When a docker container crashes and I make a new one, how can I ensure I have the settings from the last one in place? The container I am running contains Jenkins only.
You need to use a volume if you want your configuration changes to be persisted.
In the image I am using as a base (usually jenkins/jenkins:2.75-alpine), the configuration lives under: /var/jenkins_home/workspace
so all I need to do is something like:
docker run -v /path/on/host:/var/jenkins_home jenkins/jenkins:2.75-alpine
Related
I am trying to setup an OpenGrok instance from a docker image. By default svn indexer inside the image is checking for new repositories in 10 minutes.
I need to change this configuration. From where exactly I can change this.
As soon as I posted this I found the related files inside docker container at /scripts.
Here REINDEX variable is defined in start.sh script.
In my company, we're using a Jira for issue tracking. I need to write an application, that integrates with it and synchronizes some data with other services. For testing, I want to have a docker image of the Jira with some initial data.
I'm using the official atlassian/jira-core image. After the initial setup, I saved a state by running docker commit, but unfortunately the new image seems to be empty, and I need to set it up again from scratch.
What should I do to save the initial setup? I want to run tests that will change something within Jira, so reverting it back will be necessary to have reliable test suite. After I spin a new container it should have created a few users, and project with some issues. I don't want to create it manually for each new instance. Also, the setup takes a lot of time which is not acceptable for testing.
To get persistent storage you need to mount /var/atlassian/jira in your host system. /var/atlassian/jira this can be used for storing your configuration etc. so you do not need to commit, whenever you spin up a new container with /var/atlassian/jira mount path will have all the configuration that you set previously.
docker run --detach -v /you_host_path/jira:/var/atlassian/jira --publish 8080:8080 cptactionhank/atlassian-jira:latest
For logs you can mount
/opt/atlassian/jira/logs
The above is valid if you are running with the latest tag or you can explore relevant dockerfile.
Set volume mount points for installation and home directory. Changes to the
home directory needs to be persisted as well as parts of the installation
directory due to eg. logs. VOLUME ["/var/atlassian/jira", "/opt/atlassian/jira/logs"]
atlassian-jira-dockerfile
look at the entrypoint.sh , the comments from there are:
check if the server.xml file has been changed since the creation of
this Docker image. If the file has been changed the entrypoint script
will not perform modifications to the configuration file.
so I think you need to provide your server.xml to stop the init process...
If I have one ubuntu container and I ssh to it and make one file after the container is destroyed or I reboot the container the new file was destroyed because the kubernetes load the ubuntu image that does not contain my changes.
My question is what should I do to save any changes?
I know it can be done because some cloud provider do that.
For example:
ssh ubuntu#POD_IP
mkdir new_file
ls
new_file
reboot
after reboot I have
ssh ubuntu#POD_IP
ls
ls shows nothing
But I want to it save my current state.
And I want to do it automatically.
If I use docker commit I can not control my images because it makes hundreds of images. because I should make images by every changes.
If I want to use storage I should mount /. but kubernetes does not allow me to mount /. and it gives me this error
Error: Error response from daemon: invalid volume specification: '/var/lib/kubelet/pods/26c39eeb-85d7-11e9-933c-7c8bca006fec/volumes/kubernetes.io~rbd/pvc-d66d9039-853d-11e9-8aa3-7c8bca006fec:/': invalid mount config for type "bind": invalid specification: destination can't be '/'
You can try to use docker commit but you will need to ensure that your Kubernetes cluster is picking up the latest image that you committed -
docker commit [OPTIONS] CONTAINER [REPOSITORY[:TAG]]
This is going to create a new image out of your container which you can feed to Kubernetes.
Ref - https://docs.docker.com/engine/reference/commandline/commit/
Update 1 -
In case you want to do it automatically, you might need to store the changed state or the files at a centralized file system like NFS etc & then mount it to all running containers whenever required with the relevant permissions.
K8s ref - https://kubernetes.io/docs/concepts/storage/persistent-volumes/
Docker and Kubernetes don't work this way. Never run docker commit. Usually you have very little need for an ssh daemon in a container/pod and you need to do special work to make both the sshd and the main process both run (and extra work to make the sshd actually be secure); your containers will be simpler and safer if you just remove these.
The usual process involves a technique known as immutable infrastructure. You never change code in an existing container; instead, you change a recipe to build a container, and tell the cluster manager that you want an update, and it will tear down and rebuild everything from scratch. To make changes in an application running in a Kubernetes pod, you typically:
Make and test your code change, locally, with no Docker or Kubernetes involved at all.
docker build a new image incorporating your code change. It should have a unique tag, often a date stamp or a source control commit ID.
(optional but recommended) docker run that image locally and run integration tests.
docker push the image to a registry.
Change the image tag in your Kubernetes deployment spec and kubectl apply (or helm upgrade) it.
Often you'll have an automated continuous integration system do steps 2-4, and a continuous deployment system do the last step; you just need to commit and push your tested change.
Note that when you docker run the image locally in step 3, you are running the exact same image your production Kubernetes system will run. Resist the temptation to mount your local source tree into it and try to do development there! If a test fails at this point, reduce it to the simplest failing case, write a unit test for it, and fix it in your local tree. Rebuilding an image shouldn't be especially expensive.
Your question hints at the unmodified ubuntu image. Beyond some very early "hello world" type experimentation, there's pretty much no reason to use this anywhere other than the FROM line of a Dockerfile. If you haven't yet, you should work through the official Docker tutorial on building and running custom images, which will be applicable to any clustering system. (Skip all of the later tutorials that cover Docker Swarm, if you've already settled on Kubernetes as an orchestrator.)
Given a Windows application running in a Docker Windows Container, and while running changes are made to the Windows registry by the running applications, is there a docker switch/command that allows changes to the Windows Registry to be persisted, so that when the container is restarted the changed values are retained.
As a comparison, file changes can be persisted between container restarts by exposing mount points e.g.
docker volume create externalstore
docker run -v externalstore:\data microsoft/windowsservercore
What is the equivalent feature for Windows Registry?
I think you're after dynamic changes (each start and stop of the container contains different user keys you want to save for the next run), like a roaming profile, rather than a static set of registry settings but I'm writing for static as it's an easier and more likely answer.
It's worth noting the distinction between a container and an image.
Images are static templates.
Containers are started from images and while they can be stopped and restarted, you usually throw them entirely away after each execution with most enterprise designs such as with Kubernetes.
If you wish to run a docker container like a VM (not generally recommended), stopping and starting it, your registry settings should persist between runs.
It's possible to convert a container to an image by using the docker commit command. In this method, you would start the container, make the needed changes, then commit the container to an image. New containers would be started from the new image. While this is possible, it's not really recommended for the same reason that cloning a machine or upgrading an OS is not. You will get extra artifacts (files, settings, logs) that you don't really want in the image. If this is done repeatedly, it'll end up like a bad photocopy.
A better way to make a static change is to build a new image using a dockerfile. You'll need to read up on that (beyond the scope of this answer) but essentially you're writing a docker script that will make a change to an existing docker image and save it to a new image (done with docker build). The advantage of this is that it's cleaner, more repeatable, and each step of the build process is layered. Layers are advantageous for space savings. An image made with a windowsservercore base and application layer, then copied to another machine which already had a copy of the windowsservercore base, would only take up the additional space of the application layer.
If you want to repeatedly create containers and apply consistent settings to them but without building a new image, you could do a couple things:
Mount a volume with a script and set the execution point of the container/image to run that script. The script could import the registry settings and then kick off whatever application you were originally using as the execution point, note that the script would need to be a continuous loop. The MS SQL Developer image is a good example, https://github.com/Microsoft/mssql-docker/tree/master/windows/mssql-server-windows-developer. The script could export the settings you want. Not sure if there's an easy way to detect "shutdown" and have it run at that point, but you could easily set it to run in a loop writing continuously to the mounted volume.
Leverage a control system such as Docker Compose or Kubernetes to handle the setting for you (not sure offhand how practical this is for registry settings)
Have the application set the registry settings
Open ports to the container which allow remote management of the container (not recommended for security reasons)
Mount a volume where the registry files are located in the container (I'm not certain where these are or if this will work correctly)
TL;DR: You should make a new image using a dockerfile for static changes. For dynamic changes, you will probably need to use some clever scripting.
I'm trying to make a build env with docker and i want to make this automatic. i've written a custom go binary to handle build stuff and i've built an image which has the go binary, maven and java8 sdk installed.
The steps that binary does are:
Clone a git repo
Run build command
Extract build artifacts to host. (which hasnt done yet.)
I'm passing repo url as parameter to binary while running container and it does build.
But the problem is i need those artifacts in order to run builted app.
I know i can use volumes, but i dont want to use them because when build has done volumes are becoming dangle and it needs a job for deleting those dangling volumes.
I thought i can create an api for saving files into host (that means i have to run that api inside host machine) and my custom go binary can send files to the api and api will do the saving.
But when it comes to calling host from inside a container i've got a problem. i'm getting connection refused to port xx error.
Is there a better way to do it , or should i change my approach?
found an answer on accessing-host-machine-as-localhost-from-a-docker-container-thats-also-inside
Running container with --add-host option is the answer.
While you could use
docker cp CONTAINER:SRC_PATH DEST_PATH
to get the files out of your container, I still believe using a volume is the better idea. Instead of using an anonymous volume use a named one:
docker run -v /local/host/dir:/build/output YOURIMAGE
This allows you to pick up the artefacts on your host from the /local/host/dir
https://docs.docker.com/engine/tutorials/dockervolumes/#locate-a-volume