TAS for VMs Environment Variables

Environment variables are the means by which TAS for VMs 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.

Important Do not use user-provided environment variables for security sensitive information such as credentials as they might unintentionally show up in cf CLI output and Cloud Controller logs. Use user-provided service instances instead. The system-provided environment variable VCAP_SERVICES is properly redacted for user roles such as Space Supporter and in Cloud Controller log files.

View environment variables

Using the Cloud Foundry Command Line Interface (cf CLI), you can run the cf env command to view the TAS for VMs 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 TAS for VMs 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.

Environment Variable	Running	Staging	Task
`CF_INSTANCE_ADDR`	x	x	x
`CF_INSTANCE_GUID`	x		x
`CF_INSTANCE_INDEX`	x
`CF_INSTANCE_INTERNAL_IP`	x	x	x
`CF_INSTANCE_IP`	x	x	x
`CF_INSTANCE_PORT`	x	x	x
`CF_INSTANCE_PORTS`	x	x	x
`CF_STACK`		x
`DATABASE_URL`	x		x
`HOME`	x	x	x
`INSTANCE_GUID`	x
`INSTANCE_INDEX`	x
`LANG`	x	x	x
`MEMORY_LIMIT`	x	x	x
`PATH`	x	x	x
`PORT`	x
`PWD`	x	x	x
`TMPDIR`	x		x
`USER`	x	x	x
`VCAP_APP_HOST`	x
`VCAP_APP_PORT`	x
`VCAP_APPLICATION`	x	x	x
`VCAP_SERVICES`	x	x	x

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, TAS for VMs creates a DATABASE_URL environment variable based on the VCAP_SERVICES environment variable.

TAS for VMs uses the structure of the VCAP_SERVICES environment variable to populate the DATABASE_URL environment variable. TAS for VMs 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:[email protected]:5432/exampledb"
      }
    }
  ]
}

Based on this VCAP_SERVICES environment variable, TAS for VMs creates the following DATABASE_URL environment variable:

DATABASE_URL = postgres://exampleuser:[email protected]: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 TAS for VMs 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. TAS for VMs 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.

Attribute	Description
`application_id`	The GUID identifying the app.
`application_name`	The name assigned to the app when it was pushed.
`application_uris`	The URIs assigned to the app.
`application_version`	The GUID identifying a version of the app. Each time an app is pushed or restarted, this value is updated.
`cf_api`	The location of the Cloud Controller API for the TAS for VMs deployment where the app runs.
`host`	Deprecated. The IP address of the app instance.
`limits`	The limits to disk space, number of files, 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. The number of files allowed is operator-defined.
`name`	Identical to `application_name`.
`organization_id`	The GUID identifying the org where the app is deployed.
`organization_name`	The human-readable name of the org where the app is deployed.
`process_id`	The UID identifying the process. Only present in running app containers.
`process_type`	The type of process. Only present in running app containers.
`space_id`	The GUID identifying the space where the app is deployed.
`space_name`	The human-readable name of the space where the app is deployed.
`start`	The human-readable timestamp for the time the instance was started. Not provided on Diego Cells.
`started_at`	Identical to `start`. Not provided on Diego Cells.
`started_at_timestamp`	The Unix epoch timestamp for the time the instance was started. Not provided on Diego Cells.
`state_timestamp`	Identical to `started_at_timestamp`. Not provided on Diego Cells.
`uris`	Identical to `application_uris`. You must ensure that both `application_uris` and `uris` are set to the same value.
`users`	Deprecated. Not provided on Diego Cells.
`version`	Identical to `application_version`.

VCAP_SERVICES

For bindable services, TAS for VMs 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.

TAS for VMs 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.

Attribute	Description
`binding_guid`	The guid of the service binding.
`binding_name`	The name assigned to the service binding by the user.
`instance_guid`	The guid of the service instance.
`instance_name`	The name assigned to the service instance by the user.
`name`	The `binding_name`, if it exists. Otherwise, the `instance_name`.
`label`	The name of the service offering.
`tags`	An array of strings an app can use to identify a service instance.
`plan`	The service plan selected when the service instance was created.
`credentials`	A JSON object containing the service-specific credentials needed to access the service instance.
`syslog_drain_url`	The service-specific syslog drain url.
`volume_mounts`	An array of service-specific volume mounts.

To see the value of the VCAP_SERVICES environment variable for an app pushed to TAS for VMs, 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_guid": "44ceb72f-100b-4f50-87a2-7809c8b42b8d",
      "binding_name": "elephantsql-binding-c6c60",
      "instance_guid": "391308e8-8586-4c42-b464-c7831aa2ad22",
      "instance_name": "elephantsql-c6c60",
      "label": "elephantsql",
      "tags": [
        "postgres",
        "postgresql",
        "relational"
      ],
      "plan": "turtle",
      "credentials": {
        "uri": "postgres://exampleuser:[email protected]:5432/exampleuser"
      },
      "syslog_drain_url": null,
      "volume_mounts": []
    }
  ],
  "sendgrid": [
    {
      "name": "mysendgrid",
      "binding_guid": "6533b1b6-7916-488d-b286-ca33d3fa0081",
      "binding_name": null,
      "instance_guid": "8c907d0f-ec0f-44e4-87cf-e23c9ba3925d",
      "instance_name": "mysendgrid",
      "label": "sendgrid",
      "tags": [
        "smtp"
      ],
      "plan": "free",
      "credentials": {
        "hostname": "smtp.sendgrid.net",
        "username": "QvsXMbJ3rK",
        "password": "HCHMOYluTv"
      },
      "syslog_drain_url": null,
      "volume_mounts": []
    }
  ]
}

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 TAS for VMs 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.

CLI Command	Description
`running-environment-variable-group` or `revg`	Retrieves the contents of the running environment variable group.
`staging-environment-variable-group` or `sevg`	Retrieves the contents of the staging environment variable group.
`set-staging-environment-variable-group` or `ssevg`	Passes parameters as JSON to create a staging environment variable group.
`set-running-environment-variable-group` or `srevg`	Passes parameters as JSON to create a running environment variable group.

The following examples demonstrate how to retrieve the environment variables:

$ cf revg
Retrieving the contents of the running environment variable group as
[email protected]...
OK
Variable Name   Assigned Value
HTTP Proxy      198.51.100.130

$ cf sevg
Retrieving the contents of the staging environment variable group as
[email protected]...
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
[email protected]...
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
[email protected]...
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