Using Skupper podman

Skupper podman allow you to create a site using containers, without requiring Kubernetes. Typically, you create a site on a Linux host, allowing you to link to and from other sites, regardless of whether those sites are running in podman or Kubernetes.

This is a preview feature and may change before becoming fully supported by skupper.io.

About Skupper podman

Skupper podman is available with the following precedence:

skupper --platform podman <command>

Use this option to avoid changing mode, for example, if you are working on Kubernetes and podman simultaneously.

export SKUPPER_PLATFORM=podman

Use this command to use Skupper podman for the current session, for example, if you have two terminals set to different contexts. To set the environment to target Kubernetes sites:

$ export SKUPPER_PLATFORM=kubernetes
skupper switch podman

If you enter this command, all subsequent command target podman rather than Kubernetes for all terminal sessions.

To determine which mode is currently active:

$ skupper switch

podman

To switch back to target Kubernetes sites: skupper switch kubernetes

Creating a site using Skupper podman

Prerequisites

  • The latest skupper CLI is installed.

  • Podman is installed, see https://podman.io/

    1. Set your session to use Skupper podman:

      $ export SKUPPER_PLATFORM=podman

      To verify the skupper mode:

      $ skupper switch

podman

    2. Create a Skupper site:

      The simplest Skupper site allows you to link to other sites, but does not support linking to the current site.

      $ skupper init --ingress none

It is recommended to enable lingering for <username>, otherwise Skupper may not start on boot.
Skupper is now installed for user '<username>'.  Use 'skupper status' to get more information.

      If you require that other sites can link to the site you are creating:

      $ skupper init --ingress-host <machine-address>

It is recommended to enable lingering for <username>, otherwise Skupper may not start on boot.
Skupper is now installed for user '<username>'.  Use 'skupper status' to get more information.

      For more information, see podman skupper init.

    3. Check the status of your site:

      $ skupper status
Skupper is enabled for "<username>" with site name "<machine-name>-<username>" in interior mode. It is not connected to any other sites. It has no exposed services.
      You can only create one site per user. If you require a host to support many sites, create a user for each site.

Linking sites using Skupper podman

The general flow for linking podman sites is the same as for Kubernetes sites:

  1. Generate a token on one site:

    $ skupper token create <filename>

  2. Create a link from the other site:

    $ skupper link create <filename>

After you have linked to a network, you can check the link status:

$ skupper link status

Working with services using Skupper podman

The general flow for working with services is the same for Kubernetes and Podman sites.

Services exposed on Kubernetes are not automatically available to Podman sites. This is the equivalent to Kubernetes sites created using skupper init --enable-service-sync false.
Example 01: Consuming a service from a Podman site

In this variation of the hello world example, the backend service is exposed on Kubernetes site and a Podman site is linked. You deploy the frontend as a container and that container can access the backend service.

  1. Create a Podman site and link it to a Kubernetes site.

  2. Check the service from the Podman site:

    $ skupper service status

No services defined

    This result is expected because services exposed on Kubernetes are not automatically available to Podman sites.

  3. Create a service on the Podman site matching the service exposed on the Kubernetes site:

    $ skupper service create backend 8080

  4. Validate the service from the Podman site by checking the backend API health URL:

    $ podman run -it --rm --network=skupper --name=myubi ubi8/ubi curl backend:8080/api/health

OK

    This command runs a container using the skupper network and returns the results from http://backend:8080/api/health

  5. Run the frontend as a container:

    $ podman run -dp 8080:8080 --name hello-world-frontend --network skupper quay.io/skupper/hello-world-frontend

  6. Check your service network is working as expected by navigating to http://localhost:8080 and click Say hello.

    Each of the backend replicas respond, for example Hi, Perfect Parrot. I am Kind Hearted Component (backend-7c84887f9f-wxhxp).

    In this scenario, running the skupper service status command on the Podman site does not provide much detail about the service:

    $ skupper service status
Services exposed through Skupper:
╰─ backend (tcp port 8080)
Example 02: Exposing a service from a Podman site

In this variation of the hello world example, the backend service is exposed on Podman site and consumed from a frontend on a Kubernetes site.

  1. Create a Podman site and link it to a Kubernetes site.

  2. Create and expose a frontend deployment on the Kubernetes site:

    $ kubectl create deployment frontend --image quay.io/skupper/hello-world-frontend
$ kubectl expose deployment/frontend --port 8080 --type LoadBalancer

  3. Run the backend as a container:

    $ podman run -d --name hello-world-backend --network skupper quay.io/skupper/hello-world-backend

  4. Expose the backend from the Podman site.

    $ skupper expose host hello-world-backend --address backend --port 8080

  5. From the Kubernetes site, create the backend service:

    $ skupper service create backend 8080

  6. Check your service network is working as expected by navigating to your cluster URL, port 8080, and clicking Say hello.

For more information, see podman skupper expose.