Pre-start checks/scripts can be defined.

src/main.cr

@@ -36,6 +36,13 @@ class ServiceDefinition
 			token: String
 		})
 	end
+	struct Checks
+		YAML.mapping({
+			name: String,
+			file: String, # FIXME: -> String? and add directory:?
+			command: String
+		})
+	end
 	YAML.mapping({
 		name: String,
 		command: String,
@@ -55,6 +62,10 @@ class ServiceDefinition
 		consumes: {
 			type: Array(Consumes),
 			default: [] of Consumes
+		},
+		checks: {
+			type: Array(Checks),
+			default: [] of Checks
 		}
 	})
 
@@ -222,6 +233,24 @@ class Service
 	end
 
 	def start(pid_dir : String, log_dir : String)
+		@reference.checks.each do |check|
+			run_check = false
+
+			# Other tests will likely come later.
+			if check.file && ! File.exists? check.file
+				run_check = true
+			end
+
+			unless run_check
+				next
+			end
+
+			puts "  - #{check.name}"
+
+			# FIXME: Output? Only in debug mode?
+			Process.run "sh", ["-c", check.command], output: Process::Redirect::Inherit, error: Process::Redirect::Inherit
+		end
+
 		command, args = split_command command
 
 		process = Process.fork do