feat(alerting): Add gotify provider (#605)

* feat(alerting): add gotify provider feature

* feat(alerting): update alert message

* feat(test): add tests for gotify provider

* feat(docs): add documentation for gotify provider

* feat(alerting): rename apptoken to token

* feat(docs): update docs for apptoken renaming to token

---------

Co-authored-by: Bugra Kocabay <kocabay.bugra@gmail.com>
Co-authored-by: TwiN <twin@linux.com>

README.md

@@ -54,6 +54,7 @@ Have any feedback or questions? [Create a discussion](https://github.com/TwiN/ga
     - [Configuring GitHub alerts](#configuring-github-alerts)
     - [Configuring GitLab alerts](#configuring-gitlab-alerts)
     - [Configuring Google Chat alerts](#configuring-google-chat-alerts)
+    - [Configuring Gotify alerts](#configuring-gotify-alerts)
     - [Configuring Matrix alerts](#configuring-matrix-alerts)
     - [Configuring Mattermost alerts](#configuring-mattermost-alerts)
     - [Configuring Messagebird alerts](#configuring-messagebird-alerts)
@@ -423,6 +424,7 @@ ignored.
 | `alerting.github`      | Configuration for alerts of type `github`. <br />See [Configuring GitHub alerts](#configuring-github-alerts).                | `{}`    |
 | `alerting.gitlab`      | Configuration for alerts of type `gitlab`. <br />See [Configuring GitLab alerts](#configuring-gitlab-alerts).                | `{}`    |
 | `alerting.googlechat`  | Configuration for alerts of type `googlechat`. <br />See [Configuring Google Chat alerts](#configuring-google-chat-alerts).  | `{}`    |
+| `alerting.gotify`      | Configuration for alerts of type `gotify`. <br />See [Configuring Gotify alerts](#configuring-gotify-alerts).                | `{}`    |
 | `alerting.matrix`      | Configuration for alerts of type `matrix`. <br />See [Configuring Matrix alerts](#configuring-matrix-alerts).                | `{}`    |
 | `alerting.mattermost`  | Configuration for alerts of type `mattermost`. <br />See [Configuring Mattermost alerts](#configuring-mattermost-alerts).    | `{}`    |
 | `alerting.messagebird` | Configuration for alerts of type `messagebird`. <br />See [Configuring Messagebird alerts](#configuring-messagebird-alerts). | `{}`    |
@@ -638,6 +640,41 @@ endpoints:
 ```
 
 
+#### Configuring Gotify alerts
+| Parameter                                     | Description                                                                                 | Default                |
+|:----------------------------------------------|:--------------------------------------------------------------------------------------------|:-----------------------|
+| `alerting.gotify`                             | Configuration for alerts of type `gotify`                                                   | `{}`                   |
+| `alerting.gotify.server-url`                  | Gotify server URL                                                                           | Required `""`          |
+| `alerting.gotify.token`                       | Token that is used for authentication.                                                      | Required `""`          |
+| `alerting.gotify.priority`                    | Priority of the alert according to Gotify standarts.                                        | `5`                    |
+| `alerting.gotify.default-alert`               | Default alert configuration. <br />See [Setting a default alert](#setting-a-default-alert). | N/A                    |
+| `alerting.gotify.title`                       | Title of the notification                                                                   |  `"Gatus: <endpoint>"` |
+
+```yaml
+alerting:
+  gotify:
+    server-url: "https://gotify.example"
+    token: "**************"
+
+endpoints:
+  - name: website
+    url: "https://twin.sh/health"
+    interval: 5m
+    conditions:
+      - "[STATUS] == 200"
+      - "[BODY].status == UP"
+      - "[RESPONSE_TIME] < 300"
+    alerts:
+      - type: gotify
+        description: "healthcheck failed"
+        send-on-resolved: true
+```
+
+Here's an example of what the notifications look like:
+
+![Gotify notifications](.github/assets/gotify-alerts.png)
+
+
 #### Configuring Matrix alerts
 | Parameter                                | Description                                                                                | Default                            |
 |:-----------------------------------------|:-------------------------------------------------------------------------------------------|:-----------------------------------|

alerting/alert/type.go

@@ -26,6 +26,9 @@ const (
 	// TypeGoogleChat is the Type for the googlechat alerting provider
 	TypeGoogleChat Type = "googlechat"
 
+	// TypeGotify is the Type for the gotify alerting provider
+	TypeGotify Type = "gotify"
+
 	// TypeMatrix is the Type for the matrix alerting provider
 	TypeMatrix Type = "matrix"
 

alerting/config.go

@@ -14,6 +14,7 @@ import (
 	"github.com/TwiN/gatus/v5/alerting/provider/github"
 	"github.com/TwiN/gatus/v5/alerting/provider/gitlab"
 	"github.com/TwiN/gatus/v5/alerting/provider/googlechat"
+	"github.com/TwiN/gatus/v5/alerting/provider/gotify"
 	"github.com/TwiN/gatus/v5/alerting/provider/matrix"
 	"github.com/TwiN/gatus/v5/alerting/provider/mattermost"
 	"github.com/TwiN/gatus/v5/alerting/provider/messagebird"
@@ -50,6 +51,9 @@ type Config struct {
 	// GoogleChat is the configuration for the googlechat alerting provider
 	GoogleChat *googlechat.AlertProvider `yaml:"googlechat,omitempty"`
 
+	// Gotify is the configuration for the gotify alerting provider
+	Gotify *gotify.AlertProvider `yaml:"gotify,omitempty"`
+
 	// Matrix is the configuration for the matrix alerting provider
 	Matrix *matrix.AlertProvider `yaml:"matrix,omitempty"`
 

alerting/provider/gotify/gotify.go

@@ -0,0 +1,105 @@
+package gotify
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+
+	"github.com/TwiN/gatus/v5/alerting/alert"
+	"github.com/TwiN/gatus/v5/client"
+	"github.com/TwiN/gatus/v5/core"
+)
+
+const DefaultPriority = 5
+
+// AlertProvider is the configuration necessary for sending an alert using Gotify
+type AlertProvider struct {
+	// ServerURL is the URL of the Gotify server
+	ServerURL string `yaml:"server-url"`
+
+	// Token is the token to use when sending a message to the Gotify server
+	Token string `yaml:"token"`
+
+	// Priority is the priority of the message
+	Priority int `yaml:"priority,omitempty"` // Defaults to DefaultPriority
+
+	// DefaultAlert is the default alert configuration to use for endpoints with an alert of the appropriate type
+	DefaultAlert *alert.Alert `yaml:"default-alert,omitempty"`
+
+	// Title is the title of the message that will be sent
+	Title string `yaml:"title,omitempty"`
+}
+
+// IsValid returns whether the provider's configuration is valid
+func (provider *AlertProvider) IsValid() bool {
+	if provider.Priority == 0 {
+		provider.Priority = DefaultPriority
+	}
+	return len(provider.ServerURL) > 0 && len(provider.Token) > 0
+}
+
+// Send an alert using the provider
+func (provider *AlertProvider) Send(endpoint *core.Endpoint, alert *alert.Alert, result *core.Result, resolved bool) error {
+	buffer := bytes.NewBuffer(provider.buildRequestBody(endpoint, alert, result, resolved))
+	request, err := http.NewRequest(http.MethodPost, provider.ServerURL+"/message?token="+provider.Token, buffer)
+	if err != nil {
+		return err
+	}
+	request.Header.Set("Content-Type", "application/json")
+	response, err := client.GetHTTPClient(nil).Do(request)
+	if err != nil {
+		return err
+	}
+	defer response.Body.Close()
+	if response.StatusCode > 399 {
+		body, _ := io.ReadAll(response.Body)
+		return fmt.Errorf("failed to send alert to Gotify: %s", string(body))
+	}
+	return nil
+}
+
+type Body struct {
+	Message  string `json:"message"`
+	Title    string `json:"title"`
+	Priority int    `json:"priority"`
+}
+
+// buildRequestBody builds the request body for the provider
+func (provider *AlertProvider) buildRequestBody(endpoint *core.Endpoint, alert *alert.Alert, result *core.Result, resolved bool) []byte {
+	var message, results string
+	if resolved {
+		message = fmt.Sprintf("An alert for `%s` has been resolved after passing successfully %d time(s) in a row", endpoint.DisplayName(), alert.SuccessThreshold)
+	} else {
+		message = fmt.Sprintf("An alert for `%s` has been triggered due to having failed %d time(s) in a row", endpoint.DisplayName(), alert.FailureThreshold)
+	}
+	for _, conditionResult := range result.ConditionResults {
+		var prefix string
+		if conditionResult.Success {
+			prefix = "✓"
+		} else {
+			prefix = "✕"
+		}
+		results += fmt.Sprintf("\n%s - %s", prefix, conditionResult.Condition)
+	}
+	if len(alert.GetDescription()) > 0 {
+		message += " with the following description: " + alert.GetDescription()
+	}
+	message += results
+	title := "Gatus: " + endpoint.DisplayName()
+	if provider.Title != "" {
+		title = provider.Title
+	}
+	body, _ := json.Marshal(Body{
+		Message:  message,
+		Title:    title,
+		Priority: provider.Priority,
+	})
+	return body
+}
+
+// GetDefaultAlert returns the provider's default alert configuration
+func (provider AlertProvider) GetDefaultAlert() *alert.Alert {
+	return provider.DefaultAlert
+}

alerting/provider/gotify/gotify_test.go

@@ -0,0 +1,105 @@
+package gotify
+
+import (
+	"encoding/json"
+	"fmt"
+	"testing"
+
+	"github.com/TwiN/gatus/v5/alerting/alert"
+	"github.com/TwiN/gatus/v5/core"
+)
+
+func TestAlertProvider_IsValid(t *testing.T) {
+	scenarios := []struct {
+		name     string
+		provider AlertProvider
+		expected bool
+	}{
+		{
+			name:     "valid",
+			provider: AlertProvider{ServerURL: "https://gotify.example.com", Token: "faketoken"},
+			expected: true,
+		},
+		{
+			name:     "invalid-server-url",
+			provider: AlertProvider{ServerURL: "", Token: "faketoken"},
+			expected: false,
+		},
+		{
+			name:     "invalid-app-token",
+			provider: AlertProvider{ServerURL: "https://gotify.example.com", Token: ""},
+			expected: false,
+		},
+		{
+			name:     "no-priority-should-use-default-value",
+			provider: AlertProvider{ServerURL: "https://gotify.example.com", Token: "faketoken"},
+			expected: true,
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(scenario.name, func(t *testing.T) {
+			if scenario.provider.IsValid() != scenario.expected {
+				t.Errorf("expected %t, got %t", scenario.expected, scenario.provider.IsValid())
+			}
+		})
+	}
+}
+
+func TestAlertProvider_buildRequestBody(t *testing.T) {
+	var (
+		description = "custom-description"
+		//title       = "custom-title"
+		endpoint = "custom-endpoint"
+	)
+	scenarios := []struct {
+		Name         string
+		Provider     AlertProvider
+		Alert        alert.Alert
+		Resolved     bool
+		ExpectedBody string
+	}{
+		{
+			Name:         "triggered",
+			Provider:     AlertProvider{ServerURL: "https://gotify.example.com", Token: "faketoken"},
+			Alert:        alert.Alert{Description: &description, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:     false,
+			ExpectedBody: fmt.Sprintf("{\"message\":\"An alert for `%s` has been triggered due to having failed 3 time(s) in a row with the following description: %s\\n✕ - [CONNECTED] == true\\n✕ - [STATUS] == 200\",\"title\":\"Gatus: custom-endpoint\",\"priority\":0}", endpoint, description),
+		},
+		{
+			Name:         "resolved",
+			Provider:     AlertProvider{ServerURL: "https://gotify.example.com", Token: "faketoken"},
+			Alert:        alert.Alert{Description: &description, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:     true,
+			ExpectedBody: fmt.Sprintf("{\"message\":\"An alert for `%s` has been resolved after passing successfully 5 time(s) in a row with the following description: %s\\n✓ - [CONNECTED] == true\\n✓ - [STATUS] == 200\",\"title\":\"Gatus: custom-endpoint\",\"priority\":0}", endpoint, description),
+		},
+		{
+			Name:         "custom-title",
+			Provider:     AlertProvider{ServerURL: "https://gotify.example.com", Token: "faketoken", Title: "custom-title"},
+			Alert:        alert.Alert{Description: &description, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:     false,
+			ExpectedBody: fmt.Sprintf("{\"message\":\"An alert for `%s` has been triggered due to having failed 3 time(s) in a row with the following description: %s\\n✕ - [CONNECTED] == true\\n✕ - [STATUS] == 200\",\"title\":\"custom-title\",\"priority\":0}", endpoint, description),
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(scenario.Name, func(t *testing.T) {
+			body := scenario.Provider.buildRequestBody(
+				&core.Endpoint{Name: endpoint},
+				&scenario.Alert,
+				&core.Result{
+					ConditionResults: []*core.ConditionResult{
+						{Condition: "[CONNECTED] == true", Success: scenario.Resolved},
+						{Condition: "[STATUS] == 200", Success: scenario.Resolved},
+					},
+				},
+				scenario.Resolved,
+			)
+			if string(body) != scenario.ExpectedBody {
+				t.Errorf("expected:\n%s\ngot:\n%s", scenario.ExpectedBody, body)
+			}
+			out := make(map[string]interface{})
+			if err := json.Unmarshal(body, &out); err != nil {
+				t.Error("expected body to be valid JSON, got error:", err.Error())
+			}
+		})
+	}
+}

config/config.go

@@ -367,6 +367,7 @@ func validateAlertingConfig(alertingConfig *alerting.Config, endpoints []*core.E
 		alert.TypeGitHub,
 		alert.TypeGitLab,
 		alert.TypeGoogleChat,
+		alert.TypeGotify,
 		alert.TypeEmail,
 		alert.TypeMatrix,
 		alert.TypeMattermost,