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    App runtime

    The app runtime is the environment apps are executed in.

    Buildpack Apps Container Image Apps
    System libraries
    		 Provided by the Stack Provided in the container
    Network access
    		 Full access through Envoy sidecar Full access through Envoy sidecar
    File system
    		 Ephemeral storage Ephemeral storage
    Language runtime
    		 Supplied by the Stack or Buildpack Built into the container
    User
    		 Specified by the Stack Specified on the container
    Isolation mechanism
    		 Kubernetes Pod Kubernetes Pod
    DNS
    		 Provided by Kubernetes Provided by Kubernetes

    Environment variables

    Environment variables are injected into the app at runtime by Kubernetes. Variables are added based on the following order, where later values override earlier ones with the same name:

    1. Space (set by administrators)
    2. App (set by developers)
    3. System (set by Kf)

    Kf provides the following system environment variables:

    Variable Purpose
    CF_INSTANCE_ADDR The cluster-visible IP:PORT of the App instance.
    CF_INSTANCE_GUID The UUID of the App instance.
    INSTANCE_GUID Alias of CF_INSTANCE_GUID .
    CF_INSTANCE_INDEX The index number of the App instance, this will ALWAYS be 0.
    INSTANCE_INDEX Alias of CF_INSTANCE_INDEX .
    CF_INSTANCE_IP The cluster-visible IP of the App instance.
    CF_INSTANCE_INTERNAL_IP Alias of CF_INSTANCE_IP
    VCAP_APP_HOST Alias of CF_INSTANCE_IP
    CF_INSTANCE_PORT The cluster-visible port of the App instance. In Kf this is the same as PORT .
    DATABASE_URL The first URI found in a VCAP_SERVICES credential.
    LANG Required by Buildpacks to ensure consistent script load order.
    MEMORY_LIMIT The maximum amount of memory in MB the App can consume.
    PORT The port the App should listen on for requests.
    VCAP_APP_PORT Alias of PORT .
    VCAP_APPLICATION A JSON structure containing App metadata.
    VCAP_SERVICES A JSON structure specifying bound services.

    Service credentials from bound services get injected into Apps via the VCAP_SERVICES environment variable. The variable is a valid JSON object with the following structure.

    VCAPServices

    A JSON object where the keys are Service labels and the values are an array of VCAPService . The array represents every bound service with that label. User provided services are placed under the label user-provided .

    Example

     {
  "mysql": [...],
  "postgresql": [...],
  "user-provided": [...]
}

    VCAPService

    This type represents a single bound service instance.

    Example

     {
  "binding_name": string,
  "instance_name": string,
  "name": string,
  "label": string,
  "tags": string[],
  "plan": string,
  "credentials": object
}

    Fields

    Field Type Description
    binding_name
    		string The name assigned to the service binding by the user.
    instance_name
    		string The name assigned to the service instance by the user.
    name
    		string The binding_name if it exists; otherwise the instance_name .
    label
    		string The name of the service offering.
    tags
    		string[] An array of strings an app can use to identify a service instance.
    plan
    		string[] The service plan selected when the service instance was created.
    credentials
    		object The service-specific credentials needed to access the service instance.

    VCAP_APPLICATION

    The VCAP_APPLICATION environment variable is a JSON object containing metadata about the App.

    Example

      { 
  
 "application_id" 
 : 
  
 "12345" 
 , 
  
 "application_name" 
 : 
  
 "my-app" 
 , 
  
 "application_uris" 
 : 
  
 [ 
 "my-app.example.com" 
 ], 
  
 "limits" 
 : 
  
 { 
  
 "disk" 
 : 
  
 1024 
 , 
  
 "mem" 
 : 
  
 256 
  
 }, 
  
 "name" 
 : 
  
 "my-app" 
 , 
  
 "process_id" 
 : 
  
 "12345" 
 , 
  
 "process_type" 
 : 
  
 "web" 
 , 
  
 "space_name" 
 : 
  
 "my-ns" 
 , 
  
 "uris" 
 : 
  
 [ 
 "my-app.example.com" 
 ] 
 }

    Fields

    Field Type Description
    application_id
    		string The GUID identifying the App.
    application_name
    		string The name assigned to the App when it was pushed.
    application_uris
    		string[] The URIs assigned to the App.
    limits
    		object The limits to disk space, and memory permitted to the App. Memory and disk space limits are supplied when the App is deployed, either on the command line or in the App manifest. Disk and memory limits are represented as integers, with an assumed unit of MB.
    name
    		string Identical to application_name .
    process_id
    		string The UID identifying the process. Only present in running App containers.
    process_type
    		string The type of process. Only present in running App containers.
    space_name
    		string The human-readable name of the Space where the App is deployed.
    uris
    		string[] Identical to application_uris .

    Missing Fields

    Some fields in VCAP_APPLICATION that are in Cloud Foundry are currently not supported in Kf.

    Besides CF-specific and deprecated fields ( cf_api , host , users ) the fields that are not supported in Kf are:

    • application_version (identical to version )
    • organization_id
    • organization_name
    • space_id
    • start (identical to started_at )
    • started_at_timestamp (identical to state_timestamp )
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