Feat: Env variables to set health timeouts

- HEALTH_OPENVPN_DURATION_INITIAL
- HEALTH_OPENVPN_DURATION_ADDITION

internal/configuration/healthywait.go

@@ -0,0 +1,30 @@
+package configuration
+
+import (
+	"strings"
+	"time"
+)
+
+type HealthyWait struct {
+	// Initial is the initial duration to wait for the program
+	// to be healthy before taking action.
+	Initial time.Duration
+	// Addition is the duration to add to the Initial duration
+	// after Initial has expired to wait longer for the program
+	// to be healthy.
+	Addition time.Duration
+}
+
+func (settings *HealthyWait) String() string {
+	return strings.Join(settings.lines(), "\n")
+}
+
+func (settings *HealthyWait) lines() (lines []string) {
+	lines = append(lines, lastIndent+"Initial duration: "+settings.Initial.String())
+
+	if settings.Addition > 0 {
+		lines = append(lines, lastIndent+"Addition duration: "+settings.Addition.String())
+	}
+
+	return lines
+}