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Now, obviously docker-compose is a very,

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very useful tool.

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And docker-compose up and down,

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will be our best friends when working with it.

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Now, there are two other commands

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or variations of commands,

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which I want to show you.

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And there's one other thing about the naming

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of these containers and services.

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Now let me start with the commons.

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We saw docker-compose up and down in action.

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Now for the up command,

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we can also use dash dash help.

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We can use this on all Docker-related commands,

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although just on docker-compose,

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but on the up command,

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I want to use it because there's one specific option,

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which we can set, which is interesting.

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And that's the dash dash build option.

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With the dash dash build option add it to the up command,

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you force that images are rebuilt.

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Otherwise, images like this backend image here,

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which we do build based on our own Docker file,

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will only be built once.

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And if docker-composed then finds this image,

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the next time it tries to start all these services,

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it will reuse the existing image.

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This might be what you want

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and often it will not be a problem at all,

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but if you want to force it to rebuild it,

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because for example, you know that something changed

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in code and therefore a new image should be built,

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then you can force docker-compose by adding dash dash build.

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Now, if you just want to build the images defined

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in your docker-compose file,

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and with that I'm of course only referring

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to the images we build with the build key here,

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not to images you point at with image,

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these are images you are pulling from Docker Hub

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or from some other registry

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and therefore they are already build.

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But for your own images,

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if you just want to build any custom images

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to find in a docker-compose file,

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you can do that with docker-compose build.

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Now, when you run up, the build step is included.

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If a image needs to be built

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in order to start the container, it will be built.

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But if you just want to build,

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without starting a container thereafter,

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you could trigger this by running docker-compose build,

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and now it will really just do that,

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build any missing images and then not start containers.

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Just build the images.

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Now, thereafter of course, if I run docker-compose up

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in detached mode, for example, it starts these services,

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it downloads any images that might be missing.

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In my case, I deleted the Mongo image off screen

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and therefore it re-downloads this,

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but it should not rebuild the back-end image, for example,

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because we just built this and as explained a couple

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of minutes ago, docker-compose will only check

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if an image is there locally

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and if it is it will use that and not recreate it.

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Now, I also got one last note here,

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and this is related to the names of the containers,

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which are created and started.

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You can of course see them if you run the Docker PS command.

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You see, we have that running front-end,

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back-end and Mongo container.

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And you can see their names as well.

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The front-end container was named docker-complete_front_1.

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Here's the name of the backend

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and here's the name of the Mongo Db container.

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Now, what you will notice,

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is that these are not the names we defined

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in docker-compose.

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There I specified Mongo Db and back-end

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and front-end as names.

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Well, technically these are just the service names

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and they are translated to containers,

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but these are not the container names therefore.

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These names are just picked up in the container names.

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You see that Mongo Db is part of this last name.

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The full name is actually your folder name,

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your project folder name,

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then an underscore,

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then your service name,

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and then an incrementing number.

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Now, if you wanna assign your own container name,

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you can do this by adding the container name option here.

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And if I would set this to Mongo DB here,

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now I would force this name of the actual container,

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which is up and running to be Mongo Db.

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So if I now run docker-compose down,

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and then we run docker-compose up again,

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you will notice that now,

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if I run Docker PS,

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this Mongo Db container really has a name of Mongo Db.

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Now, I will remove this because I am fine

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with the auto-generated names,

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I just want to show this to you,

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so that you know that you can change these names.

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But that's it with docker-compose for now,

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it's a very powerful tool

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and it allows us to build multi-container applications

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on our local host machine

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and start and control all the containers

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together with one command and one conflict file.