Instance Profile

An Instance Profile is an abstraction over the resource characteristics of an instance (basically, as of today, CPU “cores” and RAM). StackGres represents such a profile with the CRD SGInstanceProfile. You can think of instance profiles as “t-shirt sizes”, a way to create named t-shirt sizes (such as S, M, L), that you will reference when you create your clusters. It is a way to enforce best practices by using standardized instance sizes.

The SGInstanceProfile is referenced from one or more Postgres clusters.

This is an example config definition:

apiVersion: stackgres.io/v1
kind: SGInstanceProfile
metadata:
  namespace: demo
  name: size-small
spec:
  cpu: "4"
  memory: "8Gi"

This definition is created in Kubernetes (e.g. using kubectl apply) and can be inspected (kubectl describe sginstanceprofile size-small) like any other Kubernetes resource.

You may create other instance profiles with other sizes if you wish.

An instance profile enforces resource requests and limits for the container where Patroni and Postgres will set the Pod resource using the cpu and memory values for both requests and limits. It also enforces resource requests for all the other containers under the section .spec.containers and .spec.initContainers. Those sections contain the default values specified by cpu and memory, and can be tuned later depending on the requirements of your particular use case.

StackGres clusters can reference this configuration as follows:

apiVersion: stackgres.io/v1
kind: SGCluster
metadata:
  namespace: demo
  name: cluster
spec:
# [...]
  sgInstanceProfile: 'size-small'

Resources

When an SGInstanceProfile is created specifying only cpu and memory fields under section SGInstanceProfile.spec other sections will be created assigning values based on those:

apiVersion: stackgres.io/v1
kind: SGInstanceProfile
metadata:
  namespace: demo
  name: size-small
spec:
  cpu: "4"
  memory: 8Gi
  containers:
    backup.create-backup:
      cpu: "1"
      memory: 256Mi
    cluster-controller:
      cpu: 250m
      memory: 512Mi
    dbops.run-dbops:
      cpu: "1"
      memory: 256Mi
    dbops.set-dbops-result:
      cpu: "1"
      memory: 256Mi
    envoy:
      cpu: "1"
      memory: 64Mi
    fluent-bit:
      cpu: 250m
      memory: 64Mi
    fluentd:
      cpu: "1"
      memory: 2Gi
    pgbouncer:
      cpu: 250m
      memory: 64Mi
    postgres-util:
      cpu: 250m
      memory: 64Mi
    prometheus-postgres-exporter:
      cpu: 250m
      memory: 256Mi
  initContainers:
    cluster-reconciliation-cycle:
      cpu: "4"
      memory: 8Gi
    dbops.set-dbops-running:
      cpu: "1"
      memory: 256Mi
    distributedlogs-reconciliation-cycle:
      cpu: "4"
      memory: 8Gi
    major-version-upgrade:
      cpu: "4"
      memory: 8Gi
    pgbouncer-auth-file:
      cpu: "4"
      memory: 8Gi
    relocate-binaries:
      cpu: "4"
      memory: 8Gi
    reset-patroni:
      cpu: "4"
      memory: 8Gi
    setup-arbitrary-user:
      cpu: "4"
      memory: 8Gi
    setup-scripts:
      cpu: "4"
      memory: 8Gi
  requests:
    cpu: "4"
    memory: 8Gi
    containers:
      backup.create-backup:
        cpu: "1"
        memory: 256Mi
      cluster-controller:
        cpu: 250m
        memory: 512Mi
      dbops.run-dbops:
        cpu: "1"
        memory: 256Mi
      dbops.set-dbops-result:
        cpu: "1"
        memory: 256Mi
      envoy:
        cpu: "1"
        memory: 64Mi
      fluent-bit:
        cpu: 250m
        memory: 64Mi
      fluentd:
        cpu: "1"
        memory: 2Gi
      pgbouncer:
        cpu: 250m
        memory: 64Mi
      postgres-util:
        cpu: 250m
        memory: 64Mi
      prometheus-postgres-exporter:
        cpu: 250m
        memory: 256Mi
    initContainers:
      cluster-reconciliation-cycle:
        cpu: "4"
        memory: 8Gi
      dbops.set-dbops-running:
        cpu: "1"
        memory: 256Mi
      distributedlogs-reconciliation-cycle:
        cpu: "4"
        memory: 8Gi
      major-version-upgrade:
        cpu: "4"
        memory: 8Gi
      pgbouncer-auth-file:
        cpu: "4"
        memory: 8Gi
      relocate-binaries:
        cpu: "4"
        memory: 8Gi
      reset-patroni:
        cpu: "4"
        memory: 8Gi
      setup-arbitrary-user:
        cpu: "4"
        memory: 8Gi
      setup-scripts:
        cpu: "4"
        memory: 8Gi

This allows unexperienced users to create an SGInstanceProfile without requiring much knowledge on the usage of all the containers.

You may set any value of cpu and memory in any of the above sections to null in order to remove the corresponding resources limits or requests assignment.

Resources limits

By default the SGInstanceProfile cpu and memory fields under section SGInstanceProfile.spec will be assigned as resources limits to the patroni container. Other containers will not receive any resources limits unless the SGCluster.spec.pods.resources.enableClusterLimitsRequirements is set to true. In such case each container (and init container) will be assigned the resources limits of the corresponding value of fields cpu and memory specified in section SGInstanceProfile.spec.containers.<container name> (and SGInstanceProfile.spec.initContainers.<container name>).

For example without setting SGCluster.spec.pods.resources.enableClusterLimitsRequirements a Pod resources limits would look like:

$ kubectl get pod -n demo cluster-0 --template '{{ range .spec.containers }}{{ printf "%s:\n  limits: %s\n\n" .name .resources.limits }}{{ end }}'
patroni:
  limits: map[cpu:4 memory:8Gi]

envoy:
  limits: %!s(<nil>)

pgbouncer:
  limits: %!s(<nil>)

prometheus-postgres-exporter:
  limits: %!s(<nil>)

postgres-util:
  limits: %!s(<nil>)

fluent-bit:
  limits: %!s(<nil>)

cluster-controller:
  limits: %!s(<nil>)

While with setting SGCluster.spec.pods.resources.enableClusterLimitsRequirements to true will look like:

$ kubectl get pod -n demo cluster-0 --template '{{ range .spec.containers }}{{ printf "%s:\n  limits: %s\n\n" .name .resources.limits }}{{ end }}'
patroni:
  limits: map[cpu:4 memory:8Gi]

envoy:
  limits: map[cpu:1 memory:64Mi]

pgbouncer:
  limits: map[cpu:250m memory:64Mi]

prometheus-postgres-exporter:
  limits: map[cpu:250m memory:256Mi]

postgres-util:
  limits: map[cpu:250m memory:64Mi]

fluent-bit:
  limits: map[cpu:250m memory:64Mi]

cluster-controller:
  limits: map[cpu:250m memory:512Mi]

Resources requests

SGInstanceProfile cpu and memory fields under section SGInstanceProfile.spec.requests will be assigned as the total resources requests assigned to the all the container of the Pod. Each container (and init container) will be assigned the resources requests of the corresponding value of fields cpu and memory specified in section SGInstanceProfile.spec.requests.containers.<container name> (and SGInstanceProfile.spec.requests.initContainers.<container name>). The only exception is the patroni container which resources requests values will be the values of cpu and memory fields under section SGInstanceProfile.spec.requests minus the sum of cpu and memory specified in section SGInstanceProfile.spec.requests.containers.<container name> for each container that will be created by the operator depending on SGCluster configuration.

If SGCluster.spec.pods.resources.disableResourcesRequestsSplitFromTotal is set to true then cpu and memory fields under section SGInstanceProfile.spec.requests will be assigned as resources requests to the patroni container.

For example without setting SGCluster.spec.pods.resources.disableResourcesRequestsSplitFromTotal a Pod resources limits would look like:

$ kubectl get pod -n demo cluster-0 --template '{{ range .spec.containers }}{{ printf "%s:\n  limits: %s\n\n" .name .resources.requests }}{{ end }}'
patroni:
  limits: map[cpu:1750m memory:7Gi]

envoy:
  limits: map[cpu:1 memory:64Mi]

pgbouncer:
  limits: map[cpu:250m memory:64Mi]

prometheus-postgres-exporter:
  limits: map[cpu:250m memory:256Mi]

postgres-util:
  limits: map[cpu:250m memory:64Mi]

fluent-bit:
  limits: map[cpu:250m memory:64Mi]

cluster-controller:
  limits: map[cpu:250m memory:512Mi]

While with setting SGCluster.spec.pods.resources.disableResourcesRequestsSplitFromTotal to true will look like:

$ kubectl get pod -n demo cluster-0 --template '{{ range .spec.containers }}{{ printf "%s:\n  limits: %s\n\n" .name .resources.limits }}{{ end }}'
patroni:
  limits: map[cpu:4 memory:8Gi]

envoy:
  limits: map[cpu:1 memory:64Mi]

pgbouncer:
  limits: map[cpu:250m memory:64Mi]

prometheus-postgres-exporter:
  limits: map[cpu:250m memory:256Mi]

postgres-util:
  limits: map[cpu:250m memory:64Mi]

fluent-bit:
  limits: map[cpu:250m memory:64Mi]

cluster-controller:
  limits: map[cpu:250m memory:512Mi]

In the latter case the total accounting of cpu resources requests for the Pod would be 6250m instead of 4 and for memory would be of 9Gi instead of 8Gi.

Huge Pages

Huge pages can be configured for the patroni container by setting the value of hugepages-1Gi or hugepages-2Mi (for huge pages of 1Gi or 2Mi respectively).

Make sure that the total amount of memory requested for huge pages do not surpass the total memory resources limits.

For example to specify 8 huge pages of 1Gi:

apiVersion: stackgres.io/v1
kind: SGInstanceProfile
metadata:
  namespace: demo
  name: size-small
spec:
  cpu: "4"
  memory: 8Gi
  hugePages:
    hugepages-1Gi: 8Gi

Custom containers

Any custom container (or init cunstom containers) resources limits and huge pages can be configured by creating a section SGInstanceProfile.spec.containers.custom-<custom container name> (or SGInstanceProfile.spec.initContainers.custom-<custom init container name>) and specifying cpu, memory and/or hugePages.