Software Engineer- Platform in City of London

We're looking for a Platform Engineer to join our Application Platform team. You'll help build and operate the deployment platform, tooling, and developer experience that every engineering team at dunnhumby relies on to ship software to production. This role can be based from either our London or Manchester office. You'll join at a moment when we're moving our retail analytics platform from monthly bundled releases to continuous per-service deployment on Kubernetes. You'll be hands-on with that migration in your first few months and then stay on long-term as a core member of the team that owns and evolves the platform. It's a clear path into senior platform engineering for someone who has shipped production Kubernetes work and wants to grow their craft on a platform used by hundreds of engineers.

Responsibilities:

• Build and maintain the platform primitives that enable service teams to deploy independently, including ArgoCD application manifests, GitOps repository lifecycles, reusable Helm chart templates, and External Secrets Operator configuration.
• Pair with engineers across product and data teams as they onboard onto the new platform, addressing repeated questions at the template layer to prevent recurring issues.
• Contribute to platform design discussions and help shape the paved road that engineers across dunnhumby build on.
• Author and maintain reusable GitLab CI pipeline templates covering build, test, publish, deploy, and post-deploy stages.
• Work with service teams to migrate pipelines onto the platform standard and retire bespoke per-service deployment scripts.
• Continuously improve build times, pipeline reliability, and developer feedback loops.
• Respond to platform alerts during working hours, triaging ArgoCD sync failures, secret synchronisation errors, and flaky pipelines.
• Join the Application Platform on-call rotation once ramped up (typically after the first few months).
• Instrument platform tooling with structured logging and dashboards to improve visibility without manual investigation.
• Write unit and integration tests to meet SonarQube coverage requirements and create smoke tests for deployment workflows — no green CI, no merge.
• Keep migration playbooks, ArgoCD setup guides, and per-service pipeline documentation accurate and up to date.
• Share learnings with the squad through regular knowledge-sharing sessions.

What we expect from you:

• Strong professional software or platform engineering experience, shipping code or infrastructure to production within a team environment.
• Hands-on Kubernetes experience on GKE, AKS, or EKS, with confidence using Deployments, Services, Ingress, ConfigMaps, Secrets, and RBAC.
• Helm experience, including writing or substantially modifying charts, with a solid understanding of values files, templates, hooks, and chart dependencies.
• Experience with GitLab CI or a comparable CI tool (e.g. GitHub Actions, Azure DevOps, Jenkins, CircleCI), having built or meaningfully modified pipelines rather than just used them.
• Production experience with Python or Go, with the ability to discuss real code from professional work.
• Confidence working with Linux, Bash, Docker, and standard Unix tooling.
• Strong Git practices within a team environment, including branching strategies, PR/MR workflows, review feedback, and merge conflict resolution.
• A proven track record of shipping to production in a professional team setting (not solely prototype or personal projects).
• Exposure to ArgoCD, Flux, or another GitOps tool is required.
• Experience with External Secrets Operator, Vault, or similar secret-sync patterns is beneficial.
• Familiarity with Terraform, multi-cloud environments (GCP and Azure), observability tooling (e.g. New Relic, Datadog, Prometheus, Grafana), or contract testing with Pact would be valuable.