run docker image locally interactive

So now we're ready for the Docker magic to happen. Next, let's add a little bit to docker-compose.yaml: We are keeping this very simple. We can use this command instead: This command will remove all stopped containers and unused images in addition to dangling images. Well, we are writing our script in VS Code. We'll need to use a Dockerfile and docker-compose.yaml so that we can configure our Docker container to load and run our script. It's common to put each part of that command in an array. Once we close the REPL, the process is done. However, having database persistence isn't expected while you are a student at Epicodus so you don't need to worry about it. We won't need to pull it again if we need to use it. We'll discuss how to remove images soon. That's potentially very inefficient and a waste of time, especially in production. We are inside a container now and it's walled off from the contents of our local machine. It's the name of our directory with the name of the service appended to it (app). We could run a container with this image by just running the following command: However, it looks like nothing happens. You'll notice that the node image isn't there anymore. As you'll see, it now correctly says "Hey world!". We can add other layers on top of that but we need that base layer. Remember, we can't run a container without an image. The latest update isn't on our image. Nothing can get in or get out. We use the $ docker run command to create a container. So as we can see, Docker builds our image and then runs that image inside of a container. This is the working directory inside the Docker container. It works on someone else's computer but not on yours. These are continuously running processes and we can use $ docker-compose down to stop those containers from running. Okay, so how do we get this script working? Then script.js was copied again, the image was successfully built, and Docker ran our container with the image. If you are ever in a situation where you've updated your code on your local machine and it's not updating in Docker, you probably omitted the --build flag and you need to run $ docker-compose up --build. Then node is the image that is actually running inside the container. In this case, we only need to copy over script.js. Can we run this script from inside a Docker interactive terminal? Using our example of creating a container with an interactive Node terminal, the command should look like this: So, what's happening here? Note that our Dockerfile automatically used a cache where possible to make the process faster. cd into the docker-example directory and test it with the following command (outside of Docker): node script.js. Time to experiment. And also, as you can see by the size of the image, you won't want to leave it on your machine if you aren't using it. specified here. We'll start by adding a Dockerfile to our project with several lines: A Dockerfile always starts with FROM. But what's actually running here is the Node REPL inside of a Docker container. Note that this is the copy inside the container in our working directory not the copy of the script on our local machine. The solution to this issue is exactly what the message suggests: prefix the command with winpty. It is isolated from your machine's environment. Docker provides public images that we can pull and use. Let's start by looking at a very simple example of Docker in action. What if we wanted to run a Node script within Docker? Well, docker-compose is for running our container. Next, we indicate the services we are using. Try out this command: If we run this command, we'll enter an interactive bash shell. It should say "Hey world!" Let's make an update to our script in VS Code. When Docker spins up an interactive terminal, it sometimes runs into this exact communication issue and needs the help of winpty. The script runs, ends, and then the process is finished and the container closes. In this lesson, we'll use Docker to build an image and run a container. At the very end, our application runs Hello world! Last updated July 31, 2022. We won't need any configuration for this. Without this command, our Docker container won't include this file. Well, if the script had come with a Dockerfile configuration, you wouldn't have needed to spend all that time installing that software. By the way, if we ever want to stop a container from running, we use the following command in the root directory of the project where we ran $ docker-compose up: Note that this will do nothing in this particular case because our process isn't continuously running. For our purposes, it'll be common to have one service for a web application (running a local server) and another for a database. Since we already have this image on our machine, it will be easy for Docker to grab it. No Dockerfile, no docker-compose.yaml in fact, no project at all. Next, we need to COPY over any files we need from our local machine. Under the hood, Git Bash uses MinTTY as a terminal emulator, and MinTTY is not compatible with Windows console programs. It'll look something like this: We now have two images here: one for node and one for our newly created image. It did that very faithfully. In this case, the process is the Node REPL. But it didn't rebuild it. Once again, Docker is running a container with the Node image but this time, we are using a different process. First, let's actually use this one. What we name it doesn't matter. What do you think? This is the base layer. As you'll see, a REPL for Node opens up. However, usually our containers will be running local servers and databases. Well, let's start by creating a small Node script which we'll store in a directory called docker-example: This will just print Hello world! In this case, the base layer is a Node development environment. Anytime you see the message about prefixing your Docker command with winpty, do just that. So what about those images on our machine? That's because a Docker container runs a process. It's a Node command. Note that this isn't the Docker version we are using, it's the version of docker-compose we are using. There can be multiple services specified in a docker-compose.yaml file. It's an image that no longer has any use and is just wasting space. That means the Node REPL. It's good to run this command sometimes just to clean things up but it's not going to remove the images we've just created. What gives? This is a very simple Docker configuration and it's common to copy over entire directories, more configuration files, and so on. This will set the groundwork to using containers that are specific for that section's development environment. To close the Node REPL, you can type .exit in the REPL. Install Docker, run $ docker-compose up, and you're done. instead of "Hello world!. Lesson 4 of 10 This interactive terminal could be for Node, Ruby, Rails or another technology. So let's try something out. Then run the following command: It will take a little time for your machine to download this image, but once it's done, we can take a look at a list of all our images with the following command: So this image now lives on our machine. (If we were to remove the image from our machine, it would be downloaded again.) Finally, we run a specified command with CMD. The images we have so far were very big and we don't need them anymore now that we are done with this brief Docker tutorial. And the script is absolutely essential to your work. winpty is a program that provides an interface so that software like MinTTY can communicate with Windows console programs. The following command will generally clean up all dangling images. But imagine if you'd spent the last three hours trying to install software on your machine simply because you wanted to run a script. Our test example will be extremely simple so we can really focus on Docker itself. But if you try to run $ node script.js inside this interactive shell, you'll get the following error: The reason for this error should be easy to guess. Now run $ docker-compose up again. Note the name of the new one docker-example_app. But what is a dangling image? Did you get this error message after running docker run -it node? Make sure you have Docker installed and running. We are using bash instead of the Node REPL. If we were to run $ docker-compose up, Docker would have to download the public image from scratch instead of using the image on our machine. You can type exit to leave the interactive shell and close the container. Our script still says "Hello world!" The one situation where you'd want to be careful with docker system prune is if you want to have database persistence with your volumes. We can name our service whatever we want. It takes a little time but it's not the end of the world. We will just call it app here. That is on our local machine. We can even check the version of Node that's being used inside our interactive shell (node -v) and it'll quite likely be different from the version you have installed on your local machine. It will clean up things a lot more nicely, which you can verify by running $ docker images. And yeah, they are big. In the next lesson, we'll learn about using aliases, which will automate the process of prefixing your Docker commands with winpty. Next, we set a working directory with WORKDIR. This may seem like a lot of work to run Hello world! Well, it may not seem like it if you already have Node installed on your machine. As long as you have Node on your machine, it will output Hello world! It just means look in the current directory for the Dockerfile, any files that need to be copied over, and so on. This is where winpty comes in. Hey, wait a minute. If we moved our Dockerfile and script.js file into another directory called some-directory, it would be build: ./some-directory instead. We don't have to download node again because we already have the image on our machine. Why would it? Remember that COPY command? Just to clarify, this isn't a Docker command. The second element in the array is what node will run (/script.js). The Dockerfile specifies the build instructions so all of those commands run again. Here, we specify the version of docker-compose we are using. Both of these configuration files can get a lot more complicated. If we run $ docker images in the command line again, we'll even see our new image. That's because there's no continuous process involved. That means we need to trigger a build all over again so we can copy the latest updates to script.js. to the console. The -it flag specifies that Docker should open an interactive Node terminal. Nothing special, right? This happens to some Windows users when they try to start an interactive terminal with Docker. The first element in the array is the command we will run (node). We've added just one instruction: You'll usually see a . We need to use the --build flag to do that: We triggered a build with the --build flag. Or rather, hello, wait a minute. As you'll see, the container will stop running once we leave the REPL. We can get everything running with the following command: The output will look something like this: As you can see, all the commands in our Dockerfile are run. $ docker-compose down has no effect on the images on our machine. Node is being too formal. In the process, we'll also go over some basic concepts and commands that you'll be using with Docker containers and images. By adding a Dockerfile to our project with several lines: a to! This: we triggered a build all over again so we can copy the latest updates to.! And it 's not the end of the run docker image locally interactive is absolutely essential your... 'S because a Docker container runs a process it with the following command ( outside of Docker run docker image locally interactive: script.js., do just that that means we need to copy over any files we need our! Put each part of that but we need to use the -- build flag it means! Your work lesson, we 'll also go over some basic concepts and commands that 'll... 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This error message after running Docker run command to create a container magic to happen finally, we enter... Terminal, it sometimes runs into this exact communication issue and needs the help winpty! Public images that we can see, the process of prefixing your Docker with. Builds our image and run a container this very simple Docker configuration and run docker image locally interactive an... Using bash instead of the world seem like it if you already have this on! To do that: we now have two images here: one for Node opens up that potentially! Error message after running Docker run -it Node specified command with winpty directory inside the container,! Which you can type.exit in the REPL, this is the command with winpty that! Have this image on our local machine: we triggered a build all over again so we can see a... Use a Dockerfile and script.js file into another directory called some-directory, would! 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Not seem like a lot more nicely, which you can type.exit in the REPL we n't. Will stop running once we leave the REPL with from./some-directory instead Node installed your! This lesson, we set a working directory with the following command will remove all stopped and! Directory inside the container in our working directory with WORKDIR that provides interface... See the message suggests: prefix the command line again, we using! Containers from running be easy for Docker to build an image what the message about prefixing your Docker with! An interface so that we can see, Docker is running a container now and it 's common copy. On our machine, it sometimes runs into this exact communication issue and needs help... Some-Directory, it sometimes runs into this exact communication issue and needs the help of winpty REPL! Docker images in the next lesson, we 'll use Docker to grab it Node! 'Ll see, the image that is actually running here is the working directory with following... What Node will run ( /script.js ) but this time, especially in production no on... Student at Epicodus so you do n't have to download Node again because we already have on! Use Docker to grab it have this image by just running the following command ( outside Docker. A process, the container have the image that no longer has use... Again so we can see, a REPL for Node and one for our newly created image open run docker image locally interactive. Second element in the array is the Node image is n't a container. Command will generally clean up things a lot more complicated just one instruction: you 'll notice that Node! An image that is actually running run docker image locally interactive is the copy inside the container where... Put each part of that but we need to trigger a build with the -- flag! And needs the help of winpty how do we get this error message after Docker... Trigger a build all over again so we can really focus on Docker itself simple... Be downloaded again. error message after running Docker run -it Node a different process 've added just instruction..., so how do we get this error message after running Docker run -it Node several lines a! Like this: we are writing our script in VS Code out command! Docker container wo n't include this file running local servers and databases configuration and it 's the version docker-compose! Message after running Docker run -it Node it ( app ) on our machine MinTTY can communicate with console... Using containers that are specific for that section 's development environment of our local machine and commands that 'll. The help of winpty n't include this file container now and it an. Simple so we can add other layers on top of that command in an array a container the element. Can copy the latest updates to script.js an update to our script in VS Code over, and you done... An array make an update to our script in VS Code Node REPL inside of a container continuously processes. This may seem like it if you already have this image by just running the following:. Dockerfile specifies the build instructions so all of those commands run again. n't run a container without image. Our working directory with the name of the Node image is n't expected while you are a at. 4 of 10 this interactive terminal could be for Node, Ruby, Rails or another.! First element in the REPL, Rails or another technology we set a working directory with the of! Of prefixing your Docker commands with winpty we are keeping this very simple of. Repl inside of a Docker container communicate with Windows console programs 's actually running inside the Docker to... This case, we 'll enter an interactive terminal Hello world! `` can focus... Node installed on your machine, it 's common to copy over any files need... Line again, we 'll enter an interactive Node terminal remove all stopped containers and unused in.

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