fix: make MailTemplate the mail method receiver.

fix: add subject to mail configuration.
fix: change naming scheme from MailInfo to CommitmentGroupNotification

internal/api/commitment.go

@@ -150,11 +150,11 @@ func (p *v1Provider) GetProjectCommitments(w http.ResponseWriter, r *http.Reques
 	filter := reports.ReadFilter(r, p.Cluster)
 	queryStr, joinArgs := filter.PrepareQuery(getProjectAZResourceLocationsQuery)
 	whereStr, whereArgs := db.BuildSimpleWhereClause(map[string]any{"ps.project_id": dbProject.ID}, len(joinArgs))
-	azResourceLocationsByID := make(map[db.ProjectAZResourceID]datamodel.AZResourceLocation)
+	azResourceLocationsByID := make(map[db.ProjectAZResourceID]core.AZResourceLocation)
 	err := sqlext.ForeachRow(p.DB, fmt.Sprintf(queryStr, whereStr), append(joinArgs, whereArgs...), func(rows *sql.Rows) error {
 		var (
 			id  db.ProjectAZResourceID
-			loc datamodel.AZResourceLocation
+			loc core.AZResourceLocation
 		)
 		err := rows.Scan(&id, &loc.ServiceType, &loc.ResourceName, &loc.AvailabilityZone)
 		if err != nil {
@@ -193,7 +193,7 @@ func (p *v1Provider) GetProjectCommitments(w http.ResponseWriter, r *http.Reques
 	respondwith.JSON(w, http.StatusOK, map[string]any{"commitments": result})
 }
 
-func (p *v1Provider) convertCommitmentToDisplayForm(c db.ProjectCommitment, loc datamodel.AZResourceLocation, token *gopherpolicy.Token) limesresources.Commitment {
+func (p *v1Provider) convertCommitmentToDisplayForm(c db.ProjectCommitment, loc core.AZResourceLocation, token *gopherpolicy.Token) limesresources.Commitment {
 	resInfo := p.Cluster.InfoForResource(loc.ServiceType, loc.ResourceName)
 	apiIdentity := p.Cluster.BehaviorForResource(loc.ServiceType, loc.ResourceName).IdentityInV1API
 	return limesresources.Commitment{
@@ -216,7 +216,7 @@ func (p *v1Provider) convertCommitmentToDisplayForm(c db.ProjectCommitment, loc
 	}
 }
 
-func (p *v1Provider) parseAndValidateCommitmentRequest(w http.ResponseWriter, r *http.Request) (*limesresources.CommitmentRequest, *datamodel.AZResourceLocation, *core.ResourceBehavior) {
+func (p *v1Provider) parseAndValidateCommitmentRequest(w http.ResponseWriter, r *http.Request) (*limesresources.CommitmentRequest, *core.AZResourceLocation, *core.ResourceBehavior) {
 	// parse request
 	var parseTarget struct {
 		Request limesresources.CommitmentRequest `json:"commitment"`
@@ -262,7 +262,7 @@ func (p *v1Provider) parseAndValidateCommitmentRequest(w http.ResponseWriter, r
 		return nil, nil, nil
 	}
 
-	loc := datamodel.AZResourceLocation{
+	loc := core.AZResourceLocation{
 		ServiceType:      dbServiceType,
 		ResourceName:     dbResourceName,
 		AvailabilityZone: req.AvailabilityZone,
@@ -476,7 +476,7 @@ func (p *v1Provider) DeleteProjectCommitment(w http.ResponseWriter, r *http.Requ
 	} else if respondwith.ErrorText(w, err) {
 		return
 	}
-	var loc datamodel.AZResourceLocation
+	var loc core.AZResourceLocation
 	err = p.DB.QueryRow(findProjectAZResourceLocationByIDQuery, dbCommitment.AZResourceID).
 		Scan(&loc.ServiceType, &loc.ResourceName, &loc.AvailabilityZone)
 	if errors.Is(err, sql.ErrNoRows) {
@@ -630,7 +630,7 @@ func (p *v1Provider) StartCommitmentTransfer(w http.ResponseWriter, r *http.Requ
 		return
 	}
 
-	var loc datamodel.AZResourceLocation
+	var loc core.AZResourceLocation
 	err = p.DB.QueryRow(findProjectAZResourceLocationByIDQuery, dbCommitment.AZResourceID).
 		Scan(&loc.ServiceType, &loc.ResourceName, &loc.AvailabilityZone)
 	if errors.Is(err, sql.ErrNoRows) {
@@ -702,7 +702,7 @@ func (p *v1Provider) GetCommitmentByTransferToken(w http.ResponseWriter, r *http
 		return
 	}
 
-	var loc datamodel.AZResourceLocation
+	var loc core.AZResourceLocation
 	err = p.DB.QueryRow(findProjectAZResourceLocationByIDQuery, dbCommitment.AZResourceID).
 		Scan(&loc.ServiceType, &loc.ResourceName, &loc.AvailabilityZone)
 	if errors.Is(err, sql.ErrNoRows) {
@@ -753,7 +753,7 @@ func (p *v1Provider) TransferCommitment(w http.ResponseWriter, r *http.Request)
 		return
 	}
 
-	var loc datamodel.AZResourceLocation
+	var loc core.AZResourceLocation
 	err = p.DB.QueryRow(findProjectAZResourceLocationByIDQuery, dbCommitment.AZResourceID).
 		Scan(&loc.ServiceType, &loc.ResourceName, &loc.AvailabilityZone)
 	if errors.Is(err, sql.ErrNoRows) {
@@ -918,7 +918,7 @@ func (p *v1Provider) ConvertCommitment(w http.ResponseWriter, r *http.Request) {
 	} else if respondwith.ErrorText(w, err) {
 		return
 	}
-	var sourceLoc datamodel.AZResourceLocation
+	var sourceLoc core.AZResourceLocation
 	err = p.DB.QueryRow(findProjectAZResourceLocationByIDQuery, dbCommitment.AZResourceID).
 		Scan(&sourceLoc.ServiceType, &sourceLoc.ResourceName, &sourceLoc.AvailabilityZone)
 	if errors.Is(err, sql.ErrNoRows) {
@@ -1006,7 +1006,7 @@ func (p *v1Provider) ConvertCommitment(w http.ResponseWriter, r *http.Request) {
 		http.Error(w, "conversion attempt to the same resource.", http.StatusConflict)
 		return
 	}
-	targetLoc := datamodel.AZResourceLocation{
+	targetLoc := core.AZResourceLocation{
 		ServiceType:      targetServiceType,
 		ResourceName:     targetResourceName,
 		AvailabilityZone: sourceLoc.AvailabilityZone,
@@ -1134,7 +1134,7 @@ func (p *v1Provider) UpdateCommitmentDuration(w http.ResponseWriter, r *http.Req
 		return
 	}
 
-	var loc datamodel.AZResourceLocation
+	var loc core.AZResourceLocation
 	err = p.DB.QueryRow(findProjectAZResourceLocationByIDQuery, dbCommitment.AZResourceID).
 		Scan(&loc.ServiceType, &loc.ResourceName, &loc.AvailabilityZone)
 	if errors.Is(err, sql.ErrNoRows) {

internal/collector/capacity_scrape.go

@@ -33,6 +33,7 @@ import (
 	"github.com/sapcc/go-bits/logg"
 	"github.com/sapcc/go-bits/sqlext"
 
+	"github.com/sapcc/limes/internal/core"
 	"github.com/sapcc/limes/internal/datamodel"
 	"github.com/sapcc/limes/internal/db"
 	"github.com/sapcc/limes/internal/util"
@@ -383,7 +384,7 @@ func (c *Collector) confirmPendingCommitmentsIfNecessary(serviceType db.ServiceT
 		committableAZs = []liquid.AvailabilityZone{liquid.AvailabilityZoneAny}
 	}
 	for _, az := range committableAZs {
-		loc := datamodel.AZResourceLocation{
+		loc := core.AZResourceLocation{
 			ServiceType:      serviceType,
 			ResourceName:     resourceName,
 			AvailabilityZone: az,

internal/collector/capacity_scrape_test.go

@@ -133,7 +133,9 @@ const (
 			# test automatic project quota calculation with non-default settings on */capacity resources
 			- { resource: '.*/capacity', model: autogrow, autogrow: { growth_multiplier: 1.0, project_base_quota: 10, usage_data_retention_period: 1m } }
 		mail_templates:
-			confirmed_commitments: "Domain:{{ .DomainName }} Project:{{ .ProjectName }}{{ range .Commitments }} Creator:{{ .Commitment.CreatorName }} Amount:{{ .Commitment.Amount }} Duration:{{ .Commitment.Duration }} Date:{{ .Date }} Service:{{ .Resource.ServiceType }} Resource:{{ .Resource.ResourceName }} AZ:{{ .Resource.AvailabilityZone }}{{ end }}"
+			confirmed_commitments:
+				subject: "Your recent commitment confirmations"
+				body: "Domain:{{ .DomainName }} Project:{{ .ProjectName }}{{ range .Commitments }} Creator:{{ .Commitment.CreatorName }} Amount:{{ .Commitment.Amount }} Duration:{{ .Commitment.Duration }} Date:{{ .DateString }} Service:{{ .Resource.ServiceType }} Resource:{{ .Resource.ResourceName }} AZ:{{ .Resource.AvailabilityZone }}{{ end }}"
 	`
 )
 

internal/collector/expiring_commitments.go

@@ -30,7 +30,7 @@ import (
 	"github.com/sapcc/go-bits/jobloop"
 	"github.com/sapcc/go-bits/sqlext"
 
-	"github.com/sapcc/limes/internal/datamodel"
+	"github.com/sapcc/limes/internal/core"
 	"github.com/sapcc/limes/internal/db"
 )
 
@@ -55,7 +55,7 @@ func (c *Collector) ExpiringCommitmentNotificationJob(registerer prometheus.Regi
 }
 
 type ExpiringCommitments struct {
-	Notifications        map[db.ProjectID][]datamodel.CommitmentInfo
+	Notifications        map[db.ProjectID][]core.CommitmentNotification
 	NextSubmission       time.Time
 	ShortTermCommitments []db.ProjectCommitmentID // to be excluded from mail notifications.
 }
@@ -79,14 +79,14 @@ func (c *Collector) discoverExpiringCommitments(_ context.Context, _ prometheus.
 	now := c.MeasureTime()
 	cutoff := now.Add(expiringCommitmentsNoticePeriod)
 	commitments := ExpiringCommitments{
-		Notifications:  make(map[db.ProjectID][]datamodel.CommitmentInfo),
+		Notifications:  make(map[db.ProjectID][]core.CommitmentNotification),
 		NextSubmission: now.Add(c.AddJitter(nextSumbissionInteval)),
 	}
 
 	var shortTermCommitments []db.ProjectCommitmentID
 	err := sqlext.ForeachRow(c.DB, findExpiringCommitmentsQuery, []any{cutoff}, func(rows *sql.Rows) error {
 		var pid db.ProjectID
-		var info datamodel.CommitmentInfo
+		var info core.CommitmentNotification
 		err := rows.Scan(
 			&pid,
 			&info.Resource.ServiceType, &info.Resource.ResourceName, &info.Resource.AvailabilityZone,
@@ -95,7 +95,7 @@ func (c *Collector) discoverExpiringCommitments(_ context.Context, _ prometheus.
 		if err != nil {
 			return err
 		}
-		info.Date = info.Commitment.ExpiresAt.Format(time.DateOnly)
+		info.DateString = info.Commitment.ExpiresAt.Format(time.DateOnly)
 		if info.Commitment.Duration.AddTo(now).Before(cutoff) {
 			shortTermCommitments = append(shortTermCommitments, info.Commitment.ID)
 		} else {
@@ -113,6 +113,7 @@ func (c *Collector) discoverExpiringCommitments(_ context.Context, _ prometheus.
 }
 
 func (c *Collector) processExpiringCommitmentTask(ctx context.Context, task ExpiringCommitments, _ prometheus.Labels) error {
+	template := c.Cluster.Config.MailTemplates.ExpiringCommitments
 	tx, err := c.DB.Begin()
 	if err != nil {
 		return err
@@ -131,14 +132,14 @@ func (c *Collector) processExpiringCommitmentTask(ctx context.Context, task Expi
 	projectIDs := slices.Collect(maps.Keys(task.Notifications))
 	sort.Slice(projectIDs, func(i, j int) bool { return projectIDs[i] < projectIDs[j] })
 	for _, projectID := range projectIDs {
-		var mailInfo datamodel.MailInfo
+		var notification core.CommitmentGroupNotification
 		commitments := task.Notifications[projectID]
-		err := tx.QueryRow("SELECT d.name, p.name FROM domains d JOIN projects p ON d.id = p.domain_id where p.id = $1", projectID).Scan(&mailInfo.DomainName, &mailInfo.ProjectName)
+		err := tx.QueryRow("SELECT d.name, p.name FROM domains d JOIN projects p ON d.id = p.domain_id where p.id = $1", projectID).Scan(&notification.DomainName, &notification.ProjectName)
 		if err != nil {
 			return err
 		}
-		mailInfo.Commitments = commitments
-		mail, err := mailInfo.CreateMailNotification(c.Cluster.MailTemplates.ExpiringCommitments, "Information about expiring commitments", projectID, task.NextSubmission)
+		notification.Commitments = commitments
+		mail, err := template.Render(notification, projectID, task.NextSubmission)
 		if err != nil {
 			return err
 		}

internal/collector/expiring_commitments_test.go

@@ -43,7 +43,9 @@ const (
 				capacity: 0
 				resources: []
 		mail_templates:
-			expiring_commitments: "Domain:{{ .DomainName }} Project:{{ .ProjectName }}{{ range .Commitments }} Creator:{{ .Commitment.CreatorName }} Amount:{{ .Commitment.Amount }} Duration:{{ .Commitment.Duration }} Date:{{ .Date }} Service:{{ .Resource.ServiceType }} Resource:{{ .Resource.ResourceName }} AZ:{{ .Resource.AvailabilityZone }}{{ end }}"
+			expiring_commitments: 
+				subject: "Information about expiring commitments"
+				body: "Domain:{{ .DomainName }} Project:{{ .ProjectName }}{{ range .Commitments }} Creator:{{ .Commitment.CreatorName }} Amount:{{ .Commitment.Amount }} Duration:{{ .Commitment.Duration }} Date:{{ .DateString }} Service:{{ .Resource.ServiceType }} Resource:{{ .Resource.ResourceName }} AZ:{{ .Resource.AvailabilityZone }}{{ end }}"
 `
 )
 
@@ -70,8 +72,8 @@ func Test_ExpiringCommitmentNotification(t *testing.T) {
 	`, c.MeasureTime().Add(nextSumbissionInteval).Unix())
 
 	// mail queue with an empty template should fail
-	mailTemplates := s.Cluster.MailTemplates
-	s.Cluster.MailTemplates = core.MailTemplates{ExpiringCommitments: template.New("")}
+	mailTemplates := s.Cluster.Config.MailTemplates
+	s.Cluster.Config.MailTemplates = core.MailTemplateConfiguration{ExpiringCommitments: core.MailTemplate{Compiled: template.New("")}}
 	// commitments that are already sent out for a notification are not visible in the result set anymore - a new one gets created.
 	_, err := s.DB.Exec("INSERT INTO project_commitments (id, az_resource_id, amount, created_at, creator_uuid, creator_name, duration, expires_at, state) VALUES (99, 1, 10, UNIX(0), 'dummy', 'dummy', '1 year', UNIX(0), 'expired');")
 	tr.DBChanges().Ignore()
@@ -80,14 +82,14 @@ func Test_ExpiringCommitmentNotification(t *testing.T) {
 	if err == nil {
 		t.Fatal("execution without mail template must fail")
 	}
-	s.Cluster.MailTemplates = core.MailTemplates{ExpiringCommitments: nil}
+	s.Cluster.Config.MailTemplates = core.MailTemplateConfiguration{ExpiringCommitments: core.MailTemplate{Compiled: nil}}
 	err = (job.ProcessOne(s.Ctx))
 	if err == nil {
 		t.Fatal("execution without mail template must fail")
 	}
 
 	// create a notification for the created commitment. Do not send another notification for commitments that are already marked as notified.
-	s.Cluster.MailTemplates = mailTemplates
+	s.Cluster.Config.MailTemplates = mailTemplates
 	mustT(t, job.ProcessOne(s.Ctx))
 	tr.DBChanges().AssertEqualf(`
 		UPDATE project_commitments SET notified_for_expiration = TRUE WHERE id = 99 AND transfer_token = NULL;

internal/core/cluster.go

@@ -44,12 +44,6 @@ type Cluster struct {
 	DiscoveryPlugin DiscoveryPlugin
 	QuotaPlugins    map[db.ServiceType]QuotaPlugin
 	CapacityPlugins map[string]CapacityPlugin
-	MailTemplates   MailTemplates
-}
-
-type MailTemplates struct {
-	ConfirmedCommitments *template.Template
-	ExpiringCommitments  *template.Template
 }
 
 // NewCluster creates a new Cluster instance with the given ID and
@@ -87,16 +81,16 @@ func NewCluster(config ClusterConfiguration) (c *Cluster, errs errext.ErrorSet)
 	}
 
 	// Create mail templates
-	confirmTPl, err := template.New("confirm").Parse(config.MailTemplates.ConfirmedCommitments)
+	confirmTPl, err := template.New("confirm").Parse(config.MailTemplates.ConfirmedCommitments.Body)
 	if err != nil {
 		errs.Addf("could not parse confirmation mail template: %w", err)
 	}
-	c.MailTemplates.ConfirmedCommitments = confirmTPl
-	expireTpl, err := template.New("expire").Parse(config.MailTemplates.ExpiringCommitments)
+	c.Config.MailTemplates.ConfirmedCommitments.Compiled = confirmTPl
+	expireTpl, err := template.New("expire").Parse(config.MailTemplates.ExpiringCommitments.Body)
 	if err != nil {
 		errs.Addf("could not parse expiration mail template: %w", err)
 	}
-	c.MailTemplates.ExpiringCommitments = expireTpl
+	c.Config.MailTemplates.ExpiringCommitments.Compiled = expireTpl
 
 	return c, errs
 }

internal/core/config.go

@@ -149,8 +149,8 @@ type AutogrowQuotaDistributionConfiguration struct {
 }
 
 type MailTemplateConfiguration struct {
-	ConfirmedCommitments string `yaml:"confirmed_commitments"`
-	ExpiringCommitments  string `yaml:"expiring_commitments"`
+	ConfirmedCommitments MailTemplate `yaml:"confirmed_commitments"`
+	ExpiringCommitments  MailTemplate `yaml:"expiring_commitments"`
 }
 
 // NewClusterFromYAML reads and validates the configuration in the given YAML document.

internal/datamodel/commitment_mail_notification.go → internal/core/mail.go

@@ -1,6 +1,6 @@
 /******************************************************************************
 *
-*  Copyright 2025 SAP SE
+*  Copyright 2023 SAP SE
 *
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
@@ -15,7 +15,8 @@
 *  limitations under the License.
 *
 ******************************************************************************/
-package datamodel
+
+package core
 
 import (
 	"bytes"
@@ -24,46 +25,68 @@ import (
 	"text/template"
 	"time"
 
+	"github.com/sapcc/go-api-declarations/limes"
+	"github.com/sapcc/go-api-declarations/liquid"
+
 	"github.com/sapcc/limes/internal/db"
 )
 
-type MailInfo struct {
+// CommitmentGroupNotification contains data for rendering mails notifying about commitment workflows (confirmation or expiration).
+type CommitmentGroupNotification struct {
 	DomainName  string
 	ProjectName string
-	Commitments []CommitmentInfo
+	Commitments []CommitmentNotification
+}
+
+// AZResourceLocation is a tuple identifying an AZ resource within a project.
+type AZResourceLocation struct {
+	ServiceType      db.ServiceType
+	ResourceName     liquid.ResourceName
+	AvailabilityZone limes.AvailabilityZone
 }
 
-type CommitmentInfo struct {
+// CommitmentNotification appears in type CommitmentGroupNotification.
+type CommitmentNotification struct {
 	Commitment db.ProjectCommitment
-	Date       string
+	DateString string
 	Resource   AZResourceLocation
 }
 
-func (m MailInfo) CreateMailNotification(tpl *template.Template, subject string, projectID db.ProjectID, now time.Time) (db.MailNotification, error) {
+type MailTemplate struct {
+	Subject  string             `yaml:"subject"`
+	Body     string             `yaml:"body"`
+	Compiled *template.Template `yaml:"-"` // filled during Config.Validate()
+}
+
+func (t MailTemplate) Render(m CommitmentGroupNotification, projectID db.ProjectID, now time.Time) (db.MailNotification, error) {
 	if len(m.Commitments) == 0 {
 		return db.MailNotification{}, fmt.Errorf("mail: no commitments provided for projectID: %v", projectID)
 	}
 
-	body, err := m.getMailContent(tpl)
+	if t.Subject == "" {
+		return db.MailNotification{}, fmt.Errorf("mail: subject is empty for projectID: %v", projectID)
+	}
+	body, err := t.getMailContent(m)
 	if err != nil {
 		return db.MailNotification{}, err
 	}
 	if body == "" {
-		return db.MailNotification{}, fmt.Errorf("mail: body is empty for projectID: %v", projectID)
+		return db.MailNotification{}, fmt.Errorf("mail: body has no content. Check the mail template. Halted at projectID: %v", projectID)
 	}
 
 	notification := db.MailNotification{
 		ProjectID:        projectID,
-		Subject:          subject,
+		Subject:          t.Subject,
 		Body:             body,
 		NextSubmissionAt: now,
 	}
 
 	return notification, nil
 }
 
-func (m MailInfo) getMailContent(tpl *template.Template) (string, error) {
+func (t MailTemplate) getMailContent(m CommitmentGroupNotification) (string, error) {
 	var ioBuffer bytes.Buffer
+	tpl := t.Compiled
 	if tpl == nil {
 		return "", errors.New("mail: body is empty. Check the accessiblity of the mail template")
 	}