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Allow rolling update maxSurge maxUnavailable to be configurable #30

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33 changes: 20 additions & 13 deletions README.md
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Original file line number Diff line number Diff line change
@@ -1,15 +1,17 @@
# egress-operator

An operator to produce egress gateway pods and control access to them with network policies, and a coredns plugin to route egress traffic to these pods.

The idea is that instead of authorizing egress traffic with protocol inspection,
you instead create a internal clusterIP for every external service you use, lock
it down to only a few pods via a network policy, and then set up your dns server
to resolve the external service to that clusterIP.

Built with kubebuilder: https://book.kubebuilder.io/
Built with kubebuilder: <https://book.kubebuilder.io/>

The operator accepts ExternalService objects, which aren't namespaced, which define a dns name and ports for an external service.
In the `egress-operator-system` namespace, it creates:

- An envoy configmap for a TCP/UDP proxy to that service (UDP not working until the next envoy release that enables it)
- A deployment for some envoy pods with that config
- A horizontal pod autoscaler to keep the deployment correctly sized
Expand All @@ -31,24 +33,28 @@ In the `egress-operator-system` namespace, it creates:
```bash
make run
```

This creates an ExternalService object to see the controller-manager creating managed resources in the remote cluster.

### Setting up CoreDNS plugin

The CoreDNS plugin rewrites responses for external service hostnames managed by egress-operator.

Build a CoreDNS image which contains the plugin:

```bash
cd coredns-plugin
make docker-build docker-push IMG=yourrepo/egress-operator-coredns:latest
```

You'll need to swap out the image of your coredns kubedns Deployment for `yourrepo/egress-operator-coredns:latest`:

```bash
kubectl edit deploy coredns -n kube-system # Your Deployment name may vary
```

And edit the coredns Corefile in ConfigMap to put in `egressoperator egress-operator-system cluster.local`:

```bash
kubectl edit configmap coredns-config -n kube-system # Your ConfigMap name may vary
```
Expand Down Expand Up @@ -202,15 +208,16 @@ spec:
egress.monzo.com/gateway: egress-gateway-name
```

| Variable name | Default | Description |
|------------------------------------|-------------------------------------------|----------------------------------------------------|
| ENVOY_IMAGE | `envoyproxy/envoy-alpine:v1.16.5` | Name of the Envoy Proxy image to use |
| TAINT_TOLERATION_KEY | Empty, no tolerations applied | Toleration key to apply to gateway pods |
| TAINT_TOLERATION_VALUE | Empty, no tolerations applied | Toleration value to apply to gateway pods |
| NODE_SELECTOR_KEY | Empty, no node selector added | Node selector label key to apply to gateway pods |
| NODE_SELECTOR_VALUE | Empty, no node selector added | Node selector label value to apply to gateway pods |
| POD_TOPOLOGY_ZONE_MAX_SKEW_KEY | `topology.kubernetes.io/zone` | Topology key for the zone constraint |
| POD_TOPOLOGY_ZONE_MAX_SKEW | Empty, won't inject a zone constraint | Value of maxSkew for the zone constraint |
| POD_TOPOLOGY_HOSTNAME_MAX_SKEW_KEY | `kubernetes.io/hostname` | Topology key for the hostname constraint |
| POD_TOPOLOGY_HOSTNAME_MAX_SKEW | Empty, won't inject a hostname constraint | Value of maxSkew for the hostname constraint |

| Variable name | Default | Description |
| ---------------------------------- | ----------------------------------------- | ------------------------------------------------------- |
| ENVOY_IMAGE | `envoyproxy/envoy-alpine:v1.16.5` | Name of the Envoy Proxy image to use |
| TAINT_TOLERATION_KEY | Empty, no tolerations applied | Toleration key to apply to gateway pods |
| TAINT_TOLERATION_VALUE | Empty, no tolerations applied | Toleration value to apply to gateway pods |
| NODE_SELECTOR_KEY | Empty, no node selector added | Node selector label key to apply to gateway pods |
| NODE_SELECTOR_VALUE | Empty, no node selector added | Node selector label value to apply to gateway pods |
| POD_TOPOLOGY_ZONE_MAX_SKEW_KEY | `topology.kubernetes.io/zone` | Topology key for the zone constraint |
| POD_TOPOLOGY_ZONE_MAX_SKEW | Empty, won't inject a zone constraint | Value of maxSkew for the zone constraint |
| POD_TOPOLOGY_HOSTNAME_MAX_SKEW_KEY | `kubernetes.io/hostname` | Topology key for the hostname constraint |
| POD_TOPOLOGY_HOSTNAME_MAX_SKEW | Empty, won't inject a hostname constraint | Value of maxSkew for the hostname constraint |
| ROLLING_UPDATE_MAX_UNAVAILABLE | 25% | Rolling Update max unavailable to apply to gateway pods |
| ROLLING_UPDATE_MAX_SURGE | 25% | Rolling Update max surge to apply to gateway pods |
18 changes: 16 additions & 2 deletions controllers/deployment.go
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Original file line number Diff line number Diff line change
Expand Up @@ -134,6 +134,9 @@ func deployment(es *egressv1.ExternalService, configHash string) *appsv1.Deploym
}
}

maxUnavailableStr := lookupEnvOr("ROLLING_UPDATE_MAX_UNAVAILABLE", "25%")
maxSurgeStr := lookupEnvOr("ROLLING_UPDATE_MAX_SURGE", "25%")

var resources corev1.ResourceRequirements
if es.Spec.Resources != nil {
resources = *es.Spec.Resources
Expand All @@ -150,6 +153,9 @@ func deployment(es *egressv1.ExternalService, configHash string) *appsv1.Deploym
}
}

maxUnavailable := intstr.FromString(maxUnavailableStr)
maxSurge := intstr.FromString(maxSurgeStr)

return &appsv1.Deployment{
ObjectMeta: metav1.ObjectMeta{
Name: es.Name,
Expand All @@ -163,8 +169,8 @@ func deployment(es *egressv1.ExternalService, configHash string) *appsv1.Deploym
Strategy: appsv1.DeploymentStrategy{
Type: appsv1.RollingUpdateDeploymentStrategyType,
RollingUpdate: &appsv1.RollingUpdateDeployment{
MaxUnavailable: intstr.ValueOrDefault(nil, intstr.FromString("25%")),
MaxSurge: intstr.ValueOrDefault(nil, intstr.FromString("25%")),
MaxUnavailable: &maxUnavailable,
MaxSurge: &maxSurge,
},
},
Selector: labelSelector,
Expand Down Expand Up @@ -245,3 +251,11 @@ func deployment(es *egressv1.ExternalService, configHash string) *appsv1.Deploym
},
}
}

func lookupEnvOr(envKey, envDefaultValue string) string {
valueStr, isSet := os.LookupEnv(envKey)
if !isSet || len(valueStr) == 0 {
return envDefaultValue
}
return valueStr
}