I see how to specify a docker image in ray here: https://ray.readthedocs.io/en/latest/autoscaling.html#common-cluster-configurations
But I have my own Dockerfile in my repository. Is it possible to specify that that Dockerfile get spun up on every instance ray spins up? Is the only solution to push it to an external registry somewhere and specify the image name here?
If you build your own docker image locally using docker build ., it is stored in your local docker repository. And when you run autoscaler, it should look up your local repository first before it looks up the external repository.
Related
I just started working with docker this week and came across a 'dockerfile'. I was reading up on what this file does, and the official documentation basically mentions that the FROM keyword is needed to build a "base image". These base images are pulled from Docker hub, or downloaded from there.
Silly question - Are base images always pulled from docker hub?
If so and if I understand correctly I am assuming that running the dockerfile to create an image is not done very often (only when needing to create an image) and once the image is created then the image is whats run all the time?
So the dockerfile then can be migrated to which ever enviroment and things can be set up all over again quickly?
Pardon the silly question I am just trying to understand the over all flow and how dockerfile fits into things.
If the local (on your host) Docker daemon (already) has a copy of the container image (i.e. it's been docker pull'd) specified by FROM in a Dockerfile then it's cached and won't be repulled.
Container images include a tag (be wary of ever using latest) and the image name e.g. foo combined with the tag (which defaults to latest if not specified) is the full name of the image that's checked i.e. if you have foo:v0.0.1 locally and FROM:v0.0.1 then the local copy is used but FROM foo:v0.0.2 will pull foo:v0.0.2.
There's an implicit docker.io prefix i.e. docker.io/foo:v0.0.1 that references the Docker registry that's being used.
You could repeatedly docker build container images on the machines where the container is run but this is inefficient and the more common mechanism is that, once a container image is built, it is pushed to a registry (e.g. DockerHub) and then pulled from there by whatever machines need it.
There are many container registries: DockerHub, Google Artifact Registry, Quay etc.
There are tools other than docker that can be used to interact with containers e.g. (Red Hat's) Podman.
I have a Git repo with a simple Dockerfile. First row goes like this:
FROM python:3.7
My company has an internal registry with the base images. Because of this, the DevOps guys want me to change the Dockerfile to:
FROM registry.company.com:5000/python:3.7
I don't want this infrastructure detail baked in my code. URLs may change, I may want to build this image in another environment, etc. If possible, I would rather indicate the server in the pipeline, but the documentation regarding docker build has no parameter for this.
Is there a way to avoid editing the Dockerfile in this situation?
You would use a build arg for this:
ARG registry=docker.io/library
FROM ${registry}/python:3.7
Then for the build process:
docker build --build-arg registry=registry.company.com:5000 ...
Use docker.io for the registry name for the default Docker Hub, and library is the repository for official docker images, both of which you normally don't see when using the short format. Note that I usually include the library part in the local mirror so that official docker images and other repos that are mirrored can all use the same registry variable:
ARG registry=docker.io
FROM ${registry}/library/python:3.7
That means your local registry would need to have registry.company.com:5000/library/python:3.7.
To force users to specify the registry as part of the build, then don't provide a default value to the arg (or you could default the value of registry to something internal if that's preferred):
ARG registry
FROM ${registry}/python:3.7
You can work around the situation by manually pulling and re-tagging the image. docker build (and docker run) won't try to pull an image that already appears to be present locally, but that also means there's no verification that it actually matches what Docker Hub has. That means you can pull the image from your mirror, then docker tag it to look like a Docker Hub image:
docker pull registry.company.com:5000/python:3.7
docker tag registry.company.com:5000/python:3.7 python:3.7
I would like to build docker-image on Gitlab CI/CD with alpine. This docker has to download a website (only index.html) as a file with a date every 1 hour.
All dates/ files should be saved in the docker volume.
How to start with this? I am new in docker.
First you need to run a docker container using any image you want (alpine in your case).
Then set everything in it that you want to run (like download website)
Then create a docker image and host it on gitlab docker registry
Then you simply have to code .gitlab-ci.yaml file. After pushing that to your repository
Then you need to schedule your pipeline as mentioned here
https://docs.gitlab.com/ee/user/project/pipelines/schedules.html
I am trying to create a docker image using the below command .
docker build -t mytestapp .
My DockerFile looks like this
# Set the base image
FROM rhel7:latest
USER root
# Dockerfile author / maintainer
MAINTAINER Name <email.id#example.com>
# Update application repository list and install the Redis server.
RUN mkdir /usr/local/myapp/
ADD myapp-0.0.1-jar /usr/local/myapp/
RUN java -Dspring.profiles.active=qa -jar /usr/local/myapp/myapp-0.0.1.jar
# Expose default port
EXPOSE 8080
Questions:
1) Is it fine the way I am adding the JAR file. Will it be available inside /usr/local on the container after I prepared am image from the above build.
2) When I build the image using docker build command , is the build image is pushed to docker repository hub by default.
Since the WAR file contains credentials, I don't want to push the image to Docker Hub but we would like to push to our local Docker registry using Docker distribution and pushing with docker push.
Please clarify.
Answering your questions:
Docker recommends using the COPY instructions for adding single files into an image. It will be available inside the container at /usr/local/myapp/myapp-0.0.1-jar
When you build the image it will be available on your local docker-host. It won't leave the server unless you explicitly tell it so.
Another tip I want to give you is the recommended docker image naming convention, which is [Repository/Author]/[Imagename]:[Version].
So for your image it might be called zama/mytestapp:1.0
If you want to push it into your local registry, you'll have to name your image after the syntax [LocalRegistry:Port]/[Repository/Author]/[Imagename]:[Version].
So your image might now be called registry.example.com:5000/zama/mystestapp:1.0
If you have authentication on your registry, you need to docker login first and then simply push the image with docker push registry.example.com:5000/zama/mystestapp:1.0.
Inheritance of an image is normally done using docker's from command, for example.
from centos7:centos7
In my case, I have a Dockerfile which I want to use as a base image builder, and I have two sub dockerfiles which customize that file.
I do not want to commit the original dockerfile as a container to dockerhub, so for example, I would like to do:
Dockerfile
slave/Dockerfile
master/Dockerfile
Where slave/Dockerfile looks something like this:
from ../Dockerfile
Is this (or anything similar) possible ? Or do I have to actually convert the top level Dockerfile to a container, and commit it as a dockerhub image, before I can leverage it using the docker FROM directive.
You don't have to push your images to dockerhub to be able to use them as base images. But you need to build them locally so that they are stored in your local docker repository. You can not use an image as a base image based on a relative path such as ../Dockerfile- you must base your own images on other image files that exists in your local repository.
Let's say that your base image uses the following (in the Dockerfile):
FROM centos7:centos7
// More stuff...
And when you build it you use the following:
docker build -t my/base .
What happens here is that the image centos7:centos7 is downloaded from dockerhub. Then your image my/base is built and stored (without versioning) in your local repository. You can also provide versioning to your docker container by simply providing version information like this:
docker build -t my/base:2.0 .
When an image has been built as in the example above it can then be used as a FROM-image to build other sub-images, at least on the same machine (the same local repository). So, in your sub-image you can use the following:
FROM my/base
Basically you don't have to push anything anywhere. All images lives locally on your machine. However, if you attempt to build your sub-image without a previously built base image you get an error.
For more information about building and tagging, check out the docs:
docker build
docker tag
create your own image