feat(remote): Implement lazy distributed feature (#64)
THIS IS AN EXPERIMENTAL FEATURE/IMPLEMENTATION, AND IT MAY BE REMOVED IN THE FUTURE. Note that for now, it will be an undocumented feature.
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TwiN
@ -5,11 +5,16 @@ import (
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"compress/gzip"
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"encoding/json"
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"fmt"
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"io"
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"log"
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"net/http"
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"strings"
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"time"
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"github.com/TwiN/gatus/v4/client"
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"github.com/TwiN/gatus/v4/config"
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"github.com/TwiN/gatus/v4/config/remote"
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"github.com/TwiN/gatus/v4/core"
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"github.com/TwiN/gatus/v4/storage/store"
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"github.com/TwiN/gatus/v4/storage/store/common"
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"github.com/TwiN/gatus/v4/storage/store/common/paging"
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@ -28,48 +33,89 @@ var (
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// EndpointStatuses handles requests to retrieve all EndpointStatus
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// Due to the size of the response, this function leverages a cache.
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// Must not be wrapped by GzipHandler
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func EndpointStatuses(writer http.ResponseWriter, r *http.Request) {
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page, pageSize := extractPageAndPageSizeFromRequest(r)
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gzipped := strings.Contains(r.Header.Get("Accept-Encoding"), "gzip")
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var exists bool
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var value interface{}
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if gzipped {
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writer.Header().Set("Content-Encoding", "gzip")
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value, exists = cache.Get(fmt.Sprintf("endpoint-status-%d-%d-gzipped", page, pageSize))
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} else {
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value, exists = cache.Get(fmt.Sprintf("endpoint-status-%d-%d", page, pageSize))
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}
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var data []byte
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if !exists {
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var err error
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buffer := &bytes.Buffer{}
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gzipWriter := gzip.NewWriter(buffer)
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endpointStatuses, err := store.Get().GetAllEndpointStatuses(paging.NewEndpointStatusParams().WithResults(page, pageSize))
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if err != nil {
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log.Printf("[handler][EndpointStatuses] Failed to retrieve endpoint statuses: %s", err.Error())
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http.Error(writer, err.Error(), http.StatusInternalServerError)
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return
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}
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data, err = json.Marshal(endpointStatuses)
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if err != nil {
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log.Printf("[handler][EndpointStatuses] Unable to marshal object to JSON: %s", err.Error())
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http.Error(writer, "unable to marshal object to JSON", http.StatusInternalServerError)
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return
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}
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_, _ = gzipWriter.Write(data)
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_ = gzipWriter.Close()
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gzippedData := buffer.Bytes()
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cache.SetWithTTL(fmt.Sprintf("endpoint-status-%d-%d", page, pageSize), data, cacheTTL)
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cache.SetWithTTL(fmt.Sprintf("endpoint-status-%d-%d-gzipped", page, pageSize), gzippedData, cacheTTL)
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func EndpointStatuses(cfg *config.Config) http.HandlerFunc {
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return func(writer http.ResponseWriter, r *http.Request) {
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page, pageSize := extractPageAndPageSizeFromRequest(r)
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gzipped := strings.Contains(r.Header.Get("Accept-Encoding"), "gzip")
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var exists bool
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var value interface{}
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if gzipped {
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data = gzippedData
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writer.Header().Set("Content-Encoding", "gzip")
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value, exists = cache.Get(fmt.Sprintf("endpoint-status-%d-%d-gzipped", page, pageSize))
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} else {
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value, exists = cache.Get(fmt.Sprintf("endpoint-status-%d-%d", page, pageSize))
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}
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} else {
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data = value.([]byte)
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var data []byte
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if !exists {
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var err error
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buffer := &bytes.Buffer{}
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gzipWriter := gzip.NewWriter(buffer)
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endpointStatuses, err := store.Get().GetAllEndpointStatuses(paging.NewEndpointStatusParams().WithResults(page, pageSize))
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if err != nil {
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log.Printf("[handler][EndpointStatuses] Failed to retrieve endpoint statuses: %s", err.Error())
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http.Error(writer, err.Error(), http.StatusInternalServerError)
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return
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}
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// ALPHA: Retrieve endpoint statuses from remote instances
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if endpointStatusesFromRemote, err := getEndpointStatusesFromRemoteInstances(cfg.Remote); err != nil {
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log.Printf("[handler][EndpointStatuses] Silently failed to retrieve endpoint statuses from remote: %s", err.Error())
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} else if endpointStatusesFromRemote != nil {
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endpointStatuses = append(endpointStatuses, endpointStatusesFromRemote...)
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}
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// Marshal endpoint statuses to JSON
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data, err = json.Marshal(endpointStatuses)
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if err != nil {
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log.Printf("[handler][EndpointStatuses] Unable to marshal object to JSON: %s", err.Error())
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http.Error(writer, "unable to marshal object to JSON", http.StatusInternalServerError)
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return
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}
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_, _ = gzipWriter.Write(data)
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_ = gzipWriter.Close()
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gzippedData := buffer.Bytes()
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cache.SetWithTTL(fmt.Sprintf("endpoint-status-%d-%d", page, pageSize), data, cacheTTL)
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cache.SetWithTTL(fmt.Sprintf("endpoint-status-%d-%d-gzipped", page, pageSize), gzippedData, cacheTTL)
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if gzipped {
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data = gzippedData
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}
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} else {
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data = value.([]byte)
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}
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writer.Header().Add("Content-Type", "application/json")
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writer.WriteHeader(http.StatusOK)
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_, _ = writer.Write(data)
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}
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writer.Header().Add("Content-Type", "application/json")
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writer.WriteHeader(http.StatusOK)
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_, _ = writer.Write(data)
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}
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func getEndpointStatusesFromRemoteInstances(remoteConfig *remote.Config) ([]*core.EndpointStatus, error) {
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if remoteConfig == nil || len(remoteConfig.Instances) == 0 {
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return nil, nil
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}
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var endpointStatusesFromAllRemotes []*core.EndpointStatus
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httpClient := client.GetHTTPClient(remoteConfig.ClientConfig)
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for _, instance := range remoteConfig.Instances {
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response, err := httpClient.Get(instance.URL)
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if err != nil {
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return nil, err
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}
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body, err := io.ReadAll(response.Body)
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if err != nil {
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_ = response.Body.Close()
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log.Printf("[handler][getEndpointStatusesFromRemoteInstances] Silently failed to retrieve endpoint statuses from %s: %s", instance.URL, err.Error())
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continue
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}
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var endpointStatuses []*core.EndpointStatus
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if err = json.Unmarshal(body, &endpointStatuses); err != nil {
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_ = response.Body.Close()
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log.Printf("[handler][getEndpointStatusesFromRemoteInstances] Silently failed to retrieve endpoint statuses from %s: %s", instance.URL, err.Error())
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continue
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}
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_ = response.Body.Close()
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for _, endpointStatus := range endpointStatuses {
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endpointStatus.Name = instance.EndpointPrefix + endpointStatus.Name
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}
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endpointStatusesFromAllRemotes = append(endpointStatusesFromAllRemotes, endpointStatuses...)
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}
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return endpointStatusesFromAllRemotes, nil
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}
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// EndpointStatus retrieves a single core.EndpointStatus by group and endpoint name
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