Using the aws-integrator charm - tutorial

This is in connection to the topic of Using Kubernetes with Juju. See that page for background information.

This tutorial will demonstrate the use of the ‘aws-integrator’ charm with the AWS cloud to make Kubernetes dynamic persistent volumes (PVs) available for use with Kubernetes-specific charms.

Prerequisites

The following prerequisites are assumed as a starting point for this tutorial:

  • You’re using Ubuntu 18.04 LTS.
  • Juju v.2.5.0 is installed. See the Installing Juju page.
  • A credential for the ‘aws’ cloud has been added to Juju. See the Using Amazon AWS with Juju page.
  • Sufficient permissions are assigned to the above credential in order for ‘aws-integrator’ to perform operations (see Permissions Requirements; this tutorial assigns the IAM security policy of ‘AdministratorAccess’).

Installing Kubernetes

Let’s begin by creating a controller. We’ll call it ‘aws-k8s’:

juju bootstrap aws aws-k8s

We’ll deploy Kubernetes using the ‘kubernetes-core’ bundle, which will give us a minimalist cluster. We’ll add the integrator charm to the mix by means of an overlay bundle that we’ll store in file k8s-aws-overlay.yaml:

applications:
  aws-integrator:
    charm: cs:~containers/aws-integrator
    num_units: 1
relations:
  - ['aws-integrator', 'kubernetes-master']
  - ['aws-integrator', 'kubernetes-worker']

See Overlay bundles for details on overlays.

We can now deploy the cluster like so:

juju deploy kubernetes-core --overlay k8s-aws-overlay.yaml
juju trust aws-integrator

The trust command grants ‘aws-integrator’ access to the credential used in the bootstrap command. This charm acts as a proxy for the Juju machines, acting as Kubernetes nodes, to create and attach dynamic storage volumes in the AWS backing cloud.

When a cluster is not built, but merely added, such as one originating from a public Kubernetes service like Azure’s AKS or Google’s GKE, then an integrator charm is not required. Ready-made clusters have storage built in.

It will take about ten minutes to arrive at a stable status command output:

Model    Controller  Cloud/Region   Version  SLA          Timestamp
default  aws-k8s     aws/us-east-1  2.5.0    unsupported  03:28:12Z

App                Version  Status  Scale  Charm              Store       Rev  OS      Notes
aws-integrator     1.15.71  active      1  aws-integrator     jujucharms    8  ubuntu  
easyrsa            3.0.1    active      1  easyrsa            jujucharms  195  ubuntu  
etcd               3.2.10   active      1  etcd               jujucharms  338  ubuntu  
flannel            0.10.0   active      2  flannel            jujucharms  351  ubuntu  
kubernetes-master  1.13.2   active      1  kubernetes-master  jujucharms  542  ubuntu  exposed
kubernetes-worker  1.13.2   active      1  kubernetes-worker  jujucharms  398  ubuntu  exposed

Unit                  Workload  Agent  Machine  Public address  Ports           Message
aws-integrator/0*     active    idle   0        3.90.20.92                      ready
easyrsa/0*            active    idle   0/lxd/0  10.57.10.22                     Certificate Authority connected.
etcd/0*               active    idle   0        3.90.20.92      2379/tcp        Healthy with 1 known peer
kubernetes-master/0*  active    idle   0        3.90.20.92      6443/tcp        Kubernetes master running.
  flannel/1           active    idle            3.90.20.92                      Flannel subnet 10.1.101.1/24
kubernetes-worker/0*  active    idle   1        54.160.5.2      80/tcp,443/tcp  Kubernetes worker running.
  flannel/0*          active    idle            54.160.5.2                      Flannel subnet 10.1.11.1/24

Machine  State    DNS          Inst id              Series  AZ          Message
0        started  3.90.20.92   i-06b046ea0ade98e9c  bionic  us-east-1a  running
0/lxd/0  started  10.57.10.22  juju-06e5d4-0-lxd-0  bionic  us-east-1a  Container started
1        started  54.160.5.2   i-04c67dc1d633c2794  bionic  us-east-1b  running

Adding the cluster to Juju

We’ll now copy over the cluster’s main configuration file and then use the add-k8s command to add the cluster to Juju’s list of known clouds. Here, we arbitrarily call the new cloud ‘k8s-cloud’:

mkdir ~/.kube
juju scp kubernetes-master/0:config ~/.kube/config
juju add-k8s k8s-cloud

The success of this operation can be confirmed by running juju clouds.

Adding a model

When we add a Kubernetes cluster to Juju we effectively have two clouds being managed by one controller. For us, they are named ‘aws’ and ‘k8s-cloud’. So when we want to create a model we’ll need explicitly state which cloud to place the new model in. We’ll do this now by adding a model called ‘k8s-model’ to cloud ‘k8s-cloud’:

juju add-model k8s-model k8s-cloud

Dynamic persistent volumes

As opposed to static Kubernetes persistent volumes, dynamic PVs do not need to be created in advance. They will be created on an as-needed basis by the cluster. This is generally the preferred method.

Tutorial Setting up static Kubernetes storage shows how to set up static PVs and includes information on how to inspect a cluster and its various objects using the kubectl tool.

Creating Juju storage pools

The storage pool name for operator storage must be called ‘operator-storage’ while the pool name for workload storage is arbitrary. Here, our charm has storage requirements so we’ll need a pool for it. We’ll call it ‘k8s-pool’. It is this workload storage pool that will be used at charm deployment time.

For dynamic AWS volumes, the Kubernetes provisioner is kubernetes.io/aws-ebs. We will also request a general purpose SSD drive by passing the gp2 parameter.

Our two storage pools are therefore created like this:

juju create-storage-pool operator-storage kubernetes \
    storage-class=juju-operator-storage \
    storage-provisioner=kubernetes.io/aws-ebs parameters.type=gp2
juju create-storage-pool k8s-pool kubernetes \
    storage-class=juju-unit-storage \
    storage-provisioner=kubernetes.io/aws-ebs parameters.type=gp2

Deploying a Kubernetes charm

We can now deploy a Kubernetes charm. For example, here we deploy a charm by requesting the use of the ‘k8s-pool’ workload storage pool we just set up:

juju deploy cs:~juju/gitlab-k8s
juju deploy cs:~juju/mariadb-k8s --storage database=k8s-pool,10M
juju add-relation gitlab-k8s mariadb-k8s

The output to juju status should soon look similar to this:

Model      Controller  Cloud/Region  Version  SLA          Timestamp
k8s-model  aws         k8s-cloud     2.5.0    unsupported  18:57:16Z

App          Version  Status  Scale  Charm        Store       Rev  OS          Address         Notes
gitlab-k8s            active      1  gitlab-k8s   jujucharms    0  kubernetes  10.152.183.184  
mariadb-k8s           active      1  mariadb-k8s  jujucharms    0  kubernetes  10.152.183.221  

Unit            Workload  Agent  Address     Ports     Message
gitlab-k8s/0*   active    idle   10.1.11.14  80/TCP    
mariadb-k8s/0*  active    idle   10.1.11.13  3306/TCP

Congratulations, you deployed a Kubernetes workload using dynamically provisioned volumes through the use of the AWS integrator charm!

Removing configuration and software

To remove all traces of Kubernetes and its configuration follow these steps:

juju destroy-model -y --destroy-storage k8s-model
juju remove-k8s k8s-cloud
rm -rf ~/.kube

This leaves us with Juju installed as well as an AWS controller. To remove even those things proceed as follows:

juju destroy-controller -y --destroy-all-models aws-k8s
sudo snap remove juju

Next steps

Consider the following tutorials:

To gain experience with a standalone (non-Juju) MicroK8s installation check out Ubuntu tutorial Install a local Kubernetes with MicroK8s.

Last updated 19 days ago. Help improve this document in the forum.