* Add annotation filter to Ambassador Host Source
This change makes the Ambassador Host source respect the External-DNS annotationFilter allowing for an Ambassador Host resource to specify what External-DNS deployment to use when there are multiple External-DNS deployments within the same cluster. Before this change if you had two External-DNS deployments within the cluster and used the Ambassador Host source the first External-DNS to process the resource will create the record and not the one that was specified in the filter annotation.
I added the `filterByAnnotations` function so that it matched the same way the other sources have implemented annotation filtering. I didn't add the controller check only because I wanted to keep this change to implementing the annotationFilter.
Example: Create two External-DNS deployments 1 public and 1 private and set the Ambassador Host to use the public External-DNS using the annotation filter.
```
---
apiVersion: apps/v1
kind: Deployment
metadata:
name: external-dns-private
spec:
strategy:
type: Recreate
selector:
matchLabels:
app: external-dns-private
template:
metadata:
labels:
app: external-dns-private
annotations:
iam.amazonaws.com/role: {ARN} # AWS ARN role
spec:
serviceAccountName: external-dns
containers:
- name: external-dns
image: k8s.gcr.io/external-dns/external-dns:latest
args:
- --source=ambassador-host
- --domain-filter=example.net # will make ExternalDNS see only the hosted zones matching provided domain, omit to process all available hosted zones
- --provider=aws
- --policy=upsert-only # would prevent ExternalDNS from deleting any records, omit to enable full synchronization
- --aws-zone-type=private # only look at public hosted zones (valid values are public, private or no value for both)
- --registry=txt
- --txt-owner-id= {Hosted Zone ID} # Insert Route53 Hosted Zone ID here
- --annotation-filter=kubernetes.io/ingress.class in (private)
---
apiVersion: apps/v1
kind: Deployment
metadata:
name: external-dns-public
spec:
strategy:
type: Recreate
selector:
matchLabels:
app: external-dns-public
template:
metadata:
labels:
app: external-dns-public
annotations:
iam.amazonaws.com/role: {ARN} # AWS ARN role
spec:
serviceAccountName: external-dns
containers:
- name: external-dns
image: k8s.gcr.io/external-dns/external-dns:latest
args:
- --source=ambassador-host
- --domain-filter=example.net # will make ExternalDNS see only the hosted zones matching provided domain, omit to process all available hosted zones
- --provider=aws
- --policy=upsert-only # would prevent ExternalDNS from deleting any records, omit to enable full synchronization
- --aws-zone-type= # only look at public hosted zones (valid values are public, private or no value for both)
- --registry=txt
- --txt-owner-id= {Hosted Zone ID} # Insert Route53 Hosted Zone ID here
- --annotation-filter=kubernetes.io/ingress.class in (public)
---
apiVersion: getambassador.io/v3alpha1
kind: Host
metadata:
name: your-hostname
annotations:
external-dns.ambassador-service: emissary-ingress/emissary
kubernetes.io/ingress.class: public
spec:
acmeProvider:
authority: none
hostname: your-hostname.example.com
```
Fixeskubernetes-sigs/external-dns#2632
* Add Label filltering for Ambassador Host source
Currently the `--label-filter` flag can only be used to filter CRDs, Ingress, Service and Openshift Route objects which match the label selector passed through that flag. This change extends the functionality to the Ambassador Host type object.
When the flag is not specified the default value is `labels.Everything()` which is an empty string, the same as before. An annotation based filter is inefficient because the filtering has to be done in the controller instead of the API server like with label filtering. The Annotation based filtering has been left in for legacy reasons so the Ambassador Host source can be used inconjunction with the other sources that don't yet support label filltering.
It is possible to use label based filltering with annotation based filltering so you can initially filter by label then filter the returned hosts by annotation. This is not recomended
* Update Ambassador Host source docs
Add that the Ambassador Host source now supports both annotation and label filltering.
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>
As-is, following the docs results in the following error:
```
json: cannot unmarshal number into Go struct field ObjectMeta.metadata.annotations of type string
```
Signed-off-by: Michael Shen <mishen@umich.edu>
**Description**
In the current implementation, DNS providers are called to list all
records on every loop. This is expensive in terms of number of requests
to the provider and may result in being rate limited, as reported in 1293
and 3397.
In our case, we have approximately 20,000 records in our AWS Hosted Zone.
The ListResourceRecordSets API call allows a maximum of 300 items per call.
That requires 67 API calls per external-dns deployment during every sync period
With this, we introduce an optional generic caching mechanism at the provider
level, that re-uses the latest known list of records for a given time.
This prevents from expensive Provider calls to list all records for each
object modification that does not change the actual record (annotations,
statuses, ingress routing, ...)
This introduces 2 trade-offs:
1. Any changes or corruption directly on the provider side will be
longer to detect and to resolve, up to the cache time
2. Any conflicting records in the DNS provider (such as a different
external-dns instance) injected during the cache validity will cause
the first iteration of the next reconcile loop to fail, and hence add a
delay until the next retry
**Checklist**
- [X] Unit tests updated
- [X] End user documentation updated
Change-Id: I0bdcfa994ac1b76acedb05d458a97c080284c5aa
