[feature] Implement `/api/v1/instance/peers` endpoint (#660)

* add missing license headers

* start adding instance peers get

* rename domainblock.go

* embed domain in domainblock so it can be reused

* update swagger docs

* add test instances to db

* update tests

* add/update instancepeersget

* update domain model

* add getinstancepeers to db

* instance-expose-peers, instance-expose-suspended

* add auth checks for both current filters

* attach endpoint to router

* include public comment

* obfuscate domain if required

* go mod tidy

* update swagger docs

* remove unnecessary comment

* return 'flat' peerlist if no query params provided

2 files changed, 22 insertions, 0 deletions

diff --git a/internal/db/bundb/instance.go b/internal/db/bundb/instance.go
index d16fac90b..c8a9c5776 100644
--- a/internal/db/bundb/instance.go
+++ b/internal/db/bundb/instance.go
@@ -98,6 +98,25 @@ func (i *instanceDB) CountInstanceDomains(ctx context.Context, domain string) (i
 	return count, nil
 }
 
+func (i *instanceDB) GetInstancePeers(ctx context.Context, includeSuspended bool) ([]*gtsmodel.Instance, db.Error) {
+	instances := []*gtsmodel.Instance{}
+
+	q := i.conn.
+		NewSelect().
+		Model(&instances).
+		Where("domain != ?", config.GetHost())
+
+	if !includeSuspended {
+		q = q.Where("? IS NULL", bun.Ident("suspended_at"))
+	}
+
+	if err := q.Scan(ctx); err != nil {
+		return nil, i.conn.ProcessError(err)
+	}
+
+	return instances, nil
+}
+
 func (i *instanceDB) GetInstanceAccounts(ctx context.Context, domain string, maxID string, limit int) ([]*gtsmodel.Account, db.Error) {
 	logrus.Debug("GetAccountsForInstance")
 
diff --git a/internal/db/instance.go b/internal/db/instance.go
index 45ff7d7b4..9e69d1b9b 100644
--- a/internal/db/instance.go
+++ b/internal/db/instance.go
@@ -37,4 +37,7 @@ type Instance interface {
 
 	// GetInstanceAccounts returns a slice of accounts from the given instance, arranged by ID.
 	GetInstanceAccounts(ctx context.Context, domain string, maxID string, limit int) ([]*gtsmodel.Account, Error)
+
+	// GetInstancePeers returns a slice of instances that the host instance knows about.
+	GetInstancePeers(ctx context.Context, includeSuspended bool) ([]*gtsmodel.Instance, Error)
 }