+    'django.contrib.sessions',
+    'django.contrib.messages',
+    'django.contrib.staticfiles',
+]
+
+MIDDLEWARE = [
+    'django.middleware.security.SecurityMiddleware',
+    'django.contrib.sessions.middleware.SessionMiddleware',
+    'django.middleware.common.CommonMiddleware',
+    'django.middleware.csrf.CsrfViewMiddleware',
+    'django.contrib.auth.middleware.AuthenticationMiddleware',
+    'django.contrib.messages.middleware.MessageMiddleware',
+    'django.middleware.clickjacking.XFrameOptionsMiddleware',
+]
+
+ROOT_URLCONF = 'pikudjango.urls'
+
+TEMPLATES = [
+    {
+        'BACKEND': 'django.template.backends.django.DjangoTemplates',
+        'DIRS': [],
+        'APP_DIRS': True,
+        'OPTIONS': {
+            'context_processors': [
+                'django.template.context_processors.debug',
+                'django.template.context_processors.request',
+                'django.contrib.auth.context_processors.auth',
+                'django.contrib.messages.context_processors.messages',
+            ],
+        },
+    },
+]
+
+WSGI_APPLICATION = 'pikudjango.wsgi.application'
+
+
+# Database
+# https://docs.djangoproject.com/en/2.2/ref/settings/#databases
+
+DATABASES = {
+    'default': {
+        'ENGINE': 'django.db.backends.sqlite3',
+        'NAME': os.path.join(BASE_DIR, 'db.sqlite3'),
+    }
+}
+
+DB = os.environ.get("NGINX_SERVER_NAME", None)
+if DB:
+    DATABASES["default"]["ENGINE"] = 'django.db.backends.postgresql_psycopg2'
+    DATABASES["default"]["NAME"] = DB
+
+
+# Password validation
+# https://docs.djangoproject.com/en/2.2/ref/settings/#auth-password-validators
+
+AUTH_PASSWORD_VALIDATORS = [
+    {
+        'NAME': 'django.contrib.auth.password_validation.UserAttributeSimilarityValidator',
+    },
+    {
+        'NAME': 'django.contrib.auth.password_validation.MinimumLengthValidator',
+    },
+    {
+        'NAME': 'django.contrib.auth.password_validation.CommonPasswordValidator',
+    },
+    {
+        'NAME': 'django.contrib.auth.password_validation.NumericPasswordValidator',
+    },
+]
+
+
+# Internationalization
+# https://docs.djangoproject.com/en/2.2/topics/i18n/
+
+LANGUAGE_CODE = 'en-us'
+
+TIME_ZONE = 'UTC'
+
+USE_I18N = True
+
+USE_L10N = True
+
+USE_TZ = True
+
+
+# Static files (CSS, JavaScript, Images)
+# https://docs.djangoproject.com/en/2.2/howto/static-files/
+
+STATIC_URL = '/static/'
+STATIC_ROOT = os.path.join(BASE_DIR, "static")

examples/python-postgres/pikudjango/urls.py

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+"""pikudjango URL Configuration
+
+The `urlpatterns` list routes URLs to views. For more information please see:
+    https://docs.djangoproject.com/en/2.2/topics/http/urls/
+Examples:
+Function views
+    1. Add an import:  from my_app import views
+    2. Add a URL to urlpatterns:  path('', views.home, name='home')
+Class-based views
+    1. Add an import:  from other_app.views import Home
+    2. Add a URL to urlpatterns:  path('', Home.as_view(), name='home')
+Including another URLconf
+    1. Import the include() function: from django.urls import include, path
+    2. Add a URL to urlpatterns:  path('blog/', include('blog.urls'))
+"""
+from django.contrib import admin
+from django.urls import path
+
+urlpatterns = [
+    path('admin/', admin.site.urls),
+]

examples/python-postgres/pikudjango/wsgi.py

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+"""
+WSGI config for pikudjango project.
+
+It exposes the WSGI callable as a module-level variable named ``application``.
+
+For more information on this file, see
+https://docs.djangoproject.com/en/2.2/howto/deployment/wsgi/
+"""
+
+import os
+
+from django.core.wsgi import get_wsgi_application
+
+os.environ.setdefault('DJANGO_SETTINGS_MODULE', 'pikudjango.settings')
+
+application = get_wsgi_application()

examples/python-postgres/requirements.txt

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+Django==2.1.9
+pytz==2019.1
+sqlparse==0.3.0
+psycopg2-binary==2.8.3

playbooks/postgres.yml

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+---
+- hosts: all
+  tasks:
+    - name: Install postgres
+      apt:
+        name: ["postgresql", "python-psycopg2"]
+
+    - name: Create piku postgres superuser
+      become: true
+      become_user: postgres
+      postgresql_user:
+        name: piku
+        role_attr_flags: SUPERUSER