Podman for Docker Users
Podman is the command-line interface tool that lets you interact with Libpod, a library for running and managing OCI-based containers. It is important to note that Podman doesn’t depend on a daemon, and it doesn’t require root privileges.
The first part of this tutorial focuses on similarities between Podman and Docker, and we’ll show how you can do the following:
- Move a Docker image to Podman.
- Create a bare-bones Nuxt.JS project and build a container image for it
- Push your container image to Quay.io
- Pull the image from Quay.io and run it with Docker.
In the second part of this tutorial, we’ll walk you through two of the most important features that differentiate Podman from Docker. In this section, you will do the following:
- Create a Pod with Podman
- Generate a Kubernetes Pod spec with Podman, and deploy it to a Kubernetes cluster.
Prerequisites
- This tutorial is intended for readers who have prior exposure to Docker. In the next sections, you will use commands such as
run
,build
,push
,commit
, andtag
. It is beyond the scope of this tutorial to explain how these commands work. - A running Linux system with Podman and Docker installed.
You can enter the following command to check that Podman is installed on your system:
podman versionVersion: 1.6.4
RemoteAPI Version: 1
Go Version: go1.12.12
OS/Arch: linux/amd64
Refer Podman Installation Instructions for details on how to install Podman.
Use the following command to verify if Docker is installed:
docker --versionDocker version 18.06.3-ce, build d7080c1
See the Get Docker page for details on how to install Docker.
- Git. To check if Git is installed on your system enter, type the following command:
git versiongit version 2.18.2
You can refer Getting Started — Installing Git on details of installing Git.
- Node.js 10 or higher. To check if Node.js is installed on your computer, type the following command:
node --versionv10.16.3
If Node.js is not installed, you can download the installer from the Downloads page.
- A Kubernetes Cluster. If you don’t have a running Kubernetes cluster, refer the “Create a Kubernetes Cluster with Kind” section.
- Additionally, you will need a Quay.io account.
Moving Images from Docker to Podman
If you’ve just installed Podman on a system on which you’ve already used Docker to pull one or more images, you’ll notice that running the podman images
command doesn't show your Docker images:
docker imagesREPOSITORY TAG IMAGE ID CREATED SIZE
cassandra latest b571e0906e1b 10 days ago 324MBpodman imagesREPOSITORY TAG IMAGE ID CREATED SIZE
The reason why you don’t see your Docker images is that Podman runs without root
privileges. Thus, its repository is located in the user's home directory - ~/.local/share/containers
. However, Podman can import an image directly from the Docker daemon running on your machine, through the docker-daemon
transport.
In this section, you’ll use Docker to pull the hello-world
image. Then, you'll import it into Podman. Lastly, you'll run the hello-world
image with Podman.
- Download and run the
hello-world
image by executing the following command:
sudo docker run hello-worldUnable to find image 'hello-world:latest' locally
latest: Pulling from library/hello-world
1b930d010525: Pull complete
Digest: sha256:9572f7cdcee8591948c2963463447a53466950b3fc15a247fcad1917ca215a2f
Status: Downloaded newer image for hello-world:latest
Hello from Docker!
This message shows that your installation appears to be working correctly.
To generate this message, Docker took the following steps:
1. The Docker client contacted the Docker daemon.
2. The Docker daemon pulled the "hello-world" image from the Docker Hub.
(amd64)
3. The Docker daemon created a new container from that image which runs the
executable that produces the output you are currently reading.
4. The Docker daemon streamed that output to the Docker client, which sent it
to your terminal.
To try something more ambitious, you can run an Ubuntu container with:
$ docker run -it ubuntu bash
Share images, automate workflows, and more with a free Docker ID:
https://hub.docker.com/
For more examples and ideas, visit:
https://docs.docker.com/get-started/
- The following
docker images
command lists the Docker images on your system and pretty-prints the output:
sudo docker images --format ':'hello-world:latest
- Enter the
podman pull
command specifying the transport (docker-daemon
) and the name of the image, separated by:
:
podman pull docker-daemon:hello-world:latestGetting image source signatures
Copying blob af0b15c8625b done
Copying config fce289e99e done
Writing manifest to image destination
Storing signatures
fce289e99eb9bca977dae136fbe2a82b6b7d4c372474c9235adc1741675f587e
- Once you’ve imported the image, running the
podman images
command will display thehello-world
image:
podman imagesREPOSITORY TAG IMAGE ID CREATED SIZE
docker.io/library/hello-world latest fce289e99eb9 13 months ago 5.94 kB
- To run the image, enter the following
podman run
command:
podman run hello-worldHello from Docker!
This message shows that your installation appears to be working correctly.
To generate this message, Docker took the following steps:
1. The Docker client contacted the Docker daemon.
2. The Docker daemon pulled the "hello-world" image from the Docker Hub.
(amd64)
3. The Docker daemon created a new container from that image which runs the
executable that produces the output you are currently reading.
4. The Docker daemon streamed that output to the Docker client, which sent it
to your terminal.
To try something more ambitious, you can run an Ubuntu container with:
$ docker run -it ubuntu bash
Share images, automate workflows, and more with a free Docker ID:
https://hub.docker.com/
For more examples and ideas, visit:
https://docs.docker.com/get-started/
Creating a Basic Nuxt.js Project
For the scope of this tutorial, we’ll create a simple web-application using Nuxt.JS, a progressive Vue-based framework that aims to provide a great experience for developers. Then, in the next sections, you’ll use Podman to create a container image for your project and push it Quay.io. Lastly, you’ll use Docker to run the container image.
- Nuxt.JS is distributed as an NPM package. To install it, fire up a terminal window, and execute the following command:
npm install nuxt+ nuxt@2.11.0
added 1067 packages from 490 contributors and audited 9750 packages in 75.666s
found 0 vulnerabilities
Note that the above output was truncated for brevity.
- With Nuxt.JS installed on your computer, you can create a new bare-bones project:
npx create-nuxt-app podman-nuxtjs-demo
You will be prompted to answer a few questions:
create-nuxt-app v2.14.0
✨ Generating Nuxt.js project in podman-nuxtjs-demo
? Project name podman-nuxtjs-demo
? Project description Podman Nuxt.JS demo
? Author name Appfleet
? Choose the package manager Npm
? Choose UI framework Bootstrap Vue
? Choose custom server framework None (Recommended)
? Choose Nuxt.js modules (Press <space> to select, <a> to toggle all, <i> to invert selectio
n)
? Choose linting tools ESLint
? Choose test framework None
? Choose rendering mode Universal (SSR)
? Choose development tools jsconfig.json (Recommended for VS Code)
Once you answer these questions, npm
will install the required dependencies:
🎉 Successfully created project podman-nuxtjs-demo
To get started:
cd podman-nuxtjs-demo
npm run dev
To build & start for production:
cd podman-nuxtjs-demo
npm run build
npm run start
Note that the above output was truncated for brevity.
- Enter the following commands to start your new application:
cd podman-nuxtjs-demo/ && npm run dev> podman-nuxtjs-demo@1.0.0 dev /home/vagrant/podman-nuxtjs-demo
> nuxt
╭─────────────────────────────────────────────╮
│ │
│ Nuxt.js v2.11.0 │
│ Running in development mode (universal) │
│ │
│ Listening on: http://localhost:3000/ │
│ │
╰─────────────────────────────────────────────╯
ℹ Preparing project for development 14:39:30
ℹ Initial build may take a while 14:39:30
✔ Builder initialized 14:39:30
✔ Nuxt files generated 14:39:30
✔ Client
Compiled successfully in 23.53s
✔ Server
Compiled successfully in 17.82s
ℹ Waiting for file changes 14:39:56
ℹ Memory usage: 209 MB (RSS: 346 MB) 14:39:56
- Point your browser to http://localhost:3000, and you should see something similar to the screenshot below:
Building a Container Image for Your Nuxt.JS Project
In this section, we’ll look at how you can use Podman to build a container image for thepodman-nextjs-demo
project.
- Create a file called
Dockerfile
and place the following content into it:
FROM node:10
WORKDIR /usr/src/app
COPY package*.json ./
RUN npm install
COPY . .
EXPOSE 3000
CMD [ "npm", "run", "dev" ]
☞ For a quick refresher on the above Dockerfile commands, refer the Create a Docker Image section from the Debug a Node.js Application Running in a Docker Container tutorial.
- To avoid sending large files to the build context and speed up the process, create a file called
.dockerignore
with the following content:
node_modules
npm-debug.log
.nuxt
As you can see, this is just a plain-text file containing names of the files and directories that Podman should exclude from the build.
- Build the image. Execute the following
podman build
command, specifying the-t
flag with the tagged name Podman will apply to the build image:
podman build -t podman-nuxtjs-demo:podman .STEP 1: FROM node:10
STEP 2: RUN mkdir -p /usr/src/nuxt-app
--> Using cache c7198c4f08b90ecb5575bbce23fc095e5c65fe5dc4b4f77b23192e2eae094d6f
STEP 3: WORKDIR /usr/src/nuxt-app
--> Using cache f1cc5aba3f36e122513c5ff0410f862d6099bcee886453f7fb30859f66e0ac78
STEP 4: COPY . /usr/src/nuxt-app/
--> Using cache fb4c322c98b41d446f5cceb88b3f9c451751d0cfe8ed9d0e6eb153919b498da3
STEP 5: RUN npm install
--> Using cache bb5324e79782b4522048dcc5f0f02c41b56e12198438aa59a7588a6824a435e1
STEP 6: RUN npm run build
> podman-nuxtjs-demo@1.0.0 build /usr/src/nuxt-app
> nuxt build
ℹ Production build
✔ Builder initialized
✔ Nuxt files generated
✔ Client
Compiled successfully in 2.95m
✔ Server
Compiled successfully in 10.91s
Hash: 7c4493c4d1c7b235dd8e
Version: webpack 4.41.6
Time: 177257ms
Built at: 02/11/2020 4:48:17 PM
Asset Size Chunks Chunk Names
../server/client.manifest.json 16.1 KiB [emitted]
7d497fe85470995d6e29.js 2.99 KiB 2 [emitted] [immutable] pages/index
848739217655a36af267.js 671 KiB 4 [emitted] [immutable] [big] vendors.app
90036491716edfc3e86d.js 159 KiB 1 [emitted] [immutable] commons.app
LICENSES 1.95 KiB [emitted]
b625f5fc00e8ff962762.js 2.31 KiB 3 [emitted] [immutable] runtime
eac7116f7d28455b0958.js 36 KiB 0 [emitted] [immutable] app
+ 2 hidden assets
Entrypoint app = b625f5fc00e8ff962762.js 90036491716edfc3e86d.js 848739217655a36af267.js eac7116f7d28455b0958.js
WARNING in asset size limit: The following asset(s) exceed the recommended size limit (244 KiB).
This can impact web performance.
Assets:
848739217655a36af267.js (671 KiB)
Hash: e3d9cfd644a086dc9c5b
Version: webpack 4.41.6
Time: 10916ms
Built at: 02/11/2020 4:48:29 PM
Asset Size Chunks Chunk Names
d1d703b09adf296a453d.js 3.07 KiB 1 [emitted] [immutable] pages/index
server.js 222 KiB 0 [emitted] app
server.manifest.json 145 bytes [emitted]
Entrypoint app = server.js
0d239b0083a60482b4b5fa60a99b96dd22045822e50fbd83b8a369d8179bf307
STEP 7: EXPOSE 3000
1d037e041dd4a8d6c94a9f6fb8fe6578f5e00d27aab9168bad83e7ab260bbeae
STEP 8: ENV NUXT_HOST=0.0.0.0
40d684a5441a8da38ed5198be722719f393be13a855a9e85cbc49e5c7155f7cc
STEP 9: ENV NUXT_PORT=3000
7d07961e058d66e172f4b9e01d50fb355c16060a990252c5bc7cd35d960f5f72
STEP 10: CMD ["npm", "run", "dev"]
STEP 11: COMMIT podman-nuxtjs-demo:podman
54c55a8a44f30105371652bc2c25e0fbba200ad6c945654077151194aa0a66fe
- At this point, you can check that everything went well with:
podman imagesREPOSITORY TAG IMAGE ID CREATED SIZE
localhost/podman-nuxtjs-demo podman 54c55a8a44f3 About a minute ago 1.09 GB
docker.io/library/node 10 bb78c02ca3bf 4 days ago 937 MB
- To run the
podman-nuxtjs-demo:podman
container, enter thepodman
run command and pass it the following arguments:
-dt
to specify that the container should be run in the background and that Podman should allocate a pseudo-TTY-p
with the port on the host (3000) that’ll be forwarded to the container port (3000), separated by:
.- The name of your image (
podman-nuxtjs-demo:podman
)
podman run -dt -p 3000:3000/tcp podman-nuxtjs-demo:podman
This will print out to the console the container ID:
4de08084dd1d33fcdae96cd493b3eb20406ea89ce2a3e8dbc833b38c2243ce43
- You can list your running containers with:
podman psCONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
4de08084dd1d localhost/podman-nuxtjs-demo:podman npm run dev 4 seconds ago Up 4 seconds ago 0.0.0.0:3000->3000/tcp objective_neumann
- To retrieve detailed information about your running container, enter the
podman inspect
command specifying the container ID:
podman inspect 4de08084dd1d33fcdae96cd493b3eb20406ea89ce2a3e8dbc833b38c2243ce43podman inspect 4de08084dd1d33fcdae96cd493b3eb20406ea89ce2a3e8dbc833b38c2243ce43
[
{
"Id": "4de08084dd1d33fcdae96cd493b3eb20406ea89ce2a3e8dbc833b38c2243ce43",
"Created": "2020-02-11T17:00:06.819669549Z",
"Path": "docker-entrypoint.sh",
"Args": [
"npm",
"run",
"dev"
],
"State": {
"OciVersion": "1.0.1-dev",
"Status": "running",
"Running": true,
"Paused": false,
"Restarting": false,
"OOMKilled": false,
"Dead": false,
"Pid": 10637,
"ConmonPid": 10628,
"ExitCode": 0,
"Error": "",
"StartedAt": "2020-02-11T17:00:07.317812139Z",
"FinishedAt": "0001-01-01T00:00:00Z",
"Healthcheck": {
"Status": "",
"FailingStreak": 0,
"Log": null
}
},
"Image": "54c55a8a44f30105371652bc2c25e0fbba200ad6c945654077151194aa0a66fe",
"ImageName": "localhost/podman-nuxtjs-demo:podman",
"Rootfs": "",
"Pod": "",
Note that the above output was truncated for brevity.
- To retrieve the logs from your container, run the
podman logs
command specifying the container ID or the--latest
flag:
podman logs --latest> podman-nuxtjs-demo@1.0.0 dev /usr/src/nuxt-app
> nuxt
╭─────────────────────────────────────────────╮
│ │
│ Nuxt.js v2.11.0 │
│ Running in development mode (universal) │
│ │
│ Listening on: http://10.0.2.100:3000/ │
│ │
╰─────────────────────────────────────────────╯
ℹ Preparing project for development
ℹ Initial build may take a while
✔ Builder initialized
✔ Nuxt files generated
✔ Client
Compiled successfully in 25.36s
✔ Server
Compiled successfully in 19.21s
ℹ Waiting for file changes
ℹ Memory usage: 254 MB (RSS: 342 MB)
- Display the list of running processes inside your container:
podman top 4de08084dd1dUSER PID PPID %CPU ELAPSED TTY TIME COMMAND
root 1 0 0.000 3m52.098907307s pts/0 0s npm
root 17 1 0.000 3m51.099829437s pts/0 0s sh -c nuxt
root 18 17 11.683 3m51.099997015s pts/0 27s node /usr/src/nuxt-app/node_modules/.bin/nuxt
Push Your Podman Image to Quay.io
- First, you must generate an encrypted password. Point your browser to http://quay.io, and then navigate to the Account Settings page:
- On the Account Settings page, select Generate Encrypted Password:
- When prompted, enter your Quay.io password:
- From the sidebar on the left, select Docker Login. Then, copy your encrypted password:
- You can now log in to Quay.io. Enter the
podman login
command specifying:
- The registry server (
quay.io
) - The
-u
flag with your username - The
-p
flag with the encrypted password you retrieved earlier
podman login quay.io -u <YOUR_USER_NAME> -p="<YOUR_ENCRYPTED_PASSWORD>"Login Succeeded!
- To push the
podman-nuxtjs-demo
image to Quay.io, enter the followingpodman push
command:
podman push podman-nuxtjs-demo:podman quay.io/andreipope/podman-nuxtjs-demo:podmanGetting image source signatures
Copying blob 69dfa7bd7a92 done
Copying blob 4d1ab3827f6b done
Copying blob 7948c3e5790c done
Copying blob 01727b1a72df done
Copying blob 03dc1830d2d5 done
Copying blob 1d7382716a27 done
Copying blob 062fc3317d1a done
Copying blob 3d36b8a4efb1 done
Copying blob 1708ebc408a9 done
Copying blob 0aacf878561f done
Copying blob c49b91e9cfd0 done
Copying blob 4294ef3571b7 done
Copying blob 1da55789948c done
Copying config 54c55a8a44 done
Writing manifest to image destination
Copying config 54c55a8a44 done
Writing manifest to image destination
Storing signatures
In the above command, do not forget to replace our username (andreipope
) with yours.
- Point your browser to https://quay.io/, navigate to the
podman-nuxtjs-demo
repository, and make sure the repository is public:
Run Your Podman Image with Docker
Container images are compatible between Podman and Docker. In this section, you’ll use Docker to pull the podman-nuxtjs-demo
image from Quay.io and run it. Ideally, you would want to run this on a different machine.
- You can log in to Quay.io by entering the
docker login
command and passing it the following parameters:
- The
-u
flag with your username - The
-p
flag with your encrypted password (you retrieved it from Quay.io in the previous section) - The name of the registry (
quay.io
)
docker login -u="<YOUR_USER_NAME>" -p="YOUR_ENCRYPTED_PASSWORD" quay.ioWARNING! Using --password via the CLI is insecure. Use --password-stdin.
Login Succeeded
- To run the
podman-nuxtjs-demo
image, you can use the following command:
docker run -dt -p 3000:3000/tcp quay.io/andreipope/podman-nuxtjs-demo:podmanUnable to find image 'quay.io/andreipope/podman-nuxtjs-demo:podman' locally
podman: Pulling from andreipope/podman-nuxtjs-demo
03644a8453bd: Pull complete
e2c9fbbb35b2: Pull complete
0c33fe27c91c: Pull complete
957ac2567af6: Pull complete
934d2e09d84d: Pull complete
50c60e376f59: Pull complete
3c43a52a3ecc: Pull complete
e74942a3267a: Pull complete
af1466e8bc5b: Pull complete
3f24948a552e: Pull complete
df2fea35a007: Pull complete
7045f2526057: Pull complete
5090c2f6d806: Pull complete
Digest: sha256:fcf90cfc3fe1d0f7e975db8a271003cdd51d6f177e490eb39ec1e44d3659b815
Status: Downloaded newer image for quay.io/andreipope/podman-nuxtjs-demo:podman
1c0981690d66f2cd8cb77e9573f1dd4e9d7700869e08797b42fc33590d8baabf
- Wait a bit until Docker pulls the image and creates the container. Then, issue the the
docker ps
command to display the list of running containers:
docker psCONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
1c0981690d66 quay.io/andreipope/podman-nuxtjs-demo:podman "docker-entrypoint.s…" 25 seconds ago Up 20 seconds 0.0.0.0:3000->3000/tcp practical_bose
- To make sure everything works as expected, point your browser to http://localhost:3000. You should see something similar to the screenshot below:
Creating Pods
Until now, you’ve used Podman similarly to how Docker is used. However, Podman brings a couple of new features such as the ability to create pods. A Pod is a group of tightly-coupled containers that share their storage and network resources. In a nutshell, you can use a Pod to model a logical host. In this section, we’ll walk you through the process of creating a Pod comprised of the podman-nuxtjs-demo
container and a PostgreSQL database. Note that it is beyond the scope of this tutorial to show how you can configure the storage and network for your Pod.
- Create a pod with the
podman-nuxtjs-demo
container. Enter thepodman run
with the following arguments:
-dt
to specify that the container should be run in the background and that Podman should allocate a pseudo-TTY--pod
with the name of your new Pod. Specifying-new
indicates that you want to create a new Pod. Otherwise, Podman tries to attach the container to an existing Pod.-p
with the port on host (3000) that’ll be forwarded to the container port (3000), separated by:
.- The name of your image (
podman-nuxtjs-demo:podman
)
podman run -dt --pod new:podman_demo -p 3000:3000/tcp quay.io/andreipope/podman-nuxtjs-demo:podman
This will print the identifier of your new Pod:
972c7c1db0c31a42ba4b41025078dfc6abb046f503aa413d6cca313068042041
- You can display the list of running Pods with the
podman pod list
command:
podman pod listPOD ID NAME STATUS CREATED # OF CONTAINERS INFRA ID
d15a2abd9d5b podman_demo Running 32 seconds ago 2 6a5bc0360ae2
In the output above, the number of containers is 2
. This is because all Podman Pods include something called an Infra container, which does nothing except that it goes to sleep. This way, it holds the namespace associated with the Pod so that Podman can attach other containers to the Pod.
- Print the list of running containers by entering the
podman ps
command followed by the-a
and-p
flags. This lists all containers and prints the identifiers and the names of the Pods your containers are associated with:
podman ps -apCONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES POD
972c7c1db0c3 quay.io/andreipope/podman-nuxtjs-demo:podman npm run dev 56 seconds ago Up 55 seconds ago 0.0.0.0:3000->3000/tcp festive_yonath d15a2abd9d5b
6a5bc0360ae2 k8s.gcr.io/pause:3.1 56 seconds ago Up 55 seconds ago 0.0.0.0:3000->3000/tcp d15a2abd9d5b-infra d15a2abd9d5b
As you can see, the Infra container uses the k8s.gcr.io/pause
image.
- Run the
postgres:11-alpine
image and associate it with thepodman_demo
Pod:
podman run -dt --pod podman_demo postgres:11-alpine
d395bed40988a953257b9501497c66b886b2fb6e81f48aa0ac89d7cfe2639b75
- This takes a bit of time to complete. Once everything is ready, you should see that the number of containers has been increased to
3
:
podman pod listPOD ID NAME STATUS CREATED # OF CONTAINERS INFRA ID
d15a2abd9d5b podman_demo Running 8 minutes ago 3 6a5bc0360ae2
- You can display the list of your running containers with the following
podman ps
command:
podman ps -apCONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES POD
ab5bd4810494 docker.io/library/postgres:11-alpine postgres 5 minutes ago Up 3 minutes ago 0.0.0.0:3000->3000/tcp dreamy_jackson d15a2abd9d5b
972c7c1db0c3 quay.io/andreipope/podman-nuxtjs-demo:podman npm run dev 9 minutes ago Up 9 minutes ago 0.0.0.0:3000->3000/tcp festive_yonath d15a2abd9d5b
6a5bc0360ae2 k8s.gcr.io/pause:3.1 9 minutes ago Up 9 minutes ago
- As an example, you can stop the
podman-nuxtjs-demo
container. The other containers in the Pod won't be affected, and the status of the Pod will show asRunning
:
podman stop 972c7c1db0c3972c7c1db0c31a42ba4b41025078dfc6abb046f503aa413d6cca313068042041podman pod psPOD ID NAME STATUS CREATED # OF CONTAINERS INFRA ID
d15a2abd9d5b podman_demo Running 12 minutes ago 3 6a5bc0360ae2
- To start again the container, enter the
podman start
command followed by the identifier of the container you want to start:
podman start 972c7c1db0c3972c7c1db0c31a42ba4b41025078dfc6abb046f503aa413d6cca313068042041
- At this point, if you run the
podman ps -ap
command, you should see that the status of thepodman-nuxtjs-demo
container is nowUp
:
podman ps -ap
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES POD
ab5bd4810494 docker.io/library/postgres:11-alpine postgres 7 minutes ago Up 5 minutes ago 0.0.0.0:3000->3000/tcp dreamy_jackson d15a2abd9d5b
972c7c1db0c3 quay.io/andreipope/podman-nuxtjs-demo:podman npm run dev 14 minutes ago Up 54 seconds ago 0.0.0.0:3000->3000/tcp festive_yonath d15a2abd9d5b
6a5bc0360ae2 k8s.gcr.io/pause:3.1 14 minutes ago Up 14 minutes ago 0.0.0.0:3000->3000/tcp d15a2abd9d5b-infra d15a2abd9d5b
- Lastly, let’s top the
podman_demo
pod:
podman pod stop podman_demod15a2abd9d5bcb6f403515c0ed4dd4cb7df252a87591a88975b5573eb7f20900
- Enter the following command to make sure your Pod is stopped:
podman pod psPOD ID NAME STATUS CREATED # OF CONTAINERS INFRA ID
d15a2abd9d5b podman_demo Stopped 17 minutes ago 3 6a5bc0360ae2
Generate a Kubernetes Pod Spec with Podman
Podman can perform a snapshot of your container/Pod and generate a Kubernetes spec. This way, it makes it easier for you to orchestrate your containers with Kubernetes. For the scope of this section, we’ll illustrate how to use Podman to generate a Kubernetes spec and deploy your Pod to Kubernetes.
- To create a Kubernetes spec for a container and save it into a file called
podman-nuxtjs-demo.yaml
, run the followingpodman generate kube
command:
podman generate kube <CONTAINER_ID> > podman-nuxtjs-demo.yaml
- Let’s take a look at what’s inside the
podman-nuxtjs-demo.yaml
file:
cat podman-nuxtjs-demo.yaml# Generation of Kubernetes YAML is still under development!
#
# Save the output of this file and use kubectl create -f to import
# it into Kubernetes.
#
# Created with podman-1.6.4
```YAML
apiVersion: v1
kind: Pod
metadata:
creationTimestamp: "2020-02-12T05:21:44Z"
labels:
app: objectiveneumann
name: objectiveneumann
spec:
containers:
- command:
- npm
- run
- dev
env:
- name: PATH
value: /usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
- name: TERM
value: xterm
- name: HOSTNAME
- name: container
value: podman
- name: NODE_VERSION
value: 10.19.0
- name: YARN_VERSION
value: 1.21.1
- name: NUXT_HOST
value: 0.0.0.0
- name: NUXT_PORT
value: "3000"
image: localhost/podman-nuxtjs-demo:podman
name: objectiveneumann
ports:
- containerPort: 3000
hostPort: 3000
protocol: TCP
resources: {}
securityContext:
allowPrivilegeEscalation: true
capabilities: {}
privileged: false
readOnlyRootFilesystem: false
tty: true
workingDir: /usr/src/nuxt-app
status: {}
There is a lot of output here, but the parts we’re interested in are:
metadata.labels.app
andmetadata.name
. You'll have to give them more meaningful namesspec.containers.image
. Since in real life you'll have to pull the images from a registry, you must replacelocalhost/podman-nuxtjs-demo:podman
with the address of your Quay.io container image.
- Edit the content of the
podman-nuxtjs-demo.yaml
file to the following:
# Generation of Kubernetes YAML is still under development!
#
# Save the output of this file and use kubectl create -f to import
# it into Kubernetes.
#
# Created with podman-1.6.4
apiVersion: v1
kind: Pod
metadata:
creationTimestamp: "2020-02-12T05:24:44Z"
labels:
app: podman-nuxtjs-demo
name: podman-nuxtjs-demo
spec:
containers:
- command:
- npm
- run
- dev
env:
- name: PATH
value: /usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
- name: TERM
value: xterm
- name: HOSTNAME
- name: container
value: podman
- name: NODE_VERSION
value: 10.19.0
- name: YARN_VERSION
value: 1.21.1
- name: NUXT_HOST
value: 0.0.0.0
- name: NUXT_PORT
value: "3000"
image: quay.io/andreipope/podman-nuxtjs-demo:podman
name: objectiveneumann
ports:
- containerPort: 3000
hostPort: 3000
protocol: TCP
resources: {}
securityContext:
allowPrivilegeEscalation: true
capabilities: {}
privileged: false
readOnlyRootFilesystem: false
tty: true
workingDir: /usr/src/nuxt-app
status: {}
The above spec uses the address of our container image — quay.io/andreipope/podman-nuxtjs-demo:podman
. Make sure you replace this with your address.
- Now, if your Quay.io repository is private, Kubernetes must authenticate with the registry to pull the image. Point your browser to http://quay.io, and then navigate to the Settings section of your repository. Select Generate Encrypted Password, and you’ll be asked to type your password. From the sidebar on the left, select Kubernetes Secret to download your Kubernetes secrets file:
- Next, you must refer to this Kubernetes secret from the
podman-nuxtjs-demo.yaml
. You can do this by adding a field similar to the one below:
imagePullSecrets:
- name: andreipope-pull-secret
Note that the name of our Kubernetes secret is andreipope-pull-secret
, but yours will be different.
At this point, your podman-nuxtjs-demo.yaml
file should look something like the following:
# Generation of Kubernetes YAML is still under development!
#
# Save the output of this file and use kubectl create -f to import
# it into Kubernetes.
#
# Created with podman-1.6.4
apiVersion: v1
kind: Pod
metadata:
creationTimestamp: "2020-02-12T05:24:44Z"
labels:
app: podman-nuxtjs-demo
name: podman-nuxtjs-demo
spec:
containers:
- command:
- npm
- run
- dev
env:
- name: PATH
value: /usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
- name: TERM
value: xterm
- name: HOSTNAME
- name: container
value: podman
- name: NODE_VERSION
value: 10.19.0
- name: YARN_VERSION
value: 1.21.1
- name: NUXT_HOST
value: 0.0.0.0
- name: NUXT_PORT
value: "3000"
image: quay.io/andreipope/podman-nuxtjs-demo:podman
name: objectiveneumann
ports:
- containerPort: 3000
hostPort: 3000
protocol: TCP
resources: {}
securityContext:
allowPrivilegeEscalation: true
capabilities: {}
privileged: false
readOnlyRootFilesystem: false
tty: true
workingDir: /usr/src/nuxt-app
imagePullSecrets:
- name: andreipope-pull-secret
status: {}
Create a Kubernetes Cluster with Kind (Optional)
Kind is a tool for running local Kubernetes clusters using Docker container “nodes”. Follow the steps in this section if you don’t have a running Kubernetes cluster:
Create a file called cluster.yaml
with the following content:
kind create cluster --config cluster.yaml# three node (two workers) cluster config
kind: Cluster
apiVersion: kind.x-k8s.io/v1alpha4
nodes:
- role: control-plane
- role: worker
- role: worker
- Apply the spec:
kind create cluster --config cluster.yamlCreating cluster "kind" ...
✓ Ensuring node image (kindest/node:v1.16.3) 🖼
✓ Preparing nodes 📦
✓ Writing configuration 📜
✓ Starting control-plane 🕹️
✓ Installing CNI 🔌
✓ Installing StorageClass 💾
✓ Joining worker nodes 🚜
Set kubectl context to "kind-kind"
You can now use your cluster with:
This creates a Kubernetes cluster with a control plane and two worker nodes.
Deploying to Kubernetes
- Apply your Kubernetes pull secrets spec. Enter the
kubectl create
command specifying:
- The
-f
flag with the name of the file (our example uses a file namedandreipope-secret.yml
) - The
--namespace
flag with the name of your namespace (we're using the default namespace)
kubectl create -f andreipope-secret.yml --namespace=defaultsecret/andreipope-pull-secret created
- Now you’re ready to apply the
podman-nuxt-js-demo
spec:
kubectl apply -f podman-nuxt-js-demo.yamlpod/podman-nuxtjs-demo created
- Monitor the status of your installation with:
kubectl get podsNAME READY STATUS RESTARTS AGE
podman-nuxtjs-demo 0/1 ContainerCreating 0 85s
- You can retrieve more details about the status of your installation by entering the
kubectl describe pod
followed by the name of your Pod:
kubectl describe pod podman-nuxtjs-demoName: podman-nuxtjs-demo
Namespace: default
Priority: 0
Node: kind-worker2/172.17.0.3
Start Time: Wed, 12 Feb 2020 19:36:37 +0200
Labels: app=podman-nuxtjs-demo
Annotations: kubectl.kubernetes.io/last-applied-configuration:
{"apiVersion":"v1","kind":"Pod","metadata":{"annotations":{},"creationTimestamp":"2020-02-12T05:24:44Z","labels":{"app":"podman-nuxtjs-dem...
Status: Pending
IP:
IPs: <none>
Containers:
objectiveneumann:
Container ID:
Image: quay.io/andreipope/podman-nuxtjs-demo:podman
Image ID:
Port: 3000/TCP
Host Port: 3000/TCP
Command:
npm
run
dev
State: Waiting
Reason: ContainerCreating
Ready: False
Restart Count: 0
Requests:
memory: 1Gi
Environment:
PATH: /usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
TERM: xterm
HOSTNAME:
container: podman
NODE_VERSION: 10.19.0
YARN_VERSION: 1.21.1
NUXT_HOST: 0.0.0.0
NUXT_PORT: 3000
Mounts:
/var/run/secrets/kubernetes.io/serviceaccount from default-token-rp6n5 (ro)
Conditions:
Type Status
Initialized True
Ready False
ContainersReady False
PodScheduled True
Volumes:
default-token-rp6n5:
Type: Secret (a volume populated by a Secret)
SecretName: default-token-rp6n5
Optional: false
QoS Class: Burstable
Node-Selectors: <none>
Tolerations: node.kubernetes.io/not-ready:NoExecute for 300s
node.kubernetes.io/unreachable:NoExecute for 300s
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal Scheduled 57s default-scheduler Successfully assigned default/podman-nuxtjs-demo to kind-worker2
Normal Pulling 55s kubelet, kind-worker2 Pulling image "quay.io/andreipope/podman-nuxtjs-demo:podman"
As an alternative, you can list events with the following command:
kubectl get eventsLAST SEEN TYPE REASON OBJECT MESSAGE
4m55s Normal RegisteredNode node/kind-control-plane Node kind-control-plane event: Registered Node kind-control-plane in Controller
4m37s Normal Starting node/kind-control-plane Starting kube-proxy.
4m36s Normal NodeHasSufficientMemory node/kind-worker Node kind-worker status is now: NodeHasSufficientMemory
4m36s Normal NodeHasNoDiskPressure node/kind-worker Node kind-worker status is now: NodeHasNoDiskPressure
4m36s Normal NodeHasSufficientPID node/kind-worker Node kind-worker status is now: NodeHasSufficientPID
4m35s Normal RegisteredNode node/kind-worker Node kind-worker event: Registered Node kind-worker in Controller
4m15s Normal Starting node/kind-worker Starting kube-proxy.
3m36s Normal NodeReady node/kind-worker Node kind-worker status is now: NodeReady
4m34s Normal NodeHasSufficientMemory node/kind-worker2 Node kind-worker2 status is now: NodeHasSufficientMemory
4m34s Normal NodeHasNoDiskPressure node/kind-worker2 Node kind-worker2 status is now: NodeHasNoDiskPressure
4m34s Normal NodeHasSufficientPID node/kind-worker2 Node kind-worker2 status is now: NodeHasSufficientPID
4m30s Normal RegisteredNode node/kind-worker2 Node kind-worker2 event: Registered Node kind-worker2 in Controller
4m15s Normal Starting node/kind-worker2 Starting kube-proxy.
3m34s Normal NodeReady node/kind-worker2 Node kind-worker2 status is now: NodeReady
3m29s Normal Scheduled pod/podman-nuxtjs-demo Successfully assigned default/podman-nuxtjs-demo to kind-worker2
3m27s Normal Pulling pod/podman-nuxtjs-demo Pulling image "quay.io/andreipope/podman-nuxtjs-demo:podman"
- Wait a bit until the pod is created. Then, you can list all pods with:
kubectl get podsNAME READY STATUS RESTARTS AGE
podman-nuxtjs-demo 1/1 Running 0 7m34s
- Now let’s forward all requests made to http://localhost:3000 to port 3000 on the
podman-nuxtjs-demo
Pod:
kubectl port-forward pod/podman-nuxtjs-demo 3000:3000Forwarding from 127.0.0.1:3000 -> 3000
Forwarding from [::1]:3000 -> 3000
Handling connection for 3000
Handling connection for 3000
Handling connection for 3000
Handling connection for 3000
Handling connection for 3000
Handling connection for 3000
Handling connection for 3000
- Point your browser to http://localhost:3000. If everything works well, you should see something like the following:
Congratulations on completing this tutorial, now you know enough to use Podman as a replacement for Docker. Stay tuned for our next tutorials where, amongst many other things, you’ll learn how to use Buildah.
Thanks for reading!