Celo Tech Talks Part 7 - Price Oracles


Julie Piper, an engineer at Sea Labs and the host of the Celo Tech Talk series, welcomes everyone and introduces the purpose of the educational sessions. The talks aim to share Celo technology knowledge with the community to support Celo’s mission of building an inclusive financial system. Julie mentions that the previous sessions are available on Celo Foundation’s Crowdcast and YouTube channel. She encourages feedback from the audience to improve the content and keep it relevant.

Introducing the Speakers

Audrey Pendleman and Trevor Porter from the Protocol Economics team at Sea Labs are invited to share their expertise in building Celo. Audrey and Trevor briefly introduce themselves and their motivation for joining Celo. Audrey has been working on Celo oracles for over a year, aiming to improve the existing financial system. Trevor, who recently joined Sea Labs, focuses on blockchain clients, oracles, and infrastructure.

Overview of Price Oracles

The discussion shifts to the main topic of the talk, price oracles. Julie provides a quick agenda for the session, outlining the key points to be covered. She also explains how price oracles relate to Celo’s mission and the importance of stable coins in everyday transactions.

Role and Implementation of Oracles

Audrey delves into the details, explaining the role of oracles in providing accurate and up-to-date exchange rates for stable coins. She mentions that the sorting of exchange rates occurs off-chain, with oracles responsible for reporting the current price to the sorted oracles contract. Trevor elaborates on the technical aspects, including the monitoring of trading activity, determining price, and submitting reports to the contract.

Infrastructure and Monitoring

Trevor discusses the infrastructure and monitoring measures in place for the oracles. The oracles run on Kubernetes, a container orchestrator, and communicate with the network through full nodes. The monitoring includes Prometheus metrics, which are fed into a monitoring system in Discord. Security is also emphasized, with strict permissions and a core group of on-call engineers overseeing the oracles.

Ensuring Accuracy and Robustness

The focus shifts to ensuring the accuracy and robustness of the on-chain prices reported by the oracles. Audrey explains the criteria for submitting a new report and avoiding expired reports. She also discusses the importance of considering the volume and reliability of exchanges while calculating the final value.

Roadmap and Future Plans

Julie and Trevor discuss the future plans for the oracles. They mention the goal of increasing transparency and making oracle data public. Although the oracles are currently centralized, the aim is to move towards decentralization. They also announce an upcoming tech talk on the differences between Celo’s blockchain and Go Ethereum.


Julie concludes the talk, inviting further questions and feedback from the community. She encourages the audience to reach out to Audrey and Trevor on Discord for specific inquiries. The session ends with an invitation to future Celo Tech Talks and the potential expansion of data sources and computing power for determining the current price.