Cloud Foundry Environment Variables

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Environment variables are the means by which the Cloud Foundry (CF) runtime communicates with a deployed app about its environment. This page describes the environment variables that the runtime and buildpacks set for app.

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

Install the Cloud Foundry Command Line Interface (cf CLI), and use the cf env command to view the Cloud Foundry 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

$ 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.192.0.2.34.xip.io"
  ],
  "application_version": "fb8fbcc6-8d58-479e-bcc7-3b4ce5a7f0ca",
  "cf_api": "https://api.example.com",
  "limits": {
    "disk": 1024,
    "fds": 16384,
    "mem": 256
  },
  "name": "my-app",
  "space_id": "06450c72-4669-4dc6-8096-45f9777db68a",
  "space_name": "my-space",
  "uris": [
    "my-app.192.0.2.34.xip.io"
  ],
  "users": null,
  "version": "fb8fbcc6-8d58-479e-bcc7-3b4ce5a7f0ca"
  }
}

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

App-Specific System Variables

The subsections that follow describe the environment variables that Cloud Foundry 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, refer to the buildpack documentation for Java, Node.js, and Ruby.

CF_INSTANCE_ADDR

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

Example: CF_INSTANCE_ADDR=1.2.3.4:5678

CF_INSTANCE_GUID

The UUID of the particular instance of the app.

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

CF_INSTANCE_INDEX

The index number of the app instance.

Example: CF_INSTANCE_INDEX=0

CF_INSTANCE_IP

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

Example: CF_INSTANCE_IP=1.2.3.4

CF_INSTANCE_INTERNAL_IP

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

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 generally different from the PORT of the app instance.

Example: CF_INSTANCE_PORT=61045

CF_INSTANCE_PORTS

The list of mappings between internal, or container-side, and external, or host-side, ports allocated to the instance’s container. 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.

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

DATABASE_URL

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

CF uses the structure of the VCAP_SERVICES environment variable to populate DATABASE_URL. CF recognizes any service containing a JSON object with the following form as a candidate for DATABASE_URL and uses the first candidate it finds.

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

For example, consider the following VCAP_SERVICES:

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

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

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

HOME

Root folder for the deployed app.

Example: HOME=/home/vcap/app

LANG

LANG is required by buildpacks to ensure consistent script load order.

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 will be restarted. If Cloud Foundry is asked to restart an instance too frequently, the instance will instead be terminated.

Example: MEMORY_LIMIT=512M

PORT

The port on which the app should listen for requests. The Cloud Foundry runtime 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.

Example: PORT=8080

PWD

Identifies the present working directory, where the buildpack that processed the app ran.

Example: PWD=/home/vcap/app

TMPDIR

Directory location where temporary and staging files are stored.

Example: TMPDIR=/home/vcap/tmp

USER

The user account under which the app runs.

Example: USER=vcap

VCAP_APP_PORT

Deprecated name for the PORT variable defined above.

VCAP_APPLICATION

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

The following example shows how to set the VCAP_APPLICATION environment variable:

VCAP_APPLICATION={"instance_id":"fe98dc76ba549876543210abcd1234",
"instance_index":0,"host":"0.0.0.0","port":61857,"started_at":"2013-08-12
00:05:29 +0000","started_at_timestamp":1376265929,"start":"2013-08-12 00:05:29
+0000","state_timestamp":1376265929,"limits":{"mem":512,"disk":1024,"fds":16384}
,"application_version":"ab12cd34-5678-abcd-0123-abcdef987654","application_name"
:"styx-james","application_uris":["my-app.example.com"],"version":"ab1
2cd34-5678-abcd-0123-abcdef987654","name":"my-app","uris":["my-app.example.com"]
,"users":null}

VCAP_SERVICES

For bindable services, Cloud Foundry adds connection details to the VCAP_SERVICES environment variable when you restart your app, after binding a service instance to your app.

The results are returned 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 service instance of that service that is bound to the app. The attributes that describe a bound service are defined in the table below.

The key for each service in the JSON document is the same as the value of the “label” attribute.

To see the value of VCAP_SERVICES for an app pushed to Cloud Foundry, see View Environment Variable Values.

The example below shows the value of VCAP_SERVICES for bound instances of several services available in the Pivotal Web Services 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, consider the following:

• Only the Cloud Foundry 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",
  "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