I am trying to understand what containers are supported by google cloud run.
One place in its key features are:
https://cloud.google.com/run/?hl=sr#all-features
"Any language, any library, any binary Use the programming language of
your choice, any language or operating system libraries, or even bring
your own binaries."
In another place, it says:
https://cloud.google.com/run/docs/reference/container-contract
Supported languages and images
Your container image can run code written in the programming language
of your choice and use any base image, provided that it respects the
constraints listed in this page.
Executables in the container image must be compiled for Linux 64-bit.
Cloud Run specifically supports the Linux x86_64 ABI format.
I am really confused.
Right now, Cloud Run doesn't support Windows images, it only supports Linux based containers, but Google Kubernetes Engine (GKE)now has support for windows docker based containers.
Google offers a codelab in 2 parts (part1 GCE |part2 GKE) to create windows docker containers and to use it on Compute engine (GCE) and GKE, these are the only 2 GCP products that supports windows docker images.
The main idea is create a Docker image, push this to Google Container registry and use this to create a GKE infrastructure using windows images.
The container is 64-bit Linux container. You can create any container that is compatible with that ABI. Within that container, you can do whatever you like, as long as it adheres to the container runtime contract.
Related
I have come across the word IaC many times while learning DevOps and when I googled it to know what it is it showed that it used code as it is the process of managing and provisioning computer data centers through machine-readable definition files, rather than physical hardware configuration or interactive configuration tools. So is docker also a infrastructure as code technology because it virtualizes an OS to handle multiple workloads on a single OS instance? Thanks in advance
I'm not sure exactly what you are asking, but Docker provides infrastructure as code because the Docker functionality is set via Dockerfiles and shell scripts. You don't install a list of programs manually when defining an image. You don't configure anything with a GUI in order to create an environment when you pull an image from Docker hub or when you deploy your own image.
And as said in another answer, Docker is not virtualization, as everything is actually running in your Linux kernel, but with limited resources in its own namespace. You can see a container process via htop in the host machine, for instance. There's no hypervisor. There's no overhead.
I think you misunderstud the concept, because neither Docker is an hypervidor nor containers are VMs.
From this page: https://www.docker.com/resources/what-container
A Docker container image is a lightweight, standalone, executable package of software that includes everything needed to run an application: code, runtime, system tools, system libraries and settings.
Container images become containers at runtime and in the case of Docker containers - images become containers when they run on Docker Engine.
Containers are an abstraction at the app layer that packages code and dependencies together. Multiple containers can run on the same machine and share the OS kernel with other containers, each running as isolated processes in user space.
I want to start writing a Docker image. I have a .net Core 2.0 Web Api service that I have deployed to an Amazon Linux machine. It runs fine, but I would like to automate the build and deployment process a bit.
As far as I am concerned, there is no need for a Parent image for the image I need to build. I might grab some files from a location, run some dotnet CLI commands, and run the service using Apache as a reverse proxy. I dont really see the need for a parent image in any of that.
I am asking this question because most of the examples I have seen include a base image. Most of the time its something very generic, like "From Ubuntu". I have read that most images will include a parent image. According to Docker's documentation:
A parent image is the image that your image is based on. It refers to the contents of the FROM directive in the Dockerfile. Each subsequent declaration in the Dockerfile modifies this parent image. Most Dockerfiles start from a parent image, rather than a base image. However, the terms are sometimes used interchangeably.
What exactly is the point of inheriting from Ubuntu? Even the Docker docs suggest using Debian "since it’s very tightly controlled and kept minimal". Does that just ensure that your Linux machine has an Ubuntu distribution? Does it even matter if I am using Amazon Linux but use the Debian image as my base?
A Docker image runs in a set of filesystem namespaces which are unconnected from the host's except where you've chosen to bind-mount a volume. This means that tools installed on the host are unavailable to the container: Just because the host runs Amazon Linux doesn't mean that the userspace commands Amazon Linux provides (and the libraries those commands use to run) are available to the guests.
Without a Linux distro available inside the container, you wouldn't have a package management tool (yum, apt-get, etc) with which to install the tools you need to download a file, run software (that presumably needs to be linked to a libc, a copy of OpenSSL, or other shared components). There are also runtime parts of a working Linux system such as the resolver that are provided in userland by your distro and not shared from the host in a Docker install.
Using a base image ensures that you have tools available inside your container -- and it ensures that that container will work consistently on any Linux system with a compatible kernel and hardware architecture.
It's possible in theory to bind-mount many of the tools from the host (as by exposing all of /usr as a volume), but doing so would defeat many of the advantages Docker offers in portability.
I am exploring use of containers in a new application and have looked at a fair amount of content and created a sandbox environment to explore docker and containers. My struggle is more an understanding what components needs to be containerized individually vs bundling multiple components into my own container. And what points to consider when architecting this?
Example:
I am building a python back end service to be executed via webservice call.
The service would interact with both Mongo DB, and RabbitMQ.
My questions are:
Should I run individual OS container (EG Ubuntu), Python Container, MongoDB Container, Rabbit MQ container etc? Combined they all form part of my application and by decoupling everything I have the ability to scale individually?
How would I be able to bundle/link these for deployment without losing the benefits of decoupling/decomposing into individual containers
Is an OS and python container actually required as this will all be running on an OS with python anyways?
Would love to see how people have approached this problem?
Docker's philosophy: using microservices in containers. The term "Microservice Architecture" has sprung up over the last few years to describe a particular way of designing software applications as suites of independently deployable services.
Some advantages of microservices architecture are:
Easier upgrade management
Eliminates long-term commitment to a single technology stack
Improved fault isolation
Makes it easier for a new developer to understand the functionality of a service
Improved Security
...
Should I run individual OS container (EG Ubuntu), Python Container,
MongoDB Container, Rabbit MQ container etc? Combined they all form
part of my application and by decoupling everything I have the ability
to scale individually?
You dont need an individual OS ontainer. Each container will use Docker host's kernel, and will contain only binaries required, python binaries for example.
So you will have, a python container for you python service, MongoDB container and RabbitMQ container.
How would I be able to bundle/link these for deployment without losing
the benefits of decoupling/decomposing into individual containers?
For deployments, You will use dockerfiles + docker-compose file. Dockerfiles include instructions to create a docker image. If you are just using official library images, you don't need dockerfiles.
docker-compose will help you orchestrate the container builds (from docker files), start ups, Creating required networks, Mounting required volumes and etc.
A question came up as I was giving a presentation on Docker to my team that I didn't know how to answer.
Many of the prebuilt containers on Docker Hub, for just one example the jboss/wildfly container, are built on top of containers for a specific OS (Ubuntu, CentOS, etc.). A few of these containers ARE in fact nothing but containers for these OSes.
Yet Docker's main raison d'etre, it's prime claim to fame, the basis of its claim that it is better than Virtual Machine technologies, is that it is lighter weight because it doesn't need to be built on top of an OS. But if this is so and most containers include an OS does this not defeat the purpose and invalidate the claim?
So what IS in these OS Docker images, and how is the claim of lighter weight still able to be made? Is it some stripped down version of an OS?
Can one make a Docker image that is not built on top of an OS?
What determines when an application gets OS services from the OS embedded in the container, as opposed to getting OS services from the host?
A Docker image (which will most likely contain the base system from a Linux distribution), is read only and is augmented with several layers that are enabled as you write to a location. So you can share the base image and have "add-ons" if you will. This is called a union file system. The docker documentation provides more information here. This kind of sharing makes Docker consume less resources (fs space in this case) compared to VMs, where you'd have to install a new distribution on each.
Note that you don't have to have a full Ubuntu installation (the kernel is shared with the host system, anyway), it is just that most of it is usually required by the applications you want to run in your container. You can easily find images that are stripped down, omitting files not needed to run most applications while still being viable for many targets (so you can still share the base image, see above).
I have a Docker image (in Ubuntu 14.04 environment) that I want to upload to Google Compute Engine and run as a Compute Engine (not App Engine) instance.
There is a presentation (by Google's Marc Cohen) about how to do this but it leaves out key steps (on page 34) about how to convert the Docker image to raw tar.gz format.
Can someone tell me the exact steps to
convert Docker image to correct format
upload to google storage
create google compute engine image
start google compute engine instance
If you are not bound to your Ubuntu image, then you could just use the ready made VMs with Docker support (Debian Wheezy) and drop your containers in.
For more info on using Docker on GCE, see:
Container-optimized Google Compute Engine images
Containers on Google Cloud Platform
The documentation on packaging has comprehensive steps to do all what you have enumerated.
There are some specific requirements that your install must include in order for it to be compatible with GCE; its a long list of kernel compatibility flags, disk types, NTP settings, etc. etc. so copy-pasting it here will not be prudent as this information is likely to change as GCE is updated by Google.