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Migrate TiDB to Kubernetes

This document describes how to migrate a TiDB cluster deployed in the physical or virtual machine to a Kubernetes cluster, without using any backup and restore tool.

Prerequisites

  • The physical or virtual machines outside Kubernetes have network access to the Pods in Kubernetes.
  • The physical or virtual machines outside Kubernetes can resolve the domain name of the Pods in Kubernetes. (See Step 1 for configuration details.)
  • The cluster to be migrated (that is, the source cluster) does not enable TLS between components.

Step 1: Configure DNS service in all nodes of the cluster to be migrated

  1. Get the Pod IP address list of the endpoints of the CoreDNS or kube-dns service of the Kubernetes cluster:

    kubectl describe svc/kube-dns -n kube-system
    
  2. Modify the /etc/resolv.conf configuration of the source cluster node, and add the following content to the configuration file:

    search default.svc.cluster.local svc.cluster.local cluster.local
    nameserver <CoreDNS Pod_IP_1>
    nameserver <CoreDNS Pod_IP_2>
    nameserver <CoreDNS Pod_IP_n>
    
  3. Test whether the node can successfully resolve the domain name of the Pods in Kubernetes:

    $ ping basic-pd-2.basic-pd-peer.blade.svc
    PING basic-pd-2.basic-pd-peer.blade.svc (10.24.66.178) 56(84) bytes of data.
    64 bytes from basic-pd-2.basic-pd-peer.blade.svc (10.24.66.178): icmp_seq=1 ttl=61 time=0.213 ms
    64 bytes from basic-pd-2.basic-pd-peer.blade.svc (10.24.66.178): icmp_seq=2 ttl=61 time=0.175 ms
    64 bytes from basic-pd-2.basic-pd-peer.blade.svc (10.24.66.178): icmp_seq=3 ttl=61 time=0.188 ms
    64 bytes from basic-pd-2.basic-pd-peer.blade.svc (10.24.66.178): icmp_seq=4 ttl=61 time=0.157 ms
    

Step 2: Create a TiDB cluster on Kubernetes

  1. Get the PD node address and port of the source cluster via PD Control:

    pd-ctl -u http://<address>:<port> member | jq '.members | .[] | .client_urls'
    
  2. Create the target TiDB cluster on Kubernetes, which must have at least 3 TiKV nodes. Specify the PD node address of the source cluster in the spec.pdAddresses field (starting with http://):

    spec
      ...
      pdAddresses:
      - http://pd1_addr:port
      - http://pd2_addr:port
      - http://pd3_addr:port
    
  3. Confirm that the source cluster and the target cluster compose of a new cluster that runs normally:

    • Get the number and state of stores in the new cluster:

      # Get the number of stores
      pd-ctl -u http://<address>:<port> store | jq '.count'
      # Get the state of stores
      pd-ctl -u http://<address>:<port> store | jq '.stores | .[] | .store.state_name'
      
    • Access the TiDB cluster on Kubernetes via MySQL client.

Step 3: Scale in the TiDB nodes of the source cluster

Remove all TiDB nodes of the source cluster:

Step 4: Scale in the TiKV nodes of the source cluster

Remove all TiKV nodes of the source cluster:

Step 5: Scale in the PD nodes of the source cluster

Remove all PD nodes of the source cluster:

Step 6: Delete the spec.pdAddresses field

To avoid confusion for further operations on the cluster, it is recommended that you delete the spec.pdAddresses field in the new cluster after the migration.

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