I would like to add a bit of my own insight. I was brought to faith by a brother who did not serve in the army, but had served in the Air Force (USAF) in the role of a soldier who guards airfields (forgot the name) and he went on a tour of duty in Iraq. Last time I heard from my brother Christopher he had enlisted in the navy after a fairly lengthy break from the military and was about to embark on a tour on board a ship.
So, do I believe that a Christian can be in military service? While I am sure that both in the Bible and in our world there are men and women in armed forces / police who follow God, I could never imagine serving any government, any military, and police force in any role or capacity. It is my personal conviction after seeing the essentially selfish nature of states and governments at the expense of the people. This applies to modern states and ancient states. China has never fought a major war since the end of WW2, but the US has had numerous entanglements in Viet Nam, Afghanistan, Iraq etc. None of which I believe can be justified, no offense. States have committed countless atrocities in the name of pretty much everything, with Christianity being one of those banners. Once we dig deeper we find a lot of is ABSOLUTELY NOT BIBLICAL, but driven by nothing other than human lust for money, power, and status. Political Communism (the kind believing in a dictatorship of the so-called working class), a Godless ideology, has murdered more people in history than anything else.
What I believe is that when you serve in the military, it really feels to me that when you die, you do not die for your country because your country, as understood through the artificial construct of a nation-state, does not exist if not for the artificially drawn political borders. You sacrifice for the people who RUN your country, whose selfish interests will always be put in higher priority than your life, your livelihood, if they have ANY genuine concern for you. If you're a veteran, it feels to me that you are celebrated for the value you provided to the ruling elite, not for any of your personal qualities and values as a human being though of course they will make it sound as if you ARE appreciated because you are of God's creation. I am not targeting any nation specifically but the very nature of any military / government / police service.
While there is no doubt that there are individuals who are believers of the Lord and truly serve Him who also happen to be soldiers, officials, civil servants and law enforcers etc, as we can see both in this current world and in Biblical times, it is my personal belief that I would rather not be a Christian AND carry a gun in service of any government, because God's love and God's grace is NOTHING even the most powerful state will ever be able to match. If I can be a man of God while never seeing any bloodshed unless it is a genuine defensive, life-or-death situation, I would rather not. War can be justified, but I don't believe the wars being fought by major powers today can be justified, and to passionately believe in something like patriotism, which is an idol other than God, cannot be justified to my senses.
If you were to join a Western military today, which I assume for you would be the US military, how would you feel if you were deployed and constantly had to obey orders that go against your faith? How would you feel knowing that you're part of a relentless war machine in recent history that has destroyed, rather than save, the lives of hundreds of millions both directly and indirectly all for the gain of those in power?
Now, for a hypothetical scenario. Let's say the year is 2030 and the US, after the breaking down of multilateral diplomatic talks with major powers such as China and Russia, finally decides to use military force. Let's assume you're deployed to Eastern Europe, or perhaps the Pacific. Maybe Iran. How would you feel killing someone that could be a Chinese, Russian, North Korean or Iranian brother in faith? As unlikely as it might be when you're in a state of war, what would have happened had you met that guy or gal who's decently educated and reasonable, whom during another time, you could sit down and tell them about your faith and play your part, however small it may be, in sharing the Good News? These would be very difficult questions for me, so I'd rather not be put in situations where these questions may become things to consider.
I'm not a complete pacifist. If myself or a loved one were under life-threatening circumstances, I would use self-defense to protect myself and those I care about. However, actively participating in a profession that could, and in today's world, may very well lead to the shedding of blood sooner or later, all in the name of something as artificial and arbitrary as a nation-state, does not go well with me. While there are those in the military, government, and police who have had opportunities to praise and spread the name of God and His eternal salvation, I believe there are more peaceful ways to do so.
I don't mean to offend anyone, but this is how I truly feel. Peace be with you all. State affairs can be absolutely ridiculous. My conviction to not take part in any of it means that I don't want to be part of the problem / s. I hope you can appreciate and consider a bit of what I have written, Brother. Amen.
Furthermore, apart from spiritual questions to ask yourself, there are also other considerations. No matter how much the media or anything else may glorify war and military service, the military is not the place you think it is regardless of which capacity you serve in. Does a highly disciplined, regimented, no-nonsense lifestyle really fit you? Why or why not? Have you talked to anyone you know, or on the internet, who has served or is serving? What are their feelings? What do you think you will gain from military service? Are the gains really necessary, can they be obtained in another way of form? What will you have to lose?
EDIT: I apologize, you're going to serve in the Canadian Military and I'm currently in Richmond, BC (soon to change as I'll be leaving Canada permanently), but the point still stands.