AWS integrator charm

This charm acts as a proxy to AWS and provides an interface to apply a certain set of changes via IAM roles, profiles, and tags to the instances of the applications that are related to this charm.

Usage

When on AWS, this charm can be deployed, granted trust via Juju to access AWS, and then related to an application that supports the interface. The set of permissions that the related application could request is documented in the interface's Requires API documentation.

For example, Charmed Kubernetes has support for this, and can be deployed with the following bundle overlay:

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

Then deploy Charmed Kubernetes using this overlay:

juju deploy cs:charmed-kubernetes --overlay ./k8s-aws-overlay.yaml --trust

Note: This trusts the AWS Integrator charm with the credentials used by Juju. You could instead provide alternate credentials via the `credentials` charm config option.

RDS

In addition to the integrator relation, this charm also provides a proxy to the AWS Relational Database Service (RDS) for charms using the mysql interface. Charms attached to the rds-mysql relation endpoint will have an RDS MySQL database instance created for them and access information provided via the relation.

For example, if this was deployed alongside the Mediawiki charm, it could provide the database for backing the wiki:

applications:
  aws-integrator:
    charm: cs:~containers/aws-integrator
    num_units: 1
    trust: true
  mediawiki:
    charm: cs:mediawiki
    num_units; 1
relations:
  - ['aws-integrator:rds-mysql', 'mediawiki:db']

Permissions Requirements

The credentials given to the charm must include the following access rights:

EC2
AssociateIamInstanceProfile
CreateTags
DescribeInstances
IAM
AddRoleToInstanceProfile
AttachRolePolicy
CreateInstanceProfile
CreatePolicy
CreateRole
DeleteInstanceProfile
DeletePolicy
DeleteRole
DetachRolePolicy
ListAttachedRolePolicies
ListInstanceProfiles
ListPolicies
ListRoles
RemoveRoleFromInstanceProfile
CreatePolicyVersion
ListPolicyVersions
GetPolicyVersion
DeletePolicyVersion
SetDefaultPolicyVersion
GetPolicy
STS
GetCallerIdentity
RDS
DescribeDBInstances
CreateDBInstance
DeleteDBInstance
DeleteDBInstanceAutomatedBackup

Note that these may be different from the permissions that Juju requires to operate.

Resource Usage Note

By relating to this charm, other charms can directly allocate resources, such as EBS volumes and ELBs, which could lead to cloud charges and count against quotas. Because these resources are not managed by Juju, they will not be automatically deleted when the models or applications are destroyed, nor will they show up in Juju's status or GUI. It is therefore up to the operator to manually delete these resources when they are no longer needed, using the AWS console or API.

Examples

Following are some examples using AWS integration with Charmed Kubernetes.

Creating a pod with an EBS-backed volume

This script creates a busybox pod with a persistent volume claim backed by AWS's Elastic Block Storage.

#!/bin/bash

# create a storage class using the `kubernetes.io/aws-ebs` provisioner
kubectl create -f - <<EOY
apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: ebs-1
provisioner: kubernetes.io/aws-ebs
parameters:
  type: gp2
EOY

# create a persistent volume claim using that storage class
kubectl create -f - <<EOY
kind: PersistentVolumeClaim
apiVersion: v1
metadata:
  name: testclaim
spec:
  accessModes:
    - ReadWriteOnce
  resources:
    requests:
      storage: 100Mi
  storageClassName: ebs-1
EOY

# create the busybox pod with a volume using that PVC:
kubectl create -f - <<EOY
apiVersion: v1
kind: Pod
metadata:
  name: busybox
  namespace: default
spec:
  containers:
    - image: busybox
      command:
        - sleep
        - "3600"
      imagePullPolicy: IfNotPresent
      name: busybox
      volumeMounts:
        - mountPath: "/pv"
          name: testvolume
  restartPolicy: Always
  volumes:
    - name: testvolume
      persistentVolumeClaim:
        claimName: testclaim
EOY

Creating a service with an AWS load-balancer

The following script starts the hello-world pod behind an AWS Elastic Load Balancer.

#!/bin/bash

kubectl run hello-world --replicas=5 --labels="run=load-balancer-example" --image=gcr.io/google-samples/node-hello:1.0  --port=8080
kubectl expose deployment hello-world --type=LoadBalancer --name=hello
watch kubectl get svc -o wide --selector=run=load-balancer-example

Configuration

name type Default Description
access-key string An IAM access key. It is strongly recommended that you use 'juju trust' instead, if available.
credentials string See notes
secret-key string An IAM secret key. It is strongly recommended that you use 'juju trust' instead, if available.
snap_proxy string DEPRECATED. Use snap-http-proxy and snap-https-proxy model configuration settings. HTTP/HTTPS web proxy for Snappy to use when accessing the snap store.
snap_proxy_url string DEPRECATED. Use snap-store-proxy model configuration setting. The address of a Snap Store Proxy to use for snaps e.g. http://snap-proxy.example.com
snapd_refresh string See notes

credentials

Description:

The base64-encoded contents of an AWS credentials file, which must include both 'aws_access_key_id' and 'aws_secret_access_key' fields.

This can be used from bundles with 'include-base64://' (see https://jujucharms.com/docs/stable/charms-bundles#setting-charm-configurations-options-in-a-bundle), or from the command-line with 'juju config aws credentials="$(base64 /path/to/file)"'.

It is strongly recommended that you use 'juju trust' instead, if available. This will take precedence over the 'access-key' / 'secret-key' config options.

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snapd_refresh

Description:

How often snapd handles updates for installed snaps. The default (an empty string) is 4x per day. Set to "max" to check once per month based on the charm deployment date. You may also set a custom string as described in the 'refresh.timer' section here: https://forum.snapcraft.io/t/system-options/87

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