Files
podman/docs/source/markdown/podman-kube-generate.1.md
Vikas Goel 89b415ba37 Comply to Kubernetes specifications for annotation size.
An annotation is a pair of key-value. The key has two parts, viz. a name and an optional prefix in DNS format.

The limitations on name is 63, prefix 253 chars. The limitation on total size of all key+value pairs combined is 256KB.

https://kubernetes.io/docs/concepts/overview/working-with-objects/annotations/#syntax-and-character-set

Fixes: https://github.com/containers/podman/issues/21663

Signed-off-by: Vikas Goel <vikas.goel@gmail.com>
2024-02-20 14:58:35 -08:00

248 lines
8.7 KiB
Markdown

% podman-kube-generate 1
## NAME
podman-kube-generate - Generate Kubernetes YAML based on containers, pods or volumes
## SYNOPSIS
**podman kube generate** [*options*] *container...* | *pod...* | *volume...*
## DESCRIPTION
**podman kube generate** generates Kubernetes YAML (v1 specification) from Podman containers, pods or volumes. Regardless of whether
the input is for containers or pods, Podman generates the specification as a Pod by default. The input may be in the form
of one or more containers, pods or volumes names or IDs.
`Podman Containers or Pods`
Volumes appear in the generated YAML according to two different volume types. Bind-mounted volumes become *hostPath* volume types and named volumes become *persistentVolumeClaim* volume types. Generated *hostPath* volume types are one of three subtypes depending on the state of the host path: *DirectoryOrCreate* when no file or directory exists at the host, *Directory* when host path is a directory, or *File* when host path is a file. The value for *claimName* for a *persistentVolumeClaim* is the name of the named volume registered in Podman.
Potential name conflicts between volumes are avoided by using a standard naming scheme for each volume type. The *hostPath* volume types are named according to the path on the host machine, replacing forward slashes with hyphens less any leading and trailing forward slashes. The special case of the filesystem root, `/`, translates to the name `root`. Additionally, the name is suffixed with `-host` to avoid naming conflicts with *persistentVolumeClaim* volumes. Each *persistentVolumeClaim* volume type uses the name of its associated named volume suffixed with `-pvc`.
Note that if an init container is created with type `once` and the pod has been started, it does not show up in the generated kube YAML as `once` type init containers are deleted after they are run. If the pod has only been created and not started, it is in the generated kube YAML.
Init containers created with type `always` are always generated in the kube YAML as they are never deleted, even after running to completion.
*Note*: When using volumes and generating a Kubernetes YAML for an unprivileged and rootless podman container on an **SELinux enabled system**, one of the following options must be completed:
* Add the "privileged: true" option to the pod spec
* Add `type: spc_t` under the `securityContext` `seLinuxOptions` in the pod spec
* Relabel the volume via the CLI command `chcon -t container_file_t -R <directory>`
Once completed, the correct permissions are in place to access the volume when the pod/container is created in a Kubernetes cluster.
Note that the generated Kubernetes YAML file can be used to re-run the deployment via podman-play-kube(1).
Note that if the pod being generated was created with the **--infra-name** flag set, then the generated kube yaml will have the **io.podman.annotations.infra.name** set where the value is the name of the infra container set by the user.
Also note that both Deployment and DaemonSet can only have `restartPolicy` set to `Always`.
## OPTIONS
#### **--filename**, **-f**=*filename*
Output to the given file instead of STDOUT. If the file already exists, `kube generate` refuses to replace it and returns an error.
#### **--podman-only**
Add podman-only reserved annotations in generated YAML file (Cannot be used by Kubernetes)
#### **--replicas**, **-r**=*replica count*
The value to set `replicas` to when generating a **Deployment** kind.
Note: this can only be set with the option `--type=deployment`.
#### **--service**, **-s**
Generate a Kubernetes service object in addition to the Pods. Used to generate a Service specification for the corresponding Pod output. In particular, if the object has portmap bindings, the service specification includes a NodePort declaration to expose the service. A random port is assigned by Podman in the specification.
#### **--type**, **-t**=*pod* | *deployment* | *daemonset*
The Kubernetes kind to generate in the YAML file. Currently, the only supported Kubernetes specifications are `Pod`, `Deployment` and `DaemonSet`. By default, the `Pod` specification is generated.
## EXAMPLES
Create Kubernetes Pod YAML for the specified container.
```
$ podman kube generate some-mariadb
# Save the output of this file and use kubectl create -f to import
# it into Kubernetes.
#
# Created with podman-4.8.2
# NOTE: If you generated this yaml from an unprivileged and rootless podman container on an SELinux
# enabled system, check the podman generate kube man page for steps to follow to ensure that your pod/container
# has the right permissions to access the volumes added.
---
apiVersion: v1
kind: Pod
metadata:
creationTimestamp: "2024-01-09T02:24:55Z"
labels:
app: some-mariadb-pod
name: some-mariadb-pod
spec:
containers:
- args:
- mariadbd
env:
- name: MARIADB_ROOT_PASSWORD
value: x
image: docker.io/library/mariadb:10.11
name: some-mariadb
ports:
- containerPort: 3306
hostPort: 34891
volumeMounts:
- mountPath: /var/lib/mysql
name: mariadb_data-pvc
volumes:
- name: mariadb_data-pvc
persistentVolumeClaim:
claimName: mariadb_data
```
Create Kubernetes Deployment YAML with 3 replicas for the specified container.
```
$ podman kube generate --type deployment --replicas 3 dep-ct
r
# Save the output of this file and use kubectl create -f to import
# it into Kubernetes.
#
# Created with podman-4.5.0-dev
apiVersion: apps/v1
kind: Deployment
metadata:
creationTimestamp: "2023-03-27T20:45:08Z"
labels:
app: dep-ctr-pod
name: dep-ctr-pod-deployment
spec:
replicas: 3
selector:
matchLabels:
app: dep-ctr-pod
template:
metadata:
annotations:
io.podman.annotations.ulimit: nofile=524288:524288,nproc=127332:127332
creationTimestamp: "2023-03-27T20:45:08Z"
labels:
app: dep-ctr-pod
name: dep-ctr-pod
spec:
containers:
- command:
- top
image: docker.io/library/alpine:latest
name: dep-ctr
```
Create Kubernetes Pod YAML for the specified container with the host directory `/home/user/my-data` bind-mounted onto the container path `/volume`.
```
$ podman kube generate my-container-with-bind-mounted-data
# Save the output of this file and use kubectl create -f to import
# it into Kubernetes.
#
# Created with podman-3.1.0-dev
apiVersion: v1
kind: Pod
metadata:
creationTimestamp: "2021-03-18T16:26:08Z"
labels:
app: my-container-with-bind-mounted-data
name: my-container-with-bind-mounted-data
spec:
containers:
- command:
- /bin/sh
image: docker.io/library/alpine:latest
name: test-bind-mount
volumeMounts:
- mountPath: /volume
name: home-user-my-data-host
restartPolicy: Never
volumes:
- hostPath:
path: /home/user/my-data
type: Directory
name: home-user-my-data-host
```
Create Kubernetes Pod YAML for the specified container with named volume `priceless-data` mounted onto the container path `/volume`.
```
$ podman kube generate my-container-using-priceless-data
# Save the output of this file and use kubectl create -f to import
# it into Kubernetes.
#
# Created with podman-3.1.0-dev
apiVersion: v1
kind: Pod
metadata:
creationTimestamp: "2021-03-18T16:26:08Z"
labels:
app: my-container-using-priceless-data
name: my-container-using-priceless-data
spec:
containers:
- command:
- /bin/sh
image: docker.io/library/alpine:latest
name: test-bind-mount
volumeMounts:
- mountPath: /volume
name: priceless-data-pvc
restartPolicy: Never
volumes:
- name: priceless-data-pvc
persistentVolumeClaim:
claimName: priceless-data
```
Create Kubernetes Pod YAML for the specified pod and include a service.
```
$ sudo podman kube generate -s demoweb
# Save the output of this file and use kubectl create -f to import
# it into Kubernetes.
#
# Created with podman-0.12.2-dev
apiVersion: v1
kind: Pod
metadata:
creationTimestamp: 2018-12-18T15:16:06Z
labels:
app: demoweb
name: demoweb-libpod
spec:
containers:
- command:
- python3
- /root/code/graph.py
image: quay.io/baude/demoweb:latest
name: practicalarchimedes
tty: true
workingDir: /root/code
---
apiVersion: v1
kind: Service
metadata:
creationTimestamp: 2018-12-18T15:16:06Z
labels:
app: demoweb
name: demoweb-libpod
spec:
ports:
- name: "8050"
nodePort: 31269
port: 8050
targetPort: 0
selector:
app: demoweb
type: NodePort
status:
loadBalancer: {}
```
## SEE ALSO
**[podman(1)](podman.1.md)**, **[podman-container(1)](podman-container.1.md)**, **[podman-pod(1)](podman-pod.1.md)**, **[podman-kube-play(1)](podman-kube-play.1.md)**, **[podman-kube-down(1)](podman-kube-down.1.md)**
## HISTORY
December 2018, Originally compiled by Brent Baude (bbaude at redhat dot com)