German public services union had a morning strike this morning (Thursday) that lead to cancellation of 600 mainly German and European flights. The strike is now over and the operations should resume.
Note that if you were affected this action, Lufthansa is not required to provide cash compensation due to delay per EC 261/2004, but they are required to provide care such as rebooking you to final destination on other airline or provide hotel accommodation due to delays.
Short strikes are quite common in Europe and Lufthansa got hit several times last year. You should always check your flight status and check your options getting to your final destination on other airlines. Lufthansa is required to rebook you.