CFAR Environment Variables

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This page describes the environment variables that the Cloud Foundry Application Runtime (CFAR) runtime and buildpacks set for a deployed app.

Overview

Environment variables are the means by which CFAR communicates with a deployed app about its environment.

For information about setting your own app-specific environment variables, see the Environment Variable section of the Deploying with App Manifests topic.

View Environment Variables

Using the Cloud Foundry Command Line Interface (cf CLI), you can run the cf env command to view the CFAR environment variables for your app. The cf env command displays the following environment variables:

• The VCAP_APPLICATION and VCAP_SERVICES variables provided in the container environment

• The user-provided variables set using the cf set-env command

For more information about the cf env command, see env in the cf CLI documentation. For more information about the cf set-env command, see set-env in the cf CLI documentation.

The following example demonstrates the environment variables cf env displays:

$ cf env my-app
Getting env variables for app my-app in org my-org / space my-space as
admin...
OK
System-Provided:

{
 "VCAP_APPLICATION": {
  "application_id": "fa05c1a9-0fc1-4fbd-bae1-139850dec7a3",
  "application_name": "my-app",
  "application_uris": [
    "my-app.example.com"
  ],
  "application_version": "fb8fbcc6-8d58-479e-bcc7-3b4ce5a7f0ca",
  "cf_api": "https://api.example.com",
  "limits": {
    "disk": 1024,
    "fds": 16384,
    "mem": 256
  },
  "name": "my-app",
  "organization_id": "c0134bad-97a9-468d-ab9d-e97547e3aed5",
  "organization_name": "my-org",
  "space_id": "06450c72-4669-4dc6-8096-45f9777db68a",
  "space_name": "my-space",
  "uris": [
    "my-app.example.com"
  ],
  "users": null,
  "version": "fb8fbcc6-8d58-479e-bcc7-3b4ce5a7f0ca"
  }
}

User-Provided:
MY_DRAIN: http://drain.example.com
MY_ENV_VARIABLE: 100

App-Specific System Variables

This section describes the environment variables that CFAR makes available to your app container. Some of these variables are the same across instances of a single app, and some vary from instance to instance.

You can access environment variables programmatically, including variables defined by the buildpack. For more information, see the buildpack documentation for Java, Node.js, and Ruby.

The table below lists the system variables available to your app container.

CF_INSTANCE_ADDR

The CF_INSTANCE_IP and CF_INSTANCE_PORT of the app instance, in the format IP:PORT.

For example: CF_INSTANCE_ADDR=1.2.3.4:5678

For more information, see CF_INSTANCE_IP and CF_INSTANCE_PORT.

CF_INSTANCE_GUID

The UUID of the app instance.

For example: CF_INSTANCE_GUID=41653aa4-3a3a-486a-4431-ef258b39f042

CF_INSTANCE_INDEX

The index number of the app instance.

For example: CF_INSTANCE_INDEX=0

CF_INSTANCE_IP

The external IP address of the host running the app instance.

For example: CF_INSTANCE_IP=1.2.3.4

CF_INSTANCE_INTERNAL_IP

The internal IP address of the container running the app instance.

For example: CF_INSTANCE_INTERNAL_IP=5.6.7.8

CF_INSTANCE_PORT

The external, or host-side, port corresponding to the internal, or container-side, port with value PORT. This value is usually different from the PORT of the app instance.

For example: CF_INSTANCE_PORT=61045

For more information, see PORT.

CF_INSTANCE_PORTS

The list of mappings between internal, or container-side, and external, or host-side, ports allocated to the container running the app instance. Not all of the internal ports are necessarily available for the app to bind to, as some of them may be used by system-provided services that also run inside the container. These internal and external values may differ.

For example: CF_INSTANCE_PORTS=[{external:61045,internal:8080},{external:61046,internal:2222}]

DATABASE_URL

For apps bound to certain services that use a database, CFAR creates a DATABASE_URL environment variable based on the VCAP_SERVICES environment variable.

CFAR uses the structure of the VCAP_SERVICES environment variable to populate the DATABASE_URL environment variable. CFAR recognizes any service containing a JSON object like the example below as a candidate for the DATABASE_URL environment variable and uses the first candidate it finds.

{
  "some-service": [
    {
      "credentials": {
        "uri": "SOME-DATABASE-URL"
      }
    }
  ]
}

For example, see the following VCAP_SERVICES environment variable example:

VCAP_SERVICES =
{
  "elephantsql": [
    {
      "name": "elephantsql-c6c60",
      "label": "elephantsql",
      "credentials": {
        "uri": "postgres://exampleuser:examplepass@babar.elephantsql.com:5432/exampledb"
      }
    }
  ]
}

Based on this VCAP_SERVICES environment variable, CFAR creates the following DATABASE_URL environment variable:

DATABASE_URL = postgres://exampleuser:examplepass@babar.elephantsql.com:5432/exampledb

For more information, see VCAP_SERVICES.

HOME

The root folder for the deployed app.

For example: HOME=/home/vcap/app

LANG

Required by buildpacks to ensure consistent script load order.

For example: LANG=en_US.UTF-8

MEMORY_LIMIT

The maximum amount of memory that each instance of the app can consume. You specify this value in an app manifest or with the cf CLI when pushing an app. The value is limited by space and org quotas.

If an instance exceeds the maximum limit, it is restarted. If CFAR is asked to restart an instance too frequently, the instance is terminated.

For example: MEMORY_LIMIT=512M

PORT

The port on which the app should listen for requests. CFAR allocates a port dynamically for each instance of the app, so code that obtains or uses the app port should refer to it using the PORT environment variable.

For example: PORT=8080

PWD

The present working directory where the buildpack that processed the app ran.

For example: PWD=/home/vcap/app

TMPDIR

The directory location where temporary and staging files are stored.

For example: TMPDIR=/home/vcap/tmp

USER

The user account under which the app runs.

For example: USER=vcap

VCAP_APP_PORT

Deprecated name for the PORT variable.

VCAP_APPLICATION

This environment variable contains the associated attributes for a deployed app. Results are returned in JSON format. The table below lists the attributes that are returned.

VCAP_SERVICES

For bindable services, CFAR adds connection details to the VCAP_SERVICES environment variable when you restart your app, after binding a service instance to your app. For more information about bindable services, see Services Overview.

CFAR returns the results as a JSON document that contains an object for each service for which one or more instances are bound to the app. The service object contains a child object for each instance of the service that is bound to the app.

The table below defines the attributes that describe a bound service. The key for each service in the JSON document is the same as the value of the “label” attribute.

To see the value of the VCAP_SERVICES environment variable for an app pushed to CFAR, see View Environment Variable Values.

The example below shows the value of the VCAP_SERVICES environment variable for bound instances of several services available in the Marketplace.

VCAP_SERVICES=
{
  "elephantsql": [
    {
      "name": "elephantsql-binding-c6c60",
      "binding_name": "elephantsql-binding-c6c60",
      "instance_name": "elephantsql-c6c60",
      "label": "elephantsql",
      "tags": [
        "postgres",
        "postgresql",
        "relational"
      ],
      "plan": "turtle",
      "credentials": {
        "uri": "postgres://exampleuser:examplepass@babar.elephantsql.com:5432/exampleuser"
      }
    }
  ],
  "sendgrid": [
    {
      "name": "mysendgrid",
      "binding_name": null,
      "instance_name": "mysendgrid",
      "label": "sendgrid",
      "tags": [
        "smtp"
      ],
      "plan": "free",
      "credentials": {
        "hostname": "smtp.sendgrid.net",
        "username": "QvsXMbJ3rK",
        "password": "HCHMOYluTv"
      }
    }
  ]
}

Environment Variable Groups

Environment variable groups are system-wide variables that enable operators to apply a group of environment variables to all running apps and all staging apps separately.

An environment variable group consists of a single hash of name-value pairs that are later inserted into an app container at runtime or at staging. These values can contain information such as HTTP proxy information. The values for variables set in an environment variable group are case-sensitive.

When creating environment variable groups:

• Only the CFAR operator can set the hash value for each group.

• All authenticated users can get the environment variables assigned to their app.

• All variable changes take effect after the operator restarts or restages the apps.

• Any user-defined variable takes precedence over environment variables provided by these groups.

The table below lists the commands for environment variable groups.

The following examples demonstrate how to retrieve the environment variables:

$ cf revg
Retrieving the contents of the running environment variable group as
sampledeveloper@example.com...
OK
Variable Name   Assigned Value
HTTP Proxy      198.51.100.130

$ cf sevg
Retrieving the contents of the staging environment variable group as
sampledeveloper@example.com...
OK
Variable Name   Assigned Value
HTTP Proxy      203.0.113.105
EXAMPLE-GROUP   2001

$ cf apps
Getting apps in org SAMPLE-ORG-NAME / space dev as
sampledeveloper@example.com...
OK

name    requested state   instances   memory   disk   urls
my-app  started           1/1         256M     1G     my-app.com

$ cf env APP-NAME
Getting env variables for app APP-NAME in org SAMPLE-ORG-NAME / space dev as
sampledeveloper@example.com...
OK

System-Provided:

{
  "VCAP_APPLICATION": {
  "application_name": "APP-NAME",
  "application_uris": [
    "my-app.example.com"
  ],
  "application_version": "7d0d64be-7f6f-406a-9d21-504643147d63",
  "limits": {
  "disk": 1024,
  "fds": 16384,
  "mem": 256
  },
  "name": "APP-NAME",
  "organization_id": "c0134bad-97a9-468d-ab9d-e97547e3aed5",
  "organization_name": "my-org",
  "space_id": "37189599-2407-9946-865e-8ebd0e2df89a",
  "space_name": "dev",
  "uris": [
    "my-app.example.com"
  ],
  "users": null,
  "version": "7d0d64be-7f6f-406a-9d21-504643147d63"
 }
}

Running Environment Variable Groups:
HTTP Proxy: 198.51.100.130

Staging Environment Variable Groups:
EXAMPLE-GROUP: 2001
HTTP Proxy: 203.0.113.105

The following examples demonstrate how to set environment variables:

$ cf ssevg '{"test":"198.51.100.130","test2":"203.0.113.105"}'
Setting the contents of the staging environment variable group as admin...
OK
$ cf sevg
Retrieving the contents of the staging environment variable group as admin...
OK
Variable Name   Assigned Value
test            198.51.100.130
test2           203.0.113.105

$ cf srevg '{"test3":"2001","test4":"2010"}'
Setting the contents of the running environment variable group as admin...
OK
$ cf revg
Retrieving the contents of the running environment variable group as admin...
OK
Variable Name   Assigned Value
test3           2001
test4           2010