As we've seen, Docker can simplify the entire software build and 0:00 deployment process. 0:04 Anytime you find your software runs properly on some machines but 0:06 not others, Docker can help you get things working consistently. 0:09 Here are just a few examples. 0:13 Dockers lets you run apps even if you don't know how they work internally. 0:16 Suppose your co-worker sends you a link to an internal repo, 0:20 and says she needs this app up and running by the end of the day. 0:23 But the app's poorly documented, and you struggle for hours to get it working. 0:26 Next time, if your co-worker includes a Dockerfile with the app, 0:30 all you have to do is ensure the host you're deploying to has Docker installed. 0:34 You'll be able to build an image using the Dockerfile, then use that image to run 0:39 a container on the host, and the app will immediately be up and running. 0:43 Docker also makes it easy to deploy apps to multiple environments. 0:47 Suppose you want to load test your project after it's deployed to your staging site. 0:51 You can use Docker to package your app, and put it up at a certain URL. 0:55 And then have a load tester run automatically once Docker finishes 0:59 deploying the container. 1:03 And Docker makes it easy to share your apps with others. 1:04 Suppose you want to share your apps with other teams in your company, but 1:08 sharing Git repos isn't enough. 1:11 You want to be able to immediately spin up the apps with no installation required. 1:13 You can use a Docker registry, sort of like a GitHub for 1:18 Docker to share as many Docker images as you want with your company's other teams. 1:21 Then once they use Docker to pull the images they want, 1:25 the image can be deployed as a container with one simple command. 1:28 Because Dockerfiles make running your files so 1:32 easy, Docker can handle these used cases and many more. 1:34 Docker fits right in to the DevOps movements, 1:38 infrastructure as code philosophy. 1:41 You can create containers for any app, website, or service 1:44 using a single Dockerfile, which is just the plain text file with some commands. 1:47 By now, you're hopefully thinking of adopting Docker for your own projects. 1:52 If you do, you'll be in good company. 1:56 Even though it was only released in mid-2013, it's already immensely popular. 1:59 Docker CEO announced in the 2016 DockerCon keynote that 2:04 460,000 Dockerized applications had been made. 2:09 That number had grown by a factor of 31 times over two years. 2:12 Over 4 billion containers have been pulled so far from the public Docker registry. 2:17 And as of 2016, there were 125,000 Docker Meetup members. 2:23 Clearly, Docker has a huge following. 2:28 And hundreds of thousands, if not millions, 2:31 of hours have gone into its development and improvement. 2:33 In 2017, it would be hard to name a major tech company that hasn't tried Docker. 2:36 And many are using it in production. 2:41 Docker can be used for many more purposes beyond those we've already shown. 2:44 The versions of libraries and 2:48 services that your app depends on may change over time. 2:50 Docker can act like a version control system for those dependencies 2:53 allowing you to roll back to an old version of a service, if something breaks. 2:57 Docker can help you maintain consistency between your developers work stations and 3:02 the testing and production environments. 3:06 If you bundle all the services your app depends on into a container, 3:08 you can be sure that the services your developers are writing code for 3:12 are the same services used in testing and production. 3:15 And Docker can help you deploy distributed apps. 3:19 If your app needs to run on a server cluster consisting of hundreds or 3:22 thousands of machines, configuring them manually just isn't an option. 3:26 But if you ensure Docker is installed on all those hosts, they'll be able to load 3:30 all the services your app requires from a single Docker image. 3:34 That's it for stage one. 3:38 Now, you should have a general idea of what Docker is, and 3:40 what businesses are using it for. 3:42 In stage two, we'll look at exactly how Docker works. 3:45 Ready? 3:48 Let's get to it. 3:49