Azure from scratch part 5 By Girish Kalamati

Editor's Notes

1. The Case for Containers The concepts behind Docker and other Linux containers are solid: Very small VMs that allow for much higher server density by removing redundant or unnecessary operating system elements from the VMs themselves. Nicely packaged VM stacks, which can easily be transferred, replicated, and controlled, ensuring high levels of portability. VM software stacks that are small, removing the problem and tedium of building a large stack of version-specific operating systems and tools that need lots of care and feeding to replicate and maintain. Extremely fast startup times that can facilitate a more flexible infrastructure, allowing greater latitude to respond to the needs of the moment – literally.
2. The Case for Containers The concepts behind Docker and other Linux containers are solid: Very small VMs that allow for much higher server density by removing redundant or unnecessary operating system elements from the VMs themselves. Nicely packaged VM stacks, which can easily be transferred, replicated, and controlled, ensuring high levels of portability. VM software stacks that are small, removing the problem and tedium of building a large stack of version-specific operating systems and tools that need lots of care and feeding to replicate and maintain. Extremely fast startup times that can facilitate a more flexible infrastructure, allowing greater latitude to respond to the needs of the moment – literally.
3. Docker containers are configured to maintain all configurations and dependencies internally. As a result, you can use the same container from development to production making sure there are no discrepancies or manual intervention.
4. Docker Machine Overview : You can use Docker Machine to: Install and run Docker on Mac or Windows Provision and manage multiple remote Docker hosts Provision Swarm clusters What is Docker Machine? Docker Machine is a tool that lets you install Docker Engine on virtual hosts, and manage the hosts with docker-machine commands. You can use Machine to create Docker hosts on your local Mac or Windows box, on your company network, in your data center, or on cloud providers like Azure, AWS, or Digital Ocean. Using docker-machine commands, you can start, inspect, stop, and restart a managed host, upgrade the Docker client and daemon, and configure a Docker client to talk to your host. Point the Machine CLI at a running, managed host, and you can run docker commands directly on that host. For example, run docker-machine env default to point to a host called default, follow on-screen instructions to complete env setup, and run docker ps, docker run hello-world, and so forth. Machine was the only way to run Docker on Mac or Windows previous to Docker v1.12. Starting with the beta program and Docker v1.12, Docker for Mac and Docker for Windows are available as native apps and the better choice for this use case on newer desktops and laptops. We encourage you to try out these new apps. The installers for Docker for Mac and Docker for Windows include Docker Machine, along with Docker Compose.
5. Machine was the only way to run Docker on Mac or Windows previous to Docker v1.12. Starting with the beta program and Docker v1.12, Docker for Mac and Docker for Windows are available as native apps and the better choice for this use case on newer desktops and laptops.
6. Machine was the only way to run Docker on Mac or Windows previous to Docker v1.12. Starting with the beta program and Docker v1.12, Docker for Mac and Docker for Windows are available as native apps and the better choice for this use case on newer desktops and laptops.
7. Running Docker Codes in QuickStart Terminal
8. Running Docker Codes in QuickStart Terminal
9. Running Docker Codes in QuickStart Terminal
10. Running Docker Codes in Bash Terminal
11. Running Docker Codes in Bash Terminal
12. Running Docker Codes in Bash Terminal
13. Docker-machine ls Docker-machine env ubuntu
14. Docker run mysampleimage Docker-machine ip Or  Docker-machine inspect "containerID"
15. Docker run –p 8080:3000 -v /var/www node Docker run –p 8080:3000 -v /var/www mycontainerimage Localhost:8080  Or  IP:8080 Node == image name It will create a container inside host … even it says Container volume 
16. Docker inspect myconatiner
17. Custom folder to put source code in HOST
18. Docker run –p 8080:3000 –v $(pwd):/var/www node Node == image name It will create a container inside host … even it says Container volume 
19. Docker inspect mycontainer
20. We also need to assume you are familiar with a few concepts before we continue: IP Addresses and Ports Virtual Machines Editing configuration files Basic familiarity with the ideas of code dependencies and building Machine resource usage terms, like CPU percentages, RAM use in bytes, etc.
21. A brief explanation of containers An image is a lightweight, stand-alone, executable package that includes everything needed to run a piece of software, including the code, a runtime, libraries, environment variables, and config files. A container is a runtime instance of an image—what the image becomes in memory when actually executed. It runs completely isolated from the host environment by default, only accessing host files and ports if configured to do so. Containers run apps natively on the host machine’s kernel. They have better performance characteristics than virtual machines that only get virtual access to host resources through a hypervisor. Containers can get native access, each one running in a discrete process, taking no more memory than any other executable. Virtual machines run guest operating systems—note the OS layer in each box. This is resource intensive, and the resulting disk image and application state is an entanglement of OS settings, system-installed dependencies, OS security patches, and other easy-to-lose, hard-to-replicate ephemera.
22. Conclusion The unit of scale being an individual, portable executable has vast implications. It means CI/CD can push updates to any part of a distributed application, system dependencies are not an issue, and resource density is increased. Orchestration of scaling behavior is a matter of spinning up new executables, not new VM hosts.
23. View the web page running from a container Go to localhost:8080 to access your app in a web browser. If you are using the Nano Windows Container and have not updated to the Windows Creator Update there is a bug affecting how Windows 10 talks to Containers via “NAT”(Network Address Translation). You must hit the IP of the container directly. You can get the IP address of your container with the following steps: Run docker inspect -f "{{ .NetworkSettings.Networks.nat.IPAddress }}" myapp Copy the container ip address and paste into your browser. (For example, 172.16.240.197)
24. Are you behind a proxy server? Proxy servers can block connections to your web app once it’s up and running. If you are behind a proxy server, add the following lines to your Dockerfile, using the ENV command to specify the host and port for your proxy servers: # Set proxy server, replace host:/port with values for your servers ENV http_proxy host:/port ENV https_proxy host:/port
25. Orchestration comes when we create Multi Hosts .. since distributed applications cannot be hosted on a single host because tht would be a single point of failure.
26. Yellow : Master  Orange : Workers
27. Container Level Dependencies are defined by Compose.yaml but Application level dependency/Resiliency is developers responsibility Because We have different types of containers I.e. Web Containers and DB Containers can come up at different times. DB containers can take time to come up it would be great if developers writes some code which can ping the DB container asking whether it is up ? And Then Web Container should redirect requests.
28. Task == Container
29. -p 8080:8080  1st 8080 is Host Port No 2nd 8080 is Container Port No For this kind of Multiple Hosts we Have Ingress Port at HOST which can be a single value like 8080 here , Since Load Balancers are Host aware not Container aware.  In cases when requests come from LB if some host is having issue, the container can be moved to healthy host and this mapping with 8080 will be there on the new node. The mapping will be updated into IPTable.
30. In cases when requests come from LB if some host is having issue, the container can be moved to healthy host and this mapping with 8080 will be there on the new node. The mapping will be updated into IPTable. Requests automatically redirected to right Host basing upon IPTable.  IPTable could be managed on single HUB and u can assure that u r requests will land on to only host where container is running :)