Chapter 6. Creating and managing serverless applications

Procedure

1. Create a Knative service:

   $ kn service create <service_name> --image <image> --env <key=value>

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   Example command

   $ kn service create hello --image docker.io/openshift/hello-openshift --env RESPONSE="Hello Serverless!"

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   Example output

   Creating service 'hello' in namespace 'default':
   
     0.271s The Route is still working to reflect the latest desired specification.
     0.580s Configuration "hello" is waiting for a Revision to become ready.
     3.857s ...
     3.861s Ingress has not yet been reconciled.
     4.270s Ready to serve.
   
   Service 'hello' created with latest revision 'hello-bxshg-1' and URL:
   http://hello-default.apps-crc.testing

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Procedure

1. Create a YAML file by copying the following example:

   Example Knative service YAML

   apiVersion: serving.knative.dev/v1
   kind: Service
   metadata:
     name: hello
     namespace: default
   spec:
     template:
       spec:
         containers:
           - image: docker.io/openshift/hello-openshift
             env:
               - name: RESPONSE
                 value: "Hello Serverless!"

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   In this example, the YAML file is named hello-service.yaml.

2. Navigate to the directory where the hello-service.yaml file is contained, and deploy the application by applying the YAML file:

   $ oc apply -f hello-service.yaml

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Procedure

1. Find the application URL:

   $ oc get ksvc <service_name>

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   Example output

   NAME            URL                                        LATESTCREATED         LATESTREADY           READY   REASON
   hello   http://hello-default.example.com   hello-4wsd2   hello-4wsd2   True

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2. Make a request to your cluster and observe the output:

   Example HTTP request

   $ curl http://hello-default.example.com

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   Example HTTPS request

   $ curl https://hello-default.example.com

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   Example output

   Hello Serverless!

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3. Optional. If you receive an error relating to a self-signed certificate in the certificate chain, you can add the --insecure flag to the curl command to ignore the error.

   Important

   Self-signed certificates must not be used in a production deployment. This method is only for testing purposes.

   Example command

   $ curl https://hello-default.example.com --insecure

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   Example output

   Hello Serverless!

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4. Optional. If your OpenShift Container Platform cluster is configured with a certificate that is signed by a certificate authority (CA) but not yet globally configured for your system, you can specify this with the curl command. The path to the certificate can be passed to the curl command by using the --cacert flag.

   Example command

   $ curl https://hello-default.example.com --cacert <file>

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   Example output

   Hello Serverless!

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Procedure

1. Find the application host. See the instructions in Verifying your serverless application deployment.

2. Get the public address of the ingress gateway:

   $ oc -n knative-serving-ingress get svc kourier

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   Example output

   NAME                   TYPE           CLUSTER-IP      EXTERNAL-IP                                                             PORT(S)                                                                                                                                      AGE
   kourier   LoadBalancer   172.30.51.103   a83e86291bcdd11e993af02b7a65e514-33544245.us-east-1.elb.amazonaws.com   80:31380/TCP,443:31390/TCP   67m

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   The public address is surfaced in the EXTERNAL-IP field, and in this case would be:

   a83e86291bcdd11e993af02b7a65e514-33544245.us-east-1.elb.amazonaws.com

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3. Manually set the host header of your HTTP request to the application’s host, but direct the request itself against the public address of the ingress gateway.

   Here is an example, using the information obtained from the steps in Verifying your serverless application deployment:

   $ curl -H "Host: hello-default.example.com" a83e86291bcdd11e993af02b7a65e514-33544245.us-east-1.elb.amazonaws.com
   Hello Serverless!

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   You can also make a gRPC request by setting the authority to the application’s host, while directing the request against the ingress gateway directly.

   Here is an example of what that looks like in the Golang gRPC client:

   Note

   Ensure that you append the respective port (80 by default) to both hosts as shown in the example.

   grpc.Dial(
       "a83e86291bcdd11e993af02b7a65e514-33544245.us-east-1.elb.amazonaws.com:80",
       grpc.WithAuthority("hello-default.example.com:80"),
       grpc.WithInsecure(),
   )

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