3.5. Troubleshooting
You can view the Migration Toolkit for Containers (MTC) custom resources and download logs to troubleshoot a failed migration.
If the application was stopped during the failed migration, you must roll it back manually in order to prevent data corruption.
Manual rollback is not required if the application was not stopped during migration because the original application is still running on the source cluster.
3.5.1. Viewing migration Custom Resources
The Migration Toolkit for Containers (MTC) creates the following custom resources (CRs):
MigCluster (configuration, MTC cluster): Cluster definition
MigStorage (configuration, MTC cluster): Storage definition
MigPlan (configuration, MTC cluster): Migration plan
The MigPlan
CR describes the source and target clusters, replication repository, and namespaces being migrated. It is associated with 0, 1, or many MigMigration
CRs.
Deleting a MigPlan
CR deletes the associated MigMigration
CRs.
BackupStorageLocation (configuration, MTC cluster): Location of Velero
backup objects
VolumeSnapshotLocation (configuration, MTC cluster): Location of Velero
volume snapshots
MigMigration (action, MTC cluster): Migration, created every time you stage or migrate data. Each MigMigration
CR is associated with a MigPlan
CR.
Backup (action, source cluster): When you run a migration plan, the MigMigration
CR creates two Velero
backup CRs on each source cluster:
- Backup CR #1 for Kubernetes objects
- Backup CR #2 for PV data
Restore (action, target cluster): When you run a migration plan, the MigMigration
CR creates two Velero
restore CRs on the target cluster:
- Restore CR #1 (using Backup CR #2) for PV data
- Restore CR #2 (using Backup CR #1) for Kubernetes objects
Procedure
List the
MigMigration
CRs in theopenshift-migration
namespace:$ oc get migmigration -n openshift-migration
Example output
NAME AGE 88435fe0-c9f8-11e9-85e6-5d593ce65e10 6m42s
Inspect the
MigMigration
CR:$ oc describe migmigration 88435fe0-c9f8-11e9-85e6-5d593ce65e10 -n openshift-migration
The output is similar to the following examples.
MigMigration
example output
name: 88435fe0-c9f8-11e9-85e6-5d593ce65e10 namespace: openshift-migration labels: <none> annotations: touch: 3b48b543-b53e-4e44-9d34-33563f0f8147 apiVersion: migration.openshift.io/v1alpha1 kind: MigMigration metadata: creationTimestamp: 2019-08-29T01:01:29Z generation: 20 resourceVersion: 88179 selfLink: /apis/migration.openshift.io/v1alpha1/namespaces/openshift-migration/migmigrations/88435fe0-c9f8-11e9-85e6-5d593ce65e10 uid: 8886de4c-c9f8-11e9-95ad-0205fe66cbb6 spec: migPlanRef: name: socks-shop-mig-plan namespace: openshift-migration quiescePods: true stage: false status: conditions: category: Advisory durable: True lastTransitionTime: 2019-08-29T01:03:40Z message: The migration has completed successfully. reason: Completed status: True type: Succeeded phase: Completed startTimestamp: 2019-08-29T01:01:29Z events: <none>
Velero
backup CR #2 example output that describes the PV data
apiVersion: velero.io/v1 kind: Backup metadata: annotations: openshift.io/migrate-copy-phase: final openshift.io/migrate-quiesce-pods: "true" openshift.io/migration-registry: 172.30.105.179:5000 openshift.io/migration-registry-dir: /socks-shop-mig-plan-registry-44dd3bd5-c9f8-11e9-95ad-0205fe66cbb6 creationTimestamp: "2019-08-29T01:03:15Z" generateName: 88435fe0-c9f8-11e9-85e6-5d593ce65e10- generation: 1 labels: app.kubernetes.io/part-of: migration migmigration: 8886de4c-c9f8-11e9-95ad-0205fe66cbb6 migration-stage-backup: 8886de4c-c9f8-11e9-95ad-0205fe66cbb6 velero.io/storage-location: myrepo-vpzq9 name: 88435fe0-c9f8-11e9-85e6-5d593ce65e10-59gb7 namespace: openshift-migration resourceVersion: "87313" selfLink: /apis/velero.io/v1/namespaces/openshift-migration/backups/88435fe0-c9f8-11e9-85e6-5d593ce65e10-59gb7 uid: c80dbbc0-c9f8-11e9-95ad-0205fe66cbb6 spec: excludedNamespaces: [] excludedResources: [] hooks: resources: [] includeClusterResources: null includedNamespaces: - sock-shop includedResources: - persistentvolumes - persistentvolumeclaims - namespaces - imagestreams - imagestreamtags - secrets - configmaps - pods labelSelector: matchLabels: migration-included-stage-backup: 8886de4c-c9f8-11e9-95ad-0205fe66cbb6 storageLocation: myrepo-vpzq9 ttl: 720h0m0s volumeSnapshotLocations: - myrepo-wv6fx status: completionTimestamp: "2019-08-29T01:02:36Z" errors: 0 expiration: "2019-09-28T01:02:35Z" phase: Completed startTimestamp: "2019-08-29T01:02:35Z" validationErrors: null version: 1 volumeSnapshotsAttempted: 0 volumeSnapshotsCompleted: 0 warnings: 0
Velero
restore CR #2 example output that describes the Kubernetes resources
apiVersion: velero.io/v1 kind: Restore metadata: annotations: openshift.io/migrate-copy-phase: final openshift.io/migrate-quiesce-pods: "true" openshift.io/migration-registry: 172.30.90.187:5000 openshift.io/migration-registry-dir: /socks-shop-mig-plan-registry-36f54ca7-c925-11e9-825a-06fa9fb68c88 creationTimestamp: "2019-08-28T00:09:49Z" generateName: e13a1b60-c927-11e9-9555-d129df7f3b96- generation: 3 labels: app.kubernetes.io/part-of: migration migmigration: e18252c9-c927-11e9-825a-06fa9fb68c88 migration-final-restore: e18252c9-c927-11e9-825a-06fa9fb68c88 name: e13a1b60-c927-11e9-9555-d129df7f3b96-gb8nx namespace: openshift-migration resourceVersion: "82329" selfLink: /apis/velero.io/v1/namespaces/openshift-migration/restores/e13a1b60-c927-11e9-9555-d129df7f3b96-gb8nx uid: 26983ec0-c928-11e9-825a-06fa9fb68c88 spec: backupName: e13a1b60-c927-11e9-9555-d129df7f3b96-sz24f excludedNamespaces: null excludedResources: - nodes - events - events.events.k8s.io - backups.velero.io - restores.velero.io - resticrepositories.velero.io includedNamespaces: null includedResources: null namespaceMapping: null restorePVs: true status: errors: 0 failureReason: "" phase: Completed validationErrors: null warnings: 15
3.5.2. Using the migration log reader
You can use the migration log reader to display a single filtered view of all the migration logs.
Procedure
Get the
mig-log-reader
pod:$ oc -n openshift-migration get pods | grep log
Enter the following command to display a single migration log:
$ oc -n openshift-migration logs -f <mig-log-reader-pod> -c color 1
- 1
- The
-c plain
option displays the log without colors.
3.5.3. Downloading migration logs
You can download the Velero
, Restic
, and MigrationController
pod logs in the Migration Toolkit for Containers (MTC) web console to troubleshoot a failed migration.
Procedure
- In the MTC console, click Migration plans to view the list of migration plans.
- Click the Options menu of a specific migration plan and select Logs.
Click Download Logs to download the logs of the
MigrationController
,Velero
, andRestic
pods for all clusters.You can download a single log by selecting the cluster, log source, and pod source, and then clicking Download Selected.
You can access a pod log from the CLI by using the
oc logs
command:$ oc logs <pod-name> -f -n openshift-migration 1
- 1
- Specify the pod name.
3.5.4. Updating deprecated APIs
If your source cluster uses deprecated APIs, the following warning message is displayed when you create a migration plan in the Migration Toolkit for Containers (MTC) web console:
Some namespaces contain GVKs incompatible with destination cluster
You can click See details to view the namespace and the incompatible APIs. This warning message does not block the migration.
During migration with the Migration Toolkit for Containers (MTC), the deprecated APIs are saved in the Velero
Backup #1 for Kubernetes objects. You can download the Velero
Backup, extract the deprecated API yaml
files, and update them with the oc convert
command. Then you can create the updated APIs on the target cluster.
Procedure
- Run the migration plan.
View the
MigPlan
custom resource (CR):$ oc describe migplan <migplan_name> -n openshift-migration 1
- 1
- Specify the name of the
MigPlan
CR.
The output is similar to the following:
metadata: ... uid: 79509e05-61d6-11e9-bc55-02ce4781844a 1 status: ... conditions: - category: Warn lastTransitionTime: 2020-04-30T17:16:23Z message: 'Some namespaces contain GVKs incompatible with destination cluster. See: `incompatibleNamespaces` for details' status: "True" type: GVKsIncompatible incompatibleNamespaces: - gvks: 2 - group: batch kind: cronjobs version: v2alpha1 - group: batch kind: scheduledjobs version: v2alpha1
Get the
MigMigration
name associated with theMigPlan
UID:$ oc get migmigration -o json | jq -r '.items[] | select(.metadata.ownerReferences[].uid=="<migplan_uid>") | .metadata.name' 1
- 1
- Specify the
MigPlan
CR UID.
Get the
MigMigration
UID associated with theMigMigration
name:$ oc get migmigration <migmigration_name> -o jsonpath='{.metadata.uid}' 1
- 1
- Specify the
MigMigration
name.
Get the
Velero
Backup name associated with theMigMigration
UID:$ oc get backup.velero.io --selector migration-initial-backup="<migmigration_uid>" -o jsonpath={.items[*].metadata.name} 1
- 1
- Specify the
MigMigration
UID.
Download the contents of the
Velero
Backup to your local machine by running the command for your storage provider:AWS S3:
$ aws s3 cp s3://<bucket_name>/velero/backups/<backup_name> <backup_local_dir> --recursive 1
- 1
- Specify the bucket, backup name, and your local backup directory name.
GCP:
$ gsutil cp gs://<bucket_name>/velero/backups/<backup_name> <backup_local_dir> --recursive 1
- 1
- Specify the bucket, backup name, and your local backup directory name.
Azure:
$ azcopy copy 'https://velerobackups.blob.core.windows.net/velero/backups/<backup_name>' '<backup_local_dir>' --recursive 1
- 1
- Specify the backup name and your local backup directory name.
Extract the
Velero
Backup archive file:$ tar -xfv <backup_local_dir>/<backup_name>.tar.gz -C <backup_local_dir>
Run
oc convert
in offline mode on each deprecated API:$ oc convert -f <backup_local_dir>/resources/<gvk>.json
Create the converted API on the target cluster:
$ oc create -f <gvk>.json
3.5.5. Error messages and resolutions
This section describes common error messages you might encounter with the Migration Toolkit for Containers (MTC) and how to resolve their underlying causes.
3.5.5.1. Restic timeout error
If a CA certificate error
message is displayed the first time you try to access the MTC console, the likely cause is the use of self-signed CA certificates in one of the clusters.
To resolve this issue, navigate to the oauth-authorization-server
URL displayed in the error message and accept the certificate. To resolve this issue permanently, add the certificate to the trust store of your web browser.
If an Unauthorized
message is displayed after you have accepted the certificate, navigate to the MTC console and refresh the web page.
3.5.5.2. OAuth timeout error in the MTC console
If a connection has timed out
message is displayed in the MTC console after you have accepted a self-signed certificate, the causes are likely to be the following:
- Interrupted network access to the OAuth server
- Interrupted network access to the OpenShift Container Platform console
-
Proxy configuration that blocks access to the
oauth-authorization-server
URL. See MTC console inaccessible because of OAuth timeout error for details.
You can determine the cause of the timeout.
Procedure
- Navigate to the MTC console and inspect the elements with the browser web inspector.
Check the
MigrationUI
pod log:$ oc logs <MigrationUI_Pod> -n openshift-migration
3.5.5.3. PodVolumeBackups timeout error in Velero pod log
If a migration fails because Restic times out, the following error is displayed in the Velero
pod log.
Example output
level=error msg="Error backing up item" backup=velero/monitoring error="timed out waiting for all PodVolumeBackups to complete" error.file="/go/src/github.com/heptio/velero/pkg/restic/backupper.go:165" error.function="github.com/heptio/velero/pkg/restic.(*backupper).BackupPodVolumes" group=v1
The default value of restic_timeout
is one hour. You can increase this parameter for large migrations, keeping in mind that a higher value may delay the return of error messages.
Procedure
-
In the OpenShift Container Platform web console, navigate to Operators
Installed Operators. - Click Migration Toolkit for Containers Operator.
- In the MigrationController tab, click migration-controller.
In the YAML tab, update the following parameter value:
spec: restic_timeout: 1h 1
- 1
- Valid units are
h
(hours),m
(minutes), ands
(seconds), for example,3h30m15s
.
- Click Save.
3.5.5.4. ResticVerifyErrors in the MigMigration custom resource
If data verification fails when migrating a persistent volume with the file system data copy method, the following error is displayed in the MigMigration
CR.
Example output
status: conditions: - category: Warn durable: true lastTransitionTime: 2020-04-16T20:35:16Z message: There were verify errors found in 1 Restic volume restores. See restore `<registry-example-migration-rvwcm>` for details 1 status: "True" type: ResticVerifyErrors 2
A data verification error does not cause the migration process to fail.
You can check the Restore
CR to identify the source of the data verification error.
Procedure
- Log in to the target cluster.
View the
Restore
CR:$ oc describe <registry-example-migration-rvwcm> -n openshift-migration
The output identifies the persistent volume with
PodVolumeRestore
errors.Example output
status: phase: Completed podVolumeRestoreErrors: - kind: PodVolumeRestore name: <registry-example-migration-rvwcm-98t49> namespace: openshift-migration podVolumeRestoreResticErrors: - kind: PodVolumeRestore name: <registry-example-migration-rvwcm-98t49> namespace: openshift-migration
View the
PodVolumeRestore
CR:$ oc describe <migration-example-rvwcm-98t49>
The output identifies the
Restic
pod that logged the errors.Example output
completionTimestamp: 2020-05-01T20:49:12Z errors: 1 resticErrors: 1 ... resticPod: <restic-nr2v5>
View the
Restic
pod log to locate the errors:$ oc logs -f <restic-nr2v5>
3.5.6. Direct volume migration does not complete
If direct volume migration does not complete, the target cluster might not have the same node-selector
annotations as the source cluster.
Migration Toolkit for Containers (MTC) migrates namespaces with all annotations in order to preserve security context constraints and scheduling requirements. During direct volume migration, MTC creates Rsync transfer pods on the target cluster in the namespaces that were migrated from the source cluster. If a target cluster namespace does not have the same annotations as the source cluster namespace, the Rsync transfer pods cannot be scheduled. The Rsync pods remain in a Pending
state.
You can identify and fix this issue by performing the following procedure.
Procedure
Check the status of the
MigMigration
CR:$ oc describe migmigration <pod_name> -n openshift-migration
The output includes the following status message:
Example output
... Some or all transfer pods are not running for more than 10 mins on destination cluster ...
On the source cluster, obtain the details of a migrated namespace:
$ oc get namespace <namespace> -o yaml 1
- 1
- Specify the migrated namespace.
On the target cluster, edit the migrated namespace:
$ oc edit namespace <namespace>
Add missing
openshift.io/node-selector
annotations to the migrated namespace as in the following example:apiVersion: v1 kind: Namespace metadata: annotations: openshift.io/node-selector: "region=east" ...
- Run the migration plan again.
3.5.7. Using the Velero CLI to debug Backup and Restore CRs
You can debug the Backup
and Restore
custom resources (CRs) and partial migration failures with the Velero command line interface (CLI). The Velero CLI runs in the velero
pod.
3.5.7.1. Velero command syntax
Velero CLI commands use the following syntax:
$ oc exec $(oc get pods -n openshift-migration -o name | grep velero) -- ./velero <resource> <command> <resource_id>
You can specify velero-<pod> -n openshift-migration
in place of $(oc get pods -n openshift-migration -o name | grep velero)
.
3.5.7.2. Help command
The Velero help
command lists all the Velero CLI commands:
$ oc exec $(oc get pods -n openshift-migration -o name | grep velero) -- ./velero --help
3.5.7.3. Describe command
The Velero describe
command provides a summary of warnings and errors associated with a Velero resource:
$ oc exec $(oc get pods -n openshift-migration -o name | grep velero) -- ./velero <resource> describe <resource_id>
Example
$ oc exec $(oc get pods -n openshift-migration -o name | grep velero) -- ./velero backup describe 0e44ae00-5dc3-11eb-9ca8-df7e5254778b-2d8ql
3.5.7.4. Logs command
The Velero logs
command provides the logs associated with a Velero resource:
velero <resource> logs <resource_id>
Example
$ oc exec $(oc get pods -n openshift-migration -o name | grep velero) -- ./velero restore logs ccc7c2d0-6017-11eb-afab-85d0007f5a19-x4lbf
3.5.7.5. Debugging a partial migration failure
You can debug a partial migration failure warning message by using the Velero CLI to examine the Restore
custom resource (CR) logs.
A partial failure occurs when Velero encounters an issue that does not cause a migration to fail. For example, if a custom resource definition (CRD) is missing or if there is a discrepancy between CRD versions on the source and target clusters, the migration completes but the CR is not created on the target cluster.
Velero logs the issue as a partial failure and then processes the rest of the objects in the Backup
CR.
Procedure
Check the status of a
MigMigration
CR:$ oc get migmigration <migmigration> -o yaml
status: conditions: - category: Warn durable: true lastTransitionTime: "2021-01-26T20:48:40Z" message: 'Final Restore openshift-migration/ccc7c2d0-6017-11eb-afab-85d0007f5a19-x4lbf: partially failed on destination cluster' status: "True" type: VeleroFinalRestorePartiallyFailed - category: Advisory durable: true lastTransitionTime: "2021-01-26T20:48:42Z" message: The migration has completed with warnings, please look at `Warn` conditions. reason: Completed status: "True" type: SucceededWithWarnings
Check the status of the
Restore
CR by using the Velerodescribe
command:$ oc exec $(oc get pods -n openshift-migration -o name | grep velero) -n openshift-migration -- ./velero restore describe <restore>
Phase: PartiallyFailed (run 'velero restore logs ccc7c2d0-6017-11eb-afab-85d0007f5a19-x4lbf' for more information) Errors: Velero: <none> Cluster: <none> Namespaces: migration-example: error restoring example.com/migration-example/migration-example: the server could not find the requested resource
Check the
Restore
CR logs by using the Velerologs
command:$ oc exec $(oc get pods -n openshift-migration -o name | grep velero) -n openshift-migration -- ./velero restore logs <restore>
time="2021-01-26T20:48:37Z" level=info msg="Attempting to restore migration-example: migration-example" logSource="pkg/restore/restore.go:1107" restore=openshift-migration/ccc7c2d0-6017-11eb-afab-85d0007f5a19-x4lbf time="2021-01-26T20:48:37Z" level=info msg="error restoring migration-example: the server could not find the requested resource" logSource="pkg/restore/restore.go:1170" restore=openshift-migration/ccc7c2d0-6017-11eb-afab-85d0007f5a19-x4lbf
The
Restore
CR log error message,the server could not find the requested resource
, indicates the cause of the partially failed migration.
3.5.8. Using must-gather to collect data
You must run the must-gather
tool if you open a customer support case on the Red Hat Customer Portal for the Migration Toolkit for Containers (MTC).
The openshift-migration-must-gather-rhel8
image for MTC collects migration-specific logs and data that are not collected by the default must-gather
image.
Procedure
-
Navigate to the directory where you want to store the
must-gather
data. Run the
must-gather
command:$ oc adm must-gather --image=registry.redhat.io/rhmtc/openshift-migration-must-gather-rhel8:v1.4
- Remove authentication keys and other sensitive information.
Create an archive file containing the contents of the
must-gather
data directory:$ tar cvaf must-gather.tar.gz must-gather.local.<uid>/
- Upload the compressed file as an attachment to your customer support case.
3.5.9. Rolling back a migration
You can roll back a migration by using the MTC web console or the CLI.
3.5.9.1. Rolling back a migration in the MTC web console
You can roll back a migration by using the Migration Toolkit for Containers (MTC) web console.
If your application was stopped during a failed migration, you must roll back the migration in order to prevent data corruption in the persistent volume.
Rollback is not required if the application was not stopped during migration because the original application is still running on the source cluster.
Procedure
- In the MTC web console, click Migration plans.
- Click the Options menu beside a migration plan and select Rollback.
Click Rollback and wait for rollback to complete.
In the migration plan details, Rollback succeeded is displayed.
Verify that rollback was successful in the OpenShift Container Platform web console of the source cluster:
-
Click Home
Projects. - Click the migrated project to view its status.
- In the Routes section, click Location to verify that the application is functioning, if applicable.
-
Click Workloads
Pods to verify that the pods are running in the migrated namespace. -
Click Storage
Persistent volumes to verify that the migrated persistent volume is correctly provisioned.
-
Click Home
3.5.9.1.1. Rolling back a migration from the CLI
You can roll back a migration by creating a MigMigration
custom resource (CR) from the CLI.
If your application was stopped during a failed migration, you must roll back the migration in order to prevent data corruption in the persistent volume.
Rollback is not required if the application was not stopped during migration because the original application is still running on the source cluster.
Procedure
Create a
MigMigration
CR based on the following example:$ cat << EOF | oc apply -f - apiVersion: migration.openshift.io/v1alpha1 kind: MigMigration metadata: labels: controller-tools.k8s.io: "1.0" name: migration-rollback namespace: openshift-migration spec: ... rollback: true ... migPlanRef: name: <migplan_name> 1 namespace: openshift-migration EOF
- 1
- Specify the name of the associated
MigPlan
CR.
- In the MTC web console, verify that the migrated project resources have been removed from the target cluster.
- Verify that the migrated project resources are present in the source cluster and that the application is running.
3.5.10. Known issues
This release has the following known issues:
During migration, the Migration Toolkit for Containers (MTC) preserves the following namespace annotations:
-
openshift.io/sa.scc.mcs
-
openshift.io/sa.scc.supplemental-groups
openshift.io/sa.scc.uid-range
These annotations preserve the UID range, ensuring that the containers retain their file system permissions on the target cluster. There is a risk that the migrated UIDs could duplicate UIDs within an existing or future namespace on the target cluster. (BZ#1748440)
-
- Most cluster-scoped resources are not yet handled by MTC. If your applications require cluster-scoped resources, you might have to create them manually on the target cluster.
- If a migration fails, the migration plan does not retain custom PV settings for quiesced pods. You must manually roll back the migration, delete the migration plan, and create a new migration plan with your PV settings. (BZ#1784899)
-
If a large migration fails because Restic times out, you can increase the
restic_timeout
parameter value (default:1h
) in theMigrationController
custom resource (CR) manifest. - If you select the data verification option for PVs that are migrated with the file system copy method, performance is significantly slower.
If you are migrating data from NFS storage and
root_squash
is enabled,Restic
maps tonfsnobody
. The migration fails and a permission error is displayed in theRestic
pod log. (BZ#1873641)You can resolve this issue by adding supplemental groups for
Restic
to theMigrationController
CR manifest:spec: ... restic_supplemental_groups: - 5555 - 6666
- If you perform direct volume migration with nodes that are in different availability zones, the migration might fail because the migrated pods cannot access the PVC. (BZ#1947487)