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k8stars

K8stars is a solution to deploy TARS in a Kubernetes environment and it has the following features:

  • Maintain the same functionality of TARS Framework
  • Support TARS naming service and configuration management
  • Support a smooth transfer of TARS services into container orchestrations such as Kubernetes.
  • Non-invasive; there isn’t a coupling between the deployment environment and the services

The solution

  1. Build a tarscli (command line tool) for assigning ports, generating configurations, reporting heartbeats, and retiring nodes.

Deployment example

  1. Please refer to baseserver for deploying tarsregistry
  2. Run: cd examples/simple && kubectl apply -f simpleserver.yaml
  • example description：
    • examples/simple/Dockerfile will create the container image, and cmd/tarscli/Dockerfile will build the fundamental image
    • tarscli genconf in start.sh will be used to generate tars services’ starting configuration.
    • The file _server_meta.yaml is used to configure services’ metadata. You can refer to the structure of ServerConf in app/genconf/config.go for the field information. The endpoint is tcp -h ${local_ip} -p ${random_port} by default and supports automatically filling in IP and random ports.
    • You can also find a demo HelloWorld program TestApp.Hello in Go language in the repository
  1. To confirm if deployment is successfully, log into db_tars and execute select * from t_server_conf\G. You should see that the simpleserver’s node information is registered.

TARS Deployment Directories

tarscli manages services based on the environment variables in TARS_PATH, the function of each directory is as follows:

  • ${TARS_PATH}/bin: to start scripts and binary files,
  • ${TARS_PATH}/conf: to configure files,
  • ${TARS_PATH}/log: to store log files,
  • ${TARS_PATH}/data: to provide execution status and cache files.

tarscli description

tarscli provides a set of command tools to help with tars services’ containerized deployment. If you want to designate the parameters, please refer to tarscli help. Below are the sub commands tarscli supports:

  • genconf is used to create tars services’ starting configuration files. The supported environment variables include:
    • TARS_APPLICATION : the application name, which comes from _server_meta.yaml by default.
    • TARS_SERVER: the server name, which is read from _server_meta.yaml.
    • TARS_BUILD_SERVER: the server name when compiling. It is used when the compiled server name is different from the name of the server that is running.
    • TARS_LOCATOR: can designate the address of registry, and the default path is tars-registry.default.svc.cluster.local -p 17890 (service’s address)
    • TARS_SET_ID: can designate the service set.
    • TARS_MERGE_CONF: can configure the template file, and merge it into the service’s starting configuration file.
  • Supervisor, by default, executes genconf commands first, and then starts and monitors services. The supported environment variables include:
    • TARS_START_PATH: Services’ starting script and it is TARS_PATH/bin/start.sh by default
    • TARS_STOP_PATH: services’ stopping script, and by default kills all the processes under $TARS_PATH
    • TARS_REPORT_INTERVAL: is the time it takes to report heartbeat to registry
    • TARS_DISABLE_FLOW: indicates whether the flow is enabled or disabled at the registry. This is disabled by default.
    • TARS_CHECK_INTERVAL: the time it takes to check the service status. If the status changes, it will be synced to registry.
    • TARS_BEFORE_CHECK_SCRIPT: it is the shell script that runs before each examination.
    • TARS_CHECK_SCRIPT_TIMEOUT: the timeout before each shell script execution.
    • TARS_PRESTOP_WAITTIME: the wait time period before shutting-stopping services and it makes sure nothing is lost afterward. The default is set to 80 seconds
  • hzcheck is used to synced service status and the status of Kubernetes’ pod and it needs to set pod’s readiness probe to tarscli hzcheck.
  • prestop is used to delete the corresponding configurations before services end.
    • TARS_PRESTOP_WAITTIME: the wait time period before shutting-stopping services and it makes sure nothing is lost afterward. The default is set to 80 seconds.
  • notify is used to send management commands. An example of commonly used commands is tars.setloglevel/tars.pprof.