agent/api/container/container.go
func (c *Container) IsEssential() bool {
	c.lock.RLock()
	defer c.lock.RUnlock()

	return c.Essential
}
func (c *Container) IsEssential() bool {
	c.lock.RLock()
	defer c.lock.RUnlock()

	return c.Essential
}
// IsEssential returns whether the container is an essential container or not