I shall be very much not at great length. France has been bombing Iraq and Syria for some time now. Paris was clearly an act of retaliation and not an act of aggression.
Colonialist? Yes, wars to impose governments that a first world country likes on third world countries are colonialist. That’s true of France bombing Syria and Iraq, which it has been doing for some time. That’s also true of American colonialist interventions in Afghanistan*, Iraq, Syria, Yemen, Sudan, Somalia, Nepal, the Philippines, Cameroon, et very tedious cetera. That’s before we get to the African country where we intervened in favor of the new military junta and against the supporters of the elected government. Well-intentioned or not, the wars to overthrow the governments of Iraq and now Syria were wars of aggression and hence crimes against peace and humanity.
France has been bombing Iraq and Syria for some time now. Paris was clearly an act of retaliation and not an act of aggression, at the retaliating country announced, different in that the bodies were (i) on television and (ii) white. The far larger number of bodies at the far end, receiving French, American, Russian peace through bombing campaigns, were (i) not on television and, more important, (ii) not white. With respect to NATO Article 5, NATO is a defensive alliance, not an agreement to support the pre-existing French colonialist war in the Levant.
With respect to the EU treaty: The interesting question is whether or not any EU members will point out that the treaty is a defense agreement, not an aggression agreement. France has been bombing ISIS for some time, so that the treaty is not applicable. It does not require other EU members to support French colonialist wars.
*Mr. Bin Laden being deceased, our causus belli against Afghanistan however flimsy has ceased to be applicable.