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Compute Cluster Updates

From time to time, the cluster may require updates. Simlarly, the base images leveraged in Exostellar’s stack may need those same updates.

If the Updates are Minimal

For certain CVEs where a single sed command is all that’s required, the user_data.shscripts may suffice. Similarly, instaneous or relatively trivial changes to the image are good candidates for update via user_data.sh. If the additional commands amount to more than a few seconds of per-boot work, it is recommended to use an updated version of the AMI as described below.

If the Updates are More Substantial

At times, required software in the cluster may be introduced that requires significant changes due to new dependencies. When it comes to updates that require more than 10 seconds to realize, it is recommended to leverage an updated version of the AMI and stop using the outdated image asset going forward. The steps below outline the process that will be required.

Fast Option:Replace the Contents of the Updated AMI by Leveraging the Snapshot-ID

1. With the AMI-ID, we can query AWS for the Snapshot-ID or we can find it in the AWS Console:

   1. AWS cli query for CentOS7 and Rocky9 AMIs:

      1. Code Block
         aws ec2 describe-images --image-ids <AMI_ID> --query 'Images[0].BlockDeviceMappings[?DeviceName==`/dev/sda1`].Ebs.SnapshotId' --output text

   2. AWS Console : Navigate to updated EC2 > AMIs > <AMI_ID> and look for the Block Devices entry on the page, which contains the snapshot-id embedded in string: “/dev/sda1=snap-007d78a7a00b2dc84:30:true:gp2”.

2. To swap out the previous Snapshot-ID with the new, first pull down the image information as a JSON object:

   1. Code Block
      curl -v -X GET http://${MGMT_SERVER_IP}x:5000/v1/image/<image_name> |jq . > in.json

3. Update the in.json file with the new Snpashot-ID.

4. Send the in.json file back to the Management Server:

   1. Code Block
      curl -v -d "@in.json" -H 'Content-Type: application/json' -X PUT http://${MGMT_SERVER_IP}:5000/v1/image

5. While jobs running will continue to use the previous image, jobs submitted after this point will pick up

Longer Option: Add a the New Image as a Subsequent Iteration and Reconfigure

To leave the previous image intact and unchanged, repeat the process for parsing an AMI and then update the environment.

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