How can DevOps coexist with legacy monolithic applications?

Panellists at Computing's DevOps Summit describe their experience of bimodal IT

How can DevOps coexist with monolithic legacy applications? This was a question asked of panellists during Computing's DevOps Summit yesterday.

Bi-modal IT is a reality in many organisations, and despite the management difficulties in managing a two speed enterprise, the consensus was that it can work but it depends very much on the context. So a legacy application that is not customer facing or which is not directly responsible for the organisation's competitive edge is probably best left alone. Refactoring it would be hard work, have limited benefits and might even prove counterproductive, especially if a large number of other applications depend on it.

Derek Weeks, VP and DevOps advocate at Sonatype said that while DevOps may be on everyone's lips trendy it's a mistake to believe it's the only game in town. It all depends on the business value it can bring.

"They can coexist," Weeks said. "A lot of DevOps practices are about business outcomes. Is the legacy application a competitive differentiator? If so then you need to replace it, or eat the elephant a bite at a time. But that's going to be hard if it's supporting whole business."

"We were quite fortunate at the DWP as we were given a clean slate for Universal Credit," said Tom Padgham, head of operations at the Department for Work and Pensions. "But there are plenty of examples where we have done that and it's quite a challenge. You need to break it down, change the culture. You need to ask whether it's really necessary," he said.

"Etsy is a monolithic application and it seems to be able to operate quite happily."

Aubrey Stern, DevOps lead at Pizza Hut, said that her organisation is very much a two speed business and that where the two interact can be an uncomfortable space to operate in. A few no-go areas had become apparent between the DevOps-friendly web based front end and the database-powered back end she said.

"Very often change comes down to politics - who has clout within an organisation and the power to change things. We still talk to the EDW guys but we had to say we shouldn't deal with this area because we don't have enough push within the organisation to make the changes we'd like to see."

A legacy application does not need to be large to stand in the way of change, said Rick Allan, global project delivery assurance at Zurich Insurance. Sometimes an application will have a support team that is reluctant to adapt. This can be the result of management failure. If the business benefits are communicated properly legacy teams will be reluctant to change to meet the demands of the upstart DevOps team.

"I have business teams not used to making changes," Allan said. "So you end up lots of small apps connecting everything up to make up for the ones that can't change. DevOps appears to be tech driven but it's the cart driving the horse unless it's really demanded by the business."