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KubeVirt must-gather

must-gather is a tool built on top of OpenShift must-gather that expands its capabilities to gather KubeVirt information.

Usage

oc adm must-gather --image=quay.io/kubevirt/must-gather

The command above will create a local directory with a dump of the KubeVirt state. Note that this command will only get data related to the KubeVirt part of the OpenShift cluster.

You will get a dump of:

  • The Hyperconverged Cluster Operator namespaces (and its children objects)
  • All namespaces (and their children objects) that belong to any KubeVirt resources
  • All KubeVirt CRD's definitions

By default, the VMs definitions won't be included, but only the VM Instances' custom resources.

In order to get data about other parts of the cluster (not specific to KubeVirt) you should run oc adm must-gather (without passing a custom image). Run oc adm must-gather -h to see more options.

Flags

must-gather provides a series of options to select which information to collect from the cluster. The tool will always collect all control-plane logs and information. Optional collectors can be enabled with CLI options.

To run only the default collectors:

oc adm must-gather --image=quay.io/kubevirt/must-gather -- /usr/bin/gather

To collect all default information and VMs details:

oc adm must-gather --image=quay.io/kubevirt/must-gather -- /usr/bin/gather --vms_details

Help Menu

At any time you can check the help menu for usage details of the KubeVirt must-gather

oc adm must-gather --image=quay.io/kubevirt/must-gather -- /usr/bin/gather --help
Usage: oc adm must-gather --image=quay.io/kubevirt/must-gather -- /usr/bin/gather [params...]

  A client tool for gathering KubeVirt information in an OpenShift cluster

  Available options:

  > To see this help menu and exit use
  --help

  > The tool will always collect all control-plane logs and information.
  > This will include:
  > - apiservices
  > - cdi
  > - crds
  > - crs
  > - hco
  > - nodes
  > - ns
  > - resources
  > - ssp
  > - virtualmachines
  > - webhooks

  > You can also choose to enable optional collectors combining one
  > or more of the following parameters:
  --images
  --vms_details

Parallelism

Some gathering activity can be done in parallel. Collecting resources one by one may be slow, and collecting too many resources in parallel may fail. By default, 5 processes are running in parallel, and the rest of the processes are waiting for running processes to complete. It is possible to change this default number of processes by setting the PROS environment variable, but then, the default command must be specified as well, like this:

oc adm must-gather \
   --image=quay.io/kubevirt/must-gather \
   -- PROS=7 \
   /usr/bin/gather

Targeted gathering - VM information

To collect the default control plane information and VM detailed information you can append --vms_details command line flag:

oc adm must-gather \
   --image=quay.io/kubevirt/must-gather \
   -- /usr/bin/gather --vms_details

VMs in a Namespace

The --vms_details flag supports targeted gathering. By specifying a namespace, the command will only collect detailed VM logs for the VMs in this namespace (control plane logs are always collected). For example, collecting all the VM information in namespace "vm1":

oc adm must-gather \
   --image=quay.io/kubevirt/must-gather \
   -- NS=ns1 \
   /usr/bin/gather --vms_details

Specific VM

By specifying the VM name in addition to the namespace, the --vms_details flag will only collect the specific VM information (control plane logs are always collected). For example, collecting the information of a specific VM called "testvm" in namespace "vm1":

oc adm must-gather \
   --image=quay.io/kubevirt/must-gather \
   -- NS=ns1 \
   VM=testvm \
   /usr/bin/gather --vms_details

Note: When collecting information for a specific VM, you must specify the namespace as well. Without the namespace, the gather --vms_details command exits and prints an error message.

List of Specific VMs

The VM environment variable can also be a comma-seperated list of VM names (without a space). For example:

oc adm must-gather \
   --image=quay.io/kubevirt/must-gather \
   -- NS=ns1 \
   VM="testvm1,testvm34,testvm52,testvm74" \
   /usr/bin/gather --vms_details

Gather VM by Regex Expression

The --vms_details flag also support gathering VM with regex expression.

For example, suppose we have the following VMs in the cluster:

testvm1-1 testvm1-2 testvm1-3 testvm1-4 testvm1-5  
testvm1-6 testvm1-7 testvm1-8 testvm1-9 testvm1-10
testvm2-1 testvm2-2 testvm2-3 testvm2-4 testvm2-5 
testvm2-6 testvm2-7 testvm2-8 testvm2-9 testvm2-10
testvm3-1 testvm3-2 testvm3-3 testvm3-4 testvm3-5
testvm3-6 testvm3-7 testvm3-8 testvm3-9 testvm3-10
testvm4-1 testvm4-2 testvm4-3 testvm4-4 testvm4-5
testvm4-6 testvm4-7 testvm4-8 testvm4-9 testvm4-10
testvm5-1 testvm5-2 testvm5-3 testvm5-4 testvm5-5 
testvm5-6 testvm5-7 testvm5-8 testvm5-9 testvm5-10

If we want to read only VMs that starts with testvm2, testvm3 or testvm4, and that their postfix number is odd, we can use this regex expression to for that: ^testvm[2-4]-[0-9]*[1,3,5,7,9]$.

Here is how to use it in the --vms_details flag, to search VMs by regex:

oc adm must-gather \
   --image=quay.io/kubevirt/must-gather \
   VM_EXP="^testvm[2-4]-[0-9]*[1,3,5,7,9]$" \
   /usr/bin/gather --vms_details

Here is how to use it in the --vms_details flag, to search VMs by regex in the ns1 namespace:

oc adm must-gather \
   --image=quay.io/kubevirt/must-gather \
   -- NS=ns1 \
   VM_EXP="^testvm[2-4]-[0-9]*[1,3,5,7,9]$" \
   /usr/bin/gather --vms_details

Note: When collecting information using the VM variable, the command will ignore the VM_EPR variable. Do not use both of them together.

Targeted gathering - Images information

It is possible to collect image, image-stream and image-stream-tags information using the --images flag:

oc adm must-gather --image=quay.io/kubevirt/must-gather -- /usr/bin/gather --images

The --vms_details and the --images flags support parallelism as well. To change the default number of processes of 5, add the PROS environment variable. This is only works when not using the NS environment variable:

oc adm must-gather --image=quay.io/kubevirt/must-gather -- PROS=7 /usr/bin/gather --vms_details

Or

oc adm must-gather --image=quay.io/kubevirt/must-gather -- PROS=3 /usr/bin/gather --images

Development

You can build the image locally using the Dockerfile included.

A makefile is also provided. To use it, you must pass a repository via the command-line using the variable MUST_GATHER_IMAGE. You can also specify the registry using the variable IMAGE_REGISTRY (default is quay.io) and the tag via IMAGE_TAG (default is latest).

The targets for make are as follows:

  • build: builds the image with the supplied name and pushes it
  • docker-build: builds the image but does not push it
  • docker-push: pushes an already-built image

For example:

make build MUST_GATHER_IMAGE=kubevirt/must-gather

would build the local repository as quay.io/kubevirt/must-gather:latest and then push it.