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‫Okay,

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‫so what I'm going to do is, I'm going to walk through each one of these services based on this architecture,

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‫and I'm going to create this app on the fly. I'm actually going to type the commands in here in the readme,

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‫because that seems like a logical place for me to do it. And then I'll cut and paste them into my

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‫node.

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‫If you remember, I have a 3-node Swarm over here. If I do a docker node ls,

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‫you’ll see that I have three nodes here. They're all manager nodes.

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‫I have no containers running, and no services, obviously. First thing, I know up at the top,

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‫it talks about I need networks, and I need a volume.

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‫So, probably can get the networks out of the way and I can probably wing that. I can type docker

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‫network create d overlay. Remember that the overlay network is the only kind of network we can use

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‫in a Swarm because overlay allows us to span across nodes, as if they're all on the local network.

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‫And then I want to call it backend.

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‫And then, I want to do the same exact thing, only call it frontend.

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‫Now, there's nothing inherently special about these two networks.

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‫We're just going to segment our different services into one or the other to help act like a little firewall

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‫that gives separation for protection.

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‫On this vote one,

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‫I know I need to do a docker service create, and I’ve got to name it, so I might as well put name vote. And then

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‫I’ve got to publish the port 80 to 80 in the container, and it's got to be on a specific network. So, network

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‫frontend. I need two replicas.

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‫So, replica two. And then, I might as well just copy and paste this name.

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‫Now, I'm going to go ahead and create all of these before I actually deploy them.

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‫I’m going to actually copy this one down here. This one is going to be called...it’s not going to be called vote,

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‫it's going to be called redis.

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‫You don't have to worry about publishing any ports on that.

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‫It's going to be on the frontend network.

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‫I want two replicas, and then, I’m going to call it redis three two is the image.

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‫Down here, docker service create name worker, is going to be on two networks. I’ve got to do network

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‫frontend and...whoops.

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‫I’m typing what I'm saying...let’s see, network backend, and then only one replica.

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‫…

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‫Because one replica is default,

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‫I don't actually have to specify replica and I don't specify any ports.

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‫I think, that's all I need there. I just need to copy over the image.

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‫Okay, docker service create name db network backend.

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‫See, one replica.

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‫Oh, I need to do this volume.

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‫Here's the thing about the volume. The -v command is not compatible with docker services. Because, for various

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‫reasons, services are going to be more complex than maybe your typical docker run.

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‫And there were problems and limitations with the -v back in the day.

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‫So, Docker has learned from that and improved the format. But it happens to be a little bit more verbose

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‫and maybe a little bit more difficult to remember the format starting out.

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‫It also happens to be not well documented yet in the Docker Documentation because it's less than

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‫a year old as a command. So, we're going to just copy and paste this. If it doesn't make sense to you,

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‫basically, it's this list of values that are all a part of a single mount command and the minimums are

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‫a type, a source, and a target.

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‫There's also other things you can add on, but these are the only three we need in this scenario.

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‫And you can see my source is just a named volume because I don't have any slashes in it.

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‫And if we had slashes it would have been a bind mount and we would have to had specified a different

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‫type.

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‫So down here, --mount type volume, source db data, target.

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‫I think that's correct.

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‫And then you can just, postgres 9.4.

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‫And then the last one is the result app.

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‫So, docker service create name result network backend.

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‫Publish the port. We’re going to use 5001 to port 80 in the container.

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‫I only can run one of them. By the way, the only reason we're running one of these is actually a little

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‫known issue on this app, is that this is actually using WebSockets, and WebSockets are something that require

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‫a persistent connection.

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‫...

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‫So, in the routing mesh, doesn't really do WebSockets well yet because it's going to keep switching you

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‫back and forth between containers and that WebSocket needs to be to a specific container persistently.

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‫So, with this app what we should have really, is a proxy in front of it but it's not in this app yet so

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‫probably in a later version they'll update it and fix it so that we have a proxy.

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‫That way it can be redundant

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‫and sure you're getting to the right container. We’re going to

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‫copy and paste this to the end. I just realized I'm missing the last value on these.

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‫Okay, and then I’m going to start at the top and just copy and paste. It's already created the networks.

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‫Yes, this needs to be replicas. Let me update that over here.

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‫Replicas. Okay, we’re going to create the redis. There we go.

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‫All right, created that one. Now, you'll notice, by the way, I get back a service ID but it doesn't mean that

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‫the service is actually deployed correctly.

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‫We'll look at that in a minute.

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‫Let me get the rest of these in there.

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‫All right.

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‫Now that we have that, we should be able to do the rest of our commands over here. So, docker service ls shows

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‫us all five of them. And you'll notice that the replica numbers match.

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‫That's a good sign.

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‫That means that one has been created successfully.

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‫And if I wanted to dig in deeper, I could do a docker service ps on each one.

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‫All right, so that one's been running 28 seconds.

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‫redis has been running a minute. db is running 53 seconds. vote.

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‫worker.

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‫And you'll see here in the worker, that we have a failed task that shut down, and then one that's running.

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‫That's been running for 47 seconds.

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‫Okay, so, I actually know why this happened, but you may not know, so maybe we would have to do a logs.

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‫Now this is on node2.

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‫An experimental feature that you can enable through an optional config in Docker, is actually to

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‫do the new experimental feature, docker service logs. Which actually pulls the logs from many different nodes.

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‫Hopefully, it'll be released in the next version of Docker later this year.

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‫But for now, it's experimental. So I had to enable it inside of the etc docker daemon log, or daemon.

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‫json file. And, just so you know, this is how you would enable an experimental.

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‫That's not a part of this.

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‫That's just something I did, just so that I could show this off real quick.

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00:09:00,680 --> 00:09:05,280
‫You might be seeing this error and you’re thinking, I don't know why is that happening?

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00:09:05,390 --> 00:09:16,370
‫We can look at that log. So, we can do a docker service log worker...oops...logs worker.

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‫And this is on, this particular, let’s see, these are two different...

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‫You can see here this is one, and then the number changes. Actually, yeah.

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‫This is all one right here.

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‫It says no such device or address.

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‫So, what this basically means is, I created a service that was looking for a DNS record that didn't

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‫exist because I hadn't created the other service yet. And it did the thing it's supposed to do in

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‫“Dockerland”, which is when it has an error like that, the app should crash because Docker can actually

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‫restart and redeploy things properly until the apps don't crash. And as soon as I get all my services

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‫launched, everything stopped crashing and everything now works.

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‫And we can tell that by just going back and looking at the ps worker. We see that it's been running

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‫successfully for three minutes.

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‫So let's take a look at our app.

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‫If I just pull up the IP address, I should get the dogs and cats.  I'm going to vote cats.

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‫And then if I go to that same IP on port 5001, I should see the results app. That's

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‫the app.

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‫We now know that it's working because the only way that this can change is if this goes all the way

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‫through when it gets caught up by the redis, and then processed by the worker, and then put in the database.

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‫So we know that each of our app services are able to talk to each other. And we can look at the logs

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‫if we wanted to.

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‫But, that's the demo.