$ kn service create showcase \
--image quay.io/openshift-knative/showcase \
--target ./ \
--namespace test
When you execute kn service
commands, the changes immediately propagate to the cluster. However, as an alternative, you can execute kn service
commands in offline mode. When you create a service in offline mode, no changes happen on the cluster, and instead the service descriptor file is created on your local machine.
The offline mode of the Knative CLI is a Technology Preview feature only. Technology Preview features are not supported with Red Hat production service level agreements (SLAs) and might not be functionally complete. Red Hat does not recommend using them in production. These features provide early access to upcoming product features, enabling customers to test functionality and provide feedback during the development process. For more information about the support scope of Red Hat Technology Preview features, see Technology Preview Features Support Scope. |
After the descriptor file is created, you can manually modify it and track it in a version control system. You can also propagate changes to the cluster by using the kn service create -f
, kn service apply -f
, or oc apply -f
commands on the descriptor files.
The offline mode has several uses:
You can manually modify the descriptor file before using it to make changes on the cluster.
You can locally track the descriptor file of a service in a version control system. This enables you to reuse the descriptor file in places other than the target cluster, for example in continuous integration (CI) pipelines, development environments, or demos.
You can examine the created descriptor files to learn about Knative services. In particular, you can see how the resulting service is influenced by the different arguments passed to the kn
command.
The offline mode has its advantages: it is fast, and does not require a connection to the cluster. However, offline mode lacks server-side validation. Consequently, you cannot, for example, verify that the service name is unique or that the specified image can be pulled.
You can execute kn service
commands in offline mode, so that no changes happen on the cluster, and instead the service descriptor file is created on your local machine. After the descriptor file is created, you can modify the file before propagating changes to the cluster.
The offline mode of the Knative CLI is a Technology Preview feature only. Technology Preview features are not supported with Red Hat production service level agreements (SLAs) and might not be functionally complete. Red Hat does not recommend using them in production. These features provide early access to upcoming product features, enabling customers to test functionality and provide feedback during the development process. For more information about the support scope of Red Hat Technology Preview features, see Technology Preview Features Support Scope. |
OpenShift Serverless Operator and Knative Serving are installed on your cluster.
You have installed the Knative (kn
) CLI.
In offline mode, create a local Knative service descriptor file:
$ kn service create showcase \
--image quay.io/openshift-knative/showcase \
--target ./ \
--namespace test
Service 'showcase' created in namespace 'test'.
The --target ./
flag enables offline mode and specifies ./
as the directory for storing the new directory tree.
If you do not specify an existing directory, but use a filename, such as --target my-service.yaml
, then no directory tree is created. Instead, only the service descriptor file my-service.yaml
is created in the current directory.
The filename can have the .yaml
, .yml
, or .json
extension. Choosing .json
creates the service descriptor file in the JSON format.
The --namespace test
option places the new service in the test
namespace.
If you do not use --namespace
, and you are logged in to an OpenShift Container Platform cluster, the descriptor file is created in the current namespace. Otherwise, the descriptor file is created in the default
namespace.
Examine the created directory structure:
$ tree ./
./
└── test
└── ksvc
└── showcase.yaml
2 directories, 1 file
The current ./
directory specified with --target
contains the new test/
directory that is named after the specified namespace.
The test/
directory contains the ksvc
directory, named after the resource type.
The ksvc
directory contains the descriptor file showcase.yaml
, named according to the specified service name.
Examine the generated service descriptor file:
$ cat test/ksvc/showcase.yaml
apiVersion: serving.knative.dev/v1
kind: Service
metadata:
creationTimestamp: null
name: showcase
namespace: test
spec:
template:
metadata:
annotations:
client.knative.dev/user-image: quay.io/openshift-knative/showcase
creationTimestamp: null
spec:
containers:
- image: quay.io/openshift-knative/showcase
name: ""
resources: {}
status: {}
List information about the new service:
$ kn service describe showcase --target ./ --namespace test
Name: showcase
Namespace: test
Age:
URL:
Revisions:
Conditions:
OK TYPE AGE REASON
The --target ./
option specifies the root directory for the directory structure containing namespace subdirectories.
Alternatively, you can directly specify a YAML or JSON filename with the --target
option. The accepted file extensions are .yaml
, .yml
, and .json
.
The --namespace
option specifies the namespace, which communicates to kn
the subdirectory that contains the necessary service descriptor file.
If you do not use --namespace
, and you are logged in to an OpenShift Container Platform cluster, kn
searches for the service in the subdirectory that is named after the current namespace. Otherwise, kn
searches in the default/
subdirectory.
Use the service descriptor file to create the service on the cluster:
$ kn service create -f test/ksvc/showcase.yaml
Creating service 'showcase' in namespace 'test':
0.058s The Route is still working to reflect the latest desired specification.
0.098s ...
0.168s Configuration "showcase" is waiting for a Revision to become ready.
23.377s ...
23.419s Ingress has not yet been reconciled.
23.534s Waiting for load balancer to be ready
23.723s Ready to serve.
Service 'showcase' created to latest revision 'showcase-00001' is available at URL:
http://showcase-test.apps.example.com