Merge pull request #5 from dmytrostriletskyi/develop

.gitignore

@@ -102,3 +102,5 @@ venv.bak/
 
 # mypy
 .mypy_cache/
+
+.idea/

.travis.yml

@@ -0,0 +1,19 @@
+sudo: required
+
+services:
+  - docker
+
+before_install:
+  - docker build -t heroku-load-balancer . -f Dockerfile
+  - docker run -d -p 7979:7979 -v $PWD:/heroku-load-balancer -e PORT=7979 -e HEROKU_API_KEY=$HEROKU_API_KEY -e PIPELINE_IDENTIFIER='f64cf79b-79ba-4c45-8039-57c9af5d4508' --name heroku-load-balancer heroku-load-balancer
+
+script:
+  - docker exec -it heroku-load-balancer bash -c "radon cc src -nb --total-average"
+  - docker exec -it heroku-load-balancer bash -c "cat requirements.txt requirements-dev.txt | safety check --stdin"
+  - docker exec -it heroku-load-balancer bash -c "bash <(curl -s https://linters.io/sort-requirements) requirements.txt requirements-dev.txt"
+  - docker exec -it heroku-load-balancer bash -c "bash <(curl -s https://linters.io/isort-diff) src"
+  - docker exec -it heroku-load-balancer bash -c "flake8 src"
+
+env:
+  global:
+    secure: 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

Dockerfile

@@ -0,0 +1,26 @@
+FROM ubuntu:16.04
+
+ENV LANG C.UTF-8
+ENV LC_ALL C.UTF-8
+
+RUN apt-get update && apt-get install -y \
+    software-properties-common \
+    nginx \
+    curl
+
+RUN add-apt-repository ppa:deadsnakes/ppa && apt-get update && apt-get install -y \
+    python3.6 \
+    python3.6-dev \
+    python3-pip \
+    python3-setuptools
+
+RUN ln -sfn /usr/bin/python3.6 /usr/bin/python3 && ln -sfn /usr/bin/python3 /usr/bin/python
+
+WORKDIR /heroku-load-balancer
+COPY . /heroku-load-balancer
+
+ENV PYTHONPATH="$PYTHONPATH:/heroku-load-balancer/src"
+
+RUN pip3 install -r /heroku-load-balancer/requirements.txt -r /heroku-load-balancer/requirements-dev.txt
+
+CMD /bin/bash -c "python3 src/entrypoint.py create-load-balancer --nginx-port=$PORT --heroku-api-key=$HEROKU_API_KEY --pipeline-identifier=$PIPELINE_IDENTIFIER" && mv nginx.conf /etc/nginx/nginx.conf && nginx -g 'daemon off;'

README.md

@@ -0,0 +1,117 @@
+Automatic (with no manual configuring) load balancer for your Heroku pipeline production applications.
+
+[![Release](https://img.shields.io/github/release/dmytrostriletskyi/heroku-load-balancer.svg)](https://github.com/dmytrostriletskyi/heroku-load-balancer/releases)
+[![Build Status](https://travis-ci.com/dmytrostriletskyi/heroku-load-balancer.svg?branch=develop)](https://travis-ci.com/dmytrostriletskyi/heroku-load-balancer)
+[![License: MIT](https://img.shields.io/badge/License-MIT-yellow.svg)](https://opensource.org/licenses/MIT)
+
+  * [Getting started](#getting-started)
+    * [What is a load balancer](#what-is-a-load-balancer)
+    * [Motivation](#motivation)
+    * [How to use](#how-to-use)
+    * [How it works](#how-it-works)
+  * [Development](#development)
+
+## Getting started
+
+### What is a load balancer
+
+A load balancer is a device that distributes network or application traffic across a cluster of servers. A load balancer 
+sits between the client and the server farm accepting incoming network and application traffic and distributing the 
+traffic across multiple backend servers. By balancing application requests across multiple servers, a load balancer 
+reduces individual server load and prevents any one application server from becoming a single point of failure, 
+thus improving overall application availability and responsiveness.
+
+![Illustation on how load balancer works](https://habrastorage.org/webt/iy/-s/vx/iy-svxvpqwnquwvciv7qm3pfm1u.png)
+
+### Motivation
+
+[Heroku](https://heroku.com) does not have `load balancer` paid feature to balancing your applications. It is the drawback
+comparing to [Digital Ocean](https://www.digitalocean.com/products/load-balancer) and [Amazon Web Services](https://aws.amazon.com/elasticloadbalancing/)
+which do have it.
+
+### How to use
+
+1. Press the button named `Deploy to Heroku` below.
+
+[![Deploy](https://www.herokucdn.com/deploy/button.svg)](https://heroku.com/deploy?template=https://github.com/dmytrostriletskyi/heroku-load-balancer/tree/create-docs)
+
+2. Enter the name for the application which will host the load balancer. Choose the region and add to the pipeline if needed.
+
+<img src="https://habrastorage.org/webt/xq/rp/nl/xqrpnlgqh0-3o1kldfk2pflvtvy.png" width="900" height="440">
+
+3. Visit the [Heroku account setting page](https://dashboard.heroku.com/account), find the `API Key` section, reveal the key and
+paste it to the `HEROKU_API_KEY` field. 
+
+<img src="https://habrastorage.org/webt/v0/g7/wt/v0g7wtn1qltm8-_jpfdug4djkya.png" width="900" height="104">
+
+3. Open the preferable pipeline and copy its identifier from the URL. On the screenshoot it is `f64cf79b-79ba-4c45-8039-57c9af5d4508` mentioned by red arrow at the top.
+
+<img src="https://habrastorage.org/webt/he/0j/c-/he0jc-ubwjfxajbn85lg_ysa14m.png" width="900" height="400">
+
+4. Return to the deploying page, paste the identifier to the `PIPELINE_IDENTIFER` field.
+
+<img src="https://habrastorage.org/webt/zu/1v/wo/zu1vwo1y54o_efk9jqdrxpwpgeg.png" width="900" height="90">
+
+5. Press the button named `Deploy app`. The process of deploying will start immediately as illustrated below.
+
+<img src="https://habrastorage.org/webt/0o/7l/k0/0o7lk0gv5lzp5ij14yepe17a4g4.png" width="900" height="340">
+
+6. When build is finished, you can manage your application (rename, etc.) and view it (open URL in the browser).
+
+<img src="https://habrastorage.org/webt/wh/lo/sp/whlospuzvfmazjpdsrf52iduxf0.png" width="900" height="128">
+
+7. To check if load balancer works properly, just open logs of each production back-end servers 
+(`heroku logs --tail -a application-name` in the terminal), and send the request to the load balancer application. 
+As the result, the load balancer will proxy your request to the each back-end server in round-robin method (one by one in order).
+
+<img src="https://habrastorage.org/webt/zm/bn/vj/zmbnvj7ztr3ho4y6xt6mfxt2qh4.png" width="900" height="480">
+
+### How it works
+
+1. You specify pipeline's identifier (`PIPELINE_IDENTIFER`) to create load balancer for its applications in `production` stage.
+2. Through the [Heroku API](https://devcenter.heroku.com/categories/platform-api) using your `HEROKU_API_KEY`, URLs of applications are fetched.
+3. Then [configuration file for load balancing](http://nginx.org/en/docs/http/load_balancing.html) based on fetched URLS is created.
+4. And served by the [Nginx](https://nginx.org/en) in round-robin method (one by one in order).
+
+## Development
+
+Clone the project with the following command:
+
+```bash
+$ git clone https://github.com/dmytrostriletskyi/heroku-load-balancer.git
+$ cd heroku-load-balancer
+```
+
+To build the project, use the following command:
+
+```bash
+$ docker build -t heroku-load-balancer . -f Dockerfile
+```
+
+To run the project, use the following command. It will start the server and occupate current terminal session:
+
+```bash
+$ docker run -p 7979:7979 -v $PWD:/heroku-load-balancer \
+      -e PORT=7979 \
+      -e HEROKU_API_KEY='8af7dbb9-e6b8-45bd-8c0a-87787b5ae881' \
+      -e PIPELINE_IDENTIFIER='f64cf79b-79ba-4c45-8039-57c9af5d4508' \
+      --name heroku-load-balancer heroku-load-balancer
+```
+
+If you need to enter the bash of the container, use the following command:
+
+```bash
+$ docker exec -it heroku-load-balancer bash
+```
+
+Clean all containers with the following command:
+
+```bash
+$ docker rm $(docker ps -a -q) -f
+```
+
+Clean all images with the following command:
+
+```bash
+$ docker rmi $(docker images -q) -f
+```

app.json

@@ -0,0 +1,18 @@
+{
+  "name": "heroku-load-balancer",
+  "description": "Automatic (with no manual configuring) load balancer for your Heroku pipeline production applications.",
+  "repository": "https://github.com/dmytrostriletskyi/heroku-load-balancer",
+  "env": {
+    "HEROKU_API_KEY": {
+      "description": "Heroku API key from the personal account.",
+      "required": true
+    },
+    "PIPELINE_IDENTIFIER": {
+      "description": "Pipeline identifier for creating load balancer.",
+      "required": true
+    }
+  },
+  "logo": "https://habrastorage.org/webt/w3/fp/ep/w3fpepqfjjtumhnyul4ymts-qm8.png",
+  "keywords": ["nginx", "docker", "proxy", "balancing", "balancer"],
+  "stack": "container"
+}

heroku.yml

@@ -0,0 +1,3 @@
+build:
+  docker:
+    web: Dockerfile

requirements-dev.txt

@@ -0,0 +1,11 @@
+add-trailing-comma==1.0.0
+flake8-commas==2.0.0
+flake8-comprehensions==2.1.0
+flake8-docstrings==1.3.0
+flake8-per-file-ignores==0.8.1
+flake8-print==3.1.0
+flake8==3.7.7
+isort==4.3.20
+pep8-naming==0.8.2
+radon==3.0.3
+safety==1.8.5

requirements.txt

@@ -0,0 +1,2 @@
+click==7.0
+requests==2.22.0

setup.cfg

@@ -0,0 +1,22 @@
+[isort]
+line_length=120
+multi_line_output=3
+include_trailing_comma=True
+force_grid_wrap=True
+combine_as_imports=True
+
+[flake8]
+max-line-length=120
+ignore=D200, D413, D107, D100
+per-file-ignores=
+    */__init__.py: D104, F401, D100,
+    */test_*: D205,
+    src/constants.py: E501
+
+[coverage:run]
+omit =
+    */.virtualenvs/*,
+    */virtualenv/*,
+
+    */__init__.py,
+    tests/*

src/constants.py

@@ -0,0 +1,29 @@
+NGINX_LOAD_BALANCER_CONFIG_TEMPLATE = """events <
+    worker_connections 4096;
+>
+
+http <
+    gzip on;
+    gzip_types text/plain text/css application/json application/javascript text/xml application/xml application/xml+rss text/javascript;
+
+    proxy_ssl_server_name on;
+
+    # ssl_protocols TLSv1 TLSv1.1 TLSv1.2 TLSv1.3;
+    ssl_prefer_server_ciphers on;
+    ssl_ciphers 'ECDHE-ECDSA-CHACHA20-POLY1305:ECDHE-RSA-CHACHA20-POLY1305:ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-GCM-SHA384:DHE-RSA-AES128-GCM-SHA256:DHE-RSA-AES256-GCM-SHA384:ECDHE-ECDSA-AES128-SHA256:ECDHE-RSA-AES128-SHA256:ECDHE-ECDSA-AES128-SHA:ECDHE-RSA-AES256-SHA384:ECDHE-RSA-AES128-SHA:ECDHE-ECDSA-AES256-SHA384:ECDHE-ECDSA-AES256-SHA:ECDHE-RSA-AES256-SHA:DHE-RSA-AES128-SHA256:DHE-RSA-AES128-SHA:DHE-RSA-AES256-SHA256:DHE-RSA-AES256-SHA:ECDHE-ECDSA-DES-CBC3-SHA:ECDHE-RSA-DES-CBC3-SHA:EDH-RSA-DES-CBC3-SHA:AES128-GCM-SHA256:AES256-GCM-SHA384:AES128-SHA256:AES256-SHA256:AES128-SHA:AES256-SHA:DES-CBC3-SHA:!DSS';
+
+    upstream main <
+{upstream_server_localhosts}
+    >
+
+    server <
+        listen {port};
+
+        location / <
+            proxy_pass http://main;
+        >
+    >
+
+{upstream_server_configs}
+>
+"""

src/entrypoint.py

@@ -0,0 +1,61 @@
+"""
+Provide implementation of the command line interface.
+"""
+import click
+
+from src.heroku import (
+    GetHerokuPipelineProductionApplicationsUrls,
+    HerokuApi,
+)
+from src.nginx import CreationNginxLoadBalancerConfigFile
+
+
+@click.group()
+def cli():
+    """
+    Command line interface root function.
+    """
+    pass
+
+
+@click.command()
+@click.option(
+    '--nginx-port',
+    type=int,
+    required=True,
+    help='The port to the Nginx on.',
+)
+@click.option(
+    '--heroku-api-key',
+    type=str,
+    required=True,
+    help='The account\'s Heroku API key.',
+)
+@click.option(
+    '--pipeline-identifier',
+    type=str,
+    required=True,
+    help='Pipeline identifier to fetch applications for balancing.',
+)
+def create_load_balancer(nginx_port, heroku_api_key, pipeline_identifier):
+    """
+    Create Nginx load balancer config file with pipeline's production applications URLs.
+    """
+    heroku_api = HerokuApi(
+        key=heroku_api_key,
+    )
+
+    get_heroku_pipeline_production_applications_urls = GetHerokuPipelineProductionApplicationsUrls(
+        heroku_api=heroku_api,
+    )
+
+    pipeline_production_applications_urls = get_heroku_pipeline_production_applications_urls.by_pipeline_identifier(
+        identifier=pipeline_identifier,
+    )
+
+    CreationNginxLoadBalancerConfigFile(port=nginx_port).with_urls(urls=pipeline_production_applications_urls)
+
+
+if __name__ == '__main__':
+    cli.add_command(create_load_balancer)
+    cli()

src/heroku.py

@@ -0,0 +1,73 @@
+"""
+Provide implements of the Heroku domain.
+"""
+import requests
+
+
+class HerokuApi:
+    """
+    Implements Heroku API communicator.
+    """
+
+    def __init__(self, key: str):
+        """
+        Constructor.
+        """
+        self.headers = {
+            'Accept': 'application/vnd.heroku+json; version=3',
+            'Authorization': f'Bearer {key}',
+        }
+
+    def fetch_pipeline_applications(self, identifier: str):
+        """
+        Fetch a pipeline applications by its identifier.
+        """
+        fetch_pipeline_applications_url = f'https://api.heroku.com/pipelines/{identifier}/pipeline-couplings'
+
+        response = requests.get(fetch_pipeline_applications_url, headers=self.headers)
+        response_json = response.json()
+
+        return response_json
+
+    def fetch_application(self, identifier: str):
+        """
+        Fetch an application by its identifier.
+        """
+        fetch_pipeline_applications_url = f'https://api.heroku.com/apps/{identifier}'
+
+        response = requests.get(fetch_pipeline_applications_url, headers=self.headers)
+        response_json = response.json()
+
+        return response_json
+
+
+class GetHerokuPipelineProductionApplicationsUrls:
+    """
+    Implement getting Heroku's pipeline production applications' URLs transaction.
+    """
+
+    def __init__(self, heroku_api: HerokuApi):
+        """
+        Constructor.
+        """
+        self.heroku_api = heroku_api
+
+    def by_pipeline_identifier(self, identifier):
+        """
+        Get Heroku's pipeline production applications' URLs by pipeline identifier.
+        """
+        production_applications_identifiers = []
+
+        for application in self.heroku_api.fetch_pipeline_applications(identifier=identifier):
+            if application.get('stage') == 'production':
+                application_identifier = application.get('app').get('id')
+                production_applications_identifiers.append(application_identifier)
+
+        production_applications_urls = []
+
+        for application_identifier in production_applications_identifiers:
+            application = self.heroku_api.fetch_application(identifier=application_identifier)
+            application_url = application.get('web_url')
+            production_applications_urls.append(application_url)
+
+        return production_applications_urls