From ccba0a9e18b06a956b5ca151371d222c463e64b5 Mon Sep 17 00:00:00 2001
From: Tine <tine@tjo.space>
Date: Fri, 16 Feb 2024 14:50:35 +0100
Subject: [PATCH] fix(temporal): use retry logic when connecting

---
 cmd/worker/main.go   | 14 ++++----------
 internal/temporal.go | 14 +++++++++-----
 pkg/retry/retry.go   | 23 +++++++++++++++++++++++
 3 files changed, 36 insertions(+), 15 deletions(-)
 create mode 100644 pkg/retry/retry.go

diff --git a/cmd/worker/main.go b/cmd/worker/main.go
index c574ca1..d0970d9 100644
--- a/cmd/worker/main.go
+++ b/cmd/worker/main.go
@@ -3,25 +3,19 @@ package main
 import (
 	"log"
 
+	"code.tjo.space/mentos1386/zdravko/internal"
 	"code.tjo.space/mentos1386/zdravko/internal/activities"
 	"code.tjo.space/mentos1386/zdravko/internal/config"
 	"code.tjo.space/mentos1386/zdravko/internal/workflows"
-	"go.temporal.io/sdk/client"
 	"go.temporal.io/sdk/worker"
 )
 
 func main() {
-	config := config.NewConfig()
+	cfg := config.NewConfig()
 
-	// Initialize a Temporal Client
-	// Specify the Namespace in the Client options
-	clientOptions := client.Options{
-		HostPort:  config.Temporal.ServerHost,
-		Namespace: "default",
-	}
-	temporalClient, err := client.Dial(clientOptions)
+	temporalClient, err := internal.ConnectToTemporal(cfg)
 	if err != nil {
-		log.Fatalln("Unable to create a Temporal Client", err)
+		log.Fatal(err)
 	}
 	defer temporalClient.Close()
 
diff --git a/internal/temporal.go b/internal/temporal.go
index e22ca84..a32cdfd 100644
--- a/internal/temporal.go
+++ b/internal/temporal.go
@@ -1,14 +1,18 @@
 package internal
 
 import (
+	"time"
+
 	"code.tjo.space/mentos1386/zdravko/internal/config"
+	"code.tjo.space/mentos1386/zdravko/pkg/retry"
 	"go.temporal.io/sdk/client"
 )
 
 func ConnectToTemporal(cfg *config.Config) (client.Client, error) {
-	c, err := client.Dial(client.Options{HostPort: cfg.Temporal.ServerHost})
-	if err != nil {
-		return nil, err
-	}
-	return c, nil
+	// Try to connect to the Temporal Server
+	return retry.Retry(5, 6*time.Second, func() (client.Client, error) {
+		return client.Dial(client.Options{
+			HostPort: cfg.Temporal.ServerHost,
+		})
+	})
 }
diff --git a/pkg/retry/retry.go b/pkg/retry/retry.go
new file mode 100644
index 0000000..ed14532
--- /dev/null
+++ b/pkg/retry/retry.go
@@ -0,0 +1,23 @@
+package retry
+
+import (
+	"fmt"
+	"log"
+	"time"
+)
+
+// https://stackoverflow.com/questions/67069723/keep-retrying-a-function-in-golang
+func Retry[T any](attempts int, sleep time.Duration, f func() (T, error)) (result T, err error) {
+	for i := 0; i < attempts; i++ {
+		if i > 0 {
+			log.Println("retrying after error:", err)
+			time.Sleep(sleep)
+			sleep *= 2
+		}
+		result, err = f()
+		if err == nil {
+			return result, nil
+		}
+	}
+	return result, fmt.Errorf("after %d attempts, last error: %s", attempts, err)
+}