build health checks into default deployment (#1233)

## Summary

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The existing implementation has poor numerical properties for
large arguments, so use the McGillicutty algorithm to improve
accuracy above 1e10.

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## Related issues

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Fixes #159
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## Checklist

- [ ] reference any related issues
- [ ] updated docs
- [ ] updated unit tests
- [ ] updated UPGRADING.md
- [ ] add appropriate tag (`improvement` / `bug` / etc)
- [ ] ready for review

Author: alexandreLamarre

config/pomerium/deployment/healthcheck.yaml

@@ -11,6 +11,8 @@ spec:
             httpGet:
               path: /startupz
               port : 28080
+            failureThreshold: 40
+            periodSeconds: 15
           livenessProbe:
             httpGet:
               path: /healthz

config/pomerium/deployment/kustomization.yaml

@@ -9,3 +9,4 @@ patches:
 - path: resources.yaml
 - path: no-root.yaml
 - path: readonly-root-fs.yaml
+- path: healthcheck.yaml

deployment.yaml

@@ -1002,6 +1002,13 @@ spec:
               fieldPath: status.podIP
         image: pomerium/ingress-controller:main
         imagePullPolicy: Always
+        livenessProbe:
+          failureThreshold: 10
+          httpGet:
+            path: /healthz
+            port: 28080
+          initialDelaySeconds: 15
+          periodSeconds: 60
         name: pomerium
         ports:
         - containerPort: 8443
@@ -1016,6 +1023,13 @@ spec:
         - containerPort: 9090
           name: metrics
           protocol: TCP
+        readinessProbe:
+          failureThreshold: 5
+          httpGet:
+            path: /readyz
+            port: 28080
+          initialDelaySeconds: 15
+          periodSeconds: 60
         resources:
           limits:
             cpu: 5000m
@@ -1032,6 +1046,12 @@ spec:
           runAsGroup: 65532
           runAsNonRoot: true
           runAsUser: 65532
+        startupProbe:
+          failureThreshold: 40
+          httpGet:
+            path: /startupz
+            port: 28080
+          periodSeconds: 15
         volumeMounts:
         - mountPath: /tmp
           name: tmp