This Helm chart installs a service in both Kubernetes and Istio, and exposes it outside the cluster via an Istio ingress gateway.
> helm template --namespace=[namespace] [chartname] | kubectl apply -f -All configuration for this installation is managed in values.yaml. Configuration
values can be overriden individually at installation using Helm's --set command
line option.
These three values control the names of generated Kubernetes and Istio objects, and are used to ensure commont Kubernetes labeling. These values are used to populate labels that allow for selecting all components of a particular system or service.
system,service,version- These values describe what this service and what it should be named. For example:my-website,web-server,2.
These settings control from where and how your service's docker image is acquired.
image.repository- The docker repo and image to pull.image.tag- The docker image tag to pull.image.imagePullPolicy- Kubernetes image pull policy.
Istio request authorization requires that each service have a unique service account identity to functuion correctly.
serviceAccount.name- The Kubernetes service account your service will run under.serviceAccount.create- Optionally, this chart can generate the service account. If false, the service's service account must be pre-existing.
These settings control service replicas, disruption budgets, and autoscaling.
replicaCount- The initial number of replicas to start after installing this chart.maxUnavailable- The maximum number of intentionally unavailable pods as controlled by aPodDisruptionBudget.autoscaling.minReplicas- The minimum number of replicas to run under the control of aHorizontalPodAutoscaler.autoscaling.maxReplicas- The maximum number of replicas to run under the control of aHorizontalPodAutoscaler.autoscaling.targetAverageCpuUtilization- The CPU utilization target used by theHorizontalPodAutoscalerto make autoscale decisions.
These settings expose network ports through Kubernetes and Istio. Ports are listed as an array.
ports.name- The unique name for this port. Port names should comply with Istio port naming standards by including their protocol in the name. Protocol detection works for HTTP and HTTP/2, but other protocols need help. https://istio.io/latest/docs/ops/configuration/traffic-management/protocol-selection/ports.port- The port number presented outside your container. This is the port Istio and Kubernetes will use when referring to your service's port.ports.targetPort- The internal port number inside your container. Kubernetes will map the outside port to the inside port when routing traffic to your container.
These settings configure how Istio exposes your service throug an Istio ingress
gateway. They assume the Istio ingress gateway is installed, and an Istio
Gateway object has been configured in the mesh.
istioGateway.name- The namespace/name of the IstioGatewayobject through which this service should be exposed.istioGateway.host- Bind this service's ingress configuration to a hostname.istioGateway.matchPrefix- A string array of REST route prefixes this service matches. gRPC services are matched as/protoNamespace/protoService/*.
These settings control Istio's resiliency configuration for your service. This includes timeouts, circuit breakers, retires, and outlier detection.
overallTimeout- The "top-level" timeout enforced when clients call your service. This timeout is inclusive of retries.retries.*- Istio configuration for client retry policy. See Istio retry documentation for values. Note: if retries are configured, anoverallTimeoutgreater than the sum of all retries must be used.outlierDetection.*- Istio configuration for client circuit breaker configuration. See Istio outlier detection documentation for details.
These settings configure your service's resource constraints and health check probes. They ensure your service is a well behaved queue-consumer of shared Kubernetes resources.
resources.*- Kubernetes resource request and limit configuration. See Kubernetes resource documentation for values.probes.*- Kubernetes probe configuration. See Kubernetes probe documentation for values.
These optional settings are used to populate and mount a configmap for your
service. When the generated config map changes, the associated service is automatically
resterted using a rolling restart. Generating the configmap from Helm chart values
is useful because it allows you to modify config map values durring installation
using Helm --set directives.
configMap.mountPath- The directory inside your pod to mount the config map.configMap.fileName- The file name of the config map, when mounted in the pod.configMap.content.*- YAML keys and values undercontentare copied verbatim into the configmap's content.