IAG Loyalty achieves zero-downtime app updates

The challenge

To keep pace with customer demand and market trends, the IAG Loyalty (IAGL) Shopping and Platform team continuously modifies and improves its software applications. Despite its comprehensive quality assurance process – including thorough code reviews and automated testing – certain issues only become apparent when exposed to production traffic.

These production-only problems present significant challenges, because discovering them after a full release often results in:

• Unexpected service disruptions
• Potential revenue loss
• Diminished customer experience
• Resource-intensive emergency fixes
• Reputation damage when issues affected multiple customers

Mindera collaborated with the IAGL Shopping and Platform team to develop a solution that would enable these elusive problems to be identified before they could impact the entire user base, while maintaining the company’s commitment to continuous improvement and deployment.

The solution

After careful analysis of the available deployment strategies, Mindera and IAGL determined that ‘canary releases’ offered the best solution to the challenge. This approach allows the IAGL team to test new code versions with a small percentage of users before committing to a full production deployment.

Core implementation strategy

The canary release implementation followed these key principles:

Controlled exposure: New versions are initially deployed to a small ‘canary group’, while the majority of users continue accessing the original stable version.

Comprehensive monitoring: During the canary phase, multiple performance metrics are tracked, including:

• Response times
• Error rates
• Resource utilisation
• User feedback and behaviour patterns

Gradual rollout: If no critical issues emerge during the monitoring period, the canary group size is progressively increased (10% → 25% → 50% → 100%).

Quick rollback capability: Should any unforeseen issues arise, users can immediately be returned to the stable version, minimising impact.

Technical implementation challenges

While working with the site reliability engineering (SRE) team's existing canary support, Mindera identified a critical limitation: the lack of ‘sticky session’ functionality, which ensures a user's requests are always routed to the same server instance during their session. This meant users initially routed to the stable version might have subsequent requests directed to the canary version (or vice-versa), creating inconsistent experiences and complicating our ability to isolate and identify issues.

To address this limitation, the following technical enhancements were implemented:

SRE module updates: Using existing modules and extending them to support multiple routes per service and header matching capabilities.

Custom routing rules: Establishing three distinct rules for IAGL’s own Shopping Service:

• A default route with weighted targets split between stable and canary versions
• A custom route directing specific header-identified traffic exclusively to the stable version
• A custom route directing specific header-identified traffic exclusively to the canary version

Header configuration: IAGL’s own shopping application was updated to ensure appropriate headers were sent with all requests, configurable through container environment variables.

Enhanced release management with Uplift

To complement the canary deployment strategy, the team incorporated Uplift into its workflow. This tool – already successfully used by other teams within IAGL – streamlines the release management process through structured commit messages and semantic versioning.

Key benefits of the Uplift implementation includes:

Automated version control: Shopping version (package.json) is automatically incremented according to conventional commits in the log.

Systematic git tagging: New git tags are created at appropriate release points.

Automated changelog management: The changelog file is dynamically updated by uplift, documenting all conventional commits not yet included in previous releases.

Changelog differential pipeline: A new pipeline allows the team to generate changelog differentials, clearly showing new entries since the last release and effectively addressing the gap in manually tracking unreleased features and fixes.

Dynamic task tracking: Using this pipeline, the team can compute unreleased tasks at any time, improving release visibility and planning.

The results

Ideally using outcome metrics to support the results..

The Mindera and IAGL implementation of canary deployments has delivered substantial benefits across multiple dimensions:

Risk mitigation

Gradually exposing new code to production environments has significantly reduced the potential impact of undiscovered issues. Problems affecting the canary group can be quickly identified and addressed before reaching their wider user base.

Enhanced service evaluation

Canary deployments enable multiple service versions to be evaluated simultaneously in real-world environments with actual users and authentic use cases, providing more valuable insights than isolated testing environments.

Valuable user feedback

By targeting specific user segments for canary releases, prompt, actionable feedback is received from real users, allowing features to be refined before full deployment.

Performance improvements

‘Cold-start’ issues typically associated with new system deployments are eliminated, as canary versions build momentum gradually rather than requiring immediate full-scale performance.

Operational excellence

The zero-downtime nature of canary deployments has allowed the team to maintain consistent service availability, even during significant updates. Beyond maintaining uptime, the progressive canary release strategy has also addressed previously troublesome issues with client-side errors that would typically occur when new versions were published.

Simplified recovery processes

The implementation provides a straightforward rollback mechanism, enabling quick restoration of previous versions when necessary.

Seamless uplift integration

One of the most significant advantages of the Uplift adoption has been its seamless integration into the team’s existing development workflow. The implementation required no fundamental methodology changes to the team's established processes.

Canary deployment has proven to be an ideal solution for the IAGL Shopping and Platform team, effectively reducing the risks associated with introducing changes to production environments, while minimizing infrastructure requirements. By allowingn new releases to be tested in live production settings without exposing their entire user base simultaneously, both technical resilience and customer experience has been enhanced.

The combination of canary deployments with their improved release management processes has established a more robust, reliable approach to software delivery that aligns perfectly with MIndera’s and IAGL’s commitment to quality and continuous improvement. Moving forward, the plan is to further refine our metrics and expand this approach across additional services.

Find out how you can accelerate the launch and updating of your apps – contact our mobile team today.

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About IAGL

IAG Loyalty is the International Airlines Group's (IAG) center of excellence for loyalty, managing the Avios reward currency and its associated programmes. IAG Loyalty is responsible for managing travel and leisure reward programmes, including those for British Airways, Iberia, Aer Lingus, and Vueling.

Since the launch of Avios in 2011, when British Airways and Iberia merged and International Airlines Group (IAG) was born, the organisation has evolved from a leader in travel rewards to a leader in loyalty. Over 30 years, it has created millions of memories for members around the world, harnessing their loyalty and love for travel with hotel and flight rewards and unforgettable experiences. Today, IAG Loyalty is continuing that growth on a global stage, with more than 69 million members and partnerships with the biggest names in travel, retail, hospitality, finance and more.