add sendgrid

.github/workflows/release.yaml

@@ -14,11 +14,11 @@ jobs:
     runs-on: ubuntu-latest
     steps:
     - name: Checkout
-      uses: actions/checkout@v4
+      uses: actions/checkout@v5
 
-    - uses: actions/setup-go@v5
+    - uses: actions/setup-go@v6
       with:
-        go-version: '1.24.x'
+        go-version: '1.25.x'
 
     - name: Setup KO
       uses: ko-build/setup-ko@v0.9

.github/workflows/test.yaml

@@ -21,7 +21,7 @@ jobs:
       - name: Lint
         uses: golangci/golangci-lint-action@v8
         with:
-          version: v2.4.0
+          version: v2.5.0
 
       - name: Test
         run: go test -race -covermode atomic -coverprofile=coverage.txt -v ./...

README.md

@@ -21,7 +21,7 @@ as HTTP endpoint so the other microservices that belong to you can make email re
 - [ ] Mailtrap
 - [ ] Mailjet
 - [ ] Mailgun
-- [ ] Sendgrid (avoid them if you can)
+- [X] Sendgrid
 
 Note: Anything that only uses oauth2 like zoho does will not be implemented here for foreseeable future
 

cmd/emailer/main.go

@@ -18,15 +18,17 @@ import (
 	"github.com/mrwormhole/emailer"
 	"github.com/mrwormhole/emailer/brevo"
 	"github.com/mrwormhole/emailer/resend"
+	"github.com/mrwormhole/emailer/sendgrid"
 )
 
 var debugEnabled = flag.Bool("debug", false, "in debug environment")
 
 const (
 	defaultPort = "5555"
 	// Providers Listed below
-	providerBrevo  = "brevo"
-	providerResend = "resend"
+	providerBrevo    = "brevo"
+	providerResend   = "resend"
+	providerSendgrid = "sendgrid"
 )
 
 func main() {
@@ -69,20 +71,31 @@ func main() {
 	httpClient := c.StandardClient()
 	httpClient.Timeout = 10 * time.Second
 
+	ctx := context.Background()
 	var sender emailer.Sender
+	cfg := emailer.Config{Key: key, Client: *httpClient}
 	switch {
 	case strings.EqualFold(provider, providerBrevo):
-		slog.LogAttrs(context.Background(), slog.LevelDebug, "brevo.New()")
-		sender, err = brevo.New(emailer.Config{Key: key, Client: *httpClient})
+		slog.LogAttrs(ctx, slog.LevelDebug, "brevo.New()")
+		sender, err = brevo.New(cfg)
 		if err != nil {
-			slog.LogAttrs(context.Background(), slog.LevelError, "brevo.New()", slog.String("err", err.Error()))
+			slog.LogAttrs(ctx, slog.LevelError, "brevo.New()", slog.String("err", err.Error()))
 		}
 	case strings.EqualFold(provider, providerResend):
-		slog.LogAttrs(context.Background(), slog.LevelDebug, "resend.New()")
-		sender, err = resend.New(emailer.Config{Key: key, Client: *httpClient})
+		slog.LogAttrs(ctx, slog.LevelDebug, "resend.New()")
+		sender, err = resend.New(cfg)
 		if err != nil {
-			slog.LogAttrs(context.Background(), slog.LevelError, "resend.New()", slog.String("err", err.Error()))
+			slog.LogAttrs(ctx, slog.LevelError, "resend.New()", slog.String("err", err.Error()))
 		}
+	case strings.EqualFold(provider, providerSendgrid):
+		slog.LogAttrs(ctx, slog.LevelDebug, "sendgrid.New()")
+		sender, err = sendgrid.New(cfg)
+		if err != nil {
+			slog.LogAttrs(ctx, slog.LevelError, "sendgrid.New()", slog.String("err", err.Error()))
+		}
+	default:
+		slog.LogAttrs(ctx, slog.LevelError, "unknown provider", slog.String("provider", provider))
+		os.Exit(1)
 	}
 
 	mux := http.NewServeMux()

go.mod

@@ -1,10 +1,10 @@
 module github.com/mrwormhole/emailer
 
-go 1.22
+go 1.25
 
 require (
 	github.com/google/go-cmp v0.6.0
-	github.com/hashicorp/go-retryablehttp v0.7.7
+	github.com/hashicorp/go-retryablehttp v0.7.8
 )
 
 require github.com/hashicorp/go-cleanhttp v0.5.2 // indirect

go.sum

@@ -6,8 +6,8 @@ github.com/hashicorp/go-cleanhttp v0.5.2 h1:035FKYIWjmULyFRBKPs8TBQoi0x6d9G4xc9n
 github.com/hashicorp/go-cleanhttp v0.5.2/go.mod h1:kO/YDlP8L1346E6Sodw+PrpBSV4/SoxCXGY6BqNFT48=
 github.com/hashicorp/go-hclog v1.6.3 h1:Qr2kF+eVWjTiYmU7Y31tYlP1h0q/X3Nl3tPGdaB11/k=
 github.com/hashicorp/go-hclog v1.6.3/go.mod h1:W4Qnvbt70Wk/zYJryRzDRU/4r0kIg0PVHBcfoyhpF5M=
-github.com/hashicorp/go-retryablehttp v0.7.7 h1:C8hUCYzor8PIfXHa4UrZkU4VvK8o9ISHxT2Q8+VepXU=
-github.com/hashicorp/go-retryablehttp v0.7.7/go.mod h1:pkQpWZeYWskR+D1tR2O5OcBFOxfA7DoAO6xtkuQnHTk=
+github.com/hashicorp/go-retryablehttp v0.7.8 h1:ylXZWnqa7Lhqpk0L1P1LzDtGcCR0rPVUrx/c8Unxc48=
+github.com/hashicorp/go-retryablehttp v0.7.8/go.mod h1:rjiScheydd+CxvumBsIrFKlx3iS0jrZ7LvzFGFmuKbw=
 github.com/mattn/go-colorable v0.1.13 h1:fFA4WZxdEF4tXPZVKMLwD8oUnCTTo08duU7wxecdEvA=
 github.com/mattn/go-colorable v0.1.13/go.mod h1:7S9/ev0klgBDR4GtXTXX8a3vIGJpMovkB8vQcUbaXHg=
 github.com/mattn/go-isatty v0.0.20 h1:xfD0iDuEKnDkl03q4limB+vH+GxLEtL/jb4xVJSWWEY=

sendgrid/client.go

@@ -0,0 +1,143 @@
+// Package sendgrid makes it easy to send emails via sendgrid provider. This package follows [sendgrid spec] strictly.
+//
+// Example usage:
+//
+//	 email := emailer.Email{
+//		From:        "skywalker@jedi.com",
+//		To:          []string{"vindu@sith.com"},
+//		Subject:     "peace",
+//		TextContent: "peace was never an option",
+//	 }
+//	 c, err := New(emailer.Config{key: "api-key"})
+//		if err != nil {
+//			//check err
+//		}
+//	 c.Send(ctx, email)
+//
+// [sendgrid spec]: https://www.twilio.com/docs/sendgrid/api-reference/mail-send/mail-send
+package sendgrid
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"net/http"
+	"net/http/httputil"
+	"slices"
+	"strings"
+
+	"github.com/mrwormhole/emailer"
+)
+
+const endpoint = "https://api.sendgrid.com/v3/mail/send"
+
+// EmailClient is sendgrid email client to interact with emails
+type EmailClient struct {
+	key    string
+	client http.Client
+}
+
+// New creates a new sendgrid email client with given API key and http.Client
+func New(c emailer.Config) (*EmailClient, error) {
+	if strings.TrimSpace(c.Key) == "" {
+		return nil, errors.New("sendgrid API key is blank")
+	}
+	e := &EmailClient{
+		key:    c.Key,
+		client: c.Client,
+	}
+	return e, nil
+}
+
+type emailObject struct {
+	Email string `json:"email"`
+}
+
+type personalization struct {
+	To  []emailObject `json:"to"`
+	BCC []emailObject `json:"bcc,omitempty"`
+	CC  []emailObject `json:"cc,omitempty"`
+}
+
+type content struct {
+	// Type is MIME Type (e.g., text/plain or text/html)
+	Type string `json:"type"`
+	// Value is the actual content
+	Value string `json:"value"`
+}
+
+// payload is a request that sendgrid uses to send email
+type payload struct {
+	Personalizations []personalization `json:"personalizations"`
+	From             emailObject       `json:"from"`
+	Subject          string            `json:"subject"`
+	Content          []content         `json:"content,omitempty"`
+}
+
+type errorMessage struct {
+	Errors []struct {
+		Message string `json:"message"`
+		Field   string `json:"field"`
+		Help    any    `json:"help"`
+	} `json:"errors"`
+}
+
+// Send sends a given email
+func (c *EmailClient) Send(ctx context.Context, email emailer.Email) error {
+	var p payload
+	p.From.Email = email.From
+
+	pers := personalization{}
+	for _, e := range email.To {
+		pers.To = append(pers.To, emailObject{Email: e})
+	}
+	for _, e := range email.BCC {
+		pers.BCC = append(pers.BCC, emailObject{Email: e})
+	}
+	for _, e := range email.CC {
+		pers.CC = append(pers.CC, emailObject{Email: e})
+	}
+	p.Personalizations = append(p.Personalizations, pers)
+	p.Subject = email.Subject
+
+	if email.TextContent != "" {
+		p.Content = append(p.Content, content{Type: "text/plain", Value: email.TextContent})
+	}
+	if email.HTMLContent != "" {
+		p.Content = append(p.Content, content{Type: "text/html", Value: email.HTMLContent})
+	}
+
+	raw, err := json.Marshal(p)
+	if err != nil {
+		return fmt.Errorf("json.Marshal(%v): %v", p, err)
+	}
+	req, err := http.NewRequestWithContext(ctx, http.MethodPost, endpoint, bytes.NewBuffer(raw))
+	if err != nil {
+		return fmt.Errorf("http.NewRequestWithContext(): %v", err)
+	}
+	req.Header.Add("Authorization", "Bearer "+c.key)
+	req.Header.Add("accept", "application/json")
+	req.Header.Add("content-type", "application/json")
+
+	resp, err := c.client.Do(req)
+	if err != nil {
+		return fmt.Errorf("client.Do(%v): %v", req, err)
+	}
+	defer func() {
+		_ = resp.Body.Close()
+	}()
+
+	if slices.Contains([]int{http.StatusAccepted, http.StatusCreated, http.StatusOK}, resp.StatusCode) {
+		return nil
+	}
+
+	var m errorMessage
+	if err := json.NewDecoder(resp.Body).Decode(&m); err != nil {
+		dump, _ := httputil.DumpResponse(resp, true)
+		return fmt.Errorf("json.NewDecoder(%v).Decode(): %v", string(dump), err)
+	}
+
+	return fmt.Errorf("unsuccessful response with status code(%d): %v", resp.StatusCode, m)
+}