feat: add audit exporting and filtering (#1314)

coderd/audit/filter.go

@@ -0,0 +1,42 @@
+package audit
+
+import (
+	"context"
+
+	"github.com/coder/coder/coderd/database"
+)
+
+// FilterDecision is a bitwise flag describing the actions a given filter allows
+// for a given audit log.
+type FilterDecision uint8
+
+const (
+	// FilterDecisionDrop indicates that the audit log should be dropped. It
+	// should not be stored or exported anywhere.
+	FilterDecisionDrop FilterDecision = 0
+	// FilterDecisionStore indicates that the audit log should be allowed to be
+	// stored in the Coder database.
+	FilterDecisionStore FilterDecision = 1 << iota
+	// FilterDecisionExport indicates that the audit log should be exported
+	// externally of Coder.
+	FilterDecisionExport
+)
+
+// Filters produce a FilterDecision for a given audit log.
+type Filter interface {
+	Check(ctx context.Context, alog database.AuditLog) (FilterDecision, error)
+}
+
+// DefaultFilter is the default filter used when exporting audit logs. It allows
+// storage and exporting for all audit logs.
+var DefaultFilter Filter = FilterFunc(func(ctx context.Context, alog database.AuditLog) (FilterDecision, error) {
+	// Store and export all audit logs for now.
+	return FilterDecisionStore | FilterDecisionExport, nil
+})
+
+// FilterFunc constructs a Filter from a simple function.
+type FilterFunc func(ctx context.Context, alog database.AuditLog) (FilterDecision, error)
+
+func (f FilterFunc) Check(ctx context.Context, alog database.AuditLog) (FilterDecision, error) {
+	return f(ctx, alog)
+}