Docker flatten image

By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service. Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information. This effort saved up to 25 MB, now my image size is MB. I'm having my doubts if it is worth to use Docker at all. I mean, I barely installed anything and I'm hitting 1GB over. If I will have to add some serious stuff like a database and so on I might run out of disk space.

As rexposadas said, images include all the layers and each layer includes all the dependencies for what you installed. It is also important to note that the base images like fedora:latest tend to be very bare-bones. You may be surprised by the number of dependencies your installed software has.

docker flatten image

I was able to make your installation significantly smaller by adding yum -y clean all to each line:. It is important to do that for each RUN, before the layer gets committed, or else deletes don't actually remove data. To get around this you must clean at each layer. The scratch image is 0B and you can use that to package up your code if you can compile your code into a static binary.

For example, you can compile your Go program and package it on top of scratch to make a fully usable image that is less than 5MB. The key is to not use the official Docker images, they are too big.

docker flatten image

Scratch isn't all that practical either so I'd recommend using Alpine Linux as your base image. This post about Microcontainers shows you how to build very small images base on Alpine. Here are some more things you can do :. With these both AND the recommendations from Andy and michau I was able to resize my nodejs image from 1.

Edit: One more important thing: "It took me a while to really understand that each Dockerfile command creates a new container with the deltas. With Docker v This is useful to reduce image size, for example:. I made an Ubuntu image that is actually minimal unlike other so-called "minimal" images.

Git has many more prerequisites, so the image gets larger, about MB. That's still less that the initial size of most images.

How to know you are inside a Docker container

You can also take a look at the script I wrote to make the minimal Ubuntu image for Docker. You can perhaps adapt it to Fedora, but I'm not sure how much you will be able to uninstall.

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After removing unused packages e.Do you have unused Docker images lying around? I just reclaimed 41GB. However, that they took up this much blew my mind! On a local development machine, it might be okay to consume significant hard drive space. After all, if it takes a while you can always grab another coffee or tea, take a break from the screen to rest your eyes, grab some lunch, or discuss something with a colleague.

Or do you install everything, such as development tools and Linux headers, before installing your application? Moreover, you might even see planning as somewhat dull and tedious. What base image are you using? Apt is one of the most well thought out and most feature-rich package managers available.

docker flatten image

As a result, an image based on Alpine Linux is typically around 5 MB in size. However, it should be a, relatively, straight-forward process. How many layers compose your Docker image? In the example Dockerfile above, the resulting Docker image will be composed of 7 layers, in addition to any layers in the base image.

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Building Docker images in this way allows Docker to be as efficient as possible. If a change is made in one layer, then only that layer needs to be changed. Every other layer can be fetched from cache. That way, build times are as quick as possible. For each layer you can see:. It first installs the required development packages, which subsequent packages depend on.

It then installs several system binaries. However, while it might be logical, it will result in a larger image than if those steps were combined. Moreover, gets even worse. You may wonder what the problem is, as the packages are ultimately deleted. It gets back to the point about caching that I spoke of earlier.

Do some experimenting and see how you can compact your Dockerfile configurations. Are all those files necessary?

Could some of them have been avoided?

Creating Effective Docker Images

These files, as their name implies, instruct Docker that specific files can be ignored. If not, have a look at the example below.

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The last tip I want to offer is on squashing Docker images. Docker-squash is a utility to squash multiple docker layers into one to create an image with fewer and smaller layers.How to know that you are living in the Matrix? Well, I do not know, but at least I know how to tell you if you are inside a Docker container or not.

Build and run your image

LXC is a technology to provide operating system virtualization for processes on Linux. This means, that processes can be executed in isolation without starting a real and heavy virtual machine. All processes will be executed on the same Linux kernel, but will still have their own namespaces, users and file system.

An important feature of such virtualization is that applications inside a virtual environment do not know that they are not running on real hardware.

An application will see the same environment, no matter if it is running on real or virtual resources. However, there are some tricks. It is a pseudo file system and most of it is read-only.

But every process on Linux will have an entry in this file system named by its PID :. In this directory, we find information about the executed program, its command line arguments or working directory.

And since the Linux kernel 2. This file contains information about the control group the process belongs to. Normally, it looks something like this:. But since LXC and therefore Docker makes use of cgroups, this file looks different inside a container:. As you can see, some resources like the CPU are belonging to a control group with the name of the container. We can make this a little bit easier if we use the keyword self instead of the PID.

The keyword self will always reference the folder of the calling process:. And we can wrap this into a function thanks to Henk Langeveld from StackOverflow :. Difference between save and export in Docker. Flatten a Docker container or image. Layering of Docker images.

Published May 10, Cancel Reply Write a Comment. I know you go this. But if you are using ansible. You can look for this fact.By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service.

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Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information. I made a Docker container which is fairly large.

When I commit the container to create an image, the image is about 7. But when I export the container not save the image! Of course the history is lost, but this OK for me, since the image is "done" in my opinion and ready for deployment. And: Is it a wise idea to do that or am I missing some important point? To my knowledge, you cannot using the Docker api. If you don't want to save to disk, you could probably pipe the outputstream of export into the input stream of import.

I have not tested this, but try. Now that Docker has released the multi-stage builds in The result will be your build environment layers are cached on the build server, but only a flattened copy will exist in the resulting image that you tag and push.

Note, you would typically reformulate this to have a complex build environment and only copy over a few directories. Here's an example with Go to make a single binary image from source code and a single build command without installing Go on the host and compiling outside of docker:.

The build creates both environments, the build environment and the scratch one, and then tags the scratch one:. Looking at the images, only the single binary is in the image being shipped, while the build environment is over MB:.

Learn more. How to flatten a Docker image? Ask Question. Asked 6 years, 6 months ago. Active 2 years, 3 months ago. Viewed 22k times.

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Thomas Uhrig Thomas Uhrig Do you build with the --rm option? This removes intermediate images. Or did I misunderstand the question?

There are some other tricks to make the image smaller: call a bunch of install commands in one RUNremove unneeded ubuntu packages, etc. See github. Active Oldest Votes. Up from Docker 1. Before version 1. I just did this with "Docker version 1.When it comes to Docker containers, the smaller, the better.

Smaller containers are easier to work with, deploy faster, and tend to have fewer security vulnerabilities. I worked at WePay during the transition from a monolithic application in the datacenter to a series of microservices running in the cloud.

I spent a lot of time working on the Vagrant-based CentOS development environment for the monolith, and also started maintaining a custom CentOS base image in Google Cloud. As we were all learning about Docker, images, containers, and how it all worked together, the director of DevOps declared unilaterally that we should create Docker base images for the various languages we were using PHP, Python, Java, Goand they should all be built on a core CentOS 7 Docker image.

Having a base Docker image that every application referenced with FROM in their Dockerfiles which included shared patterns for logging and metrics. Having an optimized image for specific languages made it easier for developers using those languages to rapidly spin-up new application containers.

Developers wanted to run composer install and pip install requirements. This often required development dependencies to be installed in the containers. Our build system was frequently buckling under the weight of caching and transferring large Docker images between its cluster and our Artifactory installation.

Now, some of this can be chalked up to learning a new technology. Some of this was hubris by people who made unilateral decisions. Docker images use layers to overlay newer changes over previous changes using a technology called UnionFS. If a change is made to an earlier layer, then the layer cache is invalidated for all of the later layers, and those later layers need to be rebuilt.

Unfortunately, many people including myself read that Docker image layers have filesize overhead built into them. In order to make your containers smaller, you should combine all of your commands into a single RUN statement.

By leveraging the RUN statement as it was intended, you get to take advantage of faster re-build times by leveraging the layer cache. This means that any layers e. Yes, your development Docker image may be a little larger, but we will address this later in this post.

This is the one that kills me the most because it can be so wasteful, and it stems from not understanding how to use the tools in your toolbox. Firstly, use a. Again, this is very similar to how a. You never need your. You only need your vendored code. You should ignore those as well. For example, Node. Both of these require that you install compilation tools and compile them on the OS that they run in. Flattening your images is an extra step that you can take to make your images as small as possible.

We can use this mechanism to flatten and shrink a Docker container. If we save an image to the disk, its whole history will be preserved, but if we export a container, its history gets lost and the resulting tarball will be much smaller.

By running a container and exporting the data as a tarball, you can remove all of the intermediate layers and history from the final image, removing filesize overhead and reducing the overall image size. At the time of this writing, the latest version of PHP is 7. The Alpine Linux image clocks in at just under 5 MB. So far, both of these are smaller than the base CentOS or Ubuntu images. Our application includes the New Relic agent for PHP, a few extensions, our application code, and our Composer vendor directory without dev-dependencies.

With all of our wonderfully cached layers, this brings the decompressed image size to MB.By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service. Server Fault is a question and answer site for system and network administrators. It only takes a minute to sign up. It is possible to flatten Docker images, reducing them to a single layer, forgetting the layer history. Sign up to join this community. The best answers are voted up and rise to the top.

Use multi-stage builds

Should I flatten my docker images for Google Cloud Run? Ask Question. Asked 6 months ago. Active 6 months ago. Viewed 22 times. It is supposedly faster to pull them from scratch, though it forgoes layer caching.

For an image used with Google Cloud Run, is it worth it? HectorJ HectorJ 2 2 bronze badges. A priori, I don't think you would get a relevant difference in performance. But in any case it would depend on your Docker image and your specific use case.

So I guess the only way to figure it out would be to test it for your Docker image. Active Oldest Votes. Sign up or log in Sign up using Google. Sign up using Facebook. Sign up using Email and Password. Post as a guest Name. Email Required, but never shown. The Overflow Blog.

Podcast Ben answers his first question on Stack Overflow. The Overflow Bugs vs.So you finally surrendered to containers and discovered that they solve a lot of problems and have a lot of advantages :.

An application version 1. Make sure your applications are designed to write to a shared data store. It will be easier to recreate, manage, and distribute your image. Move faster with quick references and examples for container architecture, engine, image, registry, volume, and related commands.

For now, requiring root is dangerous for others and may not be available in all environments. If your application or microservice needs to communicate to another container, use environment variables to pass the proper hostname and port from one container to another. In his current role he helps developers worldwide to be more effective in software development, and he also promotes tools and practices that help them to be more productive. He worked in several fields including application architecture and design.

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