TSN reported the one-year deal is worth $1 million.
Armstrong, who announced the deal through his Twitter account, has had trouble with injuries the past two years in Toronto with a list of ailments that included a broken nose, broken foot, tendon problem in a finger, concussion, badly sprained ankle and a bout with blurred vision and dizziness.
He played just 79 games the past two seasons combined.
The signing marks the first addition to the roster for new Canadiens GM Marc Bergevin.
Ray Whitney didn't wait long to pick a new team, and he's staying in the Pacific Division.
The Dallas Stars announced Sunday they have signed Whitney, Phoenix's leading scorer last season, to a two-year contract worth $9 million. Whitney, 40, who led the Phoenix Coyotes with 77 points last season, told TSN the Stars "were the only team that wasn't scared to give me a second year."
"That was pretty much it," he continued. "It was just the term of the deal. Obviously there is a little bit of a red flag at 40, but I think I've got a couple more (seasons) in me."
Whitney won the Stanley Cup with Carolina in 2006 and has 1,003 points in 1,229 career games. He said he understands why general managers across the NHL would be hesitant to give a 40-year-old a two-year contract, but he also said with modern medicine and the way players take care of their bodies he doesn't see that age as the end of the road for players going forward.
“Ray Whitney was among the most productive players in the league last season and showed he remains extremely capable and dangerous,” Stars general manager Joe Nieuwendyk said. “He’s a winner, a competitor and a leader, and we’re very excited he’ll be a Dallas Star.”
Whitney credited Coyotes coach Dave Tippett and the system he played in Phoenix for helping prolong his career.
"Everything has to work. You have to have a coach who believes in you and teammates that can do something with you," Whitney said. "Training is a big part of it, and diet. The older you get, you realize if you lose one of your steps you're never going to gain it back. I'm trying like (heck) to not lose one of those steps."
Minnesota agreed to terms with Torrey Mitchell on a three-year pact reportedly worth $1.9 million per season and Zenon Konopka on a two-year deal. Mitchell had nine goals and 19 points in 66 games for the Sharks this past season, his second straight campaign with nine goals.
Konopka had three goals and five points in 55 games with the Ottawa Senators. He also had 193 penalty minutes after leading the League in that category in the previous two seasons. Minnesota will be Konopka's fourth team in as many years after stops with Tampa Bay, the New York Islanders and Ottawa.
Pittsburgh and Zatkoff agreed to a two-year, two-way deal worth $525,000 in the NHL and $105,000 in the American Hockey League, according to a report by TSN's Bob McKenzie. Zatkoff was 21-17-1 with a 2.49 goals against average and .920 save percentage for Manchester of the AHL as property of the Los Angeles Kings.
TSN reports the contract is for one year, $1.15 million.
Lundin, 27, played last season for the Minnesota Wild, appearing in 17 games with two goals and two assists. Lundin missed the first 23 games of the season with a back injury and final 25 contests with a lower body injury.
He played the previous four seasons with the Tampa Bay Lightning. He had four goals and 29 assists in 224 games.
Moss had two goals and nine points in 32 games last season for the Calgary Flames. He had a career-high 20 goals in 2008-09, which was the only season in his six with the Flames that he appeared in more than 64 games.
Moss, 30, was a seventh-round pick by the Flames in the 2001 NHL Draft.
Gustavsson came to Toronto as a heralded unrestricted free agent out of Sweden in 2009. He went 39-45-15 in 107 appearances over three seasons. Gustavsson posted a 2.98 goals-against average and .900 save percentage.
The Leafs traded Gustavsson's negotiating rights to Winnipeg last weekend for a conditional seventh-round pick in the 2013 NHL Draft, but the sides never struck a deal.
The Red Wings used Ty Conklin and Joey MacDonald as backups to Howard last season. Howard started 57 games but was injured at various points of the season.
It will be interesting if Gustavsson for some reason gets the start in the 2012 NHL Winter Classic at Michigan Stadium. The Red Wings' opponent is the Maple Leafs.
TSN reports the one-year, two-way deal is worth $700,000 in the NHL, $105,000 in the AHL.
Meech, 28, played two games for the Jets last season as he recovered from an injury. He also played six regular-season games in the American Hockey League with the St. John’s IceCaps, and 15 postseason games, scoring nine points (four goals, five assists) in the Calder Cup playoffs.
"I'm very happy to be back in Philly," Leighton said, according to the team's website. "This is where I want to be and I'm excited about the team we have this year. I look forward to the opportunity to continue working with Jeff Reese."
Leighton, 31, has not played an NHL game since 2010-11, when he played one.
In parts of three seasons, all with the Flyers, he is 35-40-2 with a 2.95 goals-against average and .902 save percentage in 104 games.