Can we run a container, install software dependencies, and then use the updated container without building again the image?
You can re-use the container on the system you created it on until you delete the container, even if you exit the container. You can give the container a name at the time you first run it; e.g.:
docker run -it --name my-container ubuntu
After you exit, you can restart and reattach to the container with:
docker start my-container && docker attach my-container
Note that if you docker run with the --rm option, the container is deleted when you exit, and so you won't be able to restart it.
If you wish to turn the current state of your container (with all of its installed software dependencies, etc) into a new docker image that you can docker run or even docker push to Dockerhub, etc., you can do that with:
docker commit my-container my-image[:<tag>]
At that point,
docker run -it --rm my-image
will create and run a new container that starts from the state your original container was in when it was committed. It's exactly the same as if you had built the new image from a Dockerfile that had run all the commands you issued in the container before it was committed.
Having said all that, it's generally a better idea to build your desired docker image using a Dockerfile, because then the build steps are repeatable, and you can make changes to the build steps (e.g., what prerequisites are needed) without having to start from scratch.
I am trying to start a docker container using the ubuntu image:
docker container run -d --name ubuntu_assignment_4 6e4f1fe62
However as soon as I start the container it stops again.
Why does this happen and how can I ensure the container stays running?
The image I am trying to run here is: ubuntu:14.04
If you are going to use the ubuntu:14.04 image without any modifications to it, you would not require a separate Dockerfile. And it is not possible to keep the plain ubuntu:14.04 image running as a container.
You can directly launch the container with an interactive shell using the ubuntu:14.04 image.
docker run -it ubuntu:14.04 /bin/bash
But the plain ubuntu:14.04 image does not have curl pre-installed on it.
You will need a custom Dockerfile for this.
I can't say exactly what is happening without seeing the complete Dockerfile that was used to build the image, but I am pretty certain that the trouble you are having is just because whatever task that is being started inside the container is finishing and exiting.
Docker containers work by having some command assigned (using ENTRYPOINT or CMD directives in the Dockerfile, or as an argument to docker start or docker run on the command line) which is the program that is started when the container loads. The container will live for as long as that task continues to run, and once that program finishes the container will terminate.
To specify the startup entrypoint at the command line, try:
docker create -it [image] /bin/bash
Then start it like this:
docker start -ia [Container ID]
The container will exit once the shell exits, because this is assigning the shell as the entry point.
cURL may not be installed by default. It is possible to install it using apt-get. But again, once the shell is closed, the container will stop and any changes will be lost. As a start, try creating a new directory somewhere, and then add a file called Dockerfile with this content:
FROM ubuntu:latest
RUN apt-get update && apt-get install -y curl
ENTRYPOINT ["/bin/bash"]
That will create a new image with curl installed. then, from inside the new directory where the Dockerfile was created, use:
docker build .
docker images
which will build a new image, using the Dockerfile as the blueprint.
Once the build finishes, find the image ID for the new container, and run it using:
docker run -it [image id]
Ultimately, to make Docker really useful, the typical approach is to replace that last line in the Dockerfile (ENTRYPOINT ["command"]) with something that will continue running forever (like ENTRYPOINT ["apache2"] or ENTRYPOINT ["redis"] or similar). If you have experience using regular desktop/server OS installs, and full virtual machines like VMWare or VirtualBox, just remember that Docker is very different; the way it works and the patterns used to deploy it are not the same.
I am new to docker container. Can someone please tell me what is difference between these two commands. In my knowledge, have the same out put than why we use the bash command.
docker run -it ubuntu
docker run -it ubuntu bash
In docker, we run a linux container. As you know, a linux system is alive when it's init 0 service is alive. 'init 0' is kind of the heart of a linux system. when 'init 0' is killed, the linux system also dies.
In a containerized architecture, you run a container for simply one purpose i.e. to simply run one service. we want if the service fails, the container also dies. so we define the servcie as init 0 job for the container.
when you run docker run -it ubuntu bash, here, bash is the init 0 job for the container. As soon as you exit from bash, the container stops working.
Instead of using bash you can also try another commands like #Shmuel suggested.
Well, when we create custom images, often we want to pre-define default 'init 0' job for our custom image. If the init 0' is predefined, you don't need to mention it in docker run command.
In ubuntu image, the pre-defined 'init 0' job is bash. So, if you don't mention bash in the run command, it works the same.
docker run -it ubuntu let's you run command inside the container.
The bash is the command to run.
For example instead you can run
docker run -it ubuntu ls /home
This will list the /home dir inside the container.
The tensorflow docker container is available at https://hub.docker.com/r/tensorflow/tensorflow/ to extend this container with additional libraries such as requests I'm aware of two options.
Run the container and run pip install requests
Append pip install requests to the dockerFile that builds this container
Is there an alternative option ? Something like creating the tensorflow/tensorflow container from a dockerFile and then installing requests on this container.
Reading How to extend an existing docker image? to accomplish this create a dockerFile with these contents ? :
FROM tensorflow/tensorflow
RUN pip install requests
Your original assertion is correct, create a new Dockerfile:
FROM tensorflow/tensorflow
RUN pip install requests
now build it (note that the name should be lower case):
docker build -t me/mytensorflow .
run it:
docker run -it me/mytensorflow
execute a shell in it (docker ps -ql gives us an id of the last container to run):
docker exec -it `docker ps -ql` /bin/bash
get logs from it:
docker logs `docker ps -ql`
The ability to extend other images is what makes docker really powerful, in addition you can go look at their Dockerfile:
https://github.com/tensorflow/tensorflow/tree/master/tensorflow/tools/docker
and start from there as well without extending their docker image, this is a best practice for people using docker in production so you know everything is built in-house and not by some hacker sneaking stuff into your infrastructure. Cheers! and happy building
you could enter the running container via:
docker exec -it CONTAINER_ID bin/bash
or if a name is set:
docker exec -it CONTAINER_NAME bin/bash
I tried to start a exited container like follows,
I listed down all available containers using docker ps -a. It listed the following:
I entered the following commands to start the container which is in the exited stage and enter into the terminal of that image.
docker start 79b3fa70b51d
docker exec -it 79b3fa70b51d /bin/sh
It is throwing the following error.
FATA[0000] Error response from daemon: Container 79b3fa70b51d is not running
But when I start the container using docker start 79b3fa70b51d. It throws the container ID as output which is normal if it have everything work normally.
What is the cause of this error?
By default, docker container will exit immediately if you do not have any task running on the container.
To keep the container running in the background, try to run it with --detach (or -d) argument.
For examples:
docker pull debian
docker run -t -d --name my_debian debian
e7672d54b0c2
docker ps -a
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
e7672d54b0c2 debian "bash" 3 minutes ago Up 3 minutes my_debian
#now you can execute command on the container
docker exec -it my_debian bash
root#e7672d54b0c2:/#
Container 79b3fa70b51d seems to only do an echo.
That means it starts, echo and then exits immediately.
The next docker exec command wouldn't find it running in order to attach itself to that container and execute any command: it is too late. The container has already exited.
The docker exec command runs a new command in a running container.
The command started using docker exec will only run while the container's primary process (PID 1) is running
If it's not possible to start the main process again (for long enough), there is also the possibility to commit the container to a new image and run a new container from this image. While this is not the usual best practice workflow (the new image is not repeatable), I find it really useful to debug a failing script once in a while.
docker exec -it 6198ef53d943 bash
Error response from daemon: Container 6198ef53d9431a3f38e8b38d7869940f7fb803afac4a2d599812b8e42419c574 is not running
docker commit 6198ef53d943
sha256:ace7ca65e6e3fdb678d9cdfb33a7a165c510e65c3bc28fecb960ac993c37ef33
docker run -it ace7ca65e6e bash
root#72d38a8c787d:/#
This happens with images for which the script does not launch a service awaiting requests, therefore the container exits at the end of the script.
This is typically the case with most base OS images (centos, debian, etc.), or also with the node images.
Your best bet is to run the image in interactive mode. Example below with the node image:
docker run -it node /bin/bash
Output is
root#cacc7897a20c:/# echo $SHELL
/bin/bash
First of all, we have to start the docker container
ankit#ankit-HP-Notebook:~$ sudo docker start 3a19b39ea021
3a19b39ea021
After that, check the docker container:
ankit#ankit-HP-Notebook:~$ sudo docker ps -a
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
3a19b39ea021 coreapps/ubuntu16.04:latest "bash" 13 hours ago
Up 9 seconds ubuntu1
455b66057060 hello-world "/hello" 4 weeks ago
Exited (0) 4 weeks ago vigorous_bardeen
Then execute by using the command below:
ankit#ankit-HP-Notebook:~$ sudo docker exec -it 3a19b39ea021 bash
root#3a19b39ea021:/#
Here is what worked for me.
Get the container ID and restart.
docker ps -a --no-trunc
ace7ca65e6e3fdb678d9cdfb33a7a165c510e65c3bc28fecb960ac993c37ef33
docker restart ace7ca65e6e3fdb678d9cdfb33a7a165c510e65c3bc28fecb960ac993c37ef33
docker run -it --entrypoint /bin/bash <imageid>
This was posted by L0j1k in the below post and worked for me.
How do I get into a Docker container's shell?
use command
> docker container ls
> docker image ls
Check your Image id and note it down. Here my Image id is "6c929ca002da" , you guys have to use your own Image id instead of mine..
> docker start 6c929ca002da
here our image is in down mode we have to start it first by using image id.
6c929ca002da is my image id
> `docker exec -it 6c929ca002da bash`
after running this command you can see
your image file in running mode like this
root#6c929ca002da
Here I am using root mode go root mode by using command
sudo su
The reason is just what the accepted answer said. I add some extra information, which may provide a further understanding about this issue.
The status of a container includes Created, Running, Stopped,
Exited, Dead and others as I know.
When we execute docker create, docker daemon will create a
container with its status of Created.
When docker start, docker daemon will start a existing container
which its status may be Created or Stopped.
When we execute docker run, docker daemon will finish it in two
steps: docker create and docker start.
When docker stop, obviously docker daemon will stop a container.
Thus container would be in Stopped status.
Coming the most important one, a container actually imagine itself
holding a long time process in it. When the process exits, the
container holding process would exit too. Thus the status of this
container would be Exited.
When does the process exit? In another word, what’s the process, how did we start it?
The answer is CMD in a dockerfile or command in the following expression, which is bash by default in some images, i.e. ubutu:18.04.
docker run ubuntu:18.04 [command]
docker run -it <image_id> /bin/bash
Run in interactive mode executing then bash shell
For anyone attempting something similar using a Dockerfile...
Running in detached mode won't help. The container will always exit (stop running) if the command is non-blocking, this is the case with bash.
In this case, a workaround would be:
1. Commit the resulting image:
(container_name = the name of the container you want to base the image off of,
image_name = the name of the image to be created
docker commit container_name image_name
2. Use docker run to create a new container using the new image, specifying the command you want to run. Here, I will run "bash":
docker run -it image_name bash
This would get you the interactive login you're looking for.
Here's a solution when the docker container exits normally and you can edit the Dockerfile.
Generally, when a docker container is run, an application is served by running a command. From the Dockerfile reference,
Both CMD and ENTRYPOINT instructions define what command gets executed when
running a container. ...
Dockerfile should specify at least one of CMD or ENTRYPOINT commands.
When you build a image and not specify any command with CMD or ENTRYPOINT, the base image's CMD or ENTRYPOINT command would be executed.
For example, the Official Ubuntu Dockerfile has CMD ["/bin/bash"] (https://hub.docker.com/_/ubuntu). Now, the bin/bash/ command can accept input and docker run -it IMAGE_ID command attaches STDIN to the container. The result is that you get an interactive terminal and the container keeps running.
When a command with CMD or ENTRYPOINT is specified in the Dockerfile, this command gets executed when running the container. Now, if this command can finish without requiring any input, it will finish and the container will exit. docker run -it IMAGE_ID will NOT provide the interactive terminal in this case. An example would be the docker image built from the Dockerfile below-
FROM ubuntu
ENTRYPOINT echo hello
If you need to go to the terminal of this image, you will need to keep the container running by modifying the entrypoint command.
FROM ubuntu
ENTRYPOINT echo hello && sleep infinity
After running the container normally with docker run IMAGE_ID, you can just go to another terminal and use docker exec -it CONTAINER_ID bash to get the container's terminal.
Perhaps too late for this active community, but there are a lot of causes because a container may not execute correctly and exit writing a console message or not. For all the newbies making nodeJS containers I'll recommend you to change the Dockerfile and erase all CMD and ENTRYPOINT you may have, and add only an ENTRYPOINT to ["/bin/sh"] (See my attached test Dockerfile example). Then rebuild the Docker image and run it with the command:
docker run -it --rm your_named_image:tag
Voilà you will be getting inside the container with a shell. Then you can test your app typing the command yourself i.e. node app.js and see what is happening. After you see all is ok, you can then change your docker file and erase the ENTRYPOINT to "/bin/sh" and use yourself i.e ["node","app.js"] or whatever. Always consider the previous answers to this post; When the app inside the container finish it will stop the running container.
Here is an example for my "test" Dockerfile:
FROM node:16.4.0-alpine
ENV NODE_ENV=production
WORKDIR /app
COPY ["package.json","package-lock.json*", "./"]
RUN npm install --production
COPY ./dist .
ENTRYPOINT ["/bin/sh"]
NOTE: My source files for the app (.js) on the local computer are on directory ./dist, so I have to copy at the container as you can see.
In my case , i changed certain file names and directory names of the parent directory of the Dockerfile . Due to which container not finding the required parameters to start it again.
After renaming it back to the original names, container started like butter.
I have a different take on this. I could do a docker ps and see that there is a docker container running, I even tried to restart it, but as soon as I tried to get a session for it with New-PSSession -ContainerId $containerId -RunAsAdministrator It would error out, saying:
##[error]New-PSSession : The input ContainerId xxx does not exist,
##[error]or the corresponding container is not running.
My problem was I was running with network service and it did not have enough permissions to see the container, even though I had given it permissions to run docker commands (with docker security group configuration)
I didn't know how to enable working with containers, so I had to revert to running it as an admin user instead
In my case, I had previously killed the running container with,
sudo docker kill testdeb
So when I exec the container I got the error,
Error response from daemon: Container fcc29295fe78a425155c533506f58fc5b30a50ee9eb85c21031e8699b3f6ff01 is not running
The solution was to start the container with,
sudo docker start testdeb
Now I have a container running ,
sudo docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
fcc29295fe78 debian "bash" 9 hours ago Up 11 seconds testdeb
Which wasn't previously running
The below approach I tried works in an windows vscode environment.
docker run --name yourcontainer -p 3306:3306 -e MYSQL_ROOT_PASSWORD=your password -d mysql
I see lot of similar answers but adding port number '-p 3306:3306', made the status up and running. You can verify by using the command docker ps -a