Managing Worker Nodes
Introduction#
When deploying your ROSA cluster, you can configure many aspects of your worker nodes, but what happens when you need to change your worker nodes after they've already been created? These activities include scaling the number of nodes, changing the instance type, adding labels or taints, just to name a few.
Many of these changes are done using MachinePools. MachinePools ensure that a specified number of Machine replicas are running at any given time. Think of a MachinePool as a "template" for the kinds of Machines that make up the worker nodes of your cluster. If you'd like to learn more, see the Red Hat documentation on worker node management.
Scaling worker nodes#
Via the CLI#
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First, let's see what MachinePools already exist in our cluster. To do so, run the following command:
Your output should look similar to:
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Now, let's take a look at the machines inside of the ROSA cluster that have been created according to the instructions provided by the above MachinePools. To do so, run the following command:
For this workshop, we've deployed your ROSA cluster with nine total machines (three workers, three control planes, and three infrastructure nodes), one in each availability zone. The output will look something like this:
NAME PHASE TYPE REGION ZONE AGE user1-mobbws-6sj5f-infra-us-east-1a-cb56h Running r5.xlarge us-east-1 us-east-1a 18h user1-mobbws-6sj5f-infra-us-east-1b-t6bdg Running r5.xlarge us-east-1 us-east-1b 18h user1-mobbws-6sj5f-infra-us-east-1c-9v4pq Running r5.xlarge us-east-1 us-east-1c 18h user1-mobbws-6sj5f-master-0 Running m5.2xlarge us-east-1 us-east-1a 18h user1-mobbws-6sj5f-master-1 Running m5.2xlarge us-east-1 us-east-1b 18h user1-mobbws-6sj5f-master-2 Running m5.2xlarge us-east-1 us-east-1c 18h user1-mobbws-6sj5f-worker-us-east-1a-jrxnz Running m5.xlarge us-east-1 us-east-1a 18h user1-mobbws-6sj5f-worker-us-east-1b-2j8lc Running m5.xlarge us-east-1 us-east-1b 18h user1-mobbws-6sj5f-worker-us-east-1c-w8jl6 Running m5.xlarge us-east-1 us-east-1c 18h -
Now that we know that we have three worker nodes, let's create a MachinePool to add a new worker node using the ROSA CLI. To do so, run the following command:
rosa create machinepool -c ${WS_USER/_/-} --availability-zone ${AWS_DEFAULT_REGION}a --replicas 1 --name workshop --instance-type m5.xlargeThe output of the command should look something like this:
I: Fetching instance types I: Machine pool 'workshop' created successfully on cluster 'user1-mobbws' I: To view all machine pools, run 'rosa list machinepools -c user1-mobbws'This command adds a single m5.xlarge instance to the us-east-1a availability zone.
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Now, let's scale up our selected MachinePool from one to two machines. To do so, run the following command:
Your output should look like this:
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Now that we've scaled the MachineSet to two machines, we can see that the machine is already being created. First, let's quickly check the output of the same command we ran in step 1:
The output should look something like this:
NAME DESIRED CURRENT READY AVAILABLE AGE user1-mobbws-6sj5f-infra-us-east-1a 1 1 1 1 18h user1-mobbws-6sj5f-infra-us-east-1b 1 1 1 1 18h user1-mobbws-6sj5f-infra-us-east-1c 1 1 1 1 18h user1-mobbws-6sj5f-worker-us-east-1a 1 1 1 1 19h user1-mobbws-6sj5f-worker-us-east-1b 1 1 1 1 19h user1-mobbws-6sj5f-worker-us-east-1c 1 1 1 1 19h user1-mobbws-6sj5f-workshop-us-east-1a 2 2 1 1 4m36sNote, that the number of desired and current nodes matches the scale we specified, but only one is ready and available.
We can also run the same command we ran in step 2 to see the machine being provisioned:
The output should look something like this:
NAME PHASE TYPE REGION ZONE AGE user1-mobbws-6sj5f-infra-us-east-1a-cb56h Running r5.xlarge us-east-1 us-east-1a 18h user1-mobbws-6sj5f-infra-us-east-1b-t6bdg Running r5.xlarge us-east-1 us-east-1b 18h user1-mobbws-6sj5f-infra-us-east-1c-9v4pq Running r5.xlarge us-east-1 us-east-1c 18h user1-mobbws-6sj5f-master-0 Running m5.2xlarge us-east-1 us-east-1a 19h user1-mobbws-6sj5f-master-1 Running m5.2xlarge us-east-1 us-east-1b 19h user1-mobbws-6sj5f-master-2 Running m5.2xlarge us-east-1 us-east-1c 19h user1-mobbws-6sj5f-worker-us-east-1a-jrxnz Running m5.xlarge us-east-1 us-east-1a 18h user1-mobbws-6sj5f-worker-us-east-1b-2j8lc Running m5.xlarge us-east-1 us-east-1b 18h user1-mobbws-6sj5f-worker-us-east-1c-w8jl6 Running m5.xlarge us-east-1 us-east-1c 18h user1-mobbws-6sj5f-workshop-us-east-1a-6gz7w Provisioned m5.xlarge us-east-1 us-east-1a 51s user1-mobbws-6sj5f-workshop-us-east-1a-xh584 Running m5.xlarge us-east-1 us-east-1a 3m43s -
Now let's scale the cluster back down to a total of 4 worker nodes by scaling down the "Workshop" Machine Pool. To do so, run the following command:
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Now that we've scaled the MachineSet back down to one machines, we can see the change reflected in the cluster almost immediately. Let's quickly check the output of the same command we ran in step 5:
The output should look something like this:
NAME DESIRED CURRENT READY AVAILABLE AGE user1-mobbws-6sj5f-infra-us-east-1a 1 1 1 1 18h user1-mobbws-6sj5f-infra-us-east-1b 1 1 1 1 18h user1-mobbws-6sj5f-infra-us-east-1c 1 1 1 1 18h user1-mobbws-6sj5f-worker-us-east-1a 1 1 1 1 19h user1-mobbws-6sj5f-worker-us-east-1b 1 1 1 1 19h user1-mobbws-6sj5f-worker-us-east-1c 1 1 1 1 19h user1-mobbws-6sj5f-workshop-us-east-1a 1 1 1 1 4m36s -
Now let's scale the cluster back down to a total of 3 worker nodes by deleting the "Workshop" Machine Pool. To do so, run the following command:
Congratulations! You've successfully scaled your cluster up and back down to three nodes.