open-vault/website/source/guides/identity/authentication.html.md

---
layout: "guides"
page_title: "AppRole Pull Authentication - Guides"
sidebar_current: "guides-identity-authentication"
description: |-
  Authentication is a process in Vault by which user or machine-supplied
  information is verified to create a token with pre-configured policy.
---

# Authentication

Before a client can interact with Vault, it must authenticate against an [**auth
backend**](/docs/auth/index.html) to acquire a token. This token has policies attached so
that the behavior of the client can be governed.

Since tokens are the core method for authentication within Vault, there is a
**token** auth backend (often refer as **_token store_**). This is a special
auth backend responsible for creating and storing tokens.

### Auth Backends

Auth backends perform authentication to verify the user or machine-supplied
information. Some of the supported auth backends are targeted towards users
while others are targeted toward machines or apps. For example,
[**LDAP**](/docs/auth/ldap.html) auth backend enables user authentication using
an existing LDAP server while [**AppRole**](/docs/auth/approle.html) auth
backend is recommended for machines or apps.

The [Getting Started](/intro/getting-started/authentication.html) guide walks you
through how to enable the GitHub auth backend for user authentication.

This introductory guide focuses on generating tokens for machines or apps by
enabling the [**AppRole**](/docs/auth/approle.html) auth backend.


## Reference Material

- [Getting Started](/intro/getting-started/authentication.html)
- [Auth Backends](/docs/auth/index.html)
- [GitHub Auth APIs](/api/auth/github/index.html)


## Estimated Time to Complete

10 minutes

## Personas

The end-to-end scenario described in this guide involves two personas:

- **`admin`** with privileged permissions to configure an auth backend
- **`app`** is the consumer of secrets stored in Vault


## Challenge

Think of a scenario where a DevOps team wants to configure Jenkins to read
secrets from Vault so that it can inject the secrets to an app's environment
variables (e.g. `MYSQL_DB_HOST`) at deployment time.

Instead of hardcoding secrets in each build script as a plaintext, Jenkins
retrieves secrets from Vault.

As a user, you can authenticate with Vault using your LDAP credentials, and
Vault generates a token. This token has policies granting you to perform
appropriate operations.

How can a Jenkins server programmatically request a token so that it can read
secrets from Vault?  


## Solution

Enable **AppRole** auth backend so that the Jenkins server can obtain a Vault
token with appropriate policies attached. Since each AppRole has attached
policies, you can write fine-grained policies limiting which app can access
which path.  


## Prerequisites

To perform the tasks described in this guide, you need to have a Vault
environment.  Refer to the [Getting
Started](/intro/getting-started/install.html) guide to install Vault. Make sure
that your Vault server has been [initialized and
unsealed](/intro/getting-started/deploy.html).

### Policy requirements

-> **NOTE:** For the purpose of this guide, you can use **`root`** token to work
with Vault. However, it is recommended that root tokens are only used for just
enough initial setup or in emergencies. As a best practice, use tokens with
appropriate set of policies based on your role in the organization.

To perform all tasks demonstrated in this guide, your policy must include the
following permissions:

```shell
# Mount the AppRole auth backend
path "sys/auth/approle" {
  capabilities = [ "create", "read", "update", "delete", "sudo" ]
}

# Configure the AppRole auth backend
path "sys/auth/approle/*" {
  capabilities = [ "create", "read", "update", "delete" ]
}

# Create and manage roles
path "auth/approle/*" {
  capabilities = [ "create", "read", "update", "delete", "list" ]
}

# Write ACL policies
path "sys/policy/*" {
  capabilities = [ "create", "read", "update", "delete", "list" ]
}

# Write test data
path "secret/mysql/*" {
  capabilities = [ "create", "read", "update", "delete", "list" ]
}
```

If you are not familiar with policies, complete the
[policies](/guides/operations/policies.html) guide.


## Steps

[AppRole](/docs/auth/approle.html) is an authentication mechanism within Vault
to allow machines or apps to acquire a token to interact with Vault. It uses
**Role ID** and **Secret ID** for login.

The basic workflow is:
![AppRole auth backend workflow](/assets/images/vault-approle-workflow.png)

> For the purpose of introducing the basics of AppRole, this guide walks you
> through a very simple scenario involving only two personas (admin and app).
> Please refer to the [Advanced Features](#advanced-features) section for
> further discussions after completing the following steps.

In this guide, you are going to perform the following steps:

1. [Enable AppRole auth backend](#step1)
2. [Create a role with policy attached](#step2)
3. [Get Role ID and Secret ID](#step3)
4. [Login with Role ID & Secret ID](#step4)
5. [Read secrets using the AppRole token](#step5)

Step 1 through 3 need to be performed by an `admin` user.  Step 4 and 5 describe
the commands that an `app` runs to get a token and read secrets from Vault.


### <a name="step1"></a>Step 1: Enable AppRole auth backend
(**Persona:** admin)

Like many other auth backends, AppRole must be enabled before it can be used.

#### CLI command

Enable `approle` auth backend by executing the following command:

```shell
$ vault auth enable approle
```

#### API call using cURL

Enable `approle` auth backend by mounting its endpoint at `/sys/auth/approle`:

```shell
$ curl --header "X-Vault-Token: <TOKEN>" \
       --request POST \
       --data <PARAMETERS> \
       <VAULT_ADDRESS>/v1/sys/auth/approle
```

Where `<TOKEN>` is your valid token, and `<PARAMETERS>` holds [configuration
parameters](/api/system/auth.html#mount-auth-backend) of the backend.


**Example:**

```shell
$ curl --header "X-Vault-Token: ..." \
       --request POST \
       --data '{"type": "approle"}' \
       https://vault.rocks/v1/sys/auth/approle
```

The above example passes the **type** (`approle`) in the request payload which
at the `sys/auth/approle` endpoint.

### <a name="step2"></a>Step 2: Create a role with policy attached
(**Persona:** admin)

When you enabled AppRole auth backend, it gets mounted at the
**`/auth/approle`** path. In this example, you are going to create a role for
**`app`** persona (`jenkins` in our scenario).

The scenario in this guide requires the `app` to have the
following policy (`jenkins-pol.hcl`):

```shell
# Login with AppRole
path "auth/approle/login" {
  capabilities = [ "create", "read" ]
}

# Read test data
path "secret/mysql/*" {
  capabilities = [ "read" ]
}
```

#### CLI command

Before creating a role, create `jenkins` policy:

```shell
$ vault policy write jenkins jenkins-pol.hcl
```

The command to create a new AppRole:

```shell
$ vault write auth/approle/role/<ROLE_NAME> [parameters]
```

> There are a number of
> [parameters](/api/auth/approle/index.html#create-new-approle) that you can set
> on a role. If you want to limit the use of the generated secret ID, set
> `secret_id_num_uses` or `secret_id_ttl` parameter values. Similarly, you can
> specify `token_num_uses` and `token_ttl`. You may never want the app token to
> expire.  In such a case, specify the `period` so that the token generated by
> this AppRole is a periodic token.  To learn more about periodic token, refer to
> the [Tokens and Leases](/guides/identity/lease.html#step4) guide.

**Example:**

The following example creates a role named `jenkins` with `jenkins` policy
attached. (NOTE: This example creates a role operates in [**pull**
mode](/docs/auth/approle.html).)

```shell
$ vault write auth/approle/role/jenkins policies="jenkins"

# Read the jenkins role
$ vault read auth/approle/role/jenkins

  Key               	Value
  ---               	-----
  bind_secret_id    	true
  bound_cidr_list
  period            	0
  policies          	[jenkins]
  secret_id_num_uses	0
  secret_id_ttl     	0
  token_max_ttl     	0
  token_num_uses    	0
  token_ttl         	0
```

**NOTE:** To attach multiple policies, pass the policy names as a comma
separated string.

```shell
$ vault write auth/approle/role/jenkins policies="jenkins,anotherpolicy"
````

#### API call using cURL

Before creating a role, create `jenkins` policy:

```shell
$ curl --header "X-Vault-Token: ..." --request PUT --data @payload.json \
     https://vault.rocks/v1/sys/policy/jenkins

$ cat payload.json
{
  "policy": "path \"auth/approle/login\" {  capabilities = [ \"create\", \"read\" ] } ... }"
}
```

Now, you are ready to create a role.

**Example:**

The following example creates a role named `jenkins` with `jenkins` policy
attached. (NOTE: This example creates a role operates in [**pull**
mode](/docs/auth/approle.html).)

```shell
$ curl --header "X-Vault-Token: ..." --request POST \
       --data '{"policies":"jenkins"}' \
       https://vault.rocks/v1/auth/approle/role/jenkins
```

> There are a number of
> [parameters](/api/auth/approle/index.html#create-new-approle) that you can set
> on a role. If you want to limit the use of the generated secret ID, set
> `secret_id_num_uses` or `secret_id_ttl` parameter values. Similarly, you can
> specify `token_num_uses` and `token_ttl`. You may never want the app token to
> expire.  In such a case, specify the `period` so that the token generated by
> this AppRole is a periodic token.  To learn more about periodic token, refer to
> the [Tokens and Leases](/guides/identity/lease.html#step4) guide.


**NOTE:** To attach multiple policies, pass the policy names as a comma
separated string.

```shell
$ curl --header "X-Vault-Token:..."
       --request POST \
       --data '{"policies":"jenkins,anotherpolicy"}' \
       https://vault.rocks/v1/auth/approle/role/jenkins
````

To read the jenkins role you just created:

```shell
$ curl --header "X-Vault-Token: ..." --request GET \
        https://vault.rocks/v1/auth/approle/role/jenkins | jq
{
  "request_id": "b18054ad-1ab5-8d83-eeed-193d97026ee7",
  "lease_id": "",
  "renewable": false,
  "lease_duration": 0,
  "data": {
    "bind_secret_id": true,
    "bound_cidr_list": "",
    "period": 0,
    "policies": [
      "jenkins"
    ],
    "secret_id_num_uses": 0,
    "secret_id_ttl": 0,
    "token_max_ttl": 0,
    "token_num_uses": 0,
    "token_ttl": 0
  },
  "wrap_info": null,
  "warnings": null,
  "auth": null
}
```


### <a name="step3"></a>Step 3: Get Role ID and Secret ID
(**Persona:** admin)

**Role ID** and **Secret ID** are like a username and password that a machine or
app uses to authenticate.

Since the example created a `jenkins` role which operates in pull mode, Vault
will generate the Secret ID. You can set properties such as usage-limit, TTLs,
and expirations on the secret IDs to control its lifecycle.

#### CLI command

Now, you need to fetch the Role ID and Secret ID of a role.

To read the Role ID:

```shell
$ vault read auth/approle/role/<ROLE_NAME>/role-id
```

To generate a new Secret ID:

```shell
$ vault write -f auth/approle/role/<ROLE_NAME>/secret-id
```

NOTE: The `-f` flag forces the `write` operation to continue without any data
values specified. Alternatively, you can set
[parameters](/api/auth/approle/index.html#generate-new-secret-id)  such as
`cidr_list`.

**Example:**

```shell
$ vault read auth/approle/role/jenkins/role-id
  Key    	Value
  ---    	-----
  role_id	675a50e7-cfe0-be76-e35f-49ec009731ea

$ vault write -f auth/approle/role/jenkins/secret-id
  Key               	Value
  ---               	-----
  secret_id         	ed0a642f-2acf-c2da-232f-1b21300d5f29
  secret_id_accessor	a240a31f-270a-4765-64bd-94ba1f65703c
```

If you specified `secret_id_ttl`, `secret_id_num_uses`, or `bound_cidr_list` on
the role in [Step 2](#step2), the generated secret ID carries out the conditions.


#### API call using cURL

To read the Role ID:

```shell
$ curl --header "X-Vault-Token:..." \
       --request GET \
       <VAULT_ADDRESS>/v1/auth/approle/role/<ROLE_NAME>/role-id
```

To generate a new Secret ID:

```shell
$ curl --header "X-Vault-Token:..." \
       --request POST \
       --data <PARAMETERS>
       <VAULT_ADDRESS>/v1/auth/approle/role/<ROLE_NAME>/secret-id
```

You can pass
[parameters](/api/auth/approle/index.html#generate-new-secret-id) in the request
payload, or invoke the API with empty payload.

**Example:**

```shell
$ curl --header "X-Vault-Token:..." --request GET \
       https://vault.rocks/v1/auth/approle/role/jenkins/role-id | jq

$ curl --header "X-Vault-Token:..." --request POST \
       https://vault.rocks/v1/auth/approle/role/jenkins/secret-id | jq
```

If you specified `secret_id_ttl`, `secret_id_num_uses`, or `bound_cidr_list` on
the role in [Step 2](#step2), the generated secret ID carries out the conditions.



### <a name="step4"></a>Step 4: Login with Role ID & Secret ID
(**Persona:** app)

The client (in this case, Jenkins) uses the role ID and secret ID passed by the
admin to authenticate with Vault. If Jenkins did not receive the role ID and/or
secret ID, the admin needs to investigate.

-> Refer to the [Advanced Features](#advanced-features) section for further
discussion on distributing the role ID and secret ID to the client app
securely.

#### CLI command

To login, use `auth/approle/login` endpoint by passing the role ID and secret ID.

**Example:**

```shell
$ vault write auth/approle/login role_id="675a50e7-cfe0-be76-e35f-49ec009731ea" \
  secret_id="ed0a642f-2acf-c2da-232f-1b21300d5f29"

  Key                 	Value
  ---                 	-----
  token               	eeaf890e-4b0f-a687-4190-c75b1d6d70bc
  token_accessor      	fcee5d4e-7281-8bb0-2901-e743c52e0502
  token_duration      	768h0m0s
  token_renewable     	true
  token_policies      	[jenkins]
  token_meta_role_name	"jenkins"
```

Now you have a **client token** with `default` and `jenkins` policies attached.


#### API call using cURL

To login, use `auth/approle/login` endpoint by passing the role ID and secret ID
in the request payload.

**Example:**

```plaintext
$ cat payload.json
  {
    "role_id": "675a50e7-cfe0-be76-e35f-49ec009731ea",
    "secret_id": "ed0a642f-2acf-c2da-232f-1b21300d5f29"
  }

$ curl --request POST --data @payload.json https://vault.rocks/v1/auth/approle/login | jq
{
  "request_id": "fccae32b-1e6a-9a9c-7666-f5cb07805c1e",
  "lease_id": "",
  "renewable": false,
  "lease_duration": 0,
  "data": null,
  "wrap_info": null,
  "warnings": null,
  "auth": {
    "client_token": "3e7dd0ac-8b3e-8f88-bb37-a2890455ca6e",
    "accessor": "375c077e-bf02-a09b-c864-63d7f967e86b",
    "policies": [
      "default",
      "jenkins"
    ],
    "metadata": {
      "role_name": "jenkins"
    },
    "lease_duration": 2764800,
    "renewable": true,
    "entity_id": "54e0b765-6daf-0ff5-70b9-32c0d491f473"
  }
}
```

Now you have a **client token** with `default` and `jenkins` policies attached.


### <a name="step5"></a>Step 5: Read secrets using the AppRole token
(**Persona:** app)

Once receiving a token from Vault, the client can make future requests using
this token.

#### CLI command

**Example:**

You can pass the `client_token` returned in [Step 4](#step4) as a part of the
CLI command.

```shell
$ VAULT_TOKEN=3e7dd0ac-8b3e-8f88-bb37-a2890455ca6e vault read secret/mysql/webapp
No value found at secret/mysql/webapp
```

Alternatively, you can first authenticate with Vault using the `client_token`.

```shell
$ vault login 3e7dd0ac-8b3e-8f88-bb37-a2890455ca6e
Successfully authenticated! You are now logged in.
token: 3e7dd0ac-8b3e-8f88-bb37-a2890455ca6e
token_duration: 2762013
token_policies: [default jenkins]

$ vault read secret/mysql/webapp
No value found at secret/mysql/webapp
```

Since there is no value in the `secret/mysql/webapp`, it returns "no value
found" message.

**Optional:** Using the `admin` user's token, you can store some secrets in the
`secret/mysql/webapp` backend.

```shell
$ vault write secret/dev/config/mongodb @mysqldb.txt

$ cat mysqldb.txt
{
  "url": "foo.example.com:35533",
  "db_name": "users",
  "username": "admin",
  "password": "pa$$w0rd"
}
```

Now, try to read secrets from `secret/mysql/webapp` using `client_token` again.
This time, it should return the values you just created.


#### API call using cURL

You can now pass the `client_token` returned in [Step 4](#step4) in the
**`X-Vault-Token`** header.

**Example:**

```plaintext
$ curl --header "X-Vault-Token: 3e7dd0ac-8b3e-8f88-bb37-a2890455ca6e" \
       --request GET \
       https://vault.rocks/v1/secret/mysql/webapp | jq
{
  "errors": []
}
```

Since there is no value in the `secret/mysql/webapp`, it returns an empty array.

**Optional:** Using the **`admin`** user's token, create some secrets in the
`secret/mysql/webapp` backend.

```shell
$ curl --header "X-Vault-Token: ..." --request POST --data @mysqldb.txt \

$ cat mysqldb.text
{
  "url": "foo.example.com:35533",
  "db_name": "users",
  "username": "admin",
  "password": "p@ssw0rd"
}
```

Now, try to read secrets from `secret/mysql/webapp` using `client_token` again.
This time, it should return the values you just created.



## Advanced Features

The Role ID is equivalent to a username, and Secret ID is the corresponding
password. The app needs both to log in with Vault. Naturally, the next question
becomes how to deliver those values to the expecting client.

A common solution involves **three personas** instead of two: `admin`, `app`, and
`trusted entity`. The `trusted entity` delivers the Role ID and Secret ID to the
client by separate means.   

For example, Terraform as a trusted entity can deliver the Role ID onto the
virtual machine.  When the app runs on the virtual machine, the Role ID already
exists on the virtual machine.

![AppRole auth backend workflow](/assets/images/vault-approle-workflow2.png)

Secret ID is like a password. To keep the Secret ID confidential, use
[**response wrapping**](/docs/concepts/response-wrapping.html) so that the only
expected client can unwrap the Secret ID.

In [Step 3](#step3), you executed the following command to retrieve the Secret
ID:

```shell
$ vault write -f auth/approle/role/jenkins/secret-id
```

Instead, use response wrapping by passing the **`-wrap-ttl`** parameter:

```shell
$ vault write -wrap-ttl=60s -f auth/approle/role/jenkins/secret-id

Key                          	Value
---                          	-----
wrapping_token:              	9bbe23b7-5f8c-2aec-83dc-e97e94a2e632
wrapping_accessor:           	cb5bdc8f-0cdb-35ff-0e68-9de57a79c3bf
wrapping_token_ttl:          	1m0s
wrapping_token_creation_time:	2018-01-08 21:29:38.826611 -0800 PST
wrapping_token_creation_path:	auth/approle/role/jenkins/secret-id
```

Send this `wrapping_token` to the client so that the response can be unwrap and
obtain the Secret ID.

```shell
$ VAULT_TOKEN=9bbe23b7-5f8c-2aec-83dc-e97e94a2e632 vault unwrap

Key               	Value
---               	-----
secret_id         	575f23e4-01ad-25f7-2661-9c9bdbb1cf81
secret_id_accessor	7d8a40b7-a6fd-a634-579b-b7d673ff86fb
```

NOTE: To retrieve the Secret ID alone, you can use `jq` as follow:

```shell
$ VAULT_TOKEN=2577044d-cf86-a065-e28f-e2a14ea6eaf7 vault unwrap -format=json | jq -r ".data.secret_id"

b07d7a47-1d0d-741d-20b4-ae0de7c6d964
```


## Next steps

To learn more about response wrapping, go to [Cubbyhole Response
Wrapping](/guides/secret-mgmt/cubbyhole.html) guide.