feat(alerting): Add GitLab alerting provider (#485)

* feat: ✨ add gitlab provider

* docs: 📝 add documentation for gitlab provider

* docs: 📝 fix removed github screenshot

* refactor: ➖ remove uniuri dependency

* refactor: 🎨 correctly capitalize GitLab

* Update alerting/alert/type.go

* fix: 💡 correct comments about webhook url and authorization key

* Update alerting/provider/gitlab/gitlab.go

* Update alerting/provider/gitlab/gitlab_test.go

---------

Co-authored-by: TwiN <twin@linux.com>

README.md

@@ -51,6 +51,7 @@ Have any feedback or questions? [Create a discussion](https://github.com/TwiN/ga
     - [Configuring Discord alerts](#configuring-discord-alerts)
     - [Configuring Email alerts](#configuring-email-alerts)
     - [Configuring GitHub alerts](#configuring-github-alerts)
+    - [Configuring GitLab alerts](#configuring-gitlab-alerts)
     - [Configuring Google Chat alerts](#configuring-google-chat-alerts)
     - [Configuring Matrix alerts](#configuring-matrix-alerts)
     - [Configuring Mattermost alerts](#configuring-mattermost-alerts)
@@ -411,6 +412,7 @@ ignored.
 | `alerting.discord`     | Configuration for alerts of type `discord`. <br />See [Configuring Discord alerts](#configuring-discord-alerts).             | `{}`    |
 | `alerting.email`       | Configuration for alerts of type `email`. <br />See [Configuring Email alerts](#configuring-email-alerts).                   | `{}`    |
 | `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.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).    | `{}`    |
@@ -550,6 +552,47 @@ endpoints:
 
 ![GitHub alert](.github/assets/github-alerts.png)
 
+#### Configuring GitLab alerts
+| Parameter                           | Description                                                                                                | Default       |
+|:------------------------------------|:----------------------------------------------------------------------------------------------------------------|:--------------|
+| `alerting.gitlab`                   | Configuration for alerts of type `gitlab`                                                                       | `{}`          |
+| `alerting.gitlab.webhook-url`       | GitLab alert webhook URL (e.g. `https://gitlab.com/hlidotbe/example/alerts/notify/gatus/xxxxxxxxxxxxxxxx.json`) | Required `""` |
+| `alerting.gitlab.authorization-key` | Personal access token to use for authentication. <br />Must have at least RW on issues and RO on metadata.      | Required `""` |
+| `alerting.gitlab.severity`          | Override default severity (critical), can be one of `critical, high, medium, low, info, unknown`                | `""`          |
+| `alerting.gitlab.monitoring-tool`   | Override the monitoring tool name (gatus)                                                                       | `"gatus"`     |
+| `alerting.gitlab.environment-name`  | Set gitlab environment's name. Required to display alerts on a dashboard.                                       | `""`          |
+| `alerting.gitlab.service`           | Override endpoint displayname                                                                                   | `""` |
+| `alerting.gitlab.default-alert`     | Default alert configuration. <br />See [Setting a default alert](#setting-a-default-alert).                     | N/A           |
+
+The GitLab alerting provider creates an alert prefixed with `🚨 (gatus):` and suffixed with the endpoint's display
+name for each alert. If `send-on-resolved` is set to `true` on the endpoint alert, the alert will be automatically
+closed when the alert is resolved. See
+https://docs.gitlab.com/ee/operations/incident_management/integrations.html#configuration to configure the endpoint.
+
+```yaml
+alerting:
+  gitlab:
+    webhook-url: "https://gitlab.com/hlidotbe/example/alerts/notify/gatus/xxxxxxxxxxxxxxxx.json"
+    authorization-key: "12345"
+
+endpoints:
+  - name: example
+    url: "https://twin.sh/health"
+    interval: 5m
+    conditions:
+      - "[STATUS] == 200"
+      - "[BODY].status == UP"
+      - "[RESPONSE_TIME] < 75"
+    alerts:
+      - type: gitlab
+        failure-threshold: 2
+        success-threshold: 3
+        send-on-resolved: true
+        description: "Everything's burning AAAAAHHHHHHHHHHHHHHH"
+```
+
+![GitLab alert](.github/assets/gitlab-alerts.png)
+
 
 #### Configuring Google Chat alerts
 | Parameter                                     | Description                                                                                 | Default       |

alerting/alert/type.go

@@ -17,6 +17,9 @@ const (
 	// TypeGitHub is the Type for the github alerting provider
 	TypeGitHub Type = "github"
 
+	// TypeGitLab is the Type for the gitlab alerting provider
+	TypeGitLab Type = "gitlab"
+
 	// TypeGoogleChat is the Type for the googlechat alerting provider
 	TypeGoogleChat Type = "googlechat"
 

alerting/config.go

@@ -11,6 +11,7 @@ import (
 	"github.com/TwiN/gatus/v5/alerting/provider/discord"
 	"github.com/TwiN/gatus/v5/alerting/provider/email"
 	"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/matrix"
 	"github.com/TwiN/gatus/v5/alerting/provider/mattermost"
@@ -39,6 +40,9 @@ type Config struct {
 	// GitHub is the configuration for the github alerting provider
 	GitHub *github.AlertProvider `yaml:"github,omitempty"`
 
+	// GitLab is the configuration for the gitlab alerting provider
+	GitLab *gitlab.AlertProvider `yaml:"gitlab,omitempty"`
+
 	// GoogleChat is the configuration for the googlechat alerting provider
 	GoogleChat *googlechat.AlertProvider `yaml:"googlechat,omitempty"`
 

alerting/provider/gitlab/gitlab.go

@@ -0,0 +1,147 @@
+package gitlab
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+	"net/url"
+	"time"
+
+	"github.com/TwiN/gatus/v5/alerting/alert"
+	"github.com/TwiN/gatus/v5/client"
+	"github.com/TwiN/gatus/v5/core"
+	"github.com/google/uuid"
+)
+
+// AlertProvider is the configuration necessary for sending an alert using GitLab
+type AlertProvider struct {
+	WebhookURL       string `yaml:"webhook-url"`       // The webhook url provided by GitLab
+	AuthorizationKey string `yaml:"authorization-key"` // The authorization key provided by GitLab
+
+	// DefaultAlert is the default alert configuration to use for endpoints with an alert of the appropriate type
+	DefaultAlert *alert.Alert `yaml:"default-alert,omitempty"`
+
+	// Severity can be one of: critical, high, medium, low, info, unknown. Defaults to critical
+	Severity string `yaml:"severity,omitempty"`
+	// MonitoringTool overrides the name sent to gitlab. Defaults to gatus
+	MonitoringTool string `yaml:"monitoring-tool,omitempty"`
+	// EnvironmentName is the name of the associated GitLab environment. Required to display alerts on a dashboard.
+	EnvironmentName string `yaml:"environment-name,omitempty"`
+	// Service affected. Defaults to endpoint display name
+	Service string `yaml:"service,omitempty"`
+}
+
+// IsValid returns whether the provider's configuration is valid
+func (provider *AlertProvider) IsValid() bool {
+	if len(provider.AuthorizationKey) == 0 || len(provider.WebhookURL) == 0 {
+		return false
+	}
+	// Validate format of the repository URL
+	_, err := url.Parse(provider.WebhookURL)
+	if err != nil {
+		return false
+	}
+	return true
+}
+
+// Send creates an issue in the designed RepositoryURL if the resolved parameter passed is false,
+// or closes the relevant issue(s) if the resolved parameter passed is true.
+func (provider *AlertProvider) Send(endpoint *core.Endpoint, alert *alert.Alert, result *core.Result, resolved bool) error {
+	if len(alert.ResolveKey) == 0 {
+		alert.ResolveKey = uuid.NewString()
+	}
+
+	buffer := bytes.NewBuffer(provider.buildAlertBody(endpoint, alert, result, resolved))
+	request, err := http.NewRequest(http.MethodPost, provider.WebhookURL, buffer)
+	if err != nil {
+		return err
+	}
+	request.Header.Set("Content-Type", "application/json")
+	request.Header.Set("Authorization", fmt.Sprintf("Bearer %s", provider.AuthorizationKey))
+	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("call to provider alert returned status code %d: %s", response.StatusCode, string(body))
+	}
+	return err
+}
+
+type AlertBody struct {
+	Title                 string `json:"title,omitempty"`                   // The title of the alert.
+	Description           string `json:"description,omitempty"`             // A high-level summary of the problem.
+	StartTime             string `json:"start_time,omitempty"`              // The time of the alert. If none is provided, a current time is used.
+	EndTime               string `json:"end_time,omitempty"`                // The resolution time of the alert. If provided, the alert is resolved.
+	Service               string `json:"service,omitempty"`                 // The affected service.
+	MonitoringTool        string `json:"monitoring_tool,omitempty"`         // The name of the associated monitoring tool.
+	Hosts                 string `json:"hosts,omitempty"`                   // One or more hosts, as to where this incident occurred.
+	Severity              string `json:"severity,omitempty"`                // The severity of the alert. Case-insensitive. Can be one of: critical, high, medium, low, info, unknown. Defaults to critical if missing or value is not in this list.
+	Fingerprint           string `json:"fingerprint,omitempty"`             // The unique identifier of the alert. This can be used to group occurrences of the same alert.
+	GitlabEnvironmentName string `json:"gitlab_environment_name,omitempty"` // The name of the associated GitLab environment. Required to display alerts on a dashboard.
+}
+
+func (provider *AlertProvider) monitoringTool() string {
+	if len(provider.MonitoringTool) > 0 {
+		return provider.MonitoringTool
+	}
+	return "gatus"
+}
+
+func (provider *AlertProvider) service(endpoint *core.Endpoint) string {
+	if len(provider.Service) > 0 {
+		return provider.Service
+	}
+	return endpoint.DisplayName()
+}
+
+// buildAlertBody builds the body of the alert
+func (provider *AlertProvider) buildAlertBody(endpoint *core.Endpoint, alert *alert.Alert, result *core.Result, resolved bool) []byte {
+	body := AlertBody{
+		Title:                 fmt.Sprintf("alert(%s): %s", provider.monitoringTool(), provider.service(endpoint)),
+		StartTime:             result.Timestamp.Format(time.RFC3339),
+		Service:               provider.service(endpoint),
+		MonitoringTool:        provider.monitoringTool(),
+		Hosts:                 endpoint.URL,
+		GitlabEnvironmentName: provider.EnvironmentName,
+		Severity:              provider.Severity,
+		Fingerprint:           alert.ResolveKey,
+	}
+	if resolved {
+		body.EndTime = result.Timestamp.Format(time.RFC3339)
+	}
+
+	var results string
+	for _, conditionResult := range result.ConditionResults {
+		var prefix string
+		if conditionResult.Success {
+			prefix = ":white_check_mark:"
+		} else {
+			prefix = ":x:"
+		}
+		results += fmt.Sprintf("- %s - `%s`\n", prefix, conditionResult.Condition)
+	}
+	var description string
+	if alertDescription := alert.GetDescription(); len(alertDescription) > 0 {
+		description = ":\n> " + alertDescription
+	}
+	var message 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)
+	}
+	body.Description = message + description + "\n\n## Condition results\n" + results
+
+	json, _ := json.Marshal(body)
+	return json
+}
+
+// GetDefaultAlert returns the provider's default alert configuration
+func (provider AlertProvider) GetDefaultAlert() *alert.Alert {
+	return provider.DefaultAlert
+}

alerting/provider/gitlab/gitlab_test.go

@@ -0,0 +1,158 @@
+package gitlab
+
+import (
+	"net/http"
+	"strings"
+	"testing"
+
+	"github.com/TwiN/gatus/v5/alerting/alert"
+	"github.com/TwiN/gatus/v5/client"
+	"github.com/TwiN/gatus/v5/core"
+	"github.com/TwiN/gatus/v5/test"
+)
+
+func TestAlertDefaultProvider_IsValid(t *testing.T) {
+	scenarios := []struct {
+		Name     string
+		Provider AlertProvider
+		Expected bool
+	}{
+		{
+			Name:     "invalid",
+			Provider: AlertProvider{WebhookURL: "", AuthorizationKey: ""},
+			Expected: false,
+		},
+		{
+			Name:     "missing-webhook-url",
+			Provider: AlertProvider{WebhookURL: "", AuthorizationKey: "12345"},
+			Expected: false,
+		},
+		{
+			Name:     "missing-authorization-key",
+			Provider: AlertProvider{WebhookURL: "https://gitlab.com/hlidotbe/text/alerts/notify/gatus/xxxxxxxxxxxxxxxx.json", AuthorizationKey: ""},
+			Expected: false,
+		},
+		{
+			Name:     "invalid-url",
+			Provider: AlertProvider{WebhookURL: " http://foo.com", AuthorizationKey: "12345"},
+			Expected: false,
+		},
+	}
+	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_Send(t *testing.T) {
+	defer client.InjectHTTPClient(nil)
+	firstDescription := "description-1"
+	secondDescription := "description-2"
+	scenarios := []struct {
+		Name             string
+		Provider         AlertProvider
+		Alert            alert.Alert
+		Resolved         bool
+		MockRoundTripper test.MockRoundTripper
+		ExpectedError    bool
+	}{
+		{
+			Name:          "triggered-error",
+			Provider:      AlertProvider{WebhookURL: "https://gitlab.com/hlidotbe/text/alerts/notify/gatus/xxxxxxxxxxxxxxxx.json", AuthorizationKey: "12345"},
+			Alert:         alert.Alert{Description: &firstDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:      false,
+			ExpectedError: false,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusOK, Body: http.NoBody}
+			}),
+		},
+		{
+			Name:          "resolved-error",
+			Provider:      AlertProvider{WebhookURL: "https://gitlab.com/hlidotbe/text/alerts/notify/gatus/xxxxxxxxxxxxxxxx.json", AuthorizationKey: "12345"},
+			Alert:         alert.Alert{Description: &secondDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:      true,
+			ExpectedError: false,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusOK, Body: http.NoBody}
+			}),
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(scenario.Name, func(t *testing.T) {
+			client.InjectHTTPClient(&http.Client{Transport: scenario.MockRoundTripper})
+			err := scenario.Provider.Send(
+				&core.Endpoint{Name: "endpoint-name", Group: "endpoint-group"},
+				&scenario.Alert,
+				&core.Result{
+					ConditionResults: []*core.ConditionResult{
+						{Condition: "[CONNECTED] == true", Success: scenario.Resolved},
+						{Condition: "[STATUS] == 200", Success: scenario.Resolved},
+					},
+				},
+				scenario.Resolved,
+			)
+			if scenario.ExpectedError && err == nil {
+				t.Error("expected error, got none")
+			}
+			if !scenario.ExpectedError && err != nil {
+				t.Error("expected no error, got", err.Error())
+			}
+		})
+	}
+}
+
+func TestAlertProvider_buildAlertBody(t *testing.T) {
+	firstDescription := "description-1"
+	scenarios := []struct {
+		Name         string
+		Endpoint     core.Endpoint
+		Provider     AlertProvider
+		Alert        alert.Alert
+		ExpectedBody string
+	}{
+		{
+			Name:         "triggered",
+			Endpoint:     core.Endpoint{Name: "endpoint-name", URL: "https://example.org"},
+			Provider:     AlertProvider{},
+			Alert:        alert.Alert{Description: &firstDescription, FailureThreshold: 3},
+			ExpectedBody: "{\"title\":\"alert(gatus): endpoint-name\",\"description\":\"An alert for *endpoint-name* has been triggered due to having failed 3 time(s) in a row:\\n\\u003e description-1\\n\\n## Condition results\\n- :white_check_mark: - `[CONNECTED] == true`\\n- :x: - `[STATUS] == 200`\\n\",\"start_time\":\"0001-01-01T00:00:00Z\",\"service\":\"endpoint-name\",\"monitoring_tool\":\"gatus\",\"hosts\":\"https://example.org\"}",
+		},
+		{
+			Name:         "no-description",
+			Endpoint:     core.Endpoint{Name: "endpoint-name", URL: "https://example.org"},
+			Provider:     AlertProvider{},
+			Alert:        alert.Alert{FailureThreshold: 10},
+			ExpectedBody: "{\"title\":\"alert(gatus): endpoint-name\",\"description\":\"An alert for *endpoint-name* has been triggered due to having failed 10 time(s) in a row\\n\\n## Condition results\\n- :white_check_mark: - `[CONNECTED] == true`\\n- :x: - `[STATUS] == 200`\\n\",\"start_time\":\"0001-01-01T00:00:00Z\",\"service\":\"endpoint-name\",\"monitoring_tool\":\"gatus\",\"hosts\":\"https://example.org\"}",
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(scenario.Name, func(t *testing.T) {
+			body := scenario.Provider.buildAlertBody(
+				&scenario.Endpoint,
+				&scenario.Alert,
+				&core.Result{
+					ConditionResults: []*core.ConditionResult{
+						{Condition: "[CONNECTED] == true", Success: true},
+						{Condition: "[STATUS] == 200", Success: false},
+					},
+				},
+				false,
+			)
+			if strings.TrimSpace(string(body)) != strings.TrimSpace(scenario.ExpectedBody) {
+				t.Errorf("expected:\n%s\ngot:\n%s", scenario.ExpectedBody, body)
+			}
+		})
+	}
+}
+
+func TestAlertProvider_GetDefaultAlert(t *testing.T) {
+	if (AlertProvider{DefaultAlert: &alert.Alert{}}).GetDefaultAlert() == nil {
+		t.Error("expected default alert to be not nil")
+	}
+	if (AlertProvider{DefaultAlert: nil}).GetDefaultAlert() != nil {
+		t.Error("expected default alert to be nil")
+	}
+}

alerting/provider/provider.go

@@ -6,6 +6,7 @@ import (
 	"github.com/TwiN/gatus/v5/alerting/provider/discord"
 	"github.com/TwiN/gatus/v5/alerting/provider/email"
 	"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/matrix"
 	"github.com/TwiN/gatus/v5/alerting/provider/mattermost"
@@ -61,6 +62,7 @@ var (
 	_ AlertProvider = (*discord.AlertProvider)(nil)
 	_ AlertProvider = (*email.AlertProvider)(nil)
 	_ AlertProvider = (*github.AlertProvider)(nil)
+	_ AlertProvider = (*gitlab.AlertProvider)(nil)
 	_ AlertProvider = (*googlechat.AlertProvider)(nil)
 	_ AlertProvider = (*matrix.AlertProvider)(nil)
 	_ AlertProvider = (*mattermost.AlertProvider)(nil)

config/config.go

@@ -364,6 +364,7 @@ func validateAlertingConfig(alertingConfig *alerting.Config, endpoints []*core.E
 		alert.TypeCustom,
 		alert.TypeDiscord,
 		alert.TypeGitHub,
+		alert.TypeGitLab,
 		alert.TypeGoogleChat,
 		alert.TypeEmail,
 		alert.TypeMatrix,