Configuring Vault to use LDAP for user authentication

Question

Pulumi · Accepted Answer

In order to configure Vault to use LDAP for user authentication using Pulumi, we'll leverage the `vault.ldap.AuthBackend` resource from the Vault Pulumi provider. This resource is responsible for setting up an LDAP authentication backend in Vault, allowing you to authenticate users against an LDAP server.

Here's how you would configure Vault to use LDAP for user authentication:

1. First, you need to have an existing LDAP server with a bind DN and password.
2. Next, you'll set up the `AuthBackend` resource with your LDAP server details.
3. Finally, you'll specify the user and group attributes according to your LDAP schema.

Below is a Pulumi program written in TypeScript that demonstrates how to use the `vault.ldap.AuthBackend` resource:

```typescript
import * as pulumi from "@pulumi/pulumi";
import * as vault from "@pulumi/vault";

// Instantiate the LDAP Auth Backend
const ldapAuth = new vault.ldap.AuthBackend("ldapAuth", {
    // URL of the LDAP server
    url: "ldap://ldap.example.com",
    // Bind DN (Distinguished Name) for LDAP Integration
    binddn: "cn=read-only-admin,dc=example,dc=com",
    // Bind Password for the Bind DN
    bindpass: new pulumi.Secret("bind-password"), // This should be a sensitive value and treated as a secret
    // User DN template for binding with user supplied credentials
    userdn: "ou=users,dc=example,dc=com",
    // StartTLS - Set to `true` if you'd like to use StartTLS
    starttls: false,
    // User attribute to map the username sent by the user
    userattr: "uid",
    // Domain to use for constructing the UPN string for the directory
    upndomain: "example.com",
    // Flag to search for groups in LDAP
    useTokenGroups: false,
    // Specify the objectClass attribute that is used to denote that a group entry is a group in LDAP
    groupattr: "cn",
    // Search filter to use when looking up a group in LDAP
    groupfilter: "(|(memberUid={{.Username}})(member={{.UserDN}})(uniqueMember={{.UserDN}}))",
    // Group DN template to iterate over when looking up a group in LDAP
    groupdn: "ou=users,dc=example,dc=com",
    // Enables user and group resolution (This might be an intensive operation depending on the number of groups)
    discoverdn: false
});

// Export the Vault backend path as a stack output
export const backendPath = ldapAuth.path;
```

Here's a breakdown of what the program does:

- The `vault` provider package is imported, which contains the necessary classes and methods to interact with Vault.
- We create an instance of `vault.ldap.AuthBackend`, which is a resource used to configure the LDAP authentication backend in Vault.
- We provide a series of properties for the `AuthBackend` that your LDAP server requires for authentication:
  - `url`: The LDAP server's complete URL that Vault should authenticate against.
  - `binddn`: The distinguished name (DN) of the user that Vault will use to perform user lookups against the LDAP server.
  - `bindpass`: The password for the bind DN user. This is marked as a secret in Pulumi, making it encrypted in the state file.
  - `userdn`: The base DN from which to perform user search operations.
  - `starttls`: A boolean flag to specify if StartTLS should be used to secure the connection (assuming the LDAP server supports StartTLS).
  - `userattr`: The attribute used for matching a user record's username.
  - `upndomain`: The domain to use for constructing a user principal name (UPN) when using a separate domain.
  - `groupattr`: The attribute on the group entity that Vault will use to map the username.
  - `groupfilter`: The search filter to find an entry within the group.
  - `groupdn`: The DN that should be used to search for LDAP group memberships.
  - `discoverdn`: If set to true, Vault will discover the bind DN during login.

Once configured, Vault will authenticate users attempting to login against the LDAP server using the details specified in the resource configuration.

In this program, adjust the values to match your LDAP server configuration. Specifically, replace the LDAP URL, bind DN, bind password, user DN, and other LDAP-specific settings with the appropriate values for your environment.

Keep in mind that you will need to have the Vault Pulumi provider correctly configured and have sufficient permissions to manage Vault's authentication backends in order to successfully deploy this program.