plane/monitor/lib/healthcheck/README.md

Prime Healthcheck

Prime Healthcheck is a service that take care of checking for all the running services in the user's system. Internally the Prime Healthcheck makes network calls to each of the services that are provided in the environment variables.

Usage

PerformHealthCheck

PerformHealthCheck is the primary method that is responsible for perfoming the health check over the services provided. Essentially PerformHealthCheck looks up for environment variables provided with prefix SERVICE_, the format is along the lines of SERVICE_TESTMETHOD_NAME where name is the name of the service, the corresponding value to this would contain, the exact url to be called for that service, without the protocol. The function returns two channel, which can be used to recieve updates for healthchecks.

Function Signature

func (h *HealthCheckHandler) PerformHealthCheck(ctx context.Context, options HealthCheckOptions) (chan *HealthCheckStatus, chan *error)

package main

func main() {
    // If you have to pass custom test methods
	handler := HealthCheckHandler{
		TestIdMethodMap: T_TestIdMethodMap,
		TestIdStringMap: T_TestIdStringMap,
	}
    // If you want to use default test methods
    handler := NewHealthCheckHandler()

	t.Setenv(tt.ServiceName, tt.ServiceValue)
    options := HealthCheckOptions{
	    ConfirmTries:    3,
	    MaxRetries:      1,
		TimeoutDuration: 5 * time.Second,
		RetryDuration:   1 * time.Second,
	}
	statusChannel, errorChannel := handler.PerformHealthCheck(ctx, options)
	statuses := make([]HealthCheckStatus, 0)
	errors := make([]error, 0)
	for {
		select {
			case status, ok := <-statusChannel:
				if !ok {
					statusChannel = nil
				} else {
					statuses = append(statuses, *status)
				}
			case err, ok := <-errorChannel:
				if !ok {
					errorChannel = nil
				} else {
					errors = append(errors, *err)
					cancel()
				}
		}
		if statusChannel == nil && errorChannel == nil {
			break
			}
		}
    }

ExecuteHealthCheckWithRetries

ExecuteHealthCheckWithRetries is a method that performs the health check with retries. It uses the provided test method and options to repeatedly check the health of a service until it either succeeds or exhausts the retry attempts.

Function Signature

func (h *HealthCheckHandler) ExecuteHealthCheckWithRetries(ctx context.Context, testMethod HealthCheckMethod, options HealthCheckMethodOptions, wg *sync.WaitGroup, statusChannel chan *HealthCheckStatus, errorChannel chan *error)

GetServiceFromEnvironment

GetServiceFromEnvironment retrieves a map of services from the environment variables. It filters the environment variables to only include those with the prefix SERVICE_ and parses them into a map of service names to ServiceData.

Function Signature

func (h *HealthCheckHandler) GetServiceFromEnvironment() (map[string]*ServiceData, error)

ParseKeyValue

ParseKeyValue parses a key-value pair from the environment variables into a service name and ServiceData. It splits the key and value into their respective components and validates them.

Function Signature

func (h *HealthCheckHandler) ParseKeyValue(key string, value string) (string, *ServiceData, error)

GetEnvironmentVarMap

GetEnvironmentVarMap retrieves all environment variables and returns them as a map of key-value pairs. It filters out any empty or commented-out variables.

Function Signature

func GetEnvironmentVarMap() map[string]string

... For understanding more, please read healthcheck.go and healthcheck_method.go