Canada has been forced to use commercial shipping companies to obtain two supply ships for refueling and transferring other needed items to Canadian warships at sea. Using commercial ships for this is nothing new. Before the development of specialized naval supply ships in the early 20th century the job had long been done by civilian ships. But the widespread use of oil as ship fuel in the early 2oth century made it possible (with some special equipment and trained operators) to refuel warships at sea while both ships were moving. Same deal with transferring other supplies (food, spare parts and so on). These techniques enabled the warships to keep moving, often essential in a combat zone or on your way to one. However the need for special equipment and trained personnel meant it was easier for the navy to build, crew and operate these ships.
But like aerial refueling (almost exclusively used by the military) a growing number of nations have found it less expensive and just as effective to use civilian contractors (who buy surplus aerial tankers or convert large cargo transports to the task). The military is regularly outsourcing flight training and all sorts of technical support services. So it was no big leap to do this for warship resupply at sea.
The main reason Canada went this route was because political and bureaucratic delays in building two new naval resupply ships to replace the two elderly (46 years in service) ones that had to be retired in 2015. The commercial ships will use largely navy crews so that these sailors will maintain their skills for when the newly built naval resupply ships are ready for service in 2020 and 2021 (or thereabouts). In the meantime the Canadians have relied on allies to temporarily provide supply ships until the interim civilian ships are ready to go.