In a previous tutorial, Deploying a Kubernetes-In-Docker (KIND) Cluster Using Podman on Ubuntu Linux, we took a look at how to use Podman to deploy a KIND container.
While discussing good use cases for an article on deploying an application in a Podman Pod with my friend Jeff Kaleth, he suggested Atlassian Confluence, as he does quite a bit of work documenting things with it. Confluence tends to be consumed as SaaS these days, but sometimes you might want to run a local instance.
Traditionally, this would mean installing software either on a bare metal server or virtual machine, on top of an operating system. This would be messy, and take time and effort to get everything configured properly. Yuck!
There has to be a better way. There is!
In my previous tutorial, Deploying a Confluence Server in a Podman Pod Using Containers, I showed you how to get a minimal instance of Confluence, with a Postgres instance backing it up, in a Podman Pod, up and running in minutes.
In this tutorial, I'm going to show you how we can use Podman and our Confluence pod, running in Podman, to generate a YAML manifest that we can then deploy to Kubernetes. We're going to focus on using Podman to generate the YAML manifest, with a detour to generate a set of systemd unit files in the process!
Buckle up! Let's hit the road!
GitHub: Using Podman to Generate and Test a Kubernetes YAML Manifest
GitHub: Deploying a Confluence Server in a Podman Pod Using Containers
GitHub: Deploying a Kubernetes-In-Docker (KIND) Cluster Using Podman on Ubuntu Linux
dockerhub: atlassian/confluence-server
Podman: Managing pods and containers in a local container runtime
Podman can now ease the transition to Kubernetes and CRI-O
You will need an x64 Linux instance (physical or virtual) to deploy the Confluence container we will be using. You're also going to need Podman installed and configured on your Linux instance. If you need to accomplish this, see the References section above.
For those who followed the tutorial in my previous article, Deploying a Confluence Server in a Podman Pod Using Containers, this will look familiar.
Before we can generate a YAML manifest, we will need to create our pod, so we have something to grab a configuration snapshot from.
First, let's create directories (if needed) for our Confluence server data and our Postgres database data:
mkdir -p ~/confluence/site1/data
mkdir -p ~/confluence/site1/databaseIf you still have these directories from the first tutorial, and don't care about the site data in the site1 directory, feel free to delete the existing directories and create a fresh set of site1 directories:
sudo rm -rf ~/confluence/*mkdir -p ~/confluence/site1/data
mkdir -p ~/confluence/site1/databaseYou can create a second set of directories instead, to preserve any data from the first tutorial.
Create a new set of site2 directories:
mkdir -p ~/confluence/site2/data
mkdir -p ~/confluence/site2/databaseMoving forward, use site2 in place of site1 when creating your containers, as appropriate.
Next, let's pull our container images, so we have them. If you've done this before, do it again to refresh your container images.
Pull the atlassian/confluence-server container image:
podman pull atlassian/confluence-serverPull the postgres container image:
podman pull postgresChecking our work:
podman imagesWe should see something like the following:
REPOSITORY TAG IMAGE ID CREATED SIZE
docker.io/atlassian/confluence-server latest 3144ae928531 12 hours ago 1.42 GB
docker.io/atlassian/confluence latest 52ead2ad4991 2 weeks ago 1.42 GB
docker.io/library/postgres latest 3b6645d2c145 3 weeks ago 387 MB
k8s.gcr.io/pause 3.5 ed210e3e4a5b 2 years ago 690 kBFirst, we'll create our confluence-pod to put our atlassian/confluence-server and postgres containers in. We'll publish our Confluence server port, which is 8090, to our host on 8290, as some folks use port 8090 for Cockpit. We're going to keep the database traffic local to our pod.
Create our confluence-pod pod:
podman pod create --name confluence-pod -p 8290:8090Next, we'll add our atlassian/confluence-server and postgres containers.
Create our confluence-postgres container in the confluence-pod pod:
podman run --name confluence-postgres -e POSTGRES_USER=confluenceUser -e POSTGRES_PASSWORD=confluencePW -e POSTGRES_DB=confluenceDB -v ~/confluence/site1/database:/var/lib/postgresql/data --pod confluence-pod -d postgresNote the postgres user, password and the Confluence database password above.
Next, create our confluence-server container in the confluence-pod pod:
podman run -v ~/confluence/site1/data:/var/atlassian/application-data/confluence --name confluence-server --pod confluence-pod -d atlassian/confluenceChecking our work:
podman ps -a --podWe should see our confluence-pod pod, with the confluence-postgres and confluence-server containers:
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES POD ID PODNAME
04ed5ee269f8 k8s.gcr.io/pause:3.5 46 seconds ago Up 27 seconds ago 0.0.0.0:8290->8090/tcp 27e702e352bd-infra 27e702e352bd confluence-pod
821be37b766b docker.io/library/postgres:latest postgres 26 seconds ago Up 27 seconds ago 0.0.0.0:8290->8090/tcp confluence-postgres 27e702e352bd confluence-pod
3a344dd8b800 docker.io/atlassian/confluence:latest /entrypoint.py 7 seconds ago Up 8 seconds ago 0.0.0.0:8290->8090/tcp confluence-server 27e702e352bd confluence-podIf we point our web browser at our host, on port 8290, we should get our Confluence licensing page as shown below.
You now have a working instance of Confluence Server!
We can use Podman to export the running configuration of our confluence-pod pod in a YAML manifest that we can then use to create a copy of our confluence-pod pod in Kubernetes.
Now that we have a running confluence-pod pod with our confluence-postgres and confluence-server containers, we can capture the configuration in a YAML manifest, using the podman generate kube command.
First, let's take a look at the podman generate command:
podman generate --helpWe should see:
Generate structured data based on containers, pods or volumes
Description:
Generate structured data (e.g., Kubernetes YAML or systemd units) based on containers, pods or volumes.
Usage:
podman generate [command]
Available Commands:
kube Generate Kubernetes YAML from containers, pods or volumes.
systemd Generate systemd units.We can use the podman generate command to create both YAML manifests for Kubernetes, as well as systemd unit files that we can use to manage Podman containers in systemd. We're going to take a look at generating a YAML manifest first.
Trying the podman generate kube command:
podman generate kube confluence-podWe get the following output:
# Save the output of this file and use kubectl create -f to import
# it into Kubernetes.
#
# Created with podman-3.4.4
apiVersion: v1
kind: Pod
metadata:
creationTimestamp: "2023-03-22T19:41:43Z"
labels:
app: confluence-pod
name: confluence-pod
spec:
containers:
...We can use redirection to create a file for our YAML configuration:
podman generate kube confluence-pod > confluence-pod.yamlChecking the contents of our file:
cat confluence-pod.yamlWe should see something similar to the following:
# Save the output of this file and use kubectl create -f to import
# it into Kubernetes.
#
# Created with podman-3.4.4
apiVersion: v1
kind: Pod
metadata:
creationTimestamp: "2023-03-22T19:43:59Z"
labels:
app: confluence-pod
name: confluence-pod
spec:
containers:
...We need to edit our YAML manifest. I'm using vi, but you can use your favorite editor.
Edit manifest:
vi confluence-pod.yamlWe want to change two things in the manifest:
- Remove any timestamp or other unneeded metadata
- Change all instances of
site1tosite2, if you are using thesite2directories, if needed
We should end up with something like the following:
# Save the output of this file and use kubectl create -f to import
# it into Kubernetes.
#
# Created with podman-3.4.4
apiVersion: v1
kind: Pod
metadata:
labels:
app: confluence-pod
name: confluence-pod
spec:
containers:
- args:
- postgres
image: docker.io/library/postgres:latest
name: confluence-postgres
ports:
- containerPort: 8090
hostPort: 8290
resources: {}
securityContext:
capabilities:
drop:
- CAP_MKNOD
- CAP_NET_RAW
- CAP_AUDIT_WRITE
volumeMounts:
- mountPath: /var/lib/postgresql/data
name: home-tdean-confluence-site1-database-host-0
- args:
- /entrypoint.py
image: docker.io/atlassian/confluence:latest
name: confluence-server
resources: {}
securityContext:
capabilities:
drop:
- CAP_MKNOD
- CAP_NET_RAW
- CAP_AUDIT_WRITE
volumeMounts:
- mountPath: /var/atlassian/application-data/confluence
name: home-tdean-confluence-site1-data-host-0
restartPolicy: Never
volumes:
- hostPath:
path: /home/tdean/confluence/site1/database
type: Directory
name: home-tdean-confluence-site1-database-host-0
- hostPath:
path: /home/tdean/confluence/site1/data
type: Directory
name: home-tdean-confluence-site1-data-host-0
status: {}We now have a YAML manifest for our confluence-pod pod!
While we have a running confluence-pod pod , we're going to use Podman to generate a systemd unit file, which we will set aside for now.
Let's take a look at the podman generate command again:
podman generate --helpOnce again, we should see:
Generate structured data based on containers, pods or volumes
Description:
Generate structured data (e.g., Kubernetes YAML or systemd units) based on containers, pods or volumes.
Usage:
podman generate [command]
Available Commands:
kube Generate Kubernetes YAML from containers, pods or volumes.
systemd Generate systemd units.Let's give the podman generate systemd command a try:
podman generate systemd confluence-podWe should get output similar to the following:
# pod-27e702e352bdadc67a302d163fdd46c6abd5bc4c2357ad5178b00e84c924c33d.service
# autogenerated by Podman 3.4.4
# Wed Mar 22 19:48:11 UTC 2023
[Unit]
Description=Podman pod-27e702e352bdadc67a302d163fdd46c6abd5bc4c2357ad5178b00e84c924c33d.service
Documentation=man:podman-generate-systemd(1)
Wants=network-online.target
After=network-online.target
RequiresMountsFor=
Requires=container-3a344dd8b80039e92aa830ff37e98bc096878a1829f90c3842bb6f57588177f0.service container-821be37b766ba9f4b502956db4a0675cb2b305900e1463b253c684d7eea3993d.service
Before=container-3a344dd8b80039e92aa830ff37e98bc096878a1829f90c3842bb6f57588177f0.service container-821be37b766ba9f4b502956db4a0675cb2b305900e1463b253c684d7eea3993d.service
[Service]
Environment=PODMAN_SYSTEMD_UNIT=%n
Restart=on-failure
TimeoutStopSec=70
ExecStart=/usr/bin/podman start 04ed5ee269f8a558c66d7d4bb821653b54586d3d8d87b53dd732b09738cd8412
ExecStop=/usr/bin/podman stop -t 10 04ed5ee269f8a558c66d7d4bb821653b54586d3d8d87b53dd732b09738cd8412
ExecStopPost=/usr/bin/podman stop -t 10 04ed5ee269f8a558c66d7d4bb821653b54586d3d8d87b53dd732b09738cd8412
PIDFile=/run/user/1000/containers/overlay-containers/04ed5ee269f8a558c66d7d4bb821653b54586d3d8d87b53dd732b09738cd8412/userdata/conmon.pid
Type=forking
[Install]
WantedBy=default.target
# container-3a344dd8b80039e92aa830ff37e98bc096878a1829f90c3842bb6f57588177f0.service
# autogenerated by Podman 3.4.4
# Wed Mar 22 19:48:11 UTC 2023
[Unit]
Description=Podman container-3a344dd8b80039e92aa830ff37e98bc096878a1829f90c3842bb6f57588177f0.service
Documentation=man:podman-generate-systemd(1)
Wants=network-online.target
After=network-online.target
RequiresMountsFor=/run/user/1000/containers
BindsTo=pod-27e702e352bdadc67a302d163fdd46c6abd5bc4c2357ad5178b00e84c924c33d.service
After=pod-27e702e352bdadc67a302d163fdd46c6abd5bc4c2357ad5178b00e84c924c33d.service
[Service]
Environment=PODMAN_SYSTEMD_UNIT=%n
Restart=on-failure
TimeoutStopSec=70
ExecStart=/usr/bin/podman start 3a344dd8b80039e92aa830ff37e98bc096878a1829f90c3842bb6f57588177f0
ExecStop=/usr/bin/podman stop -t 10 3a344dd8b80039e92aa830ff37e98bc096878a1829f90c3842bb6f57588177f0
ExecStopPost=/usr/bin/podman stop -t 10 3a344dd8b80039e92aa830ff37e98bc096878a1829f90c3842bb6f57588177f0
PIDFile=/run/user/1000/containers/overlay-containers/3a344dd8b80039e92aa830ff37e98bc096878a1829f90c3842bb6f57588177f0/userdata/conmon.pid
Type=forking
[Install]
WantedBy=default.target
# container-821be37b766ba9f4b502956db4a0675cb2b305900e1463b253c684d7eea3993d.service
# autogenerated by Podman 3.4.4
# Wed Mar 22 19:48:11 UTC 2023
[Unit]
Description=Podman container-821be37b766ba9f4b502956db4a0675cb2b305900e1463b253c684d7eea3993d.service
Documentation=man:podman-generate-systemd(1)
Wants=network-online.target
After=network-online.target
RequiresMountsFor=/run/user/1000/containers
BindsTo=pod-27e702e352bdadc67a302d163fdd46c6abd5bc4c2357ad5178b00e84c924c33d.service
After=pod-27e702e352bdadc67a302d163fdd46c6abd5bc4c2357ad5178b00e84c924c33d.service
[Service]
Environment=PODMAN_SYSTEMD_UNIT=%n
Restart=on-failure
TimeoutStopSec=70
ExecStart=/usr/bin/podman start 821be37b766ba9f4b502956db4a0675cb2b305900e1463b253c684d7eea3993d
ExecStop=/usr/bin/podman stop -t 10 821be37b766ba9f4b502956db4a0675cb2b305900e1463b253c684d7eea3993d
ExecStopPost=/usr/bin/podman stop -t 10 821be37b766ba9f4b502956db4a0675cb2b305900e1463b253c684d7eea3993d
PIDFile=/run/user/1000/containers/overlay-containers/821be37b766ba9f4b502956db4a0675cb2b305900e1463b253c684d7eea3993d/userdata/conmon.pid
Type=forking
[Install]
WantedBy=default.targetWe can see that we get three unit files, one for the confluence-pod pod and one each for our confluence-postgres and confluence-server containers.
Let's put that into a file:
podman generate systemd confluence-pod > confluence-pod-systemd.txtWe're going to set our consolidated systemd unit file aside for now. Look for an article on how to put this to use in the future!
Before we test our YAML manifest, we need to delete the existing confluence-server containers and the confluence-pod pod. When we test our YAML manifest, we will be creating objects with the same name in Podman, and if these object already exist, we will get an error and the process will fail.
Delete the containers:
podman rm -f confluence-server confluence-postgresDelete the pod:
podman pod rm -f confluence-podChecking our work:
podman ps -a --podWe should not see any containers or pods:
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES POD ID PODNAMELooking great! Now we're ready to test our manifest.
We can use the podman play kube command to test our YAML manifest:
podman play kube --helpWe should see:
Play containers, pods or volumes from a structured file
Description:
Play structured data (e.g., Kubernetes YAML) based on containers, pods or volumes.
Usage:
podman play [command]
Available Commands:
kube Play a pod or volume based on Kubernetes YAML.Let's give it a try with our YAML manifest:
podman play kube confluence-pod.yamlWe should get output similar to the following:
Trying to pull docker.io/atlassian/confluence:latest...
Getting image source signatures
Copying blob d6adb981df4e [--------------------------------------] 0.0b / 0.0b
Copying blob b9cabe75b440 [--------------------------------------] 0.0b / 0.0b
Copying blob adb8bdfab6a9 [--------------------------------------] 0.0b / 0.0b
Copying blob 7c134c18e00f skipped: already exists
Copying blob 026ca17296e7 skipped: already exists
Copying blob cff6df0cca35 [--------------------------------------] 0.0b / 0.0b
Copying blob 2d76e33286b3 [--------------------------------------] 0.0b / 0.0b
Copying blob 342f22ed35dc skipped: already exists
Copying blob ac1184f53f8b skipped: already exists
Copying blob 74ac377868f8 [--------------------------------------] 0.0b / 0.0b
Copying config 3144ae9285 done
Writing manifest to image destination
Storing signatures
Pod:
c9f0e15b3548dce303a2d41e4cdc721882a4f10358d0c62525b3e592510920d6
Containers:
ea61b70bfecfaa8558bf968e059fd7882e0cdbc5b4d3005c9da1609f7de89fb0
3afce24471e61edd14595a50b2a477399a161fc0551620302535ec8bf4a9500aChecking our work:
podman ps -a --podWe should see something similar to the following:
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES POD ID PODNAME
73694bf971bc k8s.gcr.io/pause:3.5 About a minute ago Up About a minute ago 0.0.0.0:8290->8090/tcp c9f0e15b3548-infra c9f0e15b3548 confluence-pod
ea61b70bfecf docker.io/library/postgres:latest postgres About a minute ago Up About a minute ago 0.0.0.0:8290->8090/tcp confluence-pod-confluence-postgres c9f0e15b3548 confluence-pod
3afce24471e6 docker.io/atlassian/confluence:latest /entrypoint.py About a minute ago Up About a minute ago 0.0.0.0:8290->8090/tcp confluence-pod-confluence-server c9f0e15b3548 confluence-podIf we point our web browser at our host, on port 8290, we should get our Confluence licensing page as shown below.
Our YAML manifest works great with Podman! Success!
Before we wrap up, we need to delete the test confluence-server containers and the test confluence-pod pod.
Delete the containers:
podman rm -f --allDelete the pod:
podman pod rm -f --allChecking our work:
podman ps -a --podWe should not see any containers or pods:
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES POD ID PODNAMEOur manifest is looking good and passes the Podman test! Kubernetes, here we come!
So, we've shown that deploying a self-hosted Confluence server doesn't have to be a pain. We stood up a hosted instance of Confluence in short order, using the power of Podman, pods and containers. And we used that to generate a YAML manifest, based on our pod's running configuration in Podman, and used Podman to test our manifest.
Shall we take our Confluence pod manifest to Kubernetes? Why yes!
In the next tutorial, we're going to see what happens when we feed our YAML manifest for our Confluence pod into a KIND (Kubernetes-In-Docker) cluster!
Enjoy!
Tom Dean