A container is a runtime instance of an image.
/var/lib/docker/
/var/lib/docker/
/var/lib/docker/
C:\ProgramData\DockerDesktop
~/Library/Containers/com.docker.docker/Data/vms/0/
docker info | grep -i root
command to findout:CMD ["executable","param1","param2"]
(exec form, this is the preferred form)CMD ["param1","param2"]
(as default parameters to ENTRYPOINT)CMD command param1 param2
(shell form)CMD
instruction in a Dockerfile
. If you list more than one CMD
then only the last CMD
will take effect./
, as the PATH
as it causes the build to transfer the entire contents of your hard drive to the Docker daemon..
as the build context which means the current directory. If you put the Dockerfile inside another directory like /src/Dockerfile, then the context will be ./src
. The build process may take some time to finish:Successfully built fc32da11d651
at the end. This random string is the image id and not container id. try docker image inspect <image id>
to get information about this image , also to see layers which our image includes try docker image history <image id>
:docker images
which is deprecated somehow.docker pull :
docker images
command to locate the ID of the images you want to remove. When you’ve located the images you want to delete, you can pass their ID or tag to docker rmi
:--force
for removing that but the stopped container(s) will be removed too!-f
with a value of dangling=true
to the docker images
command. When you’re sure you want to delete them, you can use the docker images purge
command:docker image prune -a
will remove all images with out at least one container associate with them, the good news about this is that if you have images that are being used by containers those images won't be deleted.f1477ec11d12
. It’s just a way of referring to your image. A good analogy is how Git tags refer to a particular commit in your history..
at the end does). Next, we tell the Docker daemon to build the image and give it the specified tag.If you need to push your image to a registry usedocker build -t username/image_name:tag_name .
:1[[email protected] sandbox]# docker build -t borosan/myapp:final .2Sending build context to Docker daemon 14.85kB3Step 1/3 : FROM ubuntu4---> adafef2e596e5Step 2/3 : LABEL Description="test image" Vendor="ACME Products"6---> Using cache7---> bdeb04e9a9318Step 3/3 : RUN apt-get update && apt-get install -y nginx openssh-server9---> Using cache10---> fc32da11d65111Successfully built fc32da11d65112Successfully tagged borosan/myapp:final1314[[email protected] sandbox]#15[[email protected] sandbox]# docker image ls16REPOSITORY TAG IMAGE ID CREATED SIZE17borosan/myapp final fc32da11d651 23 minutes ago 233MB18myapp final fc32da11d651 23 minutes ago 233MB19redis latest 50541622f4f1 4 days ago 104MB20ubuntu latest adafef2e596e 2 weeks ago 73.9MB21nginx latest 9beeba249f3e 2 months ago 127MB22hello-world latest bf756fb1ae65 6 months ago 13.3kBCopied!
tag
command:TARGET_IMAGE
that refers to the SOURCE_IMAGE.
That’s all it does. It’s like assigning an existing image another name to refer to it. Notice how the tag is specified as optional here as well, by the [:TAG]
:latest
tag comes into the picture. Whenever an image is tagged without an explicit tag, it’s given the latest
tag by default. It’s an unfortunate naming choice that causes a lot of confusion. But I like to think of it as the default tag that’s given to images when you don’t specify one.docker login localhost:5000
.docker search
command does for us:--limit
flag limits the maximum number of results returned by a search.docker save
command. For example, lets save a local copy of the myapp
docker image we made:docker save
- saves a non-running container image to a filedocker export
- saves a container’s running or paused instance to a fileload
command creates a new image including its history.
Importing a container as an image using the import
command creates a new image excluding the history which results in a smaller image size compared to loading an image.