Tools in Kubernetes

Operations on TiDB in Kubernetes require some open source tools. In the meantime, there are some special requirements for operations using TiDB tools in the Kubernetes environment. This documents introduces in details the related operation tools for TiDB in Kubernetes.

Use PD Control in Kubernetes

PD Control is the command-line tool for PD (Placement Driver). To use PD Control to operate on TiDB clusters in Kubernetes, firstly you need to establish the connection from local to the PD service using kubectl port-forward:

kubectl port-forward -n <namespace> svc/<cluster-name>-pd 2379:2379 &>/tmp/portforward-pd.log &

After the above command is executed, you can access the PD service via 127.0.0.1:2379, and then use the default parameters of pd-ctl to operate. For example:

pd-ctl -d config show

Assume that your local port 2379 has been occupied and you want to switch to another port:

kubectl port-forward -n <namespace> svc/<cluster-name>-pd <local-port>:2379 &>/tmp/portforward-pd.log &

Then you need to explicitly assign a PD port for pd-ctl:

pd-ctl -u 127.0.0.1:<local-port> -d config show

Use TiKV Control in Kubernetes

TiKV Control is the command-line tool for TiKV. When using TiKV Control for TiDB clusters in Kubernetes, be aware that each operation mode involves different steps, as described below:

  • Remote Mode: In this mode, tikv-ctl accesses the TiKV service or the PD service through network. Firstly you need to establish the connection from local to the PD service and the target TiKV node using kubectl port-forward:

    kubectl port-forward -n <namespace> svc/<cluster-name>-pd 2379:2379 &>/tmp/portforward-pd.log &
    kubectl port-forward -n <namespace> <tikv-pod-name> 20160:20160 &>/tmp/portforward-tikv.log &

    After the connection is established, you can access the PD service and the TiKV node via the corresponding port in local:

    tikv-ctl --host 127.0.0.1:20160 <subcommands>
    tikv-ctl --pd 127.0.0.1:2379 compact-cluster
  • Local Mode:In this mode, tikv-ctl accesses data files of TiKV, and the running TiKV instances must be stopped. To operate in the local mode, first you need to enter the Diagnostic Mode to turn off automatic re-starting for the TiKV instance, stop the TiKV process, and use the tkctl debug command to start in the target TiKV Pod a new container that contains the tikv-ctl executable. The steps are as follows:

    1. Enter the Diagnostic mode:

      kubectl annotate pod <tikv-pod-name> -n <namespace> runmode=debug
    2. Stop the TiKV process:

      kubectl exec <tikv-pod-name> -n <namespace> -c tikv -- kill -s TERM 1
    3. Start the debug container:

      tkctl debug <tikv-pod-name> -c tikv
    4. Start using tikv-ctl in local mode. It should be noted that the root file system of tikv is under /proc/1/root, so you need to adjust the path of the data directory accordingly when executing a command:

      tikv-ctl --db /path/to/tikv/db size -r 2

      Note:

      The default db path of TiKV instances in the debug container is /proc/1/root/var/lib/tikv/db

Use TiDB Control in Kubernetes

TiDB Control is the command-line tool for TiDB. To use TiDB Control in Kubernetes, you need to access the TiDB node and the PD service from local. It is suggested you turn on the connection from local to the TiDB node and the PD service using kubectl port-forward:

kubectl port-forward -n <namespace> svc/<cluster-name>-pd 2379:2379 &>/tmp/portforward-pd.log &
kubectl port-forward -n <namespace> <tidb-pod-name> 10080:10080 &>/tmp/portforward-tidb.log &

Then you can use the tidb-ctl:

tidb-ctl schema in mysql

Use Helm

Helm is a package management tool for Kubernetes. Make sure your Helm version >= 2.11.0 and < 2.16.4. The installation steps are as follows:

  1. Refer to Helm official documentation to install Helm client.

  2. Install Helm server.

    Apply the RBAC rule required by the tiller component in the cluster and install tiller:

    kubectl apply -f https://raw.githubusercontent.com/pingcap/tidb-operator/master/manifests/tiller-rbac.yaml && \
    helm init --service-account=tiller --upgrade

    If you cannot access gcr.io, try using the mirror repository:

    helm init --service-account=tiller --upgrade --tiller-image registry.cn-hangzhou.aliyuncs.com/google_containers/tiller:$(helm version --client --short | grep -Eo 'v[0-9]\.[0-9]+\.[0-9]+')

    Confirm that the tiller pod is in the running state by the following command:

    kubectl get po -n kube-system -l name=tiller

    If RBAC is not enabled for the Kubernetes cluster, use the following command to install tiller:

    helm init --upgrade

Kubernetes applications are packed as chart in Helm. PingCAP provides the following Helm charts for TiDB in Kubernetes:

  • tidb-operator: used to deploy TiDB Operator;
  • tidb-cluster: used to deploy TiDB clusters;
  • tidb-backup: used to backup or restore TiDB clusters;
  • tidb-lightning: used to import data into a TiDB cluster;
  • tidb-drainer: used to deploy TiDB Drainer;
  • tikv-importer: used to deploy TiKV Importer.

These charts are hosted in the Helm chart repository https://charts.pingcap.org/ maintained by PingCAP. You can add this repository to your local using the following command:

helm repo add pingcap https://charts.pingcap.org/

After adding, use helm search to search for the charts provided by PingCAP:

helm search pingcap -l
NAME                    CHART VERSION   APP VERSION DESCRIPTION
pingcap/tidb-backup     v1.0.0                      A Helm chart for TiDB Backup or Restore
pingcap/tidb-cluster    v1.0.0                      A Helm chart for TiDB Cluster
pingcap/tidb-operator   v1.0.0                      tidb-operator Helm chart for Kubernetes

When a new version of chart has been released, you can use helm repo update to update the repository cached locally:

helm repo update

Common Helm operations include helm install, helm upgrade, and helm del. Helm chart usually contains many configurable parameters which could be tedious to configure manually. For convenience, it is recommended that you configure using a YAML file. Based on the conventions in the Helm community, the YAML file used for Helm configuration is named values.yaml in this document.

When performing a deployment or upgrade, you must specify the chart name (chart-name) and the name for the deployed application (release-name). You can also specify one or multiple values.yaml files to configure charts. In addition, you can use chart-version to specify the chart version (by default the latest GA is used). The steps in command line are as follows:

  • Install:

    helm install <chart-name> --name=<release-name> --namespace=<namespace> --version=<chart-version> -f <values-file>
  • Upgrade (upgrade can be done by modifying the chart-version to upgrade to the latest chart version or the values.yaml file to update the configuration):

    helm upgrade <release-name> <chart-name> --version=<chart-version> -f <values-file>
  • To delete the application deployed by Helm, run the following command:

    helm del --purge <release-name>

For more information on Helm, refer to Helm Documentation.

Use Terraform

Terraform is a Infrastructure as Code management tool. It enables users to define their own infrastructure in a manifestation style, based on which execution plans are generated to create or schedule real world compute resources. TiDB in Kubernetes use Terraform to create and manage TiDB clusters on public clouds.

Follow the steps in Terraform Documentation to install Terraform.