The Podman- an Open Containers Initiative-compliant container management tool, similar to Docker, Podman is very lightweight, there is no bigfat privileged daemon. It is built with safety in mind and it is a great alternative for development to Docker.
Did I said Podman is compliant with OCI ?.This implies among other things, that we can use any existing container image to substitute any Docker command with the Podman command, without changing anything. Current members of OCI as on 28 May 2020:
There is even an official package that provides backwards compatibility by more or less creating an alias from Docker to Podman.But first, why in the world would you stop using Docker? One thing that concerns me about Docker or, rather the way people treat Docker is that we forget about what Docker is.
Let's just explain that Docker is one of several tools for container management. This was definitely the first of its kind, widely embraced. And Docker certainly led to the industry's adoption of containers. But we have all used Docker for so long that we have stopped thinking 'container' and we think now that "Docker' is everywhere you go where you can see "Docker server," "Docker images" and "Docker registries."
And that's the language to use as an example Take "Git." Yet typically we say "git repository," and we see clearly the distinction between git as a common versions control system in the industry, and gitHub as just one of many services that collaborate on git repositories more clearly, or take Ubuntu by themselves. GitHub has been revolutionizing the way we all worked with Git repositories.
We all have various Linux preferences – I love Ubuntu, but in the end we all use Linux and all know that we use Linux operating system. We all have different preferences for Linux.
For containers, we need a similar mental change. We must understand what containers are and distinguish a line between containers and the instruments we use to work with them.
And to prove that Docker has good alternatives. But let me just talk about containers before I start. Some of you may think the alternative container management tools are not as completely developed as Docker. This
is a valid problem — no one would want to work with unstable broken applications. I'll show you how to use Podman to build and run container images.In your development environment you don't want to make a beta-test of fancy new apps.
But I am not going to give you a few reasons why you should not be worried:
(1) First of all, AWS Fargate, one of the most popular serverless platforms to run containers, dropped Docker in latest release .The beauty of this change is that it's just an implementation detail AWS Customers do not need to re-write their Dockerfiles they don't need to update their containers. From end user perspective Fargate works exactly as it did before. The only difference is that there is no Docker daemon .
(2) Openshift, one of the most popular enterprise Kubernetes platforms, replaced Docker with Cri-O back in June 2019. There is no sign of Docker in modern OpenShift clusters.
(3) OpenSUSE did exactly the same in 2018 - they switched to cri-o as the default container runtime for the Kubic project Kubernetes itself provides you with multiple choices during cluster installation.
(4) You can choose cri-o or just containerd and you won't even notice the difference in most cases More and more companies are shifting from "running Docker" to "running containers" and adapt new tools, all of which are standard-compliant and even work nicely with one another.
All of this means that in production environment Docker is just an implementation detail. You don't care which container runtime is used as long as it's stable and standards compliant To give another example, you don't care which hypervisor is used in your cloud provider.
As a developer you shouldn't be concerned with because if you don't know whether Docker is in production or not then nothing prevents you from attempting to build Docker solutions. Just do this and try Podman. Just try Podman.
What is the problem with Docker. Actually there are few,
• A single process could be a single point of failure.
• This process owned all the child processes (the running containers).
• If there is any failure in the docker daemon, then every child processes are lost its track.
• Building containers led to security vulnerabilities.
• All Docker operations had to be conducted by a user (or users) with the same full root authority.
Most importantly, there is no concept called daemon in podman. podman directly interact with Image registry, containers and image storage. with Linux kernel through the runC container runtime process (not a daemon) .
Above all, runC is a lightweight, portable container runtime. Docker is built on top of runC runtime container. Instead of using a daemon in podman, we directly use the runC runtime container.
Moving from Docker to Podman
Instead of Docker, you need to install Podman. You don't need to start or manage a daemon process like the Docker daemon. The commands you use with Docker will be the same for Podman.Docker images are compatible with Podman.Podman stores his containers and images in a place other than Docker.
Podman commands are same like docker ... just replace docker like podman pull , podman -ps , podman exec -it h33435dds bash etc...
Pull and Push to docker hub :) . Yes you can push and pull images from docker hub .
Next, I'm going to create a Containerfile. Containerfile is essentially a Dockerfile, with the one exception being that Podman's filename Developers choose this name to show explicitly that this file is not Podman-specific.
We should all start renaming our Dockerfiles to Containerfiles because multiple other Container Image Build Tools work with them Containerfile Contents are exactly the same as Dockerfile. We use the same FROM, RUN, ADD, EXPOSE and so on ...
After Containerfile is ready, we can create a container image. By default, Podman can seek to pull the image from a variety of public registries, including Dockerhub, to create the image with podman.
Finally, image is being created and we can see it by running the command "podman images" Now let's build a new container from this file. The reasons that "podman run" command accepts are more or less the same as those that "docker run" does.
Here we show all the container ports to the host and run this container in detached mode. By running the command "podman ps" We can see the container.
Podman opened a random port on the host, as we used capital "P" option. It looks like I don't want to manually execute the "podman run" command I need LanguageTool to run as a service at all times and the best way to run services on a Linux host is to use systemd.
Remember Podman does not come with a daemon-it relies on a much more stable and easy fork-exec model to spawn containers And fork and exec architecture allows to integrate Podman with systemd very nicely Podman generate command is very handy it takes the concept of one of the running containers and generates either a systemd unit file or a kubernetes pod yaml.
We did it as a personal user and not as a root user, and that's
the main difference you'll find while using Podman. There's no central, system-wide daemon that governs it.
We did it as a personal user and not as a root user, and that's the main difference you'll find while using Podman. There's no central, system-wide daemon that governs it.
Podman 's architecture helps the user who has this image and runs certain containers to properly scope every container image and container. No other person will see my photos or my containers on the network. What it means now is that I have to recreate the picture again. In reality, I don't have to rebuild that picture. There is a way for the users to copy container images.
If I restart the systemd operation, it will pick up this image and run the container, and that's all I wanted to show you today! I hope you know how easy to use Podman is. You may want to stick with Docker, but at least you know that there are different container management resources and that containers are not just Docker. If you or your company need advice or training on containerization topics, contact us.
Top comments (43)
I am sure that Podman is technically superior to Docker in many ways, HOWEVER ... that doesn't guarantee that people are going to switch overnight. For people to switch, I think that it has to be:
1) Not just 40 or 50% better than Docker, but an order of magnitude better
2) Largely "interface compatible" (API's and "commands") with Docker, so that people don't have to relearn everything from scratch, and so that a large part of the Docker ecosystem "carries over" easily
If those criteria are met then yes for many people this could be a no-brainer, you just switch out the "engine" for a better one but the way you drive the car remains virtually the same.
Like what you said: "you won't even notice the difference in most cases"
True leob.
unlike docker, podman has currently no gui like portainer.io to manage. However, it's fits well with kubernetics.
Redhat people did something really good by creating podman.
Is it more efficient (performant) compared to Docker? That's something that can win people over, if they end up spending less on their cloud infrastructure then they have an incentive to migrate.
yes. podman is equally efficient like docker + it is more secure being daemon less.
All commands are same. just we have to replace docker with podman.
Time will let us know how good podman over docker. Let's wait what other system admin says about podman
I know podman for some time, but never moved to it and I guess it's the same for many other developers ot there. The problem: it does not natively support Windows or macOS. Docker provides apps for both platforms and they run quite well. But podman just states that "you need to have some Linux VM running and you can use this tool to remotely manage podman inside the VM". There is no help, no tutorial for setting up this stack.
This is one of the main reasons for not switching.
This might be a maturity thing. Docker started out the same way - until around 2016 when they made Docker Desktop run native w/ Windows (versus piped through a VM using docker-machine).
+1 yes Max, you are right
+1 This is a real problem with windows and mac OS desktop users. However, they can use Podman as suggested by Kevin through Linux VM or remotely. Very nice, Kevin. However, here is some instructions about podman podman.io/getting-started/installa...
Why would I want to load another layer that can fail (a VM manager) when alternatives exist that can be run by every developer in my org, whether they're on macOS, Windows, or Linux? Why would my org want to put a big question mark on whether we can fully use Docker images published on Docker Hub or on our own internal repository? Docker isn't perfect — parsecs from it — but it's been a good three years since we ran into a previously-unknown unknown that couldn't have a solution pointed to with a few minutes of research?
Twenty years ago, I was as bleeding-edge as any hacker in love with his own believed ability to solve any problem just through sheer awesomeness. I got fired from my dream job because I kept installing Mandrake (what would later be Mandriva) Linux when shop and customer standards required Red Hat. ("It's compatible, isn't it?" No, not always, and the differences aren't known widely enough and solutions aren't trivial enough to add the risk and expense of deviating from standards.) It took me five years before I even understood that — by which time I'd been writing software for a living for 25 years.
Standards matter, and they tend to remain standards for real businesses until and unless a new tech can be shown to be either a) so completely frictionless that it doesn't matter technically which of the two you're using (and if that's the case, why bother switching?), or b) so revolutionary and so clearly better at solving real-world problems (beyond appealing to the Kool Kids™) that the risk and cost and pain of migration is outweighed by the demonstrable benefits. (That's how Docker, and Linux, and PCs, earned their places in the business world.)
No disruptive technology is ever fully compatible with its predecessor, and no fully compatible technology wins against an incumbent unless business reasons make that incumbent unavailable. (I worked briefly for Silicon Graphics back in the day; they didn't die because somebody out-competed them on technology.)
Docker has been one of the two or three greatest leaps forward that I've seen in the last 40 years — not because they're perfect, but because they're good enough and because they solve a set of use cases with lower risk than any direct competitor with similar reach. When that changes, and it will one day, then there'll be a new top dog. But until then, rotsa ruck moving the installed base.
+1 True Jeff.
-Standards matter.
-No disruptive technology is ever fully compatible with its predecessor, and no fully compatible technology wins against an incumbent unless business reasons make that incumbent unavailable.
-Docker has been one of the two or three greatest leaps forward that I've seen in the last 40 years — not because they're perfect, but because they're good enough and because they solve a set of use cases with lower risk than any direct competitor with similar reach.
Here is one article : Here's why podman is more secured than Docker - DevSecOps
cloudnweb.dev/2019/10/heres-why-po...
Is this true for WSL? It's probably not long until Windows is running a full Linux kernel anyway.
With the latest Windows Subsystem for Linux (WSL) 2.0 implementation, Podman now works out of the box.
redhat.com/sysadmin/podman-windows...
Small correction to your article. Indeed AWS Fargate moved away from Docker engine not to Podman or CRI-o O but moved to ContainerD the same runtime as Docker engine. aws.amazon.com/blogs/containers/un...
I hope you are right, but at the same time i think you arent. Unfortunately, there is too much investment in docker nowadays to let it just die.
Docker will not die but it need some good changes like more align towards security of containers.
Docker is so much popular that people understand 'containers' mean 'docker containers' just like 'git' means 'github'.
I try to use less docker or podman containers in production. I love lxd.
Coming from the Java world,
java -jar ...is the best container out there.It looks like runC is a tool built by Docker specifically to begin decoupling the codebase. This to me suggests that Docker is heading in a direction to address the issues mentioned and fixed with podman.
Basically docker is opensource and working to create its own competition.
docker.com/blog/runc/
I will add something more in your comment .
The Open Container Initiative (OCI)
Following Docker's release, a large community emerged around the idea of using containers as the standard unit of software delivery. As companies started using containers to package and deploy their software more and more, Docker's container runtime did not meet all technical and business needs that engineering teams could have. In response to this, the community started developing new runtimes with different implementations and capabilities. Simultaneously, new tools for building container images aimed to improve on Docker's speed or ease of use. To make sure that all container runtimes could run images produced by any build tool, the community started the Open Container Initiative — or OCI — to define industry standards around container image formats and runtimes.
Docker's original image format has become the OCI Image Specification, and various open-source build tools support it, including:
.... Read more... here .... padok.fr/en/blog/container-docker-oci
Docker is also moving to rootless. Yesterday there was a very talk about that in DockerCon by runC's maintainer.
Here's the link:
youtube.com/watch?v=uWURUtqLiqQ
+1 thanks Thomas
Quite surprised Podman hasn't been sued by Apple yet for having those three particular letters in its name.
haha after your comment they will .....
Having worked in dozens of Containerization-Projects in many companies over the years, Docker won't go away that quickly I'm afraid.
There aren't many broadly-accepted alternatives besides Docker. Docker has the advantage that "it was there first" (if we ignore LXC for a second)
Most big organizations are just now migrating to containers (I've mostly seen docker and containerd being used). Now, 7 years after docker was initially released to the public. That's how cautios/slow big organizations are.
Migrating to a new toolset during a running migration is mostly a terrible idea and almost always never happens. Even if the competing platform saves you a hell of a lot of trouble, most (big) companies prefer suffering Devs/Ops over spending precious money.
So give it a few years time until you can safely say bye-bye to docker.
The next best thing would probably be switching to plain containerD or CRI-O, since they are supported by vanilla kubernetes and thereby a safe bet for a few years.
+1 Raphael
Here is now what docker is upgrading itself in next release 20.x is go as rootless like podman. Give it a try.
New Type of Docker : Rootless + Safer : for every Docker user.
manish srivastava ・ Jun 1 ・ 9 min read
I am still that old man with LXC stick in hand :)
+1 Julien. I believe podman has three USPs that may gradually bring some more sysadmins to it's fold:
What it lacks is Gui right now. But most of us feel comfortable with our terminal 😉
+1 Julien. I believe podman has three USPs that may gradually bring some more sysadmins to it's fold:
What it lacks is Gui right now. But most of us feel comfortable with our terminal 😉
The good thing(also the bad thing) about tech is: There is always a new and better thing in the queue.
True. But there is one container technology which never got it's fame as it should have.
Lxc and LXD. Once, docker was made with it's library . Recently, they launched lxd 4.0 .
Less than 5% people uses lxd. I am also among them. ckeck out lxd too.