Chapter 10. Troubleshooting
This section describes resources for troubleshooting the Migration Toolkit for Containers (MTC).
For known issues, see the MTC release notes.
10.1. MTC workflow
You can migrate Kubernetes resources, persistent volume data, and internal container images to OpenShift Container Platform 4.6 by using the Migration Toolkit for Containers (MTC) web console or the Kubernetes API.
MTC migrates the following resources:
- A namespace specified in a migration plan.
Namespace-scoped resources: When the MTC migrates a namespace, it migrates all the objects and resources associated with that namespace, such as services or pods. Additionally, if a resource that exists in the namespace but not at the cluster level depends on a resource that exists at the cluster level, the MTC migrates both resources.
For example, a security context constraint (SCC) is a resource that exists at the cluster level and a service account (SA) is a resource that exists at the namespace level. If an SA exists in a namespace that the MTC migrates, the MTC automatically locates any SCCs that are linked to the SA and also migrates those SCCs. Similarly, the MTC migrates persistent volume claims that are linked to the persistent volumes of the namespace.
NoteCluster-scoped resources might have to be migrated manually, depending on the resource.
- Custom resources (CRs) and custom resource definitions (CRDs): MTC automatically migrates CRs and CRDs at the namespace level.
Migrating an application with the MTC web console involves the following steps:
Install the Migration Toolkit for Containers Operator on all clusters.
You can install the Migration Toolkit for Containers Operator in a restricted environment with limited or no internet access. The source and target clusters must have network access to each other and to a mirror registry.
Configure the replication repository, an intermediate object storage that MTC uses to migrate data.
The source and target clusters must have network access to the replication repository during migration. If you are using a proxy server, you must configure it to allow network traffic between the replication repository and the clusters.
- Add the source cluster to the MTC web console.
- Add the replication repository to the MTC web console.
Create a migration plan, with one of the following data migration options:
Copy: MTC copies the data from the source cluster to the replication repository, and from the replication repository to the target cluster.
NoteIf you are using direct image migration or direct volume migration, the images or volumes are copied directly from the source cluster to the target cluster.
Move: MTC unmounts a remote volume, for example, NFS, from the source cluster, creates a PV resource on the target cluster pointing to the remote volume, and then mounts the remote volume on the target cluster. Applications running on the target cluster use the same remote volume that the source cluster was using. The remote volume must be accessible to the source and target clusters.
NoteAlthough the replication repository does not appear in this diagram, it is required for migration.
Run the migration plan, with one of the following options:
Stage copies data to the target cluster without stopping the application.
A stage migration can be run multiple times so that most of the data is copied to the target before migration. Running one or more stage migrations reduces the duration of the cutover migration.
Cutover stops the application on the source cluster and moves the resources to the target cluster.
Optional: You can clear the Halt transactions on the source cluster during migration checkbox.
About MTC 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
10.2. MTC custom resource manifests
Migration Toolkit for Containers (MTC) uses the following custom resource (CR) manifests for migrating applications.
10.2.1. DirectImageMigration
The DirectImageMigration
CR copies images directly from the source cluster to the destination cluster.
apiVersion: migration.openshift.io/v1alpha1 kind: DirectImageMigration metadata: labels: controller-tools.k8s.io: "1.0" name: <direct_image_migration> spec: srcMigClusterRef: name: <source_cluster> namespace: openshift-migration destMigClusterRef: name: <destination_cluster> namespace: openshift-migration namespaces: 1 - <source_namespace_1> - <source_namespace_2>:<destination_namespace_3> 2
10.2.2. DirectImageStreamMigration
The DirectImageStreamMigration
CR copies image stream references directly from the source cluster to the destination cluster.
apiVersion: migration.openshift.io/v1alpha1 kind: DirectImageStreamMigration metadata: labels: controller-tools.k8s.io: "1.0" name: <direct_image_stream_migration> spec: srcMigClusterRef: name: <source_cluster> namespace: openshift-migration destMigClusterRef: name: <destination_cluster> namespace: openshift-migration imageStreamRef: name: <image_stream> namespace: <source_image_stream_namespace> destNamespace: <destination_image_stream_namespace>
10.2.3. DirectVolumeMigration
The DirectVolumeMigration
CR copies persistent volumes (PVs) directly from the source cluster to the destination cluster.
apiVersion: migration.openshift.io/v1alpha1 kind: DirectVolumeMigration metadata: name: <direct_volume_migration> namespace: openshift-migration spec: createDestinationNamespaces: false 1 deleteProgressReportingCRs: false 2 destMigClusterRef: name: <host_cluster> 3 namespace: openshift-migration persistentVolumeClaims: - name: <pvc> 4 namespace: <pvc_namespace> srcMigClusterRef: name: <source_cluster> namespace: openshift-migration
- 1
- Set to
true
to create namespaces for the PVs on the destination cluster. - 2
- Set to
true
to deleteDirectVolumeMigrationProgress
CRs after migration. The default isfalse
so thatDirectVolumeMigrationProgress
CRs are retained for troubleshooting. - 3
- Update the cluster name if the destination cluster is not the host cluster.
- 4
- Specify one or more PVCs to be migrated.
10.2.4. DirectVolumeMigrationProgress
The DirectVolumeMigrationProgress
CR shows the progress of the DirectVolumeMigration
CR.
apiVersion: migration.openshift.io/v1alpha1 kind: DirectVolumeMigrationProgress metadata: labels: controller-tools.k8s.io: "1.0" name: <direct_volume_migration_progress> spec: clusterRef: name: <source_cluster> namespace: openshift-migration podRef: name: <rsync_pod> namespace: openshift-migration
10.2.5. MigAnalytic
The MigAnalytic
CR collects the number of images, Kubernetes resources, and the persistent volume (PV) capacity from an associated MigPlan
CR.
You can configure the data that it collects.
apiVersion: migration.openshift.io/v1alpha1 kind: MigAnalytic metadata: annotations: migplan: <migplan> name: <miganalytic> namespace: openshift-migration labels: migplan: <migplan> spec: analyzeImageCount: true <.> analyzeK8SResources: true <.> analyzePVCapacity: true <.> listImages: false <.> listImagesLimit: 50 <.> migPlanRef: name: <migplan> namespace: openshift-migration
<.> Optional: Returns the number of images. <.> Optional: Returns the number, kind, and API version of the Kubernetes resources. <.> Optional: Returns the PV capacity. <.> Returns a list of image names. The default is false
so that the output is not excessively long. <.> Optional: Specify the maximum number of image names to return if listImages
is true
.
10.2.6. MigCluster
The MigCluster
CR defines a host, local, or remote cluster.
apiVersion: migration.openshift.io/v1alpha1 kind: MigCluster metadata: labels: controller-tools.k8s.io: "1.0" name: <host_cluster> 1 namespace: openshift-migration spec: isHostCluster: true 2 # The 'azureResourceGroup' parameter is relevant only for Microsoft Azure. azureResourceGroup: <azure_resource_group> 3 caBundle: <ca_bundle_base64> 4 insecure: false 5 refresh: false 6 # The 'restartRestic' parameter is relevant for a source cluster. restartRestic: true 7 # The following parameters are relevant for a remote cluster. exposedRegistryPath: <registry_route> 8 url: <destination_cluster_url> 9 serviceAccountSecretRef: name: <source_secret> 10 namespace: openshift-config
- 1
- Update the cluster name if the
migration-controller
pod is not running on this cluster. - 2
- The
migration-controller
pod runs on this cluster iftrue
. - 3
- Microsoft Azure only: Specify the resource group.
- 4
- Optional: If you created a certificate bundle for self-signed CA certificates and if the
insecure
parameter value isfalse
, specify the base64-encoded certificate bundle. - 5
- Set to
true
to disable SSL verification. - 6
- Set to
true
to validate the cluster. - 7
- Set to
true
to restart theRestic
pods on the source cluster after theStage
pods are created. - 8
- Remote cluster and direct image migration only: Specify the exposed secure registry path.
- 9
- Remote cluster only: Specify the URL.
- 10
- Remote cluster only: Specify the name of the
Secret
CR.
10.2.7. MigHook
The MigHook
CR defines a migration hook that runs custom code at a specified stage of the migration. You can create up to four migration hooks. Each hook runs during a different phase of the migration.
You can configure the hook name, runtime duration, a custom image, and the cluster where the hook will run.
The migration phases and namespaces of the hooks are configured in the MigPlan
CR.
apiVersion: migration.openshift.io/v1alpha1 kind: MigHook metadata: generateName: <hook_name_prefix> 1 name: <mighook> 2 namespace: openshift-migration spec: activeDeadlineSeconds: 1800 3 custom: false 4 image: <hook_image> 5 playbook: <ansible_playbook_base64> 6 targetCluster: source 7
- 1
- Optional: A unique hash is appended to the value for this parameter so that each migration hook has a unique name. You do not need to specify the value of the
name
parameter. - 2
- Specify the migration hook name, unless you specify the value of the
generateName
parameter. - 3
- Optional: Specify the maximum number of seconds that a hook can run. The default is
1800
. - 4
- The hook is a custom image if
true
. The custom image can include Ansible or it can be written in a different programming language. - 5
- Specify the custom image, for example,
quay.io/konveyor/hook-runner:latest
. Required ifcustom
istrue
. - 6
- Base64-encoded Ansible playbook. Required if
custom
isfalse
. - 7
- Specify the cluster on which the hook will run. Valid values are
source
ordestination
.
10.2.8. MigMigration
The MigMigration
CR runs a MigPlan
CR.
You can configure a Migmigration
CR to run a stage or incremental migration, to cancel a migration in progress, or to roll back a completed migration.
apiVersion: migration.openshift.io/v1alpha1 kind: MigMigration metadata: labels: controller-tools.k8s.io: "1.0" name: <migmigration> namespace: openshift-migration spec: canceled: false 1 rollback: false 2 stage: false 3 quiescePods: true 4 keepAnnotations: true 5 verify: false 6 migPlanRef: name: <migplan> namespace: openshift-migration
- 1
- Set to
true
to cancel a migration in progress. - 2
- Set to
true
to roll back a completed migration. - 3
- Set to
true
to run a stage migration. Data is copied incrementally and the pods on the source cluster are not stopped. - 4
- Set to
true
to stop the application during migration. The pods on the source cluster are scaled to0
after theBackup
stage. - 5
- Set to
true
to retain the labels and annotations applied during the migration. - 6
- Set to
true
to check the status of the migrated pods on the destination cluster are checked and to return the names of pods that are not in aRunning
state.
10.2.9. MigPlan
The MigPlan
CR defines the parameters of a migration plan.
You can configure destination namespaces, hook phases, and direct or indirect migration.
By default, a destination namespace has the same name as the source namespace. If you configure a different destination namespace, you must ensure that the namespaces are not duplicated on the source or the destination clusters because the UID and GID ranges are copied during migration.
apiVersion: migration.openshift.io/v1alpha1 kind: MigPlan metadata: labels: controller-tools.k8s.io: "1.0" name: <migplan> namespace: openshift-migration spec: closed: false 1 srcMigClusterRef: name: <source_cluster> namespace: openshift-migration destMigClusterRef: name: <destination_cluster> namespace: openshift-migration hooks: 2 - executionNamespace: <namespace> 3 phase: <migration_phase> 4 reference: name: <hook> 5 namespace: <hook_namespace> 6 serviceAccount: <service_account> 7 indirectImageMigration: true 8 indirectVolumeMigration: false 9 migStorageRef: name: <migstorage> namespace: openshift-migration namespaces: - <source_namespace_1> 10 - <source_namespace_2> - <source_namespace_3>:<destination_namespace_4> 11 refresh: false 12
- 1
- The migration has completed if
true
. You cannot create anotherMigMigration
CR for thisMigPlan
CR. - 2
- Optional: You can specify up to four migration hooks. Each hook must run during a different migration phase.
- 3
- Optional: Specify the namespace in which the hook will run.
- 4
- Optional: Specify the migration phase during which a hook runs. One hook can be assigned to one phase. Valid values are
PreBackup
,PostBackup
,PreRestore
, andPostRestore
. - 5
- Optional: Specify the name of the
MigHook
CR. - 6
- Optional: Specify the namespace of
MigHook
CR. - 7
- Optional: Specify a service account with
cluster-admin
privileges. - 8
- Direct image migration is disabled if
true
. Images are copied from the source cluster to the replication repository and from the replication repository to the destination cluster. - 9
- Direct volume migration is disabled if
true
. PVs are copied from the source cluster to the replication repository and from the replication repository to the destination cluster. - 10
- Specify one or more source namespaces. If you specify only the source namespace, the destination namespace is the same.
- 11
- Specify the destination namespace if it is different from the source namespace.
- 12
- The
MigPlan
CR is validated iftrue
.
10.2.10. MigStorage
The MigStorage
CR describes the object storage for the replication repository.
Amazon Web Services (AWS), Microsoft Azure, Google Cloud Storage, Multi-Cloud Object Gateway, and generic S3-compatible cloud storage are supported.
AWS and the snapshot copy method have additional parameters.
apiVersion: migration.openshift.io/v1alpha1 kind: MigStorage metadata: labels: controller-tools.k8s.io: "1.0" name: <migstorage> namespace: openshift-migration spec: backupStorageProvider: <backup_storage_provider> 1 volumeSnapshotProvider: <snapshot_storage_provider> 2 backupStorageConfig: awsBucketName: <bucket> 3 awsRegion: <region> 4 credsSecretRef: namespace: openshift-config name: <storage_secret> 5 awsKmsKeyId: <key_id> 6 awsPublicUrl: <public_url> 7 awsSignatureVersion: <signature_version> 8 volumeSnapshotConfig: awsRegion: <region> 9 credsSecretRef: namespace: openshift-config name: <storage_secret> 10 refresh: false 11
- 1
- Specify the storage provider.
- 2
- Snapshot copy method only: Specify the storage provider.
- 3
- AWS only: Specify the bucket name.
- 4
- AWS only: Specify the bucket region, for example,
us-east-1
. - 5
- Specify the name of the
Secret
CR that you created for the storage. - 6
- AWS only: If you are using the AWS Key Management Service, specify the unique identifier of the key.
- 7
- AWS only: If you granted public access to the AWS bucket, specify the bucket URL.
- 8
- AWS only: Specify the AWS signature version for authenticating requests to the bucket, for example,
4
. - 9
- Snapshot copy method only: Specify the geographical region of the clusters.
- 10
- Snapshot copy method only: Specify the name of the
Secret
CR that you created for the storage. - 11
- Set to
true
to validate the cluster.
10.3. Logs and debugging tools
This section describes logs and debugging tools that you can use for troubleshooting.
10.3.1. Viewing migration plan resources
You can view migration plan resources to monitor a running migration or to troubleshoot a failed migration by using the MTC web console and the command line interface (CLI).
Procedure
- In the MTC web console, click Migration Plans.
- Click the Migrations number next to a migration plan to view the Migrations page.
- Click a migration to view the Migration details.
Expand Migration resources to view the migration resources and their status in a tree view.
NoteTo troubleshoot a failed migration, start with a high-level resource that has failed and then work down the resource tree towards the lower-level resources.
Click the Options menu next to a resource and select one of the following options:
Copy
oc describe
command copies the command to your clipboard.Log in to the relevant cluster and then run the command.
The conditions and events of the resource are displayed in YAML format.
Copy
oc logs
command copies the command to your clipboard.Log in to the relevant cluster and then run the command.
If the resource supports log filtering, a filtered log is displayed.
View JSON displays the resource data in JSON format in a web browser.
The data is the same as the output for the
oc get <resource>
command.
10.3.2. Viewing a migration plan log
You can view an aggregated log for a migration plan. You use the MTC web console to copy a command to your clipboard and then run the command from the command line interface (CLI).
The command displays the filtered logs of the following pods:
-
Migration Controller
-
Velero
-
Restic
-
Rsync
-
Stunnel
-
Registry
Procedure
- In the MTC web console, click Migration Plans.
- Click the Migrations number next to a migration plan.
- Click View logs.
-
Click the Copy icon to copy the
oc logs
command to your clipboard. Log in to the relevant cluster and enter the command on the CLI.
The aggregated log for the migration plan is displayed.
10.3.3. 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.
10.3.4. Accessing performance metrics
The MigrationController
custom resource (CR) records metrics and pulls them into on-cluster monitoring storage. You can query the metrics by using Prometheus Query Language (PromQL) to diagnose migration performance issues. All metrics are reset when the Migration Controller pod restarts.
You can access the performance metrics and run queries by using the OpenShift Container Platform web console.
Procedure
-
In the OpenShift Container Platform web console, click Monitoring
Metrics. Enter a PromQL query, select a time window to display, and click Run Queries.
If your web browser does not display all the results, use the Prometheus console.
10.3.4.1. Provided metrics
The MigrationController
custom resource (CR) provides metrics for the MigMigration
CR count and for its API requests.
10.3.4.1.1. cam_app_workload_migrations
This metric is a count of MigMigration
CRs over time. It is useful for viewing alongside the mtc_client_request_count
and mtc_client_request_elapsed
metrics to collate API request information with migration status changes. This metric is included in Telemetry.
Queryable label name | Sample label values | Label description |
---|---|---|
status |
|
Status of the |
type | stage, final |
Type of the |
10.3.4.1.2. mtc_client_request_count
This metric is a cumulative count of Kubernetes API requests that MigrationController
issued. It is not included in Telemetry.
Queryable label name | Sample label values | Label description |
---|---|---|
cluster |
| Cluster that the request was issued against |
component |
| Sub-controller API that issued request |
function |
| Function that the request was issued from |
kind |
| Kubernetes kind the request was issued for |
10.3.4.1.3. mtc_client_request_elapsed
This metric is a cumulative latency, in milliseconds, of Kubernetes API requests that MigrationController
issued. It is not included in Telemetry.
Queryable label name | Sample label values | Label description |
---|---|---|
cluster |
| Cluster that the request was issued against |
component |
| Sub-controller API that issued request |
function |
| Function that the request was issued from |
kind |
| Kubernetes resource that the request was issued for |
10.3.4.1.4. Useful queries
The table lists some helpful queries that can be used for monitoring performance.
Query | Description |
---|---|
| Number of API requests issued, sorted by request type |
| Total number of API requests issued |
| API request latency, sorted by request type |
| Total latency of API requests |
| Average latency of API requests |
| Average latency of API requests, sorted by request type |
| Count of running migrations, multiplied by 100 for easier viewing alongside request counts |
10.3.5. Using the must-gather tool
You can collect logs, metrics, and information about MTC custom resources by using the must-gather
tool.
The must-gather
data must be attached to all customer cases.
You can collect data for a one-hour or a 24-hour period and view the data with the Prometheus console.
Prerequisites
-
You must be logged in to the OpenShift Container Platform cluster as a user with the
cluster-admin
role. - You must have the OpenShift CLI installed.
Procedure
-
Navigate to the directory where you want to store the
must-gather
data. Run the
oc adm must-gather
command for one of the following data collection options:To collect data for the past hour:
$ oc adm must-gather --image=registry.redhat.io/rhmtc/openshift-migration-must-gather-rhel8:v1.7
The data is saved as
must-gather/must-gather.tar.gz
. You can upload this file to a support case on the Red Hat Customer Portal.To collect data for the past 24 hours:
$ oc adm must-gather --image=registry.redhat.io/rhmtc/openshift-migration-must-gather-rhel8:v1.7 \ -- /usr/bin/gather_metrics_dump
This operation can take a long time. The data is saved as
must-gather/metrics/prom_data.tar.gz
.
Viewing metrics data with the Prometheus console
You can view the metrics data with the Prometheus console.
Procedure
Decompress the
prom_data.tar.gz
file:$ tar -xvzf must-gather/metrics/prom_data.tar.gz
Create a local Prometheus instance:
$ make prometheus-run
The command outputs the Prometheus URL.
Output
Started Prometheus on http://localhost:9090
- Launch a web browser and navigate to the URL to view the data by using the Prometheus web console.
After you have viewed the data, delete the Prometheus instance and data:
$ make prometheus-cleanup
10.3.6. Debugging Velero resources with the Velero CLI tool
You can debug Backup
and Restore
custom resources (CRs) and retrieve logs with the Velero CLI tool.
The Velero CLI tool provides more detailed information than the OpenShift CLI tool.
Syntax
Use the oc exec
command to run a Velero CLI command:
$ oc -n openshift-migration exec deployment/velero -c velero -- ./velero \ <backup_restore_cr> <command> <cr_name>
Example
$ oc -n openshift-migration exec deployment/velero -c velero -- ./velero \ backup describe 0e44ae00-5dc3-11eb-9ca8-df7e5254778b-2d8ql
Help option
Use the velero --help
option to list all Velero CLI commands:
$ oc -n openshift-migration exec deployment/velero -c velero -- ./velero \ --help
Describe command
Use the velero describe
command to retrieve a summary of warnings and errors associated with a Backup
or Restore
CR:
$ oc -n openshift-migration exec deployment/velero -c velero -- ./velero \ <backup_restore_cr> describe <cr_name>
Example
$ oc -n openshift-migration exec deployment/velero -c velero -- ./velero \ backup describe 0e44ae00-5dc3-11eb-9ca8-df7e5254778b-2d8ql
Logs command
Use the velero logs
command to retrieve the logs of a Backup
or Restore
CR:
$ oc -n openshift-migration exec deployment/velero -c velero -- ./velero \ <backup_restore_cr> logs <cr_name>
Example
$ oc -n openshift-migration exec deployment/velero -c velero -- ./velero \ restore logs ccc7c2d0-6017-11eb-afab-85d0007f5a19-x4lbf
10.3.7. 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
Example output
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 -n {namespace} exec deployment/velero -c velero -- ./velero \ restore describe <restore>
Example output
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 -n {namespace} exec deployment/velero -c velero -- ./velero \ restore logs <restore>
Example output
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.
10.3.8. Using MTC custom resources for troubleshooting
You can check the following Migration Toolkit for Containers (MTC) custom resources (CRs) to troubleshoot a failed migration:
-
MigCluster
-
MigStorage
-
MigPlan
BackupStorageLocation
The
BackupStorageLocation
CR contains amigrationcontroller
label to identify the MTC instance that created the CR:labels: migrationcontroller: ebe13bee-c803-47d0-a9e9-83f380328b93
VolumeSnapshotLocation
The
VolumeSnapshotLocation
CR contains amigrationcontroller
label to identify the MTC instance that created the CR:labels: migrationcontroller: ebe13bee-c803-47d0-a9e9-83f380328b93
-
MigMigration
Backup
MTC changes the reclaim policy of migrated persistent volumes (PVs) to
Retain
on the target cluster. TheBackup
CR contains anopenshift.io/orig-reclaim-policy
annotation that indicates the original reclaim policy. You can manually restore the reclaim policy of the migrated PVs.-
Restore
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 openshift.io/orig-reclaim-policy: delete 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
10.4. Common issues and concerns
This section describes common issues and concerns that can cause issues during migration.
10.4.1. 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> -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 the 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.
10.4.2. 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.
10.4.2.1. CA certificate error displayed when accessing the MTC console for the first time
If the MTC console displays a CA certificate error
message the first time you try to access it, the likely cause is that a cluster uses self-signed CA certificates.
Navigate to the oauth-authorization-server
URL in the error message and accept the certificate. To resolve this issue permanently, install the certificate authority so that it is trusted.
If the browser displays an Unauthorized
message after you have accepted the CA certificate, navigate to the MTC console and then refresh the web page.
10.4.2.2. OAuth timeout error in the MTC console
If the MTC console displays a connection has timed out
message after you have accepted a self-signed certificate, the cause is likely to be one of the following:
- Interrupted network access to the OAuth server
- Interrupted network access to the OpenShift Container Platform console
- Proxy configuration blocking access to the OAuth server. See MTC console inaccessible because of OAuth timeout error for details.
To determine the cause:
- Inspect the MTC console web page with a browser web inspector.
-
Check the
Migration UI
pod log for errors.
10.4.2.3. Certificate signed by unknown authority error
If you use a self-signed certificate to secure a cluster or a replication repository for the Migration Toolkit for Containers (MTC), certificate verification might fail with the following error message: Certificate signed by unknown authority
.
You can create a custom CA certificate bundle file and upload it in the MTC web console when you add a cluster or a replication repository.
Procedure
Download a CA certificate from a remote endpoint and save it as a CA bundle file:
$ echo -n | openssl s_client -connect <host_FQDN>:<port> \ 1 | sed -ne '/-BEGIN CERTIFICATE-/,/-END CERTIFICATE-/p' > <ca_bundle.cert> 2
10.4.2.4. Backup storage location errors in the Velero pod log
If a Velero
Backup
custom resource contains a reference to a backup storage location (BSL) that does not exist, the Velero
pod log might display the following error messages:
Error checking repository for stale locks Error getting backup storage location: backupstoragelocation.velero.io \"my-bsl\" not found
You can ignore these error messages. A missing BSL cannot cause a migration to fail.
10.4.2.5. Pod volume backup timeout error in the Velero pod log
If a migration fails because Restic
times out, the Velero
pod log displays the following error:
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.
10.4.2.6. Restic verification errors in the MigMigration custom resource
If data verification fails when migrating a persistent volume with the file system data copy method, the MigMigration
CR displays the following error:
MigMigration CR status
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 troubleshoot 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.PodVolumeRestore CR with Restic pod error
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>
10.4.2.7. Restic permission error when migrating from NFS storage with root_squash enabled
If you are migrating data from NFS storage and root_squash
is enabled, Restic
maps to nfsnobody
and does not have permission to perform the migration. The Restic
pod log displays the following error:
Restic permission error
backup=openshift-migration/<backup_id> controller=pod-volume-backup error="fork/exec /usr/bin/restic: permission denied" error.file="/go/src/github.com/vmware-tanzu/ velero/pkg/controller/pod_volume_backup_controller.go:280" error.function= "github.com/vmware-tanzu/velero/pkg/controller.(*podVolumeBackupController).processBackup" logSource="pkg/controller/pod_volume_backup_controller.go:280" name=<backup_id> namespace=openshift-migration
You can resolve this issue by creating a supplemental group for Restic
and adding the group ID to the MigrationController
CR manifest.
Procedure
-
Create a supplemental group for
Restic
on the NFS storage. -
Set the
setgid
bit on the NFS directories so that group ownership is inherited. Add the
restic_supplemental_groups
parameter to theMigrationController
CR manifest on the source and target clusters:spec: restic_supplemental_groups: <group_id> 1
- 1
- Specify the supplemental group ID.
-
Wait for the
Restic
pods to restart so that the changes are applied.
10.4.3. 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)
10.5. Rolling back a migration
You can roll back a migration by using the MTC web console or the CLI.
You can also roll back a migration manually.
10.5.1. Rolling back a migration by using the MTC web console
You can roll back a migration by using the Migration Toolkit for Containers (MTC) web console.
The following resources remain in the migrated namespaces for debugging after a failed direct volume migration (DVM):
- Config maps (source and destination clusters)
-
Secret
CRs (source and destination clusters) -
Rsync
CRs (source cluster)
These resources do not affect rollback. You can delete them manually.
If you later run the same migration plan successfully, the resources from the failed migration are deleted automatically.
If your application was stopped during a failed migration, you must roll back the migration 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 under Migration.
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
10.5.2. Rolling back a migration from the command line interface
You can roll back a migration by creating a MigMigration
custom resource (CR) from the command line interface.
The following resources remain in the migrated namespaces for debugging after a failed direct volume migration (DVM):
- Config maps (source and destination clusters)
-
Secret
CRs (source and destination clusters) -
Rsync
CRs (source cluster)
These resources do not affect rollback. You can delete them manually.
If you later run the same migration plan successfully, the resources from the failed migration are deleted automatically.
If your application was stopped during a failed migration, you must roll back the migration 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: <migmigration> namespace: openshift-migration spec: ... rollback: true ... migPlanRef: name: <migplan> 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.
10.5.3. Rolling back a migration manually
You can roll back a failed migration manually by deleting the stage
pods and unquiescing the application.
If you run the same migration plan successfully, the resources from the failed migration are deleted automatically.
The following resources remain in the migrated namespaces after a failed direct volume migration (DVM):
- Config maps (source and destination clusters)
-
Secret
CRs (source and destination clusters) -
Rsync
CRs (source cluster)
These resources do not affect rollback. You can delete them manually.
Procedure
Delete the
stage
pods on all clusters:$ oc delete $(oc get pods -l migration.openshift.io/is-stage-pod -n <namespace>) 1
- 1
- Namespaces specified in the
MigPlan
CR.
Unquiesce the application on the source cluster by scaling the replicas to their premigration number:
$ oc scale deployment <deployment> --replicas=<premigration_replicas>
The
migration.openshift.io/preQuiesceReplicas
annotation in theDeployment
CR displays the premigration number of replicas:apiVersion: extensions/v1beta1 kind: Deployment metadata: annotations: deployment.kubernetes.io/revision: "1" migration.openshift.io/preQuiesceReplicas: "1"
Verify that the application pods are running on the source cluster:
$ oc get pod -n <namespace>