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13.2. Configuring your function project using the func.yaml file

The func.yaml file contains the configuration for your function project. Values specified in func.yaml are used when you execute a kn func command. For example, when you run the kn func build command, the value in the build field is used. In some cases, you can override these values with command line flags or environment variables.

If you want to avoid storing sensitive information such as an API key in the function configuration, you can add a reference to an environment variable available in the local environment. You can do this by modifying the envs field in the func.yaml file.

Prerequisites

  • You need to have the function project created.
  • The local environment needs to contain the variable that you want to reference.

Procedure

  • To refer to a local environment variable, use the following syntax: 

    {{ env:ENV_VAR }}

    Substitute ENV_VAR with the name of the variable in the local environment that you want to use.

    For example, you might have the API_KEY variable available in the local environment. You can assign its value to the MY_API_KEY variable, which you can then directly use within your function:

    Example function

    name: test
namespace: ""
runtime: go
...
envs:
- name: MY_API_KEY
  value: '{{ env:API_KEY }}'
...

13.2.2. Adding annotations to functions
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You can add Kubernetes annotations to a deployed Serverless function. Annotations enable you to attach arbitrary metadata to a function, for example, a note about the function’s purpose. Annotations are added to the annotations section of the func.yaml configuration file.

There are two limitations of the function annotation feature:

  • After a function annotation propagates to the corresponding Knative service on the cluster, it cannot be removed from the service by deleting it from the func.yaml file. You must remove the annotation from the Knative service by modifying the YAML file of the service directly, or by using the OpenShift Container Platform web console.
  • You cannot set annotations that are set by Knative, for example, the autoscaling annotations.

13.2.3. Adding annotations to a function
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You can add annotations to a function. Similar to a label, an annotation is defined as a key-value map. Annotations are useful, for example, for providing metadata about a function, such as the function’s author.

Prerequisites

  • The OpenShift Serverless Operator and Knative Serving are installed on the cluster.
  • You have installed the Knative (kn) CLI.
  • You have created a function.

Procedure

  1. Open the func.yaml file for your function.

  2. For every annotation that you want to add, add the following YAML to the annotations section: 

    name: test
namespace: ""
runtime: go
...
annotations:
  <annotation_name>: "<annotation_value>"
    1
    1
    Substitute <annotation_name>: "<annotation_value>" with your annotation.

    For example, to indicate that a function was authored by Alice, you might include the following annotation: 

    name: test
namespace: ""
runtime: go
...
annotations:
  author: "alice@example.com"
  3. Save the configuration.

The next time you deploy your function to the cluster, the annotations are added to the corresponding Knative service.

You can manually add configuration for accessing secrets and config maps to your function. This might be preferable to using the kn func config interactive utility and commands, for example when you have an existing configuration snippet.

13.2.5.1. Mounting a secret as a volume
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You can mount a secret as a volume. Once a secret is mounted, you can access it from the function as a regular file. This enables you to store on the cluster data needed by the function, for example, a list of URIs that need to be accessed by the function.

Prerequisites

  • The OpenShift Serverless Operator and Knative Serving are installed on the cluster.
  • You have installed the Knative (kn) CLI.
  • You have created a function.

Procedure

  1. Open the func.yaml file for your function.

  2. For each secret you want to mount as a volume, add the following YAML to the volumes section: 

    name: test
namespace: ""
runtime: go
...
volumes:
- secret: mysecret
  path: /workspace/secret
    • Substitute mysecret with the name of the target secret.

    • Substitute /workspace/secret with the path where you want to mount the secret.

      For example, to mount the addresses secret, use the following YAML: 

      name: test
namespace: ""
runtime: go
...
volumes:
- configMap: addresses
  path: /workspace/secret-addresses
  3. Save the configuration.

13.2.5.2. Mounting a config map as a volume
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You can mount a config map as a volume. Once a config map is mounted, you can access it from the function as a regular file. This enables you to store on the cluster data needed by the function, for example, a list of URIs that need to be accessed by the function.

Prerequisites

  • The OpenShift Serverless Operator and Knative Serving are installed on the cluster.
  • You have installed the Knative (kn) CLI.
  • You have created a function.

Procedure

  1. Open the func.yaml file for your function.

  2. For each config map you want to mount as a volume, add the following YAML to the volumes section: 

    name: test
namespace: ""
runtime: go
...
volumes:
- configMap: myconfigmap
  path: /workspace/configmap
    • Substitute myconfigmap with the name of the target config map.

    • Substitute /workspace/configmap with the path where you want to mount the config map.

      For example, to mount the addresses config map, use the following YAML: 

      name: test
namespace: ""
runtime: go
...
volumes:
- configMap: addresses
  path: /workspace/configmap-addresses
  3. Save the configuration.

You can set an environment variable from a key value defined as a secret. A value previously stored in a secret can then be accessed as an environment variable by the function at runtime. This can be useful for getting access to a value stored in a secret, such as the ID of a user.

Prerequisites

  • The OpenShift Serverless Operator and Knative Serving are installed on the cluster.
  • You have installed the Knative (kn) CLI.
  • You have created a function.

Procedure

  1. Open the func.yaml file for your function.

  2. For each value from a secret key-value pair that you want to assign to an environment variable, add the following YAML to the envs section: 

    name: test
namespace: ""
runtime: go
...
envs:
- name: EXAMPLE
  value: '{{ secret:mysecret:key }}'
    • Substitute EXAMPLE with the name of the environment variable.
    • Substitute mysecret with the name of the target secret.

    • Substitute key with the key mapped to the target value.

      For example, to access the user ID that is stored in userdetailssecret, use the following YAML: 

      name: test
namespace: ""
runtime: go
...
envs:
- value: '{{ configMap:userdetailssecret:userid }}'
  3. Save the configuration.

You can set an environment variable from a key value defined as a config map. A value previously stored in a config map can then be accessed as an environment variable by the function at runtime. This can be useful for getting access to a value stored in a config map, such as the ID of a user.

Prerequisites

  • The OpenShift Serverless Operator and Knative Serving are installed on the cluster.
  • You have installed the Knative (kn) CLI.
  • You have created a function.

Procedure

  1. Open the func.yaml file for your function.

  2. For each value from a config map key-value pair that you want to assign to an environment variable, add the following YAML to the envs section: 

    name: test
namespace: ""
runtime: go
...
envs:
- name: EXAMPLE
  value: '{{ configMap:myconfigmap:key }}'
    • Substitute EXAMPLE with the name of the environment variable.
    • Substitute myconfigmap with the name of the target config map.

    • Substitute key with the key mapped to the target value.

      For example, to access the user ID that is stored in userdetailsmap, use the following YAML: 

      name: test
namespace: ""
runtime: go
...
envs:
- value: '{{ configMap:userdetailsmap:userid }}'
  3. Save the configuration.

You can set an environment variable from all values defined in a secret. Values previously stored in a secret can then be accessed as environment variables by the function at runtime. This can be useful for simultaneously getting access to a collection of values stored in a secret, for example, a set of data pertaining to a user.

Prerequisites

  • The OpenShift Serverless Operator and Knative Serving are installed on the cluster.
  • You have installed the Knative (kn) CLI.
  • You have created a function.

Procedure

  1. Open the func.yaml file for your function.

  2. For every secret for which you want to import all key-value pairs as environment variables, add the following YAML to the envs section: 

    name: test
namespace: ""
runtime: go
...
envs:
- value: '{{ secret:mysecret }}'
    1
    1
    Substitute mysecret with the name of the target secret.

    For example, to access all user data that is stored in userdetailssecret, use the following YAML: 

    name: test
namespace: ""
runtime: go
...
envs:
- value: '{{ configMap:userdetailssecret }}'
  3. Save the configuration.

You can set an environment variable from all values defined in a config map. Values previously stored in a config map can then be accessed as environment variables by the function at runtime. This can be useful for simultaneously getting access to a collection of values stored in a config map, for example, a set of data pertaining to a user.

Prerequisites

  • The OpenShift Serverless Operator and Knative Serving are installed on the cluster.
  • You have installed the Knative (kn) CLI.
  • You have created a function.

Procedure

  1. Open the func.yaml file for your function.

  2. For every config map for which you want to import all key-value pairs as environment variables, add the following YAML to the envs section: 

    name: test
namespace: ""
runtime: go
...
envs:
- value: '{{ configMap:myconfigmap }}'
    1
    1
    Substitute myconfigmap with the name of the target config map.

    For example, to access all user data that is stored in userdetailsmap, use the following YAML: 

    name: test
namespace: ""
runtime: go
...
envs:
- value: '{{ configMap:userdetailsmap }}'
  3. Save the file.
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