Docker Containers

 Docker Containers

Containers allow the developer to package an environment for applications

The advantages are to have applications run uniformly and consistently on various machine configurations.

Standardization 

Create independent and isolated user-space instances that can be managed in tandem.

Lightweight virtual machines environments that are Inexpensive to run

Docker containerization provides speed, efficiency, and scalability for application deployment.

Containers share the host's Linux kernel.

Install - Configure - Deploy -Maintain

The Dockerfile defines the container image for the application to run on. 

It tells the application how to build the image environment, libraries, operating system, code and works anywhere that Docker is installed on a Linux machine.

The example below defines a docker app for “Hello World”.

Go to Linux shell and create director called hellodocker and cd into it

john_iacovacci1@cloudshell:~ (cloud-project-examples)$ mkdir hellodocker

john_iacovacci1@cloudshell:~ (cloud-project-examples)$ cd hellodocker

john_iacovacci1@cloudshell:~/hellodocker (cloud-project-examples)$ 

joh

It starts with the app.py python file.

Open editor to create file

======================================================

# app.py

from flask import Flask

import os

app = Flask(__name__)

@app.route("/")

def hello_world():

    return "Hello, Google Cloud Users!."

if __name__ == "__main__":

    

# Cloud Run listens on the port defined by the PORT environment variable

    port = int(os.environ.get("PORT", 8080))

    app.run(debug=True, host='0.0.0.0', port=port)

========================================================

The application “Listens” to activity on a specific PORT and executes the function hello_world() when the application link is clicked.

The Dockerfile is needed which will provide the instructions for the application to run on.

========================================================# #Use the official lightweight Python image

FROM python:3.11-slim

# Set the working directory in the container

WORKDIR /app

# Copy the local code to the container

COPY . .

# Install Flask

RUN pip install Flask

# Run the web service on container startup

CMD ["python", "app.py"]

========================================================# 

Next we need to permission our account

To enable services, account needs the Service Usage Admin role roles/serviceusage.serviceUsageAdmin

The broader Editor/Owner role.

Check IAM & Admin > IAM. 

roles/serviceusage.serviceUsageAdmin

roles/resourcemanager.projectIamAdmin 

john_iacovacci1@cloudshell:~/hellodocker (cloud-project-examples)$ gcloud run deploy hello-python --source . --region us-central1 --allow-unauthenticated

Building using Dockerfile and deploying container to Cloud Run service [hello-python] in project [cloud-project-examples] region [us-central1]

Building and deploying...                                                                                                      

  Validating Service...done                                                                                                    

  Uploading sources...done                                                                                                     

  Building Container... Logs are available at [https://console.cloud.google.com/cloud-build/builds;region=us-central1/d9b9a54c-

  39c9-471c-84c5-87c7fba3cd84?project=517129368909]....done                                                                    

  Setting IAM Policy...done                                                                                                    

  Creating Revision...done                                                                                                     

  Routing traffic...done                                                                                                       

Done.                                                                                                                          

Service [hello-python] revision [hello-python-00003-hgh] has been deployed and is serving 100 percent of traffic.

Service URL: https://hello-python-517129368909.us-central1.run.app

Click on the service URL link

john_iacovacci1@cloudshell:~/hellodocker (cloud-project-examples)$