Migrate from MKE 3.x

This section instructs you on how to migrate your existing MKE 3.7 cluster to the MKE 4.x version.

Prerequisites

Verify that you have the following components in place before you begin upgrading MKE 3 to MKE 4:

An MKE cluster running the latest 3.7.x or 3.8.x release:

kubectl get nodes

NAME                                           STATUS   ROLES    AGE     VERSION
ip-172-31-103-202.us-west-2.compute.internal   Ready    master   7m3s    v1.27.7-mirantis-1
ip-172-31-104-233.us-west-2.compute.internal   Ready    master   7m3s    v1.27.7-mirantis-1
ip-172-31-191-216.us-west-2.compute.internal   Ready    <none>   6m59s   v1.27.7-mirantis-1
ip-172-31-199-207.us-west-2.compute.internal   Ready    master   8m4s    v1.27.7-mirantis-1

The latest mkectl binary, installed on your local environment:
```
mkectl version
```
Example output:
```
Version: v4.0.0-alpha.1.0
```
k0sctl version 0.19.0, installed on your local environment:
```
k0sctl version
```
Example output:
```
version: v0.19.0
commit: 9246ddc
```

A hosts.yaml file, to provide the information required by mkectl to connect to each node with SSH.

Example hosts.yaml file:

cat hosts.yaml

hosts:
  - address: <host1-external-ip>
    port: <ssh-port>
    user: <ssh-user>
    keyPath: <path-to-ssh-key>
  - address: <host2-external-ip>
    port: <ssh-port>
    user: <ssh-user>
    keyPath: <path-to-ssh-key>

A calico_kdd flag is set to true in the MKE 3 configuration file and applied to the MKE 3 cluster:
```
calico_kdd = true
```

Calico KDD (Kubernetes Datastore Driver), enabled:

Verify that the MKE 3.x instance being upgraded to MKE 4 is running the latest 3.7.x or 3.8.x release.

Obtain the MKE 3 configuration file:

$ export MKE_USERNAME=<mke-username>
$ export MKE_PASSWORD=<mke-password>
$ export MKE_HOST=<mke-fqdm-or-ip-address>
$ curl --silent --insecure -X GET "https://$MKE_HOST/api/ucp/config-toml" -H "accept: application/toml" -H "Authorization: Bearer $AUTHTOKEN" > mke-config.toml

In the cluster_config section of the MKE 3 configuration file, set the calico_kdd parameter to true.

Apply the modified MKE 3 configuration file:

$ AUTHTOKEN=$(curl --silent --insecure --data '{"username":"'$MKE_USERNAME'","password":"'$MKE_PASSWORD'"}' https://$MKE_HOST/auth/login | jq --raw-output .auth_token)
$ curl --silent --insecure -X PUT -H "accept: application/toml" -H "Authorization: Bearer $AUTHTOKEN" --upload-file 'mke-config.toml' https://$MKE_HOST/api/ucp/config-toml
{"message":"Calico datastore migration from etcd to kdd successful"}

ℹ️

The conversion of the Calico datastore from etcd to KDD typically takes about 20 seconds per node, depending on the size of the cluster. On completion, the following confirmation displays:

{"message":"Calico datastore migration from etcd to kdd successful"}

Migrate configuration

In migrating to MKE 4 from MKE 3, you can directly transfer settings using mkectl.

To convert a local MKE 3 configuration for MKE 4: set the --mke3-config flag to convert a downloaded MKE 3 configuration file into a valid MKE 4 configuration file:

mkectl init --mke3-config </path/to/mke3-config.toml>

ℹ️

To upgrade an MKE 3 cluster with GPU enabled, ensure you complete the GPU prerequisites before starting the upgrade process.

Perform the migration

An upgrade from MKE 3 to MKE 4 consists of the following steps, all of which are performed through the use of the mkectl tool:

Run pre-upgrade checks to verify the upgradability of the cluster.
Carry out pre-upgrade migrations to prepare the cluster for a migration from a hyperkube-based MKE 3 cluster to a k0s-based MKE 4 cluster.
Migrate manager nodes to k0s.
Migrate worker nodes to k0s.
Carry out post-upgrade cleanup to remove MKE 3 components.
Output the new MKE 4 config file.

To upgrade an MKE 3 cluster, use the mkectl upgrade command:

mkectl upgrade --hosts-path <path-to-hosts-yaml> \
  --mke3-admin-username <admin-username> \
  --mke3-admin-password <admin-password> \
  --external-address <external-address>\
  --config-out <path-to-desired-file-location>

The external address is the domain name of the load balancer. For details, see System requirements: Load balancer requirements.

The --config-out flag allows you to specify a path where the MKE 4 configuration file will be automatically created and saved during migration. If not specified, the configuration file prints to your console on completion. In this case, save the output to a file for future reference

The upgrade process requires time to complete. Once the process is complete, run the following command to verify that the MKE 4 cluster is operating:

sudo k0s kc get nodes

Example output:

NAME                                           STATUS   ROLES    AGE   VERSION
ip-172-31-103-202.us-west-2.compute.internal   Ready    master   29m   v1.29.3+k0s
ip-172-31-104-233.us-west-2.compute.internal   Ready    master   29m   v1.29.3+k0s
ip-172-31-191-216.us-west-2.compute.internal   Ready    <none>   29m   v1.29.3+k0s
ip-172-31-199-207.us-west-2.compute.internal   Ready    master   30m   v1.29.3+k0s

ℹ️

The MKE 3 cluster will no longer be accessible through the previously created client bundle. The docker swarm cluster will no longer be accessible as well.

In the event of an upgrade failure, the upgrade process rolls back, restoring the MKE 3 cluster to its original state.

RBAC Migrations

As MKE 4 does not support Swarm mode, the platform uses standard Kubernetes RBAC authorization. As such, the Swarm authorization configuration that is in place for MKE 3 is not present in MKE 4.

Groups

To enable the same RBAC hierarchy as in MKE 3 with orgs and teams groups, but without the two-level limitation, MKE 4 replaces orgs and teams with the Kubernetes AggregatedRoles.

Authorization structure comparison:

MKE 3:                           MKE 4:

├── entire-company (org)         ├── entire-company-org (AggregatedRole)
│   ├── development (team)       ├── development-team (AggregatedRole)
│   │   ├── bob (user)           │   ├── bob (user)
│   ├── production (team)        ├── production-team (AggregatedRole)
│   │   ├── bob (user)│          │   ├── bob (user)
│   │   ├── bill (user)          │   ├── bill (user)
│   ├── sales (team)             ├── sales-team (AggregatedRole)

Roles

Roles are bound to the aggregated roles for integration into the org, team, and user structure. Thus, what was previously an organization or a team role will have -org or -team appended to its name.

A role can be assigned at any level in the hierarchy, with its permissions granted to all members at that same level.

Example organization binding:

├── entire-company-org (AggregatedRole) -- entire-company-org (RoleBinding) -- view (Role)
│   ├── development-team (AggregatedRole)
│   │   ├── bob (user)
│   ├── production-team (AggregatedRole)
│   │   ├── bob (user)
│   │   ├── bill (user)
│   ├── sales-team (AggregatedRole)

In the example above, all members of the entire-company org group have view permissions. This includes the development-team, production-team, sales-team, bob, and bill.

Example team binding:

│   ├── development:team (AggregatedRole) -- development:team (RoleBinding) -- edit (Role)
│   │   ├── bob (user)

In the example above, the binding grants edit permissions only to the members of the development team, which only includes bob.

⚠️

Swarm roles are partially translated to Kubernetes roles. During migration, any detected Swarm role is replicated without permissions, thus preserving the org/team/user structure. If no Swarm roles are detected, a none role is created as a placeholder, as Kubernetes requires each aggregated role to have at least one role. This none role has no permissions, with its only purpose being to maintain structural integrity.

CoreDNS Lameduck migration

MKE 4 supports migration from MKE 3 systems that are running with CoreDNS and Lameduck enabled. Refer to the table below for a comparison of the CoreDNS Lameduck configuration parameters between MKE 3 and MKE 4:

MKE 3	MKE 4
[cluster_config.core_dns_lameduck_config.enabled]	dns.lameduck.enabled
[cluster_config.core_dns_lameduck_config.duration]	dns.lameduck.duration

Troubleshoot migration

You can address various potential MKE migration issues using the tips and suggestions detailed herein.

MKE 3 `etcdv3` backend is unsupported for MKE 4 upgrade

During the upgrade from MKE 3 to MKE 4, which defaults to the etcdv3 backend, you may receive the following error:

mkectl upgrade --hosts-path hosts.yaml --mke3-admin-username admin --mke3-admin-password <mke_admin_password> -l debug --config-out new-mke4.yaml --external-address <mke4_external_address>
...
Error: unable to generate upgrade config: unsupported configuration for mke4 upgrade: mke3 cluster is using etcdv3 and not kdd backend for calico

To resolve the issue, ensure that:

The MKE 3 source is the latest 3.7.x or 3.8.x release.
The calico_kdd flag in the MKE 3 configuration file is set to true.
The configuration is applied to the MKE 3 cluster.

ℹ️

A KDD mode migration is irreversible. Thus, to reduce risk, when migrating enterprise clusters, it is recommended that you work directly with Mirantis to plan the process and monitor it through to completion.