Pull requests review process for committers

Review process


These instructions assume that reviewers are members of the Cilium GitHub organization. This is required to obtain the privileges to modify GitHub labels on the pull request. See Cilium’s Contributor Ladder for details.

  1. Find Pull Requests (PRs) needing a review from you, or from one of your teams.

  2. If this PR was opened by a contributor who is not part of the Cilium organization, please assign yourself to that PR and keep track of the PR to ensure it gets reviewed and merged.

    If the contributor is a Cilium committer, then they are responsible for getting the PR in a ready to be merged state by adding the ready-to-merge label, once all reviews have been addressed and CI checks are successful, so that they (or another committer) can merge the PR.

    If this PR is a backport PR (typically with the label kind/backport) and no-one else has reviewed the PR, review the changes as a sanity check. If any individual commits deviate from the original patch, request review from the original author to validate that the backport was correctly applied.

  3. Review overall correctness of the PR according to the rules specified in the section Submitting a pull request.

  4. Set the labels accordingly. A bot called maintainer’s little helper might automatically help you with this.


    When to set


    Some commits are not signed off


    PR is outdated and needs to be rebased

  5. Validate that bugfixes are marked with kind/bug and validate whether the assessment of backport requirements as requested by the submitter conforms to the Backport Criteria.


    When to set


    PR needs to be backported to these stable releases

  6. If the PR is subject to backport, validate that the PR does not mix bugfix and refactoring of code as it will heavily complicate the backport process. Demand for the PR to be split.

  7. Validate the release-note/* label and check the release note suitability. Release notes are passed through the dedicated release-note block (see Submitting a pull request), or through the PR title if this block is missing. To check if the notes are suitable, put yourself into the perspective of a future release notes reader with lack of context and ensure the title is precise but brief.


    When to set


    Do NOT merge PR, needs a release note


    This is a non-trivial bugfix and is a user-facing bug


    This is a major feature addition, e.g. Add MongoDB support


    This is a minor feature addition, e.g. Add support for a Kubernetes version


    This is a not user-facing change , e.g. Refactor endpoint package, a bug fix of a non-released feature


    This is a CI feature or bug fix.

  8. Check for upgrade compatibility impact and if in doubt, set the label upgrade-impact and discuss in Cilium Slack’s #development channel or in the weekly meeting.


    When to set


    The code changes have a potential upgrade impact

  9. When submitting a review, provide explicit approval or request specific changes whenever possible. Clear feedback indicates whether contributors must take action before a PR can merge.

    If you need more information before you can approve or request changes, you can leave comments seeking clarity. If you do not explicitly approve or request changes, it’s best practice to raise awareness about the discussion so that others can participate. Here are some ways you can raise awareness:

    • Re-request review from codeowners in the PR

    • Raise the topic for discussion in Slack or during community meetings

    When requesting changes, summarize your feedback for the PR, including overall issues for a contributor to consider and/or encouragement for what a contributor is already doing well.

  10. When all review objectives for all CODEOWNERS are met, all CI tests have passed, and all reviewers have approved the requested changes, you can merge the PR by clicking on the “Rebase and merge” button.

Reviewer Teams

Every reviewer, including committers in the committers team, belongs to one or more teams in the Cilium organization. If you would like to add or remove yourself from any team, please submit a PR against the community repository.

Once a contributor opens a PR, GitHub automatically picks which teams should review the PR using the CODEOWNERS file. Each reviewer can see the PRs they need to review by filtering by reviews requested. A good filter is provided in this link so make sure to bookmark it.

Reviewers are expected to focus their review on the areas of the code where GitHub requested their review. For small PRs, it may make sense to simply review the entire PR. However, if the PR is quite large then it can help to narrow the area of focus to one particular aspect of the code. When leaving a review, share which areas you focused on and which areas you think that other reviewers should look into. This helps others to focus on aspects of review that have not been covered as deeply.

Belonging to a team does not mean that a reviewer needs to know every single line of code the team is maintaining. Once you have reviewed a PR, if you feel that another pair of eyes is needed, re-request a review from the appropriate team. In the following example, the reviewer belonging to the CI team is re-requesting a review for other team members to review the PR. This allows other team members belonging to the CI team to see the PR as part of the PRs that require review in the filter.


When all review objectives for all CODEOWNERS are met, all required CI tests have passed and a proper release label is set, you may set the ready-to-merge label to indicate that all criteria have been met. Maintainer’s little helper might set this label automatically if the previous requirements were met.


When to set


PR is ready to be merged

Code owners

Code owners are used by the Cilium community to consolidate common knowledge into teams that can provide consistent and actionable feedback to contributors. This section will describe groups of teams and suggestions about the focus areas for review.

The primary motivation for these teams is to provide structure around review processes to ensure that contributors know how to reach out to community members to conduct discussions, ensure contributions meet the expectations of the community, and align on the direction of proposed changes. Furthermore, while these teams are primarily drawn upon to provide review on specific pull requests, they are also encouraged to self-organize around how to make improvements to their areas of the Cilium project over time.

Any committer may self-nominate to code owner teams. Reach out to the core team on the #committers channel in Slack to coordinate. Committers do not require expert knowledge in an area in order to join a code owner team, only a willingness to engage in discussions and learn about the area.


These code owners may provide feedback for Pull Requests submitted to any repository in the Cilium project:

  • @cilium/api: Ensure the backwards-compatibility of Cilium REST and gRPC APIs, excluding Hubble which is owned by @cilium/sig-hubble-api.

  • @cilium/build: Provide feedback on languages and scripting used for build and packaging system: Make, Shell, Docker.

  • @cilium/cli: Provide user experience feedback on changes to Command-Line Interfaces. These owners are a stand-in for the user community to bring a user perspective to the review process. Consider how information is presented, consistency of flags and options.

  • @cilium/ci-structure: Provide guidance around the best use of Cilium project continuous integration and testing infrastructure, including GitHub actions, VM helpers, testing frameworks, etc.

  • @cilium/community: Maintain files that refer to Cilium community users such as USERS.md.

  • @cilium/contributing: Encourage practices that ensure an inclusive contributor community. Review tooling and scripts used by contributors.

  • @cilium/docs-structure: Ensure the consistency and layout of documentation. General feedback on the use of Sphinx, how to communicate content clearly to the community. This code owner is not expected to validate the technical correctness of submissions. Correctness is typically handled by another code owner group which is also assigned to any given piece of documentation.

  • @cilium/sig-foundations: Review changes to the core libraries and provide guidance to overall software architecture.

  • @cilium/github-sec: Responsible for maintaining the security of repositories in the Cilium project by maintaining best practices for workflow usage, for instance preventing malicious use of GitHub actions.

  • @cilium/helm: Provide input on the way that Helm can be used to configure features. These owners are a stand-in for the user community to bring a user perspective to the review process. Ensure that Helm changes are defined in manners that will be forward-compatible for upgrade and follow best practices for deployment (for example, being GitOps-friendly).

  • @cilium/sig-hubble-api: Review all Hubble API related changes. The Hubble API covers gRPC and metrics endpoints. The team ensures that API changes are backward compatible or that a new API version is created for backward incompatible changes.

  • @cilium/metrics: Provide recommendations about the types, names and labels for metrics to follow best practices. This includes considering the cardinality impact of metrics being added or extended.

  • @cilium/release-managers: Review files related to releases like AUTHORS and VERSION.

  • @cilium/security: Provide feedback on changes that could have security implications for Cilium, and maintain security-related documentation.

  • @cilium/vendor: Review vendor updates for software dependencies to check for any potential upstream breakages / incompatibilities. Discourage the use of unofficial forks of upstream libraries if they are actively maintained.

Repository Owners

The following code owners are responsible for a range of general feedback for contributions to specific repositories:

  • @cilium/sig-hubble: Review all Cilium and Hubble code related to observing system events, exporting those via gRPC protocols outside the node and outside the cluster. those event channels, for example via TLS.

  • @cilium/hubble-ui: Maintain the Hubble UI graphical interface.

  • @cilium/tetragon: Review of all Tetragon code, both for Go and C (for eBPF).

The teams above are responsible for reviewing the majority of contributions to the corresponding repositories. Additionally, there are “maintainer” teams listed below which may not be responsible for overall code review for a repository, but they have administrator access to the repositories and so they can assist with configuring GitHub repository settings, secrets, and related processes. For the full codeowners for individual repositories, see the CODEOWNERS file in the corresponding repository.

Cloud Integrations

The following codeowner groups provide insight into the integrations with specific cloud providers:

Cilium Internals

The following codeowner groups cover more specific knowledge about Cilium Agent internals or the way that particular Cilium features interact with external software and protocols:

  • @cilium/docker: Maintain the deprecated docker-plugin.

  • @cilium/endpoint: Provide background on how the Cilium Endpoint package fits into the overall agent architecture, relationship with generation of policy / datapath constructs, serialization and restore from disk.

  • @cilium/envoy: Maintain the L7 proxy integration with Envoy. This includes the configurations for Envoy via xDS protocols as well as the extensible proxylib framework for Go-based layer 7 filters.

  • @cilium/egress-gateway: Maintain the egress gateway control plane and datapath logic.

  • @cilium/fqdn: Maintain the L7 DNS proxy integration.

  • @cilium/ipcache: Provide background on how the userspace IPCache structure fits into the overall agent architecture, ordering constraints with respect to network policies and encryption. Handle the relationship between Kubernetes state and datapath state as it pertains to remote peers.

  • @cilium/ipsec: Maintain the kernel IPsec configuration and related eBPF logic to ensure traffic is correctly encrypted.

  • @cilium/kvstore: Review Cilium interactions with key-value stores, particularly etcd. Understand the client libraries used by Cilium for sharing state between nodes and clusters.

  • @cilium/loader: Maintain the tooling that allows eBPF programs to be loaded into the kernel: LLVM, bpftool, use of cilium/ebpf for loading programs in the agent, ELF templating, etc.

  • @cilium/operator: Review operations that occur once per cluster via the Cilium Operator component. Take care of the corresponding garbage collection and leader election logic.

  • @cilium/proxy: Review low-level implementations used to redirect L7 traffic to the actual proxy implementations (FQDN, Envoy, …).

  • @cilium/sig-agent: Provide Cilium (agent) general Go review. Internal architecture, core data structures and daemon startup.

  • @cilium/sig-bgp: Review changes to our BGP integration.

  • @cilium/sig-clustermesh: Ensure the reliability of state sharing between clusters to ensure that each cluster maintains a separate fault domain.

  • @cilium/sig-datapath: Provide feedback on all eBPF code changes, use of the kernel APIs for configuring the networking and socket layers. Coordination of kernel subsystems such as xfrm (IPsec), iptables / nftables, tc. Maintain the control plane layers that populate most eBPF maps; account for endianness and system architecture impacts on the datapath code.

  • @cilium/sig-hubble: Review all Cilium and Hubble code related to observing system events, exporting those via gRPC protocols outside the node and outside the cluster. Ensure the security of those event channels, for example via TLS.

  • @cilium/sig-ipam: Coordinate the implementation between all of the IP Address Management modes, provide awareness/insight into IP resource exhaustion and garbage collection concerns.

  • @cilium/sig-k8s: Provide input on all interactions with Kubernetes, both for standard resources and CRDs. Ensure best practices are followed for the coordination of clusterwide state in order to minimize memory usage.

  • @cilium/sig-lb: Maintain the layers necessary to coordinate all load balancing configurations within the agent control plane, including Services, ClusterIP, NodePorts, Maglev, local redirect policies, and NAT46/NAT64.

  • @cilium/sig-policy: Ensure consistency of semantics for all network policy representations. Responsible for all policy logic from Kubernetes down to eBPF policymap entries, including all intermediate layers such as the Policy Repository, SelectorCache, PolicyCache, CachedSelectorPolicy, EndpointPolicy, etc.

  • @cilium/sig-scalability: Maintain scalability and performance tests. Provide input on scalability and performance related changes.

  • @cilium/sig-servicemesh: Provide input on the way that Service Mesh constructs such as Gateway API are converted into lower-level constructs backed by eBPF or Envoy configurations. Maintain the CRDs necessary for Service Mesh functionality.

  • @cilium/wireguard: Maintain the kernel WireGuard configuration and datapath impacts related to ensuring traffic is encrypted correctly when WireGuard mode is enabled.