Fortune 500 Architecture Migration

TL;DR

I led Eventbrite's architectural shift from monorepo to polyrepo, growing adoption from 2 to 40 teams (90%) and unblocking independent deployments.

Context

Eventbrite's monorepo had become a liability. Teams couldn't move independently—merge conflicts were constant, deployments were coupled, and a bug in one team's code could block everyone.

Problem

• The monorepo slowed every team down
• Constant merge conflicts between teams
• Coupled deployments—one team's issue blocked all deploys
• No team could own its own deployment cadence
• Only 2 teams had migrated after months of effort

What I Did

1. Assessment: I mapped dependencies and identified the best migration candidates
2. Coalition building: I built buy-in across engineering leadership for the shift
3. Migration path: I designed an incremental path that didn't disrupt active development
4. Governance model: I created standardized templates and policies for polyrepo teams

• Polyrepo governance: automated compliance checks, dependency management, and security policies
• Template standardization: consistent CI/CD, testing, and deployment patterns across repos
• Dependency management: automated updates and security patching
• Migration tooling: scripts and guides for teams moving off the monorepo

Key Decisions

Governance through templates

Rather than centralize control, I encoded governance into templates—teams got autonomy within guardrails.

Incremental migration

No big-bang cutover. I let teams migrate when ready, with support from the platform team.

Clear ownership

I gave each repo a single owning team with full deployment authority.

Results

• Teams deploy independently without coordinating with everyone else
• Merge conflicts between teams eliminated
• Each team owns its own deployment cadence

Lessons Learned

1. Migration needs a coalition: architectural change needs leadership buy-in and clear communication to affected teams.
2. Autonomy with guardrails: teams want freedom; platform teams need consistency. Templates bridge the gap.
3. Don't force it: let early adopters prove value—success stories drive organic adoption.
4. Ownership clarity matters: a clear ownership model ended the "whose bug is this?" debates.