I have pulled an image from the docker hub. I want to modify the docker file for this image. Where is the docker file located on my Machine? Thanks.
The Dockerfile isn't on your machine. Once the image is built, it exists independently of the Dockerfile, just like a compiled C program doesn't need its source code kept around to function. You can partially recover the Dockerfile via the docker history command, but this won't show you files added with ADD or COPY, and various "image squishing" programs can further obfuscate things. The recommended way to get an image's Dockerfile is to go to the repository from which the image was built (hopefully linked from the image's Docker Hub page). If there's no public repository, you're out of luck.
I'm not sure if this helps, I'm a noob in this.
Pulling an image alone is going to download the image alone, without the supplementary files. If you need those, please go to the Github webpage where the image is (if you got it from Github), then push clone or download button on the right. If you have no access to webpages (on a VM for instance), install 'developer tools' and then write 'git clone ' where is the link that appears after pressing clone or download.
If you check the directory where you cloned the link, you'll find all the files you need.
Related
I am quite newbie in docker, and I am trying to find the way to tell version for a docker hub tagged image.
For instance, the jenkins/jenkins:lts-latest image, listed here https://hub.docker.com/r/jenkins/jenkins/tags/, what image version does actually aliase? And how can I infer the correspondent dockerfile/branch in jenkins repo?
I tried with docker search but I couldn't. I tried also to find a clue in the official Jenkins github dockerfile repo: https://github.com/jenkinsci/docker, but I don't see any bindung tag or anything that gives me a hint on the source of the image
Another example, I have a Kubernetes cluster, and when I check my Nexus pod, I see likewise that the image is defined as sonatype/nexus3:latest.
In this case at least I have the imageID: docker-pullable://sonatype/nexus3#sha256:434a2564aa64646464afaf.. but once again I don't know how to map it to the actual version of the software
For the repo you asked, the answer is No.
When setup repo on dockerhub, there are two kinds of options for user to choose as follows:
1) Create Repository:
In this way, dockerhub just create a repo for user, and user need to build his own image on local server, tag it, and push it to dockerhub.
When user push his image to dockerhub, no additional information about the source version will be appended, so can't get any source map from dockerhub.
jenkins/jenkins, just this kind of repo.
2) Create Automated Build
In this way, dockerhub will fetch the code from github or bitbucket, and build the image on its cloud infrastructure, so it will know exactly what source commit is for current docker image.
jenkins/jnlp-slave, just this kind of repo.
Then, you can click its Build Details on the web page, click into one link, e.g. 3.26-1-alpine, you will see log mentioned 0a0239228bf2fd26d2458a91dd507e3c564bc7d0 is the source commit.
To sum up, for the repo you mentioned in the question, they are not Automated Build, so you cannot get the map for the image & source code, but if you happen to find a repo in dockerhub which is Automated Build later & want to know the map, then you can.
As long as I understand your question, you are trying to tag the docker image exact with same version as of your software version. For that I use to create image tag:
$ export VERSION="2.31-b19"
$ docker tag "<user>/<image>:${VERSION}" "<docker_hub_user>/<repo>:latest"
If this is not the case. Please explain your use case a bit more so that we can provide you a better workaround.
Our production/staging docker image build pulls the latest code from our repository and then it installs all required dependencies, this process takes a while.
This is why for development we are using a volume to map the application code to a local folder.
Is there a way to commit the local changes in the mapped volume to the actual image data storage? So that we don't have to rebuild it all the time?
Being able to put your code and label that docker image is what people use it for. You shouldn't be deploying code at run-time in production. Instead you should be building images and tagging them based on version.
You want to know what is running on your production and you also want the ability to rollback to previous version.
Now coming back to your rebuilding the code part. There are multiple ways to improve the build times
Create base images
You can create base images and just put code on top of that base image. This base image will have your necessary softwares (Node etc). And in your Dockerfile you will just copy the code.
Instead of Git Checkout Use Tag URL
You can download a specific branch/tag as a zip file instead of the whole repository and unzip it. I have seen sometimes Git repos are 100MB and the code is only 4-5 MB. This can save you time
Use multistage build
Multistage builds are not going to save you build time but they will save you image size. This is only needed if you deploy lots of containers
I want to keep the images that I used in my docker hub account while maintaining reference to the pulled image. Something like when you fork a project in github.
Currently I have tried jwilder/nginx-proxy image. Now that I am satisfied with it, I committed the working container to username/nginx-proxy image and push it.
The problem with this approach is it is like a fresh image and it doesn't show the layer from jwilder/nginx-proxy. No documentation or even Dockerfile.
If you push the image, there is no reference to the original, that behavior is normal. You can put that reference or link using your "repo info".
The Dockerfile is only shown if you did an automated build linking your github or bitbucket account and the push is automatically done based on the Dockerfile of your project.
Is there a way to clone a Dockerfile from GitLab with the docker command?
I want to use the feature that allow pull and commit.
I am not sure if I have understand well but these pull and commit update the Dockerfile from the git repositories ? Or is it only locally in the next images ?
If not, is there a way to get all the change you made from the previous image made by the Dockerfile into another Dockerfile ?
I know you can clone with Git directly, but like for npm, you can also use Git url like git+https:// or git+ssh://
The pull/commit commands affect the related image and operate directly against your configured registry, which is the official Docker Hub Registry unless configured otherwise. Perhaps some confusion may arise from the registry's support for Automated Builds, where the registry is directly bound to a repository and rebuilds the image every time the targeted repository branch changes.
If you wish to reuse someone's Docker image, the best approach is to simply reference it via the FROM instruction in your Dockerfile and effectively fork the image. While it's certainly possible to clone the original source repository and continue editing the Dockerfile contained therein, you usually do not want to go down that path.
So if there exists such a foo/bar image you want to continue building upon, the best, most direct approach to do so is to create your own Dockerfile, inherit the image by setting it as a base for your succeeding instructions via FROM foo/bar and possibly pushing your baz/bar image back into the registry if you want it to be publicly available for others to re-base upon.
I'm new to docker and I wonder why there is no command to fetch AUTOMATED BUILD-repo's Dockerfile to build image locally from it (can be convenient some times I guess, instead of opening browser, peeking for github reference on repo's page and then using git to clone)
I have created dockerfileview to fetch Dockerfile from Docker Hub.
https://github.com/remore/dockerfileview
The automated build normally has a githubrepo behind it and links to the original repository in the build details section under the Source Repository heading. Which automated build are you looking for the source file for?
If you would like to search for images from the command line you can run docker search TERM to find images (but not their docker files). You can also use docker history to give a rough approximation of the commands that went in the docker file.
e.g.