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AWS Controllers for Kubernetes Hands-on

#aws #ack #cloudopz #rds

Abstract

  • In the world of Infrastructure as code (IaC) there are many tools support us to create AWS resources quickly such as CDK, Pulumi, Terraform. Today I introduce AWS Controllers for Kubernetes (ACK)
  • AWS Controllers for Kubernetes (ACK) lets you define and use AWS service resources directly from Kubernetes. With ACK, you can take advantage of AWS-managed services for your Kubernetes applications without needing to define resources outside of the cluster or run services that provide supporting capabilities like databases or message queues within the cluster.
  • This post provides step-by-step to create AWS RDS postgres in private VPC using ACK and then access the database to prove it works.

Table Of Contents

πŸš€ Introduction of ACK

πŸš€ Install the ACK service controller for RDS

⚑ $ export HELM_EXPERIMENTAL_OCI=1
⚑ $ helm pull oci://public.ecr.aws/aws-controllers-k8s/rds-chart --version=v0.0.17
⚑ $ tar xf rds-chart-v0.0.17.tgz
⚑ $ helm install rds-chart --generate-name --set=aws.region=ap-northeast-2


## πŸš€ **Create ACK ServiceAccount base on IRSA** <a name="Create-ACK-ServiceAccount-base-on-IRSA"></a>
- This step requires IAM role for service account here is ACK RDS. Note that the role needs permission to manage RDS resource. We can limit permission by restrict resource. And to protect the resource from incident of deleteing the `DBInstance` (describe later), we can set `Deny` action of `rds:DeleteDBInstance`
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{
"Version": "2012-10-17",
"Statement": [
{
"Condition": {
"StringEquals": {
"aws:RequestedRegion": "ap-northeast-2"
}
},
"Action": "rds:",
"Resource": "arn:aws:rds:ap-northeast-2:123456789012:",
"Effect": "Allow",
"Sid": "CreateRds"
},
{
"Action": "rds:DeleteDBInstance",
"Resource": "*",
"Effect": "Deny",
"Sid": "DenyDeleteRds"
}
]
}


- Generate SA yaml and update IRSA to apply, replace the IAM ARN role with yours.

  

  ack-sa.yaml
  



apiVersion: v1
kind: ServiceAccount
metadata:
labels:
    app.kubernetes.io/component: controller
    app.kubernetes.io/name: ack-rds-controller
name: ack-rds-controller
annotations:
    eks.amazonaws.com/role-arn: arn:aws:iam::123456789012:role/ack-rds-controller-d1






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- Apply the manifest
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kf apply -f ack-sa.yaml


## πŸš€ **Create RDS secret keys** <a name="Create-RDS-secret-keys"></a>
- Best practice is to protect the RDS user password
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export RDS_DB_USERNAME=rds_username
export RDS_DB_PASSWORD=rds_password

kubectl create secret generic rds-postgresql-user-creds \
--from-literal=username="${RDS_DB_USERNAME}" \
--from-literal=password="${RDS_DB_PASSWORD}"


## πŸš€ **Create subnet group** <a name="Create-subnet-group"></a>
- The subnet group contains all subnet of EKS private VPC
- Get subnets from EKS VPC, replace the VPC ID and the region with yours
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EKS_SUBNET_IDS=$(aws ec2 describe-subnets --filters "Name=vpc-id,Values=vpc-0eb6477bf2c8430cd" --query 'Subnets[*].SubnetId' --output text --region ap-northeast-2)


- Generate yaml file inherit ${EKS_SUBNET_IDS} above
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cat <<-EOF > ack/ack-rds-subnet-groups.yaml
apiVersion: rds.services.k8s.aws/v1alpha1
kind: DBSubnetGroup
metadata:
name: rds-postgresql-subnet-group
spec:
name: rds-postgresql-subnet-group
description: RDS for app in EKS
subnetIDs:
$(printf "    - %s\n" ${EKS_SUBNET_IDS})
tags:
    - key: stage
      value: development
    - key: owner
      value: dev
EOF
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- Apply the manifest
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kf apply -f ack/ack-rds-subnet-groups.yaml


## πŸš€ **Create security group to allow traffic from EKS pods to the RDS** <a name="Create-security-group-to-allow-traffic-from-EKS-pods-to-the-RDS"></a>
- First we create a SG in the EKS VPC to attach to the RDS, replace the VPC ID with your EKS VPC ID and appropriate region
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RDS_SECURITY_GROUP_ID=$(aws ec2 create-security-group \
--group-name rds-postgres-sg \
--description "SG to allow traffic from EKS pod to RDS" \
--vpc-id vpc-0eb6477bf2c8430cd \
--output text --region ap-northeast-2
)


- Then we need to allow traffic from EKS worker nodes. **There are two ways**
  1. In RDS SG, allow traffic from CIDR range of the EKS VPC
     - Get CIDR range of EKS VCP using command line
       ```


       EKS_CIDR_RANGE=$(aws ec2 describe-vpcs --vpc-ids vpc-0eb6477bf2c8430cd --query 'Vpcs[].CidrBlock' --output text --region ap-northeast-2)
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 - Create ingress in the SG to allow traffic from the above CIDR
    ```
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     aws ec2 authorize-security-group-ingress \
     --group-id "${RDS_SECURITY_GROUP_ID}" \
     --protocol tcp \
     --port 5432 \
     --cidr "${EKS_CIDR_RANGE}" \
     --region ap-northeast-2
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  2. In RDS SG, allow traffic from the security group which is attached to all EKS nodes (in general, traffic is allowed from the network interfaces that are associated with the source security group for the specified protocol and port, read more from [Understand Pods communication](https://dev.to/aws-builders/understand-pods-communication-338c) at `Security groups for your VPC` specifying a security group as the source for a rule)

  <img src="https://github.com/vumdao/aws-ack-hands-on/blob/master/images/rds-sg.png?raw=true" width="1100" />

## πŸš€ **Create DBInstance** <a name="Create-DBInstance"></a>
- Create DBInstance manifest, replace security group ID in `vpcSecurityGroupIDs` with the one you created in previous step `RDS_SECURITY_GROUP_ID`. Here we select RDS instance type `db.t3.micro` as it is free tier, master user and password maps with the RDS secret keys created in previous step, `engine: postgres` version 10
  

  ack/ack-rds-postgresql.yaml
  


apiVersion: rds.services.k8s.aws/v1alpha1

  kind: DBInstance

  metadata:

    name: "rds-postgresql-dev"

  spec:

    allocatedStorage: 20

    autoMinorVersionUpgrade: true

    backupRetentionPeriod: 7

    dbInstanceClass: db.t3.micro

    dbInstanceIdentifier: "rds-postgresql-dev"

    dbSubnetGroupName: rds-postgresql-subnet-group

    engine: postgres

    engineVersion: "10"

    masterUsername: "rds_user"

    masterUserPassword:

      namespace: default

      name: rds-postgresql-user-creds

      key: password

    multiAZ: true

    publiclyAccessible: false

    storageEncrypted: true

    storageType: gp2

    vpcSecurityGroupIDs:

      - sg-009c3a2658d1f7165

    tags:

      - key: stage

        value: development

      - key: owner

        value: dev







  





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- Apply the yaml
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kf apply -f ack/ack-rds-postgresql.yaml


- Check created `DBInstance`
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⚑ $ kf get DBInstance
NAME AGE
rds-postgresql-dev 1h


  <img src="https://github.com/vumdao/aws-ack-hands-on/blob/master/images/rds.png?raw=true" width="1100" />

## πŸš€ **Access RDS through EKS pod** <a name="Access-RDS-through-EKS-pod"></a>
- This step proves RDS works well and EKS pods in private VPC can read/write to the RDS use master user
- Build `postgresql-client` docker image and push it to ECR or any container image repository
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FROM alpine:3
RUN apk add --no-cache postgresql-client
CMD while true; do sleep 5; echo psql-client; done


- Create postgresql client deployment
  

  psql-client.yaml
  


apiVersion: apps/v1

  kind: Deployment

  metadata:

    labels:

      app: psql-client

    name: psql-client

  spec:

    replicas: 1

    selector:

      matchLabels:

        app: psql-client-deployment

    template:

      metadata:

        labels:

          app: psql-client-deployment

      spec:

        containers:

          - image: 123456789012.dkr.ecr.ap-northeast-2.amazonaws.com/psql/client:latest

            name: psql-client







  





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- Apply the deployment and then get pod
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~ $ kf apply -f ack/psql-client.yaml
deployment.apps/psql-client created

~ $ kf get pod
NAME READY STATUS RESTARTS AGE
psql-client-9d45f759-8swtr 1/1 Running 0 44m


- Go into the pod to access RDS, get RDS private endpoint in the console or using AWS CLI or using `kubectl`
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~ $ aws rds describe-db-instances --db-instance-identifier rds-postgresql-dev --region ap-northeast-2 --query 'DBInstances[0].Endpoint.Address'
"rds-postgresql-dev.xxxxxxxxxxxx.ap-northeast-2.rds.amazonaws.com"

~ $ kubectl get dbinstance rds-postgresql-dev -o jsonpath='{.status.endpoint.address}'
"rds-postgresql-dev.xxxxxxxxxxxx.ap-northeast-2.rds.amazonaws.com"

~ $ kf exec -it psql-client-9d45f759-8swtr -- sh
/ # psql -h rds-postgresql-dev.xxxxxxxxxxxx.ap-northeast-2.rds.amazonaws.com -U rds_user -d postgres
postgres=> \du
List of roles
Role name | Attributes | Member of
--------------------+------------------------------------------------------------+-------------------------------------------------------------
rds_user | Create role, Create DB +| {rds_superuser}
| Password valid until infinity |
rds_ad | Cannot login | {}
rds_iam | Cannot login | {}
rds_password | Cannot login | {}
rds_replication | Cannot login | {}
rds_superuser | Cannot login | {pg_monitor,pg_signal_backend,rds_replication,rds_password}
rdsadmin | Superuser, Create role, Create DB, Replication, Bypass RLS+| {}
| Password valid until infinity |
rdsrepladmin | No inheritance, Cannot login, Replication | {}

postgres=> CREATE DATABASE "rds-test";
CREATE DATABASE

postgres=> \l rds-test
List of databases
Name | Owner | Encoding | Collate | Ctype | Access privileges
----------+--------------------+----------+-------------+-------------+-------------------
rds-test | rds_user | UTF8 | en_US.UTF-8 | en_US.UTF-8 |
(1 row)


## πŸš€ **Clean-up workspace** <a name="Clean-up-workspace"></a>
- Delete `DBInstance`, note that if you deny `rds:DeleteDBInstance` in ACK role to protect your RDS then this step requires more action such as remove the deny or delete RDS manually then force delete `DBInstance`. Here assume ACK RDS role has permission of deleting the RDS
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⚑ $ kf delete DBInstance rds-postgresql-dev
dbinstance.rds.services.k8s.aws "rds-postgresql-dev" deleted


- Delete `psql-client` deployment
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⚑ $ kf delete -f ack/psql-client.yaml
deployment.apps "psql-client" deleted


- Delete RDS secret key
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⚑ $ kf delete secret rds-postgresql-user-creds
secret "rds-postgresql-user-creds" deleted


- Delete RDS security group
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⚑ $ aws ec2 delete-security-group --group-id sg-009c3a2658d1f7165 --region ap-northeast-2


- Uninstall ACK RDS
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⚑ $ helm list
NAME NAMESPACE REVISION UPDATED STATUS CHART APP VERSION
rds-chart-1648053478 default 1 2022-03-23 23:38:11.397906502 +0700 +07 deployed rds-chart-v0.0.17 v0.0.17

⚑ $ helm uninstall rds-chart-1648053478
release "rds-chart-1648053478" uninstalled


- Finally delete the IRSA for ACK RDS
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⚑ $ cdk destroy AckControllerSA --profile vc-mfa
Are you sure you want to delete: AckControllerSA (y/n)? y
AckControllerSA: destroying...

βœ… AckControllerSA: destroyed


## πŸš€ **Conclusion** <a name="Conclusion"></a>
- Using ACK to create AWS resources is a big plus for those ones love managing AWS resources through k8s manifests within the EKS cluster
- We can combine cdk8s to create ACK yaml files

---

References:
- [Deploy Amazon RDS databases for applications in Kubernetes](https://aws.amazon.com/blogs/database/deploy-amazon-rds-databases-for-applications-in-kubernetes/)

---



    
      

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