I need to have an ubuntu image and then run a build process using that image. All is well until the build gets to the point of doing docker build etc.
Lets say I use the following to test this:
Dockerfile
FROM ubuntu:latest
I then build that - docker build -t ubuntudkr .
Next, I run it like:
docker run -ti -v /var/run/docker.sock:/var/run/docker.sock ubuntudkr
When I then run docker ps inside this container, I get the error bash: docker: command not found
All the examples I've found says I need to run:
docker run -v /var/run/docker.sock:/var/run/docker.sock \
-ti docker
They all use the docker image which contains the docker library. Is my answer then to install docker inside my base image to make it work? Does this then not go against what docker themselves says?
There are many other blog posts out there that gave the same advice, but my example does work. Where do I go wrong?
Replace the image ubuntu:latest in your dockerfile by the official docker:latest image wich contains docker binaries and does exactly what you want: https://hub.docker.com/_/docker
If you want to keep the Ubuntu image, you must install Docker tools following your error. By default, the Ubuntu image does not contain Docker binaries as a regular Ubuntu installation.
Related
It's CentOS 7, already installed vi and vim in my CentOS and I can use them. I run docker in CentOS, when I excute this line below:
docker exec -it mysolr /bin/bash
I cannot use vi/vim in the solr container:
bash: vim: command not found
Why is that and how do I fix it so I can use vi/vim to edit file in docker container?
A typical Docker image contains a minimal set of libraries and utilities to run one specific program. Additionally, Docker container filesystems are not long-lived: it is extremely routine to delete and recreate a container, for instance to use a newer version of a base image.
The upshot of this is that you never want to directly edit files in a Docker container, and most images aren't set up with "rich" editing tools. (BusyBox contains a minimal vi and so most Alpine-based images will too.) If you make some change, it will be lost as soon as you delete the container. (Similarly, you usually can install vim or emacs or whatever, but it will get lost as soon as the container is deleted: installing software in a running container isn't usually a best practice.)
There are two good ways to deal with this, depending on what kind of file it is.
If the file is part of the application, like a source file, edit, debug, and test it outside of Docker space. Once you're convinced it's right (by running unit tests and by running the program locally), docker build a new image with it, and docker run a new container with the new image.
ed config.py
pytest
docker build -t imagename .
docker run -d -p ... --name containername imagename
...
ed config.py
pytest
docker build -t imagename .
docker stop containername
docker run -d -p ... --name containername imagename
If the file is configuration that needs to be injected when the application starts, the docker run -v option is a good way to push it in. You can directly edit the config file on your host, but you'll probably need to restart (or delete and recreate) the container for it to notice.
ed config.txt
docker run \
-v $PWD/config.txt:/etc/whatever/config.txt \
--name containername -p ... \
imagename
...
ed config.txt
docker stop containername
docker rm containername
docker run ... imagename
I am using ubuntu 18.04
I have docker-ce installed
I have a file named Dockerfile
I didn't have any other files
how can I start using this container
Firstly you need to build an image from Dockerfile. To do this:
Go to the directory containing Dockerfile
Run (change <image_name> to some meaningful name): docker build -t <image_name> .
After image is built we can finally run it: docker run -it <image_name>
There multiple options how the image can be run so I encourage you to read some docs.
I'm learning how to use docker.
I want to deploy a microservice for swagger. I can do
docker pull schickling/swagger-ui
docker run -p 80:8080 -e API_URL=http://myapiurl/api.json swaggerapi/swagger-ui
To deploy it, I need a dockerfile i can run.
How do i generate the dockerfile in a way I can run it with docker build ?
The original question asks for a Dockerfile, perhaps for some CI/CD workflow, so this answer addresses that requirement:
Create a very simple Dockerfile beginning with
FROM schickling/swagger-ui
Then from that directory run
$ docker build -t mycontainername .
Which can then be run:
$ docker run -p 80:8080 -e API_URL=http://myapiurl/api.json mycontainername
Usually the docker pull pulls the Dockerfile. The Dockerfile for swagger is on the docker repo for it if you wanted to edit it or customize it.
(https://hub.docker.com/r/schickling/swagger-ui/~/dockerfile/)
That one should work with the build command. The build command builds the image, the run command turns the image into a container. The docker pull command should pull the image in. You don't need to run docker build for it as you should already have the image from the pull. You only need to do docker run.
I am trying to build a new docker image using docker provided base Ubuntu image. I'll be using docker file to run few scripts and install applications on the base image. However my script requirement is that the hostname should remain same. I couldn't find any information on OS names for docker images. Does anybody has an idea that once we add layers to a docker image does the OS name remains same.
You can set the hostname with the -h argument to Docker run, otherwise it gets the short form of the container ID as the hostname:
$ docker run --rm -it debian bash
root#0d36e1b1ac93:/# exit
exit
$ docker run --rm -h myhost -it debian bash
root#myhost:/# exit
exit
As far as I know, you can't tell docker build to use a given hostname, but see Dockerfile HOSTNAME Instruction for docker build like docker run -h.
I am getting into Docker and am trying to better understand how it works out there in the "real world".
It occurs to me that, in practice:
You need a way to version Docker images
You need a way to tell the Docker engine (running on a VM) to stop/start/restart a particular container
You need a way to tell the Docker engine which version of a image to run
Does Docker ship with built-in commands for handling each of these? If not what tools/strategies are used for accomplishing them? Also, when I build a Docker image (via, say, docker build -t myapp .), what file type is produced and where is it located on the machine?
docker has all you need to build images and run containers. You can create your own image by writing a Dockerfile or by pulling it from the docker hub.
In the Dockerfile you specify another image as the basis for your image, run command install things. Images can have tags, for example the ubuntu image can have the latest or 12.04 tag, that can be specified with ubuntu:latest notation.
Once you have built the image with docker build -t image-name . you can create containers from that image with `docker run --name container-name image-name.
docker ps to see running containers
docker rm <container name/id> to remove containers
Suppose we have a docker file like bellow:
->Build from git without versioning:
sudo docker build https://github.com/lordash/mswpw.git#fecomments:comments
in here:
fecomments is branch name and comments is the folder name.
->building from git with tag and version:
sudo docker build https://github.com/lordash/mswpw.git#fecomments:comments -t lordash/comments:v1.0
->Now if you want to build from a directory: first go to comments directory the run command sudo docker build .
->if you want to add tag you can use -t or -tag flag to do that:
sudo docker build -t lordash . or sudo docker build -t lordash/comments .
-> Now you can version your image with the help of tag:
sudo docker build -t lordash/comments:v1.0 .
->you can also apply multiple tag to an image:
sudo docker build -t lordash/comments:latest -t lordash/comments:v1.0 .