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In this video, you'll learn how to run containers in either Docker or Popman.

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So the Popman command on Red Hat is fully compatible with the Docker command.

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And if you're on Red Hat and you want to follow along exactly with the Docker command, there's

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an easy solution, use export alias Docker is Popman.

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And unless you are a very advanced user, you won't notice any difference.

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To run a container, the basic idea is the command Docker run image, where image refers

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to the name of the specific container image that was found on Docker Hub.

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Docker Hub is the standard container registry that Docker is using.

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Check it out on hub.docker.com.

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It has a website that allows you to search for container images.

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The run command is commonly used with options minus D, which runs the container in detached mode.

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Without minus D, it's going to occupy your screen and you don't see anything else.

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Minus IT is commonly used to run a container in interactive terminal mode.

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That is what you want to do if you want to run a shell on the container you just started.

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And to get an overview of all containers that you just started, you use Docker PS, optionally

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with the minus A option, which will also show you containers that have been started in the

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past and which are now no longer running.

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Let me show you.

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So we have already done a Docker run minus D nginx.

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And if at this point I'm using Docker PS, then I can see my currently running container.

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The container has an ID, which I can use for managing.

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It uses standard command, which is normally a script with the name Docker entry point,

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which is going to take care of what exactly you want to do.

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It's exposing its services on the port.

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And it has an automatically generated name that you might want to use for managing.

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If I would use Docker run minus IT BusyBox, then we have another example.

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I'm using the BusyBox container image, which is a commonly used container image.

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It's commonly used because it's so small.

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It's a minimal Linux distribution that fits in just a couple of megabytes.

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Now here you can see that suddenly I'm in a root shell.

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And that is because I'm within the BusyBox container image.

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I would advise if you're ever wondering where you are, check out the OS release file.

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And oh boy, BusyBox is so small, it doesn't even have an OS release.

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OS release is a file that's a Linux Foundation standard.

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It should be there on all Linux distributions to identify the distribution where you are.

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Now here I'm in the shell that was started by BusyBox.

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If I'm going to use exit, I'm exiting that shell.

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But then when I'm using Docker PS, I don't see BusyBox anymore.

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That's because the shell was the primary command.

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And if you exit the container primary command, it's gone.

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So now I need Docker PS minus A.

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And Docker PS minus A is showing all of them, including containers that were exited.

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Now when containers are running, you can manage them.

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In order to do so, there's a couple of commands involved.

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Starting with Docker inspect, which shows properties of your containers.

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Docker stop will stop a running container.

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And Docker exec minus T, container name slash bin slash bash,

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opens a shell in a currently running container.

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And that is useful for debugging.

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Let me show you.

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So I want to inspect my quirky query, which is the nginx container.

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Docker inspect qutab will do it for me.

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And here we can see in JSON format everything that is going on in the container.

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An important part is the path.

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Path is the default application, which was started with these arguments.

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And here you can see that it has started nginx.

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And if you scroll further down, you can find all the properties of the container.

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And that is really useful if your container isn't doing what you want it to do.

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Now this quirky query container is running in the background.

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And I can connect to it using Docker exec minus IT for the interactive terminal on a quirky query.

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And I'm going to run slash bin slash bash.

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Now one thing you should notice, not all containers have bin bash on board.

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Because containers are often used as minimal environments.

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And if it's giving an error message on bin bash, I would advise you use bin sh instead.

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So now I'm inside the container, and I can check, for instance, which processes are running.

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Well, that doesn't work exactly for the simple reason that, as you can see here, the ps command is not found.

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That's the nature of containers.

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Containers are minimal environments.

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They are images that contain what you need to run your application and nothing else.

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So in this case, ps command not found, well, that's not going to work.

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But I can use ls to see files in this container.

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When I use exit, don't worry, you don't shut the container down.

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Look, Docker ps is still showing it.

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I used exit on the Docker exec shell that I just started.

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And this Docker exec shell was a secondary command.

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This doesn't show, so it doesn't shut down the entire container.

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If you want to shut down a container, use Docker stop on your container.

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And now it will go away.

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Let's check that.

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Docker ps doesn't show it anymore.

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And that's exactly what I wanted.

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We also need to talk about accessing container workloads.

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The entry point application, that's a standard application that your container is starting.

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And that can expose a port.

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But this port, by default, is not accessible from the outside,

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because network-wise, containers run in an isolated environment.

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Only root containers will have an IP address on the isolated container network.

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To access a container, you need port forwarding to expose the container port on the host where it is running.

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You do that using a command like docker run minus p 8080 colon 80 nginx,

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which will run the container based on an nginx image and expose the container port on port 8080.

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You cannot expose ports on containers that have already been started.

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Let me show you.

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So I'm going to use docker run minus p 8080 colon 80 nginx.

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Of course, the first port number, that's where you expose your port, needs to be available.

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And oops, let me also use minus d.

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Notice that the arguments for docker run should always be behind docker run and not behind the container name.

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Because if you put the argument behind the name of the container image,

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it's going to be interpreted as an argument for the primary command that your container image is going to run.

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Good. Now when I use docker ps, I can see that it has 0000 8080 forwarding to port 80,

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meaning that if I would use curl to localhost 8080, I'm getting access.

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Oh, no curl? Let's fix that.

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sudo apt install curl.

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And now I'm going to try it again.

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curl localhost, and there we can see welcome to nginx.

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It doesn't give anything cool, but it does prove that the container is accessible.