Scorpio (Frontlines: Evolution, #1) by Marko Kloos

On a distant Earth colony, an orphaned survivor of an alien invasion discovers that the greatest world-ending dangers aren’t behind her.

It’s been eight years since an alien invasion drove a small surviving group of settlers to seek refuge in an underground shelter. Cut off from the rest of humanity, the ragtag band has maintained a narrowly functioning colony due to communal effort and salvage runs. Alex Archer has her own duties as a dog handler. While this off-world colony may be harsh, Ash, Alex’s black shepherd raised to sense threats, makes living in it a little nicer.