Tokens are the core method for authentication within Vault. You can use tokens to log in with Vault. If you log in with Vault via an auth method, a successful authentication generates a token. Regardless, clients need valid tokens to read secrets from Vault.
There are two types of Vault tokens: service token and batch token. Vault persists the service tokens in its storage backend. You can renew a service token or revoke it as necessary. On the other hand, Vault does not persist the batch tokens. Batch tokens are encrypted binary large objects (blobs) that carry enough information to perform Vault actions. Therefore, batch tokens are extremely lightweight and scalable; however, they lack most of the flexibility and features of service tokens.
This tutorial focuses on the service tokens. Read the batch tokens tutorial to learn the usage of batch tokens.
»Service token lifecycle
Every non-root token has a time-to-live (TTL). When a token expires, Vault automatically revokes it. If you create a new token, the token you used to create the token becomes the parent token. Once the parent token expires, so do all its children regardless of their own TTLs.
Suppose a hierarchy exists with respective TTL as follows:
In this scenario, the token s.1d3fd4b2.. will expire in two hours. Although its
child token (s.794b6f2f...) has TTL of three hours, Vault will revoke the
child token when its parent expires.
When the top-level token (s.b519c6aa...) expires, Vault will revoke all tokens
under the tree (s.6a2cf3e7..., s.1d3fd4b2..., and s.794b6f2f...)
regardless of their TTL.
»TTL and max TTL
If the token is renewable, you can use vault token renew command to extend the
token's TTL before it expires. You can repeatedly renew a token until it reaches
its maximum TTL.
For example, if a token's TTL is 30 minutes and the maximum TTL is 24 hours, you can renew the token before reaching the 30 minutes. You can renew the token multiple times if you are using it. However, once the token reaches the 24 hours of its first creation, you can no longer renew the token.
Important: If you do not explicitly set the token's TTL or maximum TTL, it takes the system max TTL which is 32 days by default. (You can change the system default in the Vault server configuration file.) This means that Vault stores the token in its storage backend for 32 days even if you are not using it.
»Prerequisites
To perform the tasks described in this tutorial, you need to have a Vault environment. Refer to the Getting Started tutorial to install Vault.
NOTE: An interactive tutorial is also available if you do not have a Vault environment to perform the steps described in this tutorial. Click the Show Terminal button to start.
»Start Vault
Start a Vault dev server with root as the root token.
Insecure operation: Do not run a Vault dev server in production. This approach is only used here to simplify the unsealing process for this demonstration.
Export an environment variable for the vault CLI to address the Vault server.
Login with the root token.
The Vault server is ready for you to explore service tokens.
»Token types
Tokens allow Vault clients to read or write secrets from Vault; therefore, it is critical to use a specific type of token based on the use case.
In this tutorial, you will learn the lifecycle of different token types.
| Token type | Usage |
|---|---|
| Use limit tokens | Tokens that are only good to invoke a specific number of operations. |
| Periodic service tokens | Tokens that can be renewed indefinitely. |
| Short-lived tokens | Tokens that are valid for a short time to avoid keeping unused tokens. |
| Orphan tokens | Tokens that are root of their own token tree. |
Then, you will learn how to manage tokens.
»Tokens with use limit
In addition to TTL and max TTL, you can set the number of uses for tokens. The tokens with a use limit expire at the end of their last use regardless of their remaining TTLs. On the same note, use limit tokens expire at the end of their TTLs regardless of their remaining uses.
To create tokens with a use limit, set the number of uses when you create them.
To view optional parameters to create tokens, run the command with -help flag.
There are a number of parameters you can set.
Create a token with TTL of 1 hour and a use limit of 2. Attach the
default policy.
Example output:
»Verification
Store the generated token in an environment variable,
USE_LIMIT_TOKEN.Example:
Set the
VAULT_TOKENvalue to the token you just generated, and invoke any CLI command.Example output:
Notice that the
num_usesis now1.Run another CLI command using the token.
Try to read the value now using the same token.
The first command read the token's properties and then wrote a value to the cubbyhole secrets engine. This exhausted the use limit of 2 for this token. Therefore, the attempt to read the secret from the cubbyhole failed.
»Periodic service tokens
Root or sudo users have the ability to generate periodic tokens. Periodic tokens have a TTL (validity period), but no max TTL; therefore, they may live for an infinite duration of time so long as they are renewed within their TTL. This is useful for long-running services that cannot handle regenerating a token.
NOTE: When you set period, it becomes the token renewal period (TTL).
When a period and an explicit max TTL were both set on a token, it behaves as a
periodic token. However, once the explicit max TTL is reached, the token will be
revoked. Refer to the renew service tokens to learn
more about the period and the maximum TTL.
Create a token with 24 hours period.
You can see the generated token's metadata. In this example, the generated token
value is s.s7bMPX51JesC1VYJwdZf8ylt.
Example output:
You can renew the generated token indefinitely for as long as it does not expire. If you do not renew, the token expires after 24 hours.
Jump to the Renew service tokens section to learn how to renew the generated token.
»Short-lived tokens
Create a new service token with TTL of 60 seconds which means that the token gets automatically revoked after 60 seconds.
Create a token with TTL of 60 seconds.
Lookup the generated token's metadata.
Example output:
NOTE: The vault token lookup command returns the token's properties.
In this example, it shows that this token has 38 more seconds before it expires.
When you execute a Vault command using the new token immediately following its
creation, it should work. Wait for 60 seconds and try again. It returns
Code: 403. Errors: which indicates a forbidden API call due to expired
token usage.
»Orphan tokens
Orphan tokens are not children of their parent; therefore, orphan tokens do not expire when their parent does.
NOTE: Orphan tokens still expire when their own max TTL is reached.
The following CLI command requires root token or sudo capability on the
auth/token/create path.
Lookup the generated token's metadata.
Example output:
»Token role
Instead of passing a number of parameters, you can create a role with a set of parameter values set.
Create a token role named zabbix.
Create a token for zabbix role.
The generated token is valid for 8 hours and it is renewable, and multiple policies are attached.
»Renew service tokens
You can renew the service token's TTL as long as it has not expired.
Create a token and save its value in a file,
test_token.txt.The generated token has a TTL of 45 seconds, and max TTL of 2 minutes (120 seconds).
Renew the token's TTL before the token expires.
Example output:
Renew and extend the token's TTL to 60 seconds.
Example output:
Notice that the token TTL (
token_duration) is now 1 minute instead of 45 seconds.
Because the explicit max TTL is set to 2 minutes, you will not be able to renew the token after 2 minutes.
As time passes, Vault returns a message such as TTL of "26s" exceeded the effective max_ttl of "10s"; TTL value is capped accordingly to indicate that
the token TTL cannot exceed 2 minutes from its creation time. Eventually, the
token expires and Vault automatically revokes it. Once the token expires, the
renew command returns token not found message.
»Revoke service tokens
If a user or machine needs a temporal access to Vault, you can set a short TTL or a number of uses to a service token so the token is automatically revoked at the end of its life. But if any suspicious activity was detected, Vault has built-in support for revocation of service tokens before reaching its TTL.
You can revoke service tokens using the vault token revoke command or the
auth/token/revoke API endpoint.
In this section, you are going to create tokens with the following hierarchy and inspect the token lifecycle.
Create a
testpolicy.If you are not familiar with policies, complete the policies tutorial.
Create a token and save its value in a file,
parent_token.txt.The generated token has a TTL of 1 minute (60 seconds).
Create a token using the parent token and save its value in a file,
child_token.txt.The generated token has a TTL of 3 minute (180 seconds) while its parent token's TTL is 1 minute.
Create an orphan token using the parent token and save its value in a file,
orphan_token.txt.The generated token is an orphan token with a TTL of 3 minute (180 seconds).
Revoke the parent token.
Verify that the token no longer exists by looking it up.
Vault returns an error message.
Look up the child token.
Vault returns the
bad tokenerror because Vault revoked the child token along with its parent token.Look up the orphan token.
Because each orphan token is the root of its own token tree, it exists until it expires. Therefore, the command displays the detail information about the orphan token.
Instead of revoking using a token value, revoke tokens with a token
accessor
using the -accessor flag.
»Apply token types
You learned how you can set the token's lifecycle. The next step is to apply this to generate tokens for your applications. Vault clients first authenticate with Vault using an auth method to acquire a token. There are auth methods aimed to authenticate applications or machines. Once its identity was verified, Vault server will return a token with appropriate policies attached.
Use the AppRole auth method to demonstrate this.
Enable the
approleauth method.Create a role for your app specifying that the generated token type is periodic and expires after 24 hours if not renewed.
This example defines a role named, "jenkins". The tokens generated for this role will be a periodic token with
jenkinspolicy attached.
»Verification
NOTE: If you are not familiar with the AppRole auth method, read the AppRole Pull Authentication tutorial.
Retrieve the RoleID for the
jenkinsrole and save it in a file,role_id.txt.Generate a SecretID for the
jenkinsrole and save it in a file,secret_id.txt.Authenticate with Vault using the generated
role_idandsecret_id.Example output:
View the token details.
Example:
The output shows the
periodof 24 hours, and thejenkinspolicy is attached.
»Next steps
This tutorial walked through the Vault token fundametal. You rarely create
tokens using the vault token create commands or the /auth/token/create
endpoint. In most cases, you specify the type of token in the context of auth
methods as demonstrated in the Apply token type section.
Integrating your application to read or write secrets to Vault may require:
- Authenticate with Vault using an auth method
- Maintain the token
- Renew or revoke the token if necessary
Vault Agent can help to simplify the introduction of Vault to your applications. The App Integration collection lists tutorials that introduce different approaches.
But first, go through the Batch tokens tutorial to understand the difference between the service tokens and batch tokens so that you can decide which token type is best suited for your use case.
