The Scottish champions recently confirmed that they were in talks with the 31-year-old, who has been a free agent since 2012 due to persistent injury problems.
Deila now expects Celtic to conclude a deal for the shot-stopper in the near future.
"We are getting closer with Craig Gordon, it is down to the small details. We can make this happen but it's not confirmed yet," he told the Daily Record.
"We need to have alternatives. You always make contingency plans. If you are going to bring in older players then they need to have the right mentality and Craig has that."
Celtic are back in action on July 15, when they host KR Reykjavik in the first leg of their Champions League second-round qualifying tie.