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Add tutorial to DynamoDB registry docs
The existing docs described how to configure the DynamoDB registry, but didn't have a tutorial for someone to walk through. Signed-off-by: Michael Shen <mishen@umich.edu> Co-authored-by: Michel Loiseleur <97035654+mloiseleur@users.noreply.github.com>
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Michael Shen
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# The DynamoDB registry
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The DynamoDB registry stores DNS record metadata in an AWS DynamoDB table.
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## The DynamoDB Table
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By default, the DynamoDB registry stores data in the table named `external-dns`.
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A different table may be specified using the `--dynamodb-table` flag.
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A different region may be specified using the `--dynamodb-region` flag.
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The table must have a partition (hash) key named `k` and string type.
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The table must not have a sort (range) key.
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As opposed to the default TXT registry, the DynamoDB registry stores DNS record metadata in an AWS DynamoDB table instead of in TXT records in a hosted zone.
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This following tutorial extends [Setting up ExternalDNS for Services on AWS](../tutorials/aws.md) to use the DynamoDB registry instead.
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## IAM permissions
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The ExternalDNS Role must be granted the following permissions:
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The ExternalDNS [IAM Policy](../tutorials/aws.md#iam-policy) must additionally be granted the following permissions:
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```json
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{
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@ -33,10 +25,138 @@ The ExternalDNS Role must be granted the following permissions:
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The region and account ID may be specified explicitly specified instead of using wildcards.
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## Create a DynamoDB Table
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By default, the DynamoDB registry stores data in the table named `external-dns` and it needs to exist before configuring ExternalDNS to use the DynamoDB registry.
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If the DynamoDB table has a different name, it may be specified using the `--dynamodb-table` flag.
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If the DynamoDB table is in a different region, it may be specified using the `--dynamodb-region` flag.
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The following command creates a DynamoDB table with the name: `external-dns`:
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> The table must have a partition (HASH) key named `k` of type string (`S`) and the table must NOT have a sort (RANGE) key.
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```bash
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aws dynamodb create-table \
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--table-name external-dns \
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--attribute-definitions \
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AttributeName=k,AttributeType=S \
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--key-schema \
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AttributeName=k,KeyType=HASH \
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--provisioned-throughput \
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ReadCapacityUnits=5,WriteCapacityUnits=5 \
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--table-class STANDARD
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```
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## Set up a hosted zone
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Follow [Set up a hosted zone](../tutorials/aws.md#set-up-a-hosted-zone)
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## Modify ExternalDNS deployment
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The ExternalDNS deployment from [Deploy ExternalDNS](../tutorials/aws.md#deploy-externaldns) needs the following modifications:
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* `--registry=txt` should be changed to `--registry=dynamodb`
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* Add `--dynamodb-table=external-dns` to specify the name of the DynamoDB table, its value defaults to `external-dns`
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* Add `--dynamodb-region=us-east-1` to specify the region of the DynamoDB table
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For example:
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```yaml
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apiVersion: apps/v1
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kind: Deployment
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metadata:
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name: external-dns
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labels:
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app.kubernetes.io/name: external-dns
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spec:
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strategy:
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type: Recreate
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selector:
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matchLabels:
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app.kubernetes.io/name: external-dns
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template:
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metadata:
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labels:
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app.kubernetes.io/name: external-dns
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spec:
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containers:
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- name: external-dns
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image: registry.k8s.io/external-dns/external-dns:v0.14.1
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args:
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- --source=service
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- --source=ingress
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- --domain-filter=example.com # will make ExternalDNS see only the hosted zones matching provided domain, omit to process all available hosted zones
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- --provider=aws
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- --policy=upsert-only # would prevent ExternalDNS from deleting any records, omit to enable full synchronization
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- --aws-zone-type=public # only look at public hosted zones (valid values are public, private or no value for both)
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- --registry=dynamodb # previously, --registry=txt
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- --dynamodb-table=external-dns # defaults to external-dns
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- --dynamodb-region=us-east-1 # set to the region the DynamoDB table in
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- --txt-owner-id=my-hostedzone-identifier
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env:
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- name: AWS_DEFAULT_REGION
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value: us-east-1 # change to region where EKS is installed
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# # Uncomment below if using static credentials
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# - name: AWS_SHARED_CREDENTIALS_FILE
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# value: /.aws/credentials
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# volumeMounts:
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# - name: aws-credentials
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# mountPath: /.aws
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# readOnly: true
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# volumes:
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# - name: aws-credentials
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# secret:
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# secretName: external-dns
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```
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## Validate ExternalDNS works
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Create either a [Service](../tutorials/aws.md#verify-externaldns-works-service-example) or an [Ingress](../tutorials/aws.md#verify-externaldns-works-ingress-example) and
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After roughly two minutes, check that the corresponding entry was created in the DynamoDB table:
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```bash
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aws dynamodb scan --table-name external-dns
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```
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This will show something like:
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```
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{
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"Items": [
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{
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"k": {
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"S": "nginx.example.com#A#"
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},
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"o": {
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"S": "my-identifier"
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},
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"l": {
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"M": {
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"resource": {
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"S": "service/default/nginx"
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}
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}
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}
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}
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],
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"Count": 1,
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"ScannedCount": 1,
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"ConsumedCapacity": null
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}
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```
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## Clean up
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In addition to the clean up steps in [Setting up ExternalDNS for Services on AWS](../tutorials/aws.md#clean-up), delete the DynamoDB table that was used as a registry.
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```bash
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aws dynamodb delete-table \
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--table-name external-dns
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```
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## Caching
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The DynamoDB registry can optionally cache DNS records read from the provider. This can mitigate
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rate limits imposed by the provider.
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The DynamoDB registry can optionally cache DNS records read from the provider. This can mitigate rate limits imposed by the provider.
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Caching is enabled by specifying a cache duration with the `--txt-cache-interval` flag.
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@ -856,6 +856,10 @@ env:
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key: {{ YOUR_SECRET_KEY }}
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```
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## DynamoDB Registry
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The DynamoDB Registry can be used to store dns records metadata. See the [DynamoDB Registry Tutorial](../registry/dynamodb.md) for more information.
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## Clean up
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Make sure to delete all Service objects before terminating the cluster so all load balancers get cleaned up correctly.
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