This repository contains a controller that allows you to operate a Varnish cache on Kubernetes.
This controller is not intended to be a replacement of a regular ingress controller. Instead, it is intended to be used between your regular Ingress controller and your application's service.
+---------+ +---------+ +-------------+
| Ingress |----->| Varnish |----->| Application |
+---------+ +---------+ +-------------+
The Varnish controller needs the following prerequisites to run:
- A Go-template that will be used to generate a VCL configuration file
- An application Kubernetes service that will be used as backend for the Varnish controller
- A Varnish Kubernetes service that will be used as frontend for the Varnish controller
- If RBAC is enabled in your cluster, you'll need a ServiceAccount with a role that grants
WATCHaccess to theendpointsresource in the respective namespace
After starting, the Varnish controller will watch the configured Varnish service's endpoints and application service's endpoints; on startup and whenever these change, it will use the supplied VCL template to generate a new Varnish configuration and load this configuration at runtime.
The controller does not ship with any preconfigured configuration; the upstream connection and advanced features like load balancing are possible, but need to be configured in the VCL template supplied by you.
It can run in high avalability mode using multiple Varnish and application pods.
+---------+
| Ingress |
+---------+
|
+---------+
| Service |
+---------+
/ \
+---------------+ +---------------+
| Varnish 1 |--| Varnish 2 |
| Signaller 1 |--| Signaller 2 |
+---------------+ +---------------+
| \/ |
| /\ |
+---------------+ +---------------+
| Application 1 | | Application 2 |
+---------------+ +---------------+
The Signaller component supports broadcasting PURGE and BAN requests to all Varnish nodes.
SUBJECT TO CHANGE
Start by creating a ConfigMap that contains a VCL template:
apiVersion: v1
kind: ConfigMap
metadata:
name: vcl-template
data:
default.vcl.tmpl: |
vcl 4.0;
import std;
import directors;
{{ range .Frontends }}
backend fe-{{ .Name }} {
.host = "{{ .Host }}";
.port = "{{ .Port }}";
}
{{- end }}
backend fe-primary {
.host = "{{ .PrimaryFrontend.Host }}";
.port = "{{ .PrimaryFrontend.Port }}";
}
{{ range .Backends }}
backend be-{{ .Name }} {
.host = "{{ .Host }}";
.port = "{{ .Port }}";
}
{{- end }}
backend be-primary {
.host = "{{ .PrimaryBackend.Host }}";
.port = "{{ .PrimaryBackend.Port }}";
}
acl purgers {
"127.0.0.1";
"localhost";
"::1";
{{- range .Frontends }}
"{{ .Host }}";
{{- end }}
{{- range .Backends }}
"{{ .Host }}";
{{- end }}
}
sub vcl_init {
new cluster = directors.hash();
{{ range .Frontends -}}
cluster.add_backend({{ .Name }}, 1);
{{ end }}
new lb = directors.round_robin();
{{ range .Backends -}}
lb.add_backend(be-{{ .Name }});
{{ end }}
}
sub vcl_recv
{
# Set backend hint for non cachable objects.
set req.backend_hint = lb.backend();
# ...
# Routing logic. Pass a request to an appropriate Varnish node.
# See https://info.varnish-software.com/blog/creating-self-routing-varnish-cluster for more info.
unset req.http.x-cache;
set req.backend_hint = cluster.backend(req.url);
set req.http.x-shard = req.backend_hint;
if (req.http.x-shard != server.identity) {
return(pass);
}
set req.backend_hint = lb.backend();
# ...
return(hash);
}
# ...Create a Secret object that contains the secret for the Varnish administration port:
$ kubectl create secret generic varnish-secret --from-literal=secret=$(head -c32 /dev/urandom | base64)
If RBAC is enabled in your cluster, you will need to create a ServiceAccount with a respective Role.
$ kubectl create serviceaccount kube-httpcache
$ kubectl apply -f https://raw.githubusercontent.com/mittwald/kube-httpcache/master/deploy/kubernetes/rbac.yaml
$ kubectl create rolebinding kube-httpcache --role=kube-httpcache --serviceaccount=kube-httpcache
- Create a
StatefulSetfor the Varnish controller:
apiVersion: apps/v1
kind: StatefulSet
metadata:
name: cache-statefulset
labels:
app: cache
spec:
serviceName: cache-service
replicas: 2
updateStrategy:
type: RollingUpdate
selector:
matchLabels:
app: cache
template:
metadata:
labels:
app: cache
spec:
containers:
- name: cache
image: quay.io/spaces/kube-httpcache:stable
imagePullPolicy: Always
args:
- -admin-addr=0.0.0.0
- -admin-port=6083
- -signaller-enable=true
- -signaller-port=8090
- -frontend-watch=true
- -frontend-namespace=$(NAMESPACE)
- -frontend-service=frontend-service
- -backend-watch=true
- -backend-namespace=$(NAMESPACE)
- -backend-service=backend-service
- -varnish-secret-file=/etc/varnish/k8s-secret/secret
- -varnish-vcl-template=/etc/varnish/tmpl/default.vcl.tmpl
- -varnish-storage=malloc,128M
env:
- name: NAMESPACE
valueFrom:
fieldRef:
fieldPath: metadata.namespace
volumeMounts:
- name: template
mountPath: /etc/varnish/tmpl
- name: secret
mountPath: /etc/varnish/k8s-secret
serviceAccountName: kube-httpcache # when using RBAC
restartPolicy: Always
volumes:
- name: template
configMap:
name: vcl-template
- name: secret
secret:
secretName: varnish-secret- Create a service for the Varnish controller:
apiVersion: v1
kind: Service
metadata:
name: cache-service
labels:
app: cache
spec:
ports:
- name: "http"
port: 80
targetPort: 80
- name: "signaller"
port: 8090
targetPort: 8090
selector:
app: cache- Create an ingress to forward requests to cache service. You may end up with two URLs: http://www.example.com, http://signaller.example.com. An Ingress for signaller is optional, if you choose to have it, make sure to limit access to it.
To broadcast a BAN request to all Varnish endpoints, run:
$ curl -H "X-Url: /path" -X BAN http://cache-service:8090
or
$ curl -H "X-Url: /path" -X BAN http://signaller.example.com
To broadcast a PURGE request to all Varnish endpoints, run:
$ curl -H "X-Host: www.example.com" -X PURGE http://cache-service:8090/path
or
$ curl -H "X-Host: www.example.com" -X PURGE http://signaller.example.com/path
Specific headers for PURGE/BAN requests depend on your Varnish configuration. E.g. X-Host header is set for convenience, because signaller is listening on other URL than Varnish. However, you need to suport such headers in your VCL.
sub vcl_recv
{
# ...
# Purge logic
if ( req.method == "PURGE" ) {
if ( client.ip !~ privileged ) {
return (synth(403, "Not allowed."));
}
if (req.http.X-Host) {
set req.http.host = req.http.X-Host;
}
return (purge);
}
# Ban logic
if ( req.method == "BAN" ) {
if ( client.ip !~ privileged ) {
return (synth(403, "Not allowed."));
}
if (req.http.Cache-Tags) {
ban("obj.http.Cache-Tags ~ " + req.http.Cache-Tags);
return (synth(200, "Ban added " + req.http.host));
}
if (req.http.X-Url) {
ban("obj.http.X-Url == " + req.http.X-Url);
return (synth(200, "Ban added " + req.http.host));
}
return (synth(403, "Cache-Tags or X-Url header missing."));
}
# ...
}