Wednesday’s goalless draw at the Tofiq Bahramov Stadium meant defender Dedryck Boyata’s header at Parkhead in the first leg proved enough to see Celtic into the play-off draw on Friday.
Armstrong’s first European experience with the Scottish champions after signing from Dundee United in the January transfer window was against Italian giants Inter Milan in the last 32 of the Europa League last season.
Although the Hoops lost 4-3 on aggregate, he believes the experience of playing such a big club stands him and the rest of the squad in good stead for whoever stands between them and this campaign’s Champions League group stage.
Ronny Deila’s seeded side could face Maccabi Tel Aviv (Israel), Partizan Belgrade (Serbia), Malmo (Sweden), Skenderbeu Korce (Albania) or FC Astana (Kazakhstan).
Armstrong said: “Those games (against Inter Milan) were a good experience for me and the squad – to know we can play well in those big ties.
“And we’re optimistic and excited about the next round, and hope to achieve the ultimate goal and get into the group stages.
“It was a tough game against Qarabag. We knew they had to come out and do something to get back into the tie and we were happy to keep our shape and play on the counter.
“I thought it was very well played by ourselves.”
Armstrong admitted the Baku heat, despite the late evening kick-off, and the poor condition of the scorched pitch, made it an even more challenging evening against the Azerbaijan champions.
“It was tough and tiring and so it was nice to have the water breaks,” he said.
“The surface wasn’t great either. You had to concentrate at all times and couldn’t afford to look away.
“So it was a very challenging night both physically and mentally but you could see the emotion on our faces when the final whistle went, we were all delighted.”