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Posts Tagged ‘Active Directory’

Logging into a Kubernetes cluster with an OIDC LDAP account

09/09/2019 Comments off

I confess, most of my experience with Kubernetes is with Pivotal Container Service (PKS) Enterprise.  PKS makes it rather easy to get started and I found that I took some tasks for granted.

In PKS Enterprise, one can use the pks cli to not only life-cycle clusters, but to obtain the credentials to the cluster and automatically update the kubeconfig with the account information.  So, administrative/operations users can run the command “pks get-credentials my-cluster” to have a kubeconfig updated with the authentication tokens and parameters to connect to my-cluster.

K8s OIDC using UAA on PKS

The PKS controller includes the User Account and Authentication (UAA) component, which is used to authenticate users into PKS Enterprise.  UAA can also be easily configured to connect to an existing LDAP service – this is the desired configuration in most organizations so that users account exist in one place (Active Directory in my example).

So, I found myself wondering “I don’t want to provide the PKS CLI to developers, so how can they connect kubectl to the cluster?”

Assumptions:

  • PKS Enterprise on vSphere (with or without NSX-T)
  • Active Directory
  • Developer user account belongs to the k8s-devs security group in AD

Prerequisite configuration:

  1. UAA on PKS configured a with UAA User Account Store: LDAP Server.  This links UAA to LDAP/Active Directory
  2. User Search Filter: userPrincipalName={0}  This means that users can login as user@domain.tld
  3. Group Search Filter: member={0} This ensures that AD groups may be used rather than specifying individual users
  4. Configure created clusters to use UAA as the OIDC provider: Enabled  This pre-configures the kubernetes API to use OpenID Connect with UAA. If not using PKS Enterprise, you’ll need to provide another OpenID Connect-Compliant endpoint (like Dex), link it to Active Directory and update the kubernetes cluster api manually to use the OpenID Authentication.

 

Operator: Create Role and RoleBinding:

While authentication is handled by OIDC/UAA/LDAP, Authorization must be configured on the cluster to provide access to resources via RBAC.  This is done by defining a Role (or clusterRole) that indicates what actions may be taken on what resources and a RoleBinding which links the Role to one or more “subjects”.

  1.  Authenticate to kubernetes cluster with an administrative account (for example, using PKS cli to connect)
  2.  Create yaml file for our Role and RoleBinding:
    kind: Role
    apiVersion: rbac.authorization.k8s.io/v1
    metadata:
      name: developers
    rules:
    - apiGroups: ["", "extensions", "apps"]
      resources: ["deployments", "replicasets", "pods"]
      verbs: ["get", "list", "watch", "create", "update", "patch", "delete"] 
      # You can also use ["*"]
    ---
    kind: RoleBinding
    apiVersion: rbac.authorization.k8s.io/v1beta1
    metadata:
      name: developer-dev-binding
    subjects:
    - kind: Group
      name: k8s-devs
      apiGroup: rbac.authorization.k8s.io
    roleRef:
      kind: Role
      name: developers
      apiGroup: rbac.authorization.k8s.io
    

    In the example above, we’re creating a Role named “developers”, granting access to the core, extensions and apps API groups and several actions against deployments, replicaSets and pods. Notice that developers in this role would have have access to secrets (for example)
    The example RoleBinding binds a group named “k8s-devs” to the developers role. Notice that we have not created the k8s-devs group in Kubernetes or UAA; it exists in Active Directory

  3. Use Kubectl to apply the yaml, creating the Role and Rolebinding in the targeted namespace

 

Creating the kubeconfig – the hard way

To get our developer connected with kubectl, they’ll need a kubeconfig with the authentication and connection details.  The Hard way steps are:

  1. Operator obtains the cluster’s certificate authority data.  This can be done via curl or by copying the value from the existing kubeconfig.
  2. Operator creates a template kubeconfig, replacing the value specified, then sends it to the developer user
    apiVersion: v1
    clusters:
    - cluster:
      certificate-authority-data: <OBTAINED IN STEP 1 >
      server: < FQDN to Master Node. >
      name: PROVIDED-BY-ADMIN
    contexts:
    - context:
        cluster: PROVIDED-BY-ADMIN
        user: PROVIDED-BY-USER
      name:  PROVIDED-BY-ADMIN
    current-context: PROVIDED-BY-ADMIN
    kind: Config
    preferences: {}
    users:
    - name: PROVIDED-BY-USER
      user:
        auth-provider:
          config:
            client-id: pks_cluster_client
            cluster_client_secret: ""
            id-token: PROVIDED-BY-USER
            idp-issuer-url: https://PROVIDED-BY-ADMIN:8443/oauth/token
            refresh-token:  PROVIDED-BY-USER
          name: oidc
  3. The developer user obtains the id_token and refresh_token from UAA, via a curl command
    curl 'https://PKS-API:8443/oauth/token' -k -XPOST -H
    'Accept: application/json' -d "client_id=pks_cluster_client&client_secret=""&grant_type=password&username=UAA-USERNAME&response_type=id_token" --data-urlencode password=UAA-PASSWORD
  4. The developer user updates the kubeconfig with the id_token and refresh token in the kubeconfig

 

Creating the kubeconfig – the easy way

Assuming the developer is using Mac or Linux…

  1. Install jq on developer workstation
  2. Download the get-pks-k8s-config.sh script, make it executable (chmod +x get-pks.k8s.config.sh)
  3. Execute the script (replace the params with your own)
    ./get-pks-k8s-config.sh --API=api.pks.mydomain.com \
    --CLUSTER=cl1.pks.mydomain.com \
    --USER=dev1@mydomain.com \
    --NS=scratch
    • API – FQDN to PKS Controller, for UAA
    • CLUSTER – FQDN to master node of k8s cluster
    • USER – userPrincipalName for the user
    • NS – Namespace to target; optional
  4. After entering the user’s password, the script will set the params in the kubeconfig and switch context automatically

Try it out
Our developer user should able to “see” pods but not namespaces for example:

dev1 can see pods but not namespaces

 

Creating the kubeconfig – the easiest way

  1. Provide the developer with the PKS CLI tool, remember we have not added them to any group or role with PKS admin permissions.
  2. Provide the developer with the PKS API endpoint FQDN and the cluster name
  3. The developer may run this command to generate the updated kubeconfig and set the current context
    pks get-kubeconfig CLUSTERNAME -a API -u USER -k

    • CLUSTERNAME is the name of the cluster
    • API – FQDN to PKS Controller
    • USER – userPrincipalName for the user
  4. You’ll be prompted for the account password. Once entered, the tool will fetch the user-specific kubeconfig.

Use PKS CLI to get the kubeconfig

 

Deploy vCenter Log Insight Windows Agent using GPO

07/02/2014 Comments off

The VMware documentation covers this, but I thought I’d add my “insight” (get it? har har)

Prerequsities

  1. Get Microsoft Orca.  It’s part of the SDK found here.
  2. Get the vCenter Log Insight Windows Agent from my.vmware.com if you haven’t already
  3. An appropriate network location for GPO-delivered installers containing the vCLI Agent MSI

Orca Steps

  1. Launch Orca, choose file|open and select thevCLI Agent MSI (VMware-vCenter-Log-Insight-Agent-2.0.3-1879692_1.msi in this case)

    vCLI MSI open in Orca

    vCLI MSI open in Orca

  2. Within Orca, click Transform|New Transform

    Create new transform

    Create new transform

  3. Click the “Property” table to load its rows

    Property Table

    Property Table

  4. Right-click under the populated rows and choose “Add Row”
  5. In the “Add Row” dialog, enter the property as “SERVERHOST” and the value as theFQDN of yourvCenter Log Insight server, click OK.  Notice thenew record has a green box around it?  That means it’ll be included in the transform file.

    Add SERVERHOST Property

    Add SERVERHOST Property

  6. On the menu, choose Transform|Generate Transform.  Put it in the same folder as the vCLI Agent MSI, give it a descriptive name.
  7. Once the mst is saved, you can close Orca.

GPO Steps

  1. Create a new or open an existing GPO in Group Policy Management Editor
  2. Expand Computer Configuration|Policies|Software Settings, right-click Software installation and choose New|Package

    Add software installation package to GPO

    Add software installation package to GPO

  3. Select thevCLI MSI on the network share, select the “Advanced” option on the Deploy Software dialog, click OK.

    Choose the Advanced Option

    Choose the Advanced Option

  4. On the VMware vCenter Log Insight Agent Properties dialog, navigate to the Modifications tab.
  5. Click the “Add” button and select themst you created earlier. Click OK.  Make other changes to the package as appropriate for your environment and click OK to save.

    Modifications Tab

    Modifications Tab

  6. Like all other GPOs, link it to the appropriate OU(s) containing the computers you want the agent deployed on.

Creating an LDAP configuration for Active Directory in vCloud Application Director

03/19/2014 Comments off

The documentation for (vFabric) vCloud Application Director is pretty sparse in this area, so here’s what worked for me.

Preparation:
You should have some idea how you want App Director to get its information from Active Directory. You can point it at a single domain controller (or GC) or a virtual IP address if you have them behind a load-balancer.

In my case, I have only two domain controllers and they’re both configured as Global Catalog servers. AD-integrated DNS is used and the “(same as parent folder)” A records in the zone resolve to the domain controllers. Only point the integration at the domain FQDN if all of the possible responders listen on the same port.

TCP Port Usage
389 (caution!) LDAP
636 LDAP over SSL
3268 LDAP Global Catalog
3269 LDAP Global Catalog over SSL

While logged into the AppD CLI as admin, run this command:

create-ldap-config

Question Answer I used
Use SSL to communicate to LDAP server (ldaps)? no
Server name/IP: ragazzi.lab
Server port: 3268 (see above)
Server base DN: dc=ragazzi,dc=lab
Does your LDAP server support anonymous query?: no
Username to use when querying for users? serviceaccount@ragazzi.lab
Password to use when querying for users? ********
Base DN of user sub-tree: <blank>
Username attribute sAMAccountName
User UID attribute objectSid
User’s group membership attribute memberOf
User’s first name attribute givenName
User’s last name attribute sn
User’s email address attribute <blank>
Base DN of group sub-tree <blank>
Group name attribute cn
Group UID attribute objectSid
Group’s member list attribute member
Name for the configuration ragazzilab (the configuration name should not have a dot in it)

After completion, run this to be sure it looks right:

list-ldap-configs

If it looks good, run this to activate your config:

activate-ldap-config --configname yourconfig

Replace “yourconfig” with the name of your LDAP config

Lastly, lets make sure it works by testing that AppD can retrieve information about a user from AD. Run this

test-named-ldap-config --configname yourconfig --name thatusername

Replace “yourconfig” with the name of your LDAP config and “thatusername” with an actual username.

It should return details about the user, be sure that the group membership information looks right.