Praefect: add basic framework for adding praefect startup checks

This commit provides a simple framework for praefect cluster checks that
can warn the user if there is a problem with their setup. These checks
will be consumed by a subcommand.

Changelog: added

1 files changed, 34 insertions, 0 deletions

diff --git a/internal/praefect/checks.go b/internal/praefect/checks.go
new file mode 100644
index 000000000..2da522ad9
--- /dev/null
+++ b/internal/praefect/checks.go
@@ -0,0 +1,34 @@
+package praefect
+
+import (
+	"fmt"
+
+	migrate "github.com/rubenv/sql-migrate"
+	"gitlab.com/gitlab-org/gitaly/v14/internal/praefect/config"
+	"gitlab.com/gitlab-org/gitaly/v14/internal/praefect/datastore/glsql"
+	"gitlab.com/gitlab-org/gitaly/v14/internal/praefect/datastore/migrations"
+)
+
+// Severity is a type that indicates the severity of a check
+type Severity string
+
+const (
+	// Warning indicates a severity level of warning
+	Warning Severity = "warning"
+	// Fatal indicates a severity level of fatal
+	// any checks that are Fatal will prevent Praefect from starting up
+	Fatal = "fatal"
+)
+
+// Check is a struct representing a check on the health of a Gitaly cluster's setup. These are separate from the "healthcheck"
+// concept which is more concerned with the health of the praefect service. These checks are meant to diagnose any issues with
+// the praefect cluster setup itself and will be run on startup/restarts.
+type Check struct {
+	Run         func() error
+	Name        string
+	Description string
+	Severity    Severity
+}
+
+// CheckFunc is a function type that takes a praefect config and returns a Check
+type CheckFunc func(conf config.Config) *Check