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@algermissen
Created March 6, 2021 16:26
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package main
import (
"encoding/base64"
"encoding/json"
"fmt"
"log"
"net/http"
)
// Google pubsub message envelope
type PubsubMessage struct {
Message Message `json:"message"`
}
// Google pubsub message
type Message struct {
PublishTime string `json:"publishTime"`
Attributes map[string]string `json:"attributes"`
Data string `json:"data"`
}
// Optional payload structure (if we want to send data beyond the attributes)
type MyEventPayload struct {
MyField string `json:"my_field"`
}
func main() {
handler := func(w http.ResponseWriter, req *http.Request) {
var pubsubMessage PubsubMessage
decoderBody := json.NewDecoder(req.Body)
if err := decoderBody.Decode(&pubsubMessage); err != nil {
log.Printf("unmarshal pubsub push message: %v\n", err)
w.WriteHeader(http.StatusBadRequest)
return
}
// Debug
// fmt.Printf("PublishTime: %s\n", pubsubMessage.Message.PublishTime)
// fmt.Printf("Data: %s\n", pubsubMessage.Message.Data)
// for k, v := range pubsubMessage.Message.Attributes {
// fmt.Printf(" %s => %s\n", k, v)
// }
fmt.Printf("Received change event from eventlog:\n")
fmt.Printf(" timestamp: %s\n", pubsubMessage.Message.Attributes["timestamp"])
fmt.Printf(" environment: %s\n", pubsubMessage.Message.Attributes["environment"])
fmt.Printf(" rsid: %s\n", pubsubMessage.Message.Attributes["rsid"])
fmt.Printf(" resource_uri: %s\n", pubsubMessage.Message.Attributes["resource_uri"])
fmt.Printf(" change_type: %s\n", pubsubMessage.Message.Attributes["change_type"])
// This is all we actually need - you can now get the data using HTTP GET on the
// provided resource URI.
// Optionally do something with the message data
if pubsubMessage.Message.Data != "" {
jsonBytes, err := base64.StdEncoding.DecodeString(pubsubMessage.Message.Data)
if err != nil {
log.Printf("base64 decode message data: %v\n", err)
w.WriteHeader(http.StatusBadRequest)
return
}
var payload MyEventPayload
if err := json.Unmarshal(jsonBytes, &payload); err != nil {
log.Printf("unmarshall event payload: %v\n", err)
w.WriteHeader(http.StatusBadRequest)
return
}
}
w.WriteHeader(http.StatusNoContent)
}
http.HandleFunc("/events", handler)
err := http.ListenAndServe(":8080", nil)
if err != nil {
log.Fatal(err)
}
}
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