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Unless section we created our docker file and built a new image for a new application we should now

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be able to start up our application by running docker run and that will specify the image we just created.

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So you will put in your docker username slash visit's And remember you do not have to specify the tag

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by putting on colon colon latest at the end but you actually can if you want to.

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So we can run this right here and we'll start up our application.

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No notice so we immediately get an error message.

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It says read it's connection to something something something failed.

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So our application is attempting to start up but there's no register server running for it to connect

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to.

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So in this section we're going to focus on getting a separate container running a Gratus server.

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Now as far as getting up a separate read as server goes well it's going to be pretty darn straightforward.

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We're going to run the same exact command that we've ran throughout this course or run docker run rattus

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like so and so that's going to reach out to the docker hub.

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It's going to pull down to read assistance and all start up a copy of read us on our local machine and

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boom just like that.

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There's our read a server.

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So that's it.

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That's the reticence instance we're going to use no customization to the docker image for it whatsoever.

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It's now that we have our talk or e-mail or read a server running.

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I'm going to open up a second terminal window and inside the second window or now try running docker

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run my image again.

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So say Dr. Ron.

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Stephen Grider slash visit's.

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Let's run that and you'll notice.

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Well it looks like we still have the same error message we had before.

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Even though we are now running a red S server inside of a separate container.

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So what's the problem.

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Well let's think about it for a second.

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Here's what's going on on your computer right now.

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You've got a node application in one container and the read us application in the separate dock or container.

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Now these two containers do not have any automatic communication between the two whatsoever.

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They are two absolutely isolated processes that don't have any communication.

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So in order to make sure that our node app has the ability to kind of reach out to the red a server

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and stored information or work with it in some fashion we need to set up some networking infrastructure

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between the two.

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You know when it comes to setting up some networking functionality between two separate containers we

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have for right now two options to look at here's are two options.

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We can either make use of the dockers Seelye that we've been making use of throughout this course so

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far.

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You know I'm talking about the docker command that we've been using at our terminal throughout this

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entire course.

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This built in Dr. Seelye has functionality tied to it that will allow us to set up a network between

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two separate containers.

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However there's a little issue with it and the issue is basically just that it's a real pain in the

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neck to do when you make use of Dr. Selye to set up some networking.

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It's going to involve a handful of different commands that we rewrite on every single time you start

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up your different containers.

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Now of course we could make some type of little script to run all that stuff for us but you know certainly

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it's gonna involve a lot of typing and a lot of thought on how we're going to set up all this networking

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stuff.

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I'm going to be honest with you I have just about never seen people in industry ever make an use of

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Dockers built in the dock or.

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Let me very clear here never making use of Dharker ceilings built in networking features to connect

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two containers together much more frequently.

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What you're going to see in what you and I are going to do inside this course is we're going to make

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use of a separate CSI tool called docker compose docker compose is a separate tool that gets installed

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along with docker.

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So if you right now flip back over to your terminal and run docker dash compose like so you should see

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some content appear on the screen and list out a series of different commands for you to run docker

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compose a separate Seelye.

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It's already installed on your machine.

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Now when you start introducing Dharker compose it's going to very quickly start getting confusing.

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What docker composed does and what Dr. Seelye does and what the relationship between the two is.

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It's the best thing I can tell you is that Ducker can pose really exists to keep you from having to

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write out a ton of different repetitive commands with the Dr. Selye Sarette throughout this course we've

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been running stuff like Daka run and Dharker attach an exec and we've been specifying ports and tags

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and all this stuff to us all the time.

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Now definitely as we learn this stuff you know we need to use Takhar Seelye and learn it.

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But at a certain point time you say OK you know I understand this Dr. Selye stuff and you get tired

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of writing out those commands.

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So one of the big purposes of Dharker compose is to just avoid having to write out all these really

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annoying tiny little options every time you want to start up a container The other big thing that Dr.

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compose is going to do for us is it's going to make it very easy and very straightforward to start up

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multiple docker containers at the same time and automatically connect them together with some form of

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networking and it's all going to happen behind the scenes for us quite automatically.

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So again as soon as you start seeing this terminology here of Dharker compose you know keeping all these

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docker terms straight in your head gets a little bit confusing.

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I to tell you this right now.

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I mean repeat it several times.

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The purpose of Dr. compose is to essentially function as Dr. Seelye but allow you to kind of issue multiple

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commands much more quickly.

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So let's take a quick break right here.

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We're going to come back the next section and we're going to get a little bit more familiar with Dr.

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compose and how it works.