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---
reviewers:
- davidopp
- madhusudancs
title: Configure Multiple Schedulers
content_template: templates/task
---
{{% capture overview %}}
Kubernetes ships with a default scheduler that is described [here](/docs/admin/kube-scheduler/).
If the default scheduler does not suit your needs you can implement your own scheduler.
Not just that, you can even run multiple schedulers simultaneously alongside the default
scheduler and instruct Kubernetes what scheduler to use for each of your pods. Let's
learn how to run multiple schedulers in Kubernetes with an example.
A detailed description of how to implement a scheduler is outside the scope of this
document. Please refer to the kube-scheduler implementation in
[pkg/scheduler](https://github.com/kubernetes/kubernetes/tree/{{< param "githubbranch" >}}/pkg/scheduler)
in the Kubernetes source directory for a canonical example.
{{% /capture %}}
{{% capture prerequisites %}}
{{< include "task-tutorial-prereqs.md" >}} {{< version-check >}}
{{% /capture %}}
{{% capture steps %}}
## Package the scheduler
Package your scheduler binary into a container image. For the purposes of this example,
let's just use the default scheduler (kube-scheduler) as our second scheduler as well.
Clone the [Kubernetes source code from GitHub](https://github.com/kubernetes/kubernetes)
and build the source.
```shell
git clone https://github.com/kubernetes/kubernetes.git
cd kubernetes
make
```
Create a container image containing the kube-scheduler binary. Here is the `Dockerfile`
to build the image:
```docker
FROM busybox
ADD ./_output/dockerized/bin/linux/amd64/kube-scheduler /usr/local/bin/kube-scheduler
```
Save the file as `Dockerfile`, build the image and push it to a registry. This example
pushes the image to
[Google Container Registry (GCR)](https://cloud.google.com/container-registry/).
For more details, please read the GCR
[documentation](https://cloud.google.com/container-registry/docs/).
```shell
docker build -t gcr.io/my-gcp-project/my-kube-scheduler:1.0 .
gcloud docker -- push gcr.io/my-gcp-project/my-kube-scheduler:1.0
```
## Define a Kubernetes Deployment for the scheduler
Now that we have our scheduler in a container image, we can just create a pod
config for it and run it in our Kubernetes cluster. But instead of creating a pod
directly in the cluster, let's use a [Deployment](/docs/concepts/workloads/controllers/deployment/)
for this example. A [Deployment](/docs/concepts/workloads/controllers/deployment/) manages a
[Replica Set](/docs/concepts/workloads/controllers/replicaset/) which in turn manages the pods,
thereby making the scheduler resilient to failures. Here is the deployment
config. Save it as `my-scheduler.yaml`:
{{< codenew file="admin/sched/my-scheduler.yaml" >}}
An important thing to note here is that the name of the scheduler specified as an
argument to the scheduler command in the container spec should be unique. This is the name that is matched against the value of the optional `spec.schedulerName` on pods, to determine whether this scheduler is responsible for scheduling a particular pod.
Note also that we created a dedicated service account `my-scheduler` and bind the cluster role
`system:kube-scheduler` to it so that it can acquire the same privileges as `kube-scheduler`.
Please see the
[kube-scheduler documentation](/docs/admin/kube-scheduler/) for
detailed description of other command line arguments.
## Run the second scheduler in the cluster
In order to run your scheduler in a Kubernetes cluster, just create the deployment
specified in the config above in a Kubernetes cluster:
```shell
kubectl create -f my-scheduler.yaml
```
Verify that the scheduler pod is running:
```shell
kubectl get pods --namespace=kube-system
```
```
NAME READY STATUS RESTARTS AGE
....
my-scheduler-lnf4s-4744f 1/1 Running 0 2m
...
```
You should see a "Running" my-scheduler pod, in addition to the default kube-scheduler
pod in this list.
To run multiple-scheduler with leader election enabled, you must do the following:
First, update the following fields in your YAML file:
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* `--leader-elect=true`
* `--lock-object-namespace=lock-object-namespace`
* `--lock-object-name=lock-object-name`
If RBAC is enabled on your cluster, you must update the `system:kube-scheduler` cluster role. Add your scheduler name to the resourceNames of the rule applied for endpoints resources, as in the following example:
```
kubectl edit clusterrole system:kube-scheduler
```
```yaml
Release 1.8 (#5659) * GC now supports non-core resources * Add two examples about how to analysis audits of kube-apiserver (#4264) * Deprecate system:nodes binding * [1.8] StatefulSet `initialized` annotation is now ignored. * inits the kubeadm upgrade docs addresses kubernetes/kubernetes.github.io/issues/4689 * adds kubeadm upgrade cmd to ToC addresses kubernetes/kubernetes.github.io/issues/4689 * add workload placement docs * ScaleIO - document udpate for 1.8 * Add documentation on storageClass.mountOptions and PV.mountOptions (#5254) * Add documentation on storageClass.mountOptions and PV.mountOptions * convert notes into callouts * Add docs for CustomResource validation add info about supported fields * advanced audit beta features (#5300) * Update job workload doc with backoff failure policy (#5319) Add to the Jobs documentation how to use the new backoffLimit field that limit the number of Pod failure before considering the Job as failed. * Documented additional AWS Service annotations (#4864) * Add device plugin doc under concepts/cluster-administration. (#5261) * Add device plugin doc under concepts/cluster-administration. * Update device-plugins.md * Update device-plugins.md Add meta description. Fix typo. Change bare metal deployment to manual deployment. * Update device-plugins.md Fix typo again. * Update page.version. (#5341) * Add documentation on storageClass.reclaimPolicy (#5171) * [Advanced audit] use new herf for audit-api (#5349) This tag contains all the changes in v1beta1 version. Update it now. * Added documentation around creating the InitializerConfiguration for the persistent volume label controller in the cloud-controller-manager (#5255) * Documentation for kubectl plugins (#5294) * Documentation for kubectl plugins * Update kubectl-plugins.md * Update kubectl-plugins.md * Updated CPU manager docs to match implementation. (#5332) * Noted limitation of alpha static cpumanager. * Updated CPU manager docs to match implementation. - Removed references to CPU pressure node condition and evictions. - Added note about new --cpu-manager-reconcile-period flag. - Added note about node allocatable requirements for static policy. - Noted limitation of alpha static cpumanager. * Move cpu-manager task link to rsc mgmt section. * init containers annotation removed in 1.8 (#5390) * Add documentation for TaintNodesByCondition (#5352) * Add documentation for TaintNodesByCondition * Update nodes.md * Update taint-and-toleration.md * Update daemonset.md * Update nodes.md * Update taint-and-toleration.md * Update daemonset.md * Fix deployments (#5421) * Document extended resources and OIR deprecation. (#5399) * Document extended resources and OIR deprecation. * Updated extended resources doc per reviews. * reverts extra spacing in _data/tasks.yml * addresses `kubeadm upgrade` review comments Feedback from @chenopis, @luxas, and @steveperry-53 addressed with this commit * HugePages documentation (#5419) * Update cpu-management-policies.md (#5407) Fixed the bad link. Modified "cpu" to "CPU". Added more 'yaml' as supplement. * Update RBAC docs for v1 (#5445) * Add user docs for pod priority and preemption (#5328) * Add user docs for pod priority and preemption * Update pod-priority-preemption.md * More updates * Update docs/admin/kubeadm.md for 1.8 (#5440) - Made a couple of minor wording changes (not strictly 1.8 related). - Did some reformatting (not strictly 1.8 related). - Updated references to the default token TTL (was infinite, now 24 hours). - Documented the new `--discovery-token-ca-cert-hash` and `--discovery-token-unsafe-skip-ca-verification` flags for `kubeadm join`. - Added references to the new `--discovery-token-ca-cert-hash` flag in all the default examples. - Added a new _Security model_ section that describes the security tradeoffs of the various discovery modes. - Documented the new `--groups` flag for `kubeadm token create`. - Added a note of caution under _Automating kubeadm_ that references the _Security model_ section. - Updated the component version table to drop 1.6 and add 1.8. - Update `_data/reference.yml` to try to get the sidebar fixed up and more consistent with `kubefed`. * Update StatefulSet Basics for 1.8 release (#5398) * addresses `kubeadm upgrade` review comments 2nd iteration review comments by @luxas * adds kubelet upgrade section to kubeadm upgrade * Fix a bulleted list on docs/admin/kubeadm.md. (#5458) I updated this doc yesterday and I was absolutely sure I fixed this, but I just saw that this commit got lost somehow. This was introduced recently in https://github.com/kubernetes/kubernetes.github.io/pull/5440. * Clarify the API to check for device plugins * Moving Flexvolume to separate out-of-tree section * addresses `kubeadm upgrade` review comments CC: @luxas * fixes kubeadm upgrade index * Update Stackdriver Logging documentation (#5495) * Re-update WordPress and MySQL PV doc to use apps/v1beta2 APIs (#5526) * Update statefulset concepts doc to use apps/v1beta2 APIs (#5420) * add document on kubectl's behavior regarding initializers (#5505) * Update docs/admin/kubeadm.md to cover self-hosting in 1.8. (#5497) This is a new beta feature in 1.8. * Update kubectl patch doc to use apps/v1beta2 APIs (#5422) * [1.8] Update "Run Applications" tasks to apps/v1beta2. (#5525) * Update replicated stateful application task for 1.8. * Update single instance stateful app task for 1.8. * Update stateless app task for 1.8. * Update kubectl patch task for 1.8. * fix the link of persistent storage (#5515) * update the admission-controllers.md index.md what-is-kubernetes.md link * fix the link of persistent storage * Add quota support for local ephemeral storage (#5493) * Add quota support for local ephemeral storage update the doc to this alpha feature * Update resource-quotas.md * Updated Deployments concepts doc (#5491) * Updated Deployments concepts doc * Addressed comments * Addressed more comments * Modify allocatable storage to ephemeral-storage (#5490) Update the doc to use ephemeral-storage instead of storage * Revamped concepts doc for ReplicaSet (#5463) * Revamped concepts doc for ReplicaSet * Minor changes to call out specific versions for selector defaulting and immutability * Addressed doc review comments * Remove petset documentations (#5395) * Update docs to use batch/v1beta1 cronjobs (#5475) * add federation job doc (#5485) * add federation job doc * Update job.md Edits for clarity and consistency * Update job.md Fixed a typo * update DaemonSet concept for 1.8 release (#5397) * update DaemonSet concept for 1.8 release * Update daemonset.md Fix typo. than -> then * Update bootstrap tokens doc for 1.8. (#5479) * Update bootstrap tokens doc for 1.8. This has some changes I missed when I was updating the main kubeadm documention: - Bootstrap tokens are now beta, not alpha (https://github.com/kubernetes/features/issues/130) - The apiserver flag to enable the authenticator changedin 1.8 (https://github.com/kubernetes/kubernetes/pull/51198) - Added `auth-extra-groups` documentaion (https://github.com/kubernetes/kubernetes/pull/50933) - Updated the _Token Management with `kubeadm`_ section to link to the main kubeadm docs, since it was just duplicated information. * Update bootstrap-tokens.md * Updated the Cassandra tutorial to use apps/v1beta2 (#5548) * add docs for AllowPrivilegeEscalation (#5448) Signed-off-by: Jess Frazelle <acidburn@microsoft.com> * Add local ephemeral storage alpha feature in managing compute resource (#5522) * Add local ephemeral storage alpha feature in managing compute resource Since 1.8, we add the local ephemeral storage alpha feature as one resource type to manage. Add this feature into the doc. * Update manage-compute-resources-container.md * Update manage-compute-resources-container.md * Update manage-compute-resources-container.md * Update manage-compute-resources-container.md * Update manage-compute-resources-container.md * Update manage-compute-resources-container.md * Added documentation for Metrics Server (#5560) * authorization: improve authorization debugging docs (#5549) * Document mount propagation (#5544) * Update /docs/setup/independent/create-cluster-kubeadm.md for 1.8. (#5524) This introduction needed a couple of small tweaks to cover the `--discovery-token-ca-cert-hash` flag added in https://github.com/kubernetes/kubernetes/pull/49520 and some version bumps. * Add task doc for alpha dynamic kubelet configuration (#5523) * Fix input/output of selfsubjectaccess review (#5593) * Add docs for implementing resize (#5528) * Add docs for implementing resize * Update admission-controllers.md * Added link to PVC section * minor typo fixes * Update NetworkPolicy concept guide with egress and CIDR changes (#5529) * update zookeeper tutorial for 1.8 release * add doc for hostpath type (#5503) * Federated Hpa feature doc (#5487) * Federated Hpa feature doc * Federated Hpa feature doc review fixes * Update hpa.md * Update hpa.md * update cloud controller manager docs for v1.8 * Update cronjob with defaults information (#5556) * Kubernetes 1.8 reference docs (#5632) * Kubernetes 1.8 reference docs * Kubectl reference docs for 1.8 * Update side bar with 1.8 kubectl and api ref docs links * remove petset.md * update on state of HostAlias in 1.8 with hostNetwork Pod support (#5644) * Fix cron job deletion section (#5655) * update imported docs (#5656) * Add documentation for certificate rotation. (#5639) * Link to using kubeadm page * fix the command output fix the command output * fix typo in api/resources reference: "Worloads" * Add documentation for certificate rotation. * Create TOC entry for cloud controller manager. (#5662) * Updates for new versions of API types * Followup 5655: fix link to garbage collection (#5666) * Temporarily redirect resources-reference to api-reference. (#5668) * Update config for 1.8 release. (#5661) * Update config for 1.8 release. * Address reviewer comments. * Switch references in HPA docs from alpha to beta (#5671) The HPA docs still referenced the alpha version. This switches them to talk about v2beta1, which is the appropriate version for Kubernetes 1.8 * Deprecate openstack heat (#5670) * Fix typo in pod preset conflict example Move container port definition to the correct line. * Highlight openstack-heat provider deprecation The openstack-heat provider for kube-up is being deprecated and will be removed in a future release. * Temporarily fix broken links by redirecting. (#5672) * Fix broken links. (#5675) * Fix render of code block (#5674) * Fix broken links. (#5677) * Add a small note about auto-bootstrapped CSR ClusterRoles (#5660) * Update kubeadm install doc for v1.8 (#5676) * add draft workloads api content for 1.8 (#5650) * add draft workloads api content for 1.8 * edits per review, add tables, for 1.8 workloads api doc * fix typo * Minor fixes to kubeadm 1.8 upgrade guide. (#5678) - The kubelet upgrade instructions should be done on every host, not just worker nodes. - We should just upgrade all packages, instead of calling out kubelet specifically. This will also upgrade kubectl, kubeadm, and kubernetes-cni, if installed. - Draining nodes should also ignore daemonsets, and master errors can be ignored. - Make sure that the new kubeadm download is chmoded correctly. - Add a step to run `kubeadm version` to verify after downloading. - Manually approve new kubelet CSRs if rotation is enabled (known issue). * Release 1.8 (#5680) * Fix versions for 1.8 API ref docs * Updates for 1.8 kubectl reference docs * Kubeadm /docs/admin/kubeadm.md cleanup, editing. (#5681) * Update docs/admin/kubeadm.md (mostly 1.8 related). This is Fabrizio's work, which I'm committing along with my edits (in a commit on top of this). * A few of my own edits to clarify and clean up some Markdown.
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- apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
annotations:
rbac.authorization.kubernetes.io/autoupdate: "true"
labels:
kubernetes.io/bootstrapping: rbac-defaults
name: system:kube-scheduler
rules:
- apiGroups:
- ""
resourceNames:
- kube-scheduler
- my-scheduler
resources:
- endpoints
verbs:
- delete
- get
- patch
- update
```
## Specify schedulers for pods
Now that our second scheduler is running, let's create some pods, and direct them to be scheduled by either the default scheduler or the one we just deployed. In order to schedule a given pod using a specific scheduler, we specify the name of the
scheduler in that pod spec. Let's look at three examples.
- Pod spec without any scheduler name
{{< codenew file="admin/sched/pod1.yaml" >}}
When no scheduler name is supplied, the pod is automatically scheduled using the
default-scheduler.
Save this file as `pod1.yaml` and submit it to the Kubernetes cluster.
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```shell
kubectl create -f pod1.yaml
```
- Pod spec with `default-scheduler`
{{< codenew file="admin/sched/pod2.yaml" >}}
A scheduler is specified by supplying the scheduler name as a value to `spec.schedulerName`. In this case, we supply the name of the
default scheduler which is `default-scheduler`.
Save this file as `pod2.yaml` and submit it to the Kubernetes cluster.
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```shell
kubectl create -f pod2.yaml
```
- Pod spec with `my-scheduler`
{{< codenew file="admin/sched/pod3.yaml" >}}
In this case, we specify that this pod should be scheduled using the scheduler that we
deployed - `my-scheduler`. Note that the value of `spec.schedulerName` should match the name supplied to the scheduler
command as an argument in the deployment config for the scheduler.
Save this file as `pod3.yaml` and submit it to the Kubernetes cluster.
```shell
kubectl create -f pod3.yaml
```
Verify that all three pods are running.
```shell
kubectl get pods
```
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### Verifying that the pods were scheduled using the desired schedulers
In order to make it easier to work through these examples, we did not verify that the
pods were actually scheduled using the desired schedulers. We can verify that by
changing the order of pod and deployment config submissions above. If we submit all the
pod configs to a Kubernetes cluster before submitting the scheduler deployment config,
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we see that the pod `annotation-second-scheduler` remains in "Pending" state forever
while the other two pods get scheduled. Once we submit the scheduler deployment config
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and our new scheduler starts running, the `annotation-second-scheduler` pod gets
scheduled as well.
Alternatively, one could just look at the "Scheduled" entries in the event logs to
verify that the pods were scheduled by the desired schedulers.
```shell
kubectl get events
```
{{% /capture %}}