init draft

Author: bennzhang

Dockerfile

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+FROM python:2.7
+
+# Creating Application Source Code Directory
+RUN mkdir -p /usr/src/app
+
+# Setting Home Directory for containers
+WORKDIR /usr/src/app
+
+# Installing python dependencies
+COPY requirements.txt /usr/src/app/
+RUN pip install --no-cache-dir -r requirements.txt
+
+# Copying src code to Container
+COPY . /usr/src/app
+
+# Application Environment variables
+#ENV APP_ENV development
+ENV PORT 8080
+
+# Exposing Ports
+EXPOSE $PORT
+
+# Setting Persistent data
+VOLUME ["/app-data"]
+
+# Running Python Application
+CMD gunicorn -b :$PORT -c gunicorn.conf.py main:app

README.md

@@ -1 +1,155 @@
-# python-app-docker-demo
+# python-app-docker-demo
+This demo shows two steps:
++ Install `docker-ce` on Centos 7
++ Build and run a simple docker image with a python+flask+gunicorn web application.
+
+## Install docker-ce on Centos 7
+Refer to https://docs.docker.com/engine/installation/linux/docker-ce/centos/
+You can also find [other OS installation docs from here](https://docs.docker.com/engine/installation).
+
+#### Uninstall old versions
+```
+$ sudo yum remove docker \
+                  docker-common \
+                  docker-selinux \
+                  docker-engine
+```
+
+#### Install using repository
+```
+sudo yum install -y yum-utils device-mapper-persistent-data lvm2
+sudo yum-config-manager --add-repo https://download.docker.com/linux/centos/docker-ce.repo
+sudo yum install docker-ce
+sudo systemctl start docker
+sudo docker run hello-world
+```
+
+Other commands: 
++ check docker status 
+```
+sudo systemctl status docker.service
+```
+
++ stop docker 
+```
+sudo systemctl stop docker
+```
+
++ uninstall docker-ce
+```
+sudo yum remove docker-ce
+```
+
++ remove all images, container, volumes
+```
+sudo rm -rf /var/lib/docker
+```
+
+## Build/Run a simple python+flask docker web app 
+
+#### Create the Dockerfile
+
+```
+FROM python:2.7
+
+# Creating Application Source Code Directory
+RUN mkdir -p /usr/src/app
+
+# Setting Home Directory for containers
+WORKDIR /usr/src/app
+
+# Installing python dependencies
+COPY requirements.txt /usr/src/app/
+RUN pip install --no-cache-dir -r requirements.txt
+
+# Copying src code to Container
+COPY . /usr/src/app
+
+# Application Environment variables
+#ENV APP_ENV development
+ENV PORT 8080
+
+# Exposing Ports
+EXPOSE $PORT
+
+# Setting Persistent data
+VOLUME ["/app-data"]
+
+# Running Python Application
+CMD gunicorn -b :$PORT -c gunicorn.conf.py main:app
+```
+
+#### Build your image
+Normally, image name convention is something like: `
+{company/application-name}:{version-number}`. In the demo, I just use `{application-name}:{version-number}`
+
+```
+sudo docker build -t my-python-app:1.0.1 .
+```
+
+#### check all docker images
+```
+$ sudo docker images
+REPOSITORY              TAG                 IMAGE ID            CREATED             SIZE
+my-python-app           1.0.1               2b628d11ba3a        22 minutes ago      701.6 MB
+docker.io/python        2.7                 b1d5c2d7dda8        13 days ago         679.3 MB
+docker.io/hello-world   latest              05a3bd381fc2        5 weeks ago         1.84 kB
+```
+
+`2b628d11ba3a` is the image ID, some commands based on the ID.
+
++ tag 
+```
+sudo docker tag 2b628d11ba3a my-python-app:1.0.1
+sudo docker tag 2b628d11ba3a my-python-app:latest
+```
+
++ remove image
+```
+$ sudo docker rmi --force 2b628d11ba3a
+```
+
+#### Run your image
+```
+$ sudo docker run -d -p 8080:8080 my-python-app:1.0.1
+```
+
+
+You can use `sudo docker ps` to list all running containers. 
+```
+$ sudo docker ps
+CONTAINER ID        IMAGE                 COMMAND                  CREATED             STATUS              PORTS                    NAMES
+4de6041072b7        my-python-app:1.0.1   "/bin/sh -c 'gunicorn"   20 minutes ago      Up 20 minutes       0.0.0.0:8080->8080/tcp   elegant_kowalevski
+```
+
+`4de6041072b7` is the running container id. Some commands below are what you might need.
+
++ display logs in running container
+```
+$ sudo docker logs 4de6041072b7
+[2017-10-23 20:29:49 +0000] [7] [INFO] Starting gunicorn 19.6.0
+[2017-10-23 20:29:49 +0000] [7] [INFO] Listening at: http://0.0.0.0:8080 (7)
+[2017-10-23 20:29:49 +0000] [7] [INFO] Using worker: gthread
+[2017-10-23 20:29:49 +0000] [11] [INFO] Booting worker with pid: 11
+[2017-10-23 20:29:49 +0000] [12] [INFO] Booting worker with pid: 12
+
+```
+
++ stop your container
+```
+$ sudo docker stop 4de6041072b7
+```
+
++ login inside the container
+```
+$ sudo docker exec -it 4de6041072b7 /bin/sh
+# ls /usr/src/app
+Dockerfile  README.md  gunicorn.conf.py  gunicorn_pid.txt  main.py  main.pyc  requirements.txt
+# exit
+```
+
+#### Test your application
+```
+$ curl http://localhost:8080
+Hello World
+```

gunicorn.conf.py

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+#By default the multi-process version of the runtime is launched via the Gunicorn webserver and is configured to use gevent-based concurrency and a number of processes equal to the number of CPU cores available.
+
+#This can be changed by creating a file called gunicorn.conf.py in your applications root directory, which will override the default gunicorn.conf.py included with this project
+
+
+import multiprocessing
+
+# Use threaded workers. Thread-based concurrency is provided via the 'futures'
+# package. 'gevent' or other workers would be candidates, except that the ndb
+# library has its own concurrency model that conflicts with gevent and possibly
+# with similar approaches.
+worker_class = 'gthread'
+
+# Use a number of workers equal to the number of CPU cores available.
+# Reducing this number on a multicore instance will reduce memory consumption,
+# but will also reduce the app's ability to utilize all available CPU resources.
+#workers = multiprocessing.cpu_count()
+#workers = 8 # good
+workers = 2 # good
+
+# Use an arbitrary number of threads for concurrency. This will dictate the
+# maximum number of requests handled concurrently by EACH worker.
+threads = 25
+
+# Settings specific to the Managed VMs production environment such as "bind"
+# and "logfile" are set in the Dockerfile's ENTRYPOINT directive.
+
+# Store the process ID of gunicorn.  Used for testing.
+pidfile = 'gunicorn_pid.txt'

main.py

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+# Copyright 2015 Google Inc. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# [START app]
+import logging
+
+from flask import Flask, request, jsonify
+
+app = Flask(__name__)
+
+@app.route('/')
+def hello():
+    """Return a friendly HTTP greeting."""
+    return 'Hello World'
+
+@app.errorhandler(500)
+def server_error(e):
+    logging.exception('An error occurred during a request.')
+    return """
+    An internal error occurred: <pre>{}</pre>
+    See logs for full stacktrace.
+    """.format(e), 500
+
+if __name__ == '__main__':
+    app.run(host='0.0.0.0', port=8081)

main.pyc

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+Flask==0.10.1
+gunicorn==19.6.0
+futures==3.0.5