Authenticate requests against membership information that is stored in a Lightweight Directory Access Protocol (LDAP) server.

This feature is available with a Gloo Gateway license only.

If you import or export resources across workspaces, your policies might not apply. For more information, see Import and export policies.

About LDAP

The Lightweight Directory Access Protocol (LDAP) is an open protocol that you can use to store and retrieve hierarchically structured data over a network. Many enterprises use LDAP to centrally store and secure organizational information. In particular, LDAP is often used for membership directories. You might set up LDAP to store information such as the following:

You can deploy an LDAP server to your Kubernetes cluster. Then, use a Gloo Gateway external auth policy to authenticate users and control access based on their group membership details in the LDAP server.

Want to learn more about LDAP? Try out this LDAP tutorial by Digital Ocean.

How does LDAP work with Gloo Gateway?

Upon receiving an authentication request that uses LDAP, Gloo Gateway performs the following steps.

  1. Gloo Gateway looks for a Basic Authentication header on the request to extract the username (uid) and credentials (userPassword).
  2. If the header is not present, a 401 response is returned.
  3. If the header is present, Gloo Gateway extracts the username from the basic auth header. Then, it builds the distinguished name (DN) for the user entry by substituting the username from the header for the %s placeholder in the LDAP userDnTemplate setting.
    To prevent injection attacks, Gloo Gateway removes special characters from the username before continuing to the next bind step.
  4. Gloo Gateway performs a BIND operation with the LDAP server, using the DN for the user entry from the previous step.
  5. If the bind operation fails, a 401 response is returned. This response means that the user could not be found or the credentials are incorrect.
  6. Gloo Gateway issues a search operation for the user entry (with a base scope). In the user entry, Gloo Gateway looks for an attribute with a name equal to membershipAttributeName.
  7. Gloo Gateway checks if one of the values for the attribute matches one of the allowedGroups in the policy. If so, Gloo Gateway completes the request. Otherwise, Gloo Gateway returns a 403 response. This response means that although the user can be authenticated, the user does not have the appropriate permissions to complete the request.

Before you begin

This guide assumes that you use the same names for components like clusters, workspaces, and namespaces as in the getting started, and that your Kubernetes context is set to the cluster you store your Gloo config in (typically the management cluster). If you have different names, make sure to update the sample configuration files in this guide.

Follow the getting started instructions to:

  1. Set up Gloo Gateway in a single cluster.

  2. Deploy sample apps.

  3. Configure an HTTP listener on your gateway and set up basic routing for the sample apps.

  4. Make sure that the external auth service is installed and running. If not, install the external auth service in your single or multicluster environment.

    kubectl get pods -A -l app=ext-auth-service
  5. Make sure that you have the ldapsearch CLI tool on your local machine. This tool is part of the default developer tools in macOS. You can check if you have the tool by running the following command to print the usage details. To install LDAP and Helper utilities, see this Digital Ocean guide.

    ldapsearch --help

Deploy an LDAP server

Before you can create an LDAP external auth policy, you must have an LDAP server. The following example configures a simple set of users and groups, and deploys the LDAP server to your cluster.

  1. Download the sample LDAP setup script.

  2. Review what the sample LDAP setup script does. For in-depth information, see About the LDAP setup script. In short, the script sets up LDAP users and groups, as well as creates the following Kubernetes resources:

    • A configmap with the LDAP server setup configuration.
    • A deployment to run OpenLDAP.
    • A service to provide access to the deployment.
  3. Make the downloaded script executable.

    chmod +x setup-ldap.sh
  4. Run the LDAP setup script. The script accepts an optional string argument to specify the namespace to create the resources in. Otherwise, you can omit the argument to create the resources in the default namespace.


    Example output:

    No namespace provided, using default namespace
    Creating configmap with LDAP server bootstrap config...
    configmap/ldap created
    Creating LDAP service and deployment...
    deployment.apps/ldap created
    service/ldap created
  5. Enable port-forwarding on the deployment so that you can test the LDAP server.

    kubectl port-forward deployment/ldap 8088:389
  6. In a new tab in your terminal, search for the distinguished names (DNs) of all entries in the solo and io domain components (DCs). For more information about this command, see the LDAP docs.

    ldapsearch -H ldap://localhost:8088 -D "cn=admin,dc=solo,dc=io" -w "solopwd" -b "dc=solo,dc=io" -LLL dn

    Example output:

    dn: dc=solo,dc=io
    dn: cn=admin,dc=solo,dc=io
    dn: ou=people,dc=solo,dc=io
    dn: uid=marco,ou=people,dc=solo,dc=io
    dn: uid=rick,ou=people,dc=solo,dc=io
    dn: uid=scottc,ou=people,dc=solo,dc=io
    dn: ou=groups,dc=solo,dc=io
    dn: cn=developers,ou=groups,dc=solo,dc=io
    dn: cn=sales,ou=groups,dc=solo,dc=io
    dn: cn=managers,ou=groups,dc=solo,dc=io

Good job, now you have an LDAP server running! Continue to Configure an external auth policy with LDAP.

About the LDAP setup script

The LDAP setup script sets up a basic LDAP server with a few different users and groups. This setup includes the Kubernetes resources to create in the cluster.

Click this paragraph to expand the full sample script.

The root of the LDAP directory hierarchy is the dc=solo,dc=io entry, which has two child entries for users and groups.

ou=groups,dc=solo,dc=io is the parent entry for user groups in the organization. It has three groups:

  • cn=developers,ou=groups,dc=solo,dc=io
  • cn=sales,ou=groups,dc=solo,dc=io
  • cn=managers,ou=groups,dc=solo,dc=io
03_people.ldif: |
  # Create a parent 'people' entry
  dn: ou=people,dc=solo,dc=io
  objectClass: organizationalUnit
  ou: people
  description: All solo.io people

  # Add 'marco'
  dn: uid=marco,ou=people,dc=solo,dc=io
  objectClass: inetOrgPerson
  cn: Marco Schwarz
  sn: Schwarz
  uid: marco
  userPassword: marcopwd
  mail: marco.schwarz@solo.io

  # Add 'rick'
  dn: uid=rick,ou=people,dc=solo,dc=io
  objectClass: inetOrgPerson
  cn: Rick Duke
  sn: Duke
  uid: rick
  userPassword: rickpwd
  mail: rick.duke@solo.io

  # Add 'scottc'
  dn: uid=scottc,ou=people,dc=solo,dc=io
  objectClass: inetOrgPerson
  cn: Scott Crawley
  sn: Crawley
  uid: scottc
  userPassword: scottcpwd
  mail: scott.crawley@solo.io

ou=people,dc=solo,dc=io is the parent entry for people in the organization. It has the following entries:

  • uid=marco,ou=people,dc=solo,dc=io
  • uid=rick,ou=people,dc=solo,dc=io
  • uid=scott,ou=people,dc=solo,dc=io
04_groups.ldif: |+
  # Create top level 'group' entry
  dn: ou=groups,dc=solo,dc=io
  objectClass: organizationalUnit
  ou: groups
  description: Generic parent entry for groups

  # Create the 'developers' entry under 'groups'
  dn: cn=developers,ou=groups,dc=solo,dc=io
  objectClass: groupOfNames
  cn: developers
  description: Developers group
  member: uid=marco,ou=people,dc=solo,dc=io
  member: uid=rick,ou=people,dc=solo,dc=io
  member: uid=scottc,ou=people,dc=solo,dc=io

  # Create the 'sales' entry under 'groups'
  dn: cn=sales,ou=groups,dc=solo,dc=io
  objectClass: groupOfNames
  cn: sales
  description: Sales group
  member: uid=scottc,ou=people,dc=solo,dc=io

  # Create the 'managers' entry under 'groups'
  dn: cn=managers,ou=groups,dc=solo,dc=io
  objectClass: groupOfNames
  cn: managers
  description: Managers group
  member: uid=rick,ou=people,dc=solo,dc=io

The user credentials and memberships are summarized in the following table.

Username Password Member of developers Member of sales Member of managers
marco marcopwd
rick rickpwd
scott scottpwd

Configure an external auth policy with LDAP

Create the external auth policy with LDAP.

You can do the following steps in a different order, depending on when you want the policy to take effect. For example, you might want the policy to always take effect as soon as the route is created. To do so, you can create the policy before you add the route to the route table.
  1. Create an external auth server to use for your policy.

    kubectl apply -f - <<EOF
    apiVersion: admin.gloo.solo.io/v2
    kind: ExtAuthServer
      name: ext-auth-server
      namespace: bookinfo
          number: 8083
          cluster: $CLUSTER_NAME
          name: ext-auth-service
          namespace: gloo-mesh-addons
  2. Create an external auth policy that uses the LDAP server.

    When you create the policy with a destination selector, only Kubernetes services can be specified in the applyToDestination section. Gloo virtual destinations or Gloo external services are not supported.

    kubectl apply -f - <<EOF
    apiVersion: security.policy.gloo.solo.io/v2
    kind: ExtAuthPolicy
      name: ratings-ldap
      namespace: bookinfo
      - route:
            route: ratings
          name: ext-auth-server
          namespace: bookinfo
          cluster: $CLUSTER_NAME
          - ldap:
              address: "ldap://ldap.default.svc.cluster.local:389"
              userDnTemplate: "uid=%s,ou=people,dc=solo,dc=io"
              membershipAttributeName: memberOf
              - "cn=managers,ou=groups,dc=solo,dc=io"

Review the following table to understand this configuration. For more information, see the API reference.

Setting Description
applyToRoutes Use labels to configure which routes to apply the policy to. This example label matches the app and route from the example route table that you apply separately. If omitted and you do not have another selector such as applyToDestinations, the policy applies to all routes in the workspace.
server The external auth server to use for the policy.
ldap Configure the LDAP server details.
address The address of the LDAP server that Gloo Gateway queries when a request matches the policy. This example uses the Kubernetes DNS name and port of the LDAP service that you deployed in the default namespace.
userDnTemplate The template string for Gloo Gateway to build the DNs of the user entry to authenticate and authorize. The string must have a single occurrence of the %s placeholder. This placeholder is used to substitute the value from the request header that you want to look for, such as the user ID (uid) in this example. In this example, the template matches the format of the user entry DNs in the config map.
membershipAttributeName A case-insensitive name of the attribute with the names of the groups that a user entry is a member of. If not set, the default value memberOf is used. In the example, the config map sets memberOf automatically for each user entry that is in a group.
allowedGroups The DNs of the user groups that are allowed to access services that are protected by this policy. In this example, only members of "cn=managers,ou=groups,dc=solo,dc=io" group can get successful responses.

Verify the external auth LDAP policy

To test the LDAP policy, make a series of requests as different users. The following table is based off the users that you created in your LDAP config map. The username and password are encoded to base 64 in the format username:password so that you can pass them in a basic auth header.

Username Password Basic auth header Notes
marco marcopwd Authorization: Basic bWFyY286bWFyY29wd2Q= Member of developers group
rick rickpwd Authorization: Basic cmljazpyaWNrcHdk Member of developers and managers groups
john doe Authorization: Basic am9objpkb2U= Unknown user, not a member of any group
  1. Send a request to the ratings app without any auth header. Now, the request is blocked with a 401 Unauthorized response.

    curl -vik --resolve www.example.com:80:${INGRESS_GW_IP} http://www.example.com:80/ratings/1
    curl -vik --resolve www.example.com:443:${INGRESS_GW_IP} https://www.example.com:443/ratings/1

  2. Repeat the previous step with the credentials of the unknown member, john. The request is blocked with the same 401 Unauthorized response.

    curl -vik --resolve www.example.com:80:${INGRESS_GW_IP} http://www.example.com:80/ratings/1 -H "Authorization: Basic am9objpkb2U="
    curl -vik --resolve www.example.com:443:${INGRESS_GW_IP} https://www.example.com:443/ratings/1 -H "Authorization: Basic am9objpkb2U="

  3. Try a request with the credentials of a known member, marco. This user is a member of the developers group, but the LDAP policy only grants permission to members of the managers group. The request is blocked, but this time with a 403 Forbidden response to indicate the lack of permissions.

    curl -vik --resolve www.example.com:80:${INGRESS_GW_IP} http://www.example.com:80/ratings/1 -H "Authorization: Basic bWFyY286bWFyY29wd2Q="
    curl -vik --resolve www.example.com:443:${INGRESS_GW_IP} https://www.example.com:443/ratings/1 -H "Authorization: Basic bWFyY286bWFyY29wd2Q="

  4. Finally, send a request with the credentials of rick, who is a member of the managers group and meets the LDAP policy requirements.

    curl -vik --resolve www.example.com:80:${INGRESS_GW_IP} http://www.example.com:80/ratings/1 -H "Authorization: Basic cmljazpyaWNrcHdk"
    curl -vik --resolve www.example.com:443:${INGRESS_GW_IP} https://www.example.com:443/ratings/1 -H "Authorization: Basic cmljazpyaWNrcHdk"

    The request succeeds!

    HTTP/1.1 200 OK


You can optionally remove the resources that you set up as part of this guide.
  1. Remove the LDAP server that you created.
    kubectl delete configmap ldap
    kubectl delete deployment ldap
    kubectl delete service ldap
  2. Remove the Gloo resources that you created.
    kubectl -n bookinfo delete ExtAuthServer ext-auth-server
    kubectl -n bookinfo delete ExtAuthPolicy ratings-ldap