CONTRIBUTING.md

Contributing

If you would like to contribute please read OpenTelemetry Collector contributing guidelines before you begin your work.

Pull-request title

The title for your pull-request should contain the component type and name in brackets, plus a short statement for your change. For instance:

[processor/tailsampling] fix AND policy

Changelog

Pull requests that contain user-facing changes will require a changelog entry. Keep in mind the following types of users:

1. Those who are consuming the telemetry exported from the collector
2. Those who are deploying or otherwise managing the collector or its configuration
3. Those who are depending on APIs exported from collector packages
4. Those who are contributing to the repository

The changelog is primarily directed at the first three groups but it is sometimes appropriate to include important updates relevant only to the forth group.

If a changelog entry is not required, a maintainer or approver will add the Skip Changelog label to the pull request.

Examples

Changelog entry required:

• Changes to the configuration of the collector or any component
• Changes to the telemetry emitted from and/or processed by the collector
• Changes to the prerequisites or assumptions for running a collector
• Changes to an API exported by a collector package
• Meaningful changes to the performance of the collector

Judgement call:

• Major changes to documentation
• Major changes to tests or test frameworks
• Changes to developer tooling in the repo

No changelog entry:

• Typical documentation updates
• Refactorings with no meaningful change in functionality
• Most changes to tests
• Chores, such as enabling linters, or minor changes to the CI process

Adding a Changelog Entry

The CHANGELOG.md file in this repo is autogenerated from .yaml files in the ./.chloggen directory.

Your pull-request should add a new .yaml file to this directory. The name of your file must be unique since the last release.

During the collector release process, all ./.chloggen/*.yaml files are transcribed into CHANGELOG.md and then deleted.

Recommended Steps

1. Create an entry file using make chlog-new. This generates a file based on your current branch (e.g. ./.chloggen/my-branch.yaml)
2. Fill in all fields in the new file
3. Run make chlog-validate to ensure the new file is valid
4. Commit and push the file

Alternately, copy ./.chloggen/TEMPLATE.yaml, or just create your file from scratch.

Adding New Components

Before any code is written, open an issue providing the following information:

• Who's the sponsor for your component. A sponsor is an approver who will be in charge of being the official reviewer of the code and become a code owner for the component. For vendor-specific components, it's good to have a volunteer sponsor. If you can't find one, we'll assign one in a round-robin fashion. A vendor-specific component directly interfaces with a vendor-specific API and is expected to be maintained by a representative of the same vendor. For non-vendor specific components, having a sponsor means that your use case has been validated.
• Some information about your component, such as the reasoning behind it, use-cases, telemetry data types supported, and anything else you think is relevant for us to make a decision about accepting the component.
• The configuration options your component will accept. This will help us understand what it does and have an idea of how the implementation might look like.

Components comprise of exporters, extensions, receivers, and processors. The key criteria to implementing a component is to:

• Implement the component.Component interface
• Provide a configuration structure which defines the configuration of the component
• Provide the implementation which performs the component operation

Familiarize yourself with the interface of the component that you want to write, and use existing implementations as reference. Building a Trace Receiver tutorial provides a detailed example of building a component.

NOTICE: The Collector is in Beta stage and as such the interfaces may undergo breaking changes. Component creators must be available to update or review their components when such changes happen, otherwise the component will be excluded from the default builds.

Generally, maintenance of components is the responsibility of contributors who authored them. If the original author or some other contributor does not maintain the component it may be excluded from the default build. The component will be excluded if it causes build problems, has failing tests or otherwise causes problems to the rest of the repository and the rest of contributors.

• Create your component under the proper folder and use Go standard package naming recommendations.
• Use a boiler-plate Makefile that just references the one at top level, ie.: include ../../Makefile.Common - this allows you to build your component with required build configurations for the contrib repo while avoiding building the full repo during development.
• Each component has its own go.mod file. This allows custom builds of the collector to take a limited sets of dependencies - so run go mod commands as appropriate for your component.
• Implement the needed interface on your component by importing the appropriate component from the core repo. Follow the pattern of existing components regarding config and factory source files and tests.
• Implement your component as appropriate. Provide end-to-end tests (or mock backend/client as appropriate). Target is to get 80% or more of code coverage.
• Add a README.md on the root of your component describing its configuration and usage, likely referencing some of the yaml files used in the component tests. We also suggest that the yaml files used in tests have comments for all available configuration settings so users can copy and modify them as needed.
• Add a replace directive at the root go.mod file so your component is included in the build of the contrib executable.
• Add your component to versions.yaml.
• All components must be included in internal/components/ and in the respective testing harnesses. To align with the test goal of the project, components must be testable within the framework defined within the folder. If a component can not be properly tested within the existing framework, it must increase the non testable components number with a comment within the PR explaining as to why it can not be tested.
• Add the sponsor for your component and yourself to a new line for your component in the .github/CODEOWNERS file.
• Run make generate-gh-issue-templates to add your component to the dropdown list in the issue templates.

Releasing New Components

After a component has been approved and merged, and has been enabled in internal/components/, it must be added to the OpenTelemetry Collector Contrib's release manifest.yaml to be included in the distributed otelcol-contrib binaries and docker images.

Rotating sponsors

The following GitHub users are the currently available sponsors, either by being an approver or a maintainer of the contrib repository. The list is ordered based on a random sort of the list of sponsors done live at the Collector SIG meeting on 27-Apr-2022 and serves as the seed for the round-robin selection of sponsors, as described in the section above.

• @dashpole
• @TylerHelmuth
• @djaglowski
• @codeboten
• @Aneurysm9
• @mx-psi
• @jpkrohling
• @dmitryax
• @evan-bradley
• @MovieStoreGuy
• @bogdandrutu

Whenever a sponsor is picked from the top of this list, please move them to the bottom.

Adding metrics to existing receivers

Following these steps for contributing additional metrics to existing receivers.

• Read instructions here on how to fork, build and create PRs. The only difference is to change repository name from opentelemetry-collector to opentelemetry-collector-contrib
• Edit metadata.yaml of your metrics receiver to add new metrics, e.g.: redisreceiver/metadata.yaml
• To generate new metrics on top of this updated YAML file.
  • Run cd receiver/redisreceiver
  • Run go generate ./...
• Review the changed files and merge the changes into your forked repo.
• Create PR from Github web console following the instructions above.

General Recommendations

Below are some recommendations that apply to typical components. These are not rigid rules and there are exceptions but in general try to follow them.

• Avoid introducing batching, retries or worker pools directly on receivers and exporters. Typically, these are general cases that can be better handled via processors (that also can be reused by other receivers and exporters).
• When implementing exporters try to leverage the exporter helpers from the core repo, see exporterhelper package. This will ensure that the exporter provides zPages and a standard set of metrics.
• replace statements in go.mod files can be automatically inserted by running make crosslink. For more information on the crosslink tool see the README here.

Adding Labels via Comments

In order to facilitate proper label usage and to empower Code Owners, you are able to add labels to issues via comments. To add a label through a comment, post a new comment on an issue starting with /label, followed by a space-separated list of your desired labels. Supported labels come from the table below, or correspond to a component defined in the CODEOWNERS file.

The following general labels are supported:

Label	Label in Comment
good first issue	good-first-issue
help wanted	help-wanted
needs discussion	needs-discussion
needs triage	needs-triage
waiting for author	waiting-for-author

To delete a label, prepend the label with -. Note that you must make a new comment to modify labels; you cannot edit an existing comment.

Example label comment:

/label receiver/prometheus help-wanted -exporter/prometheus

Becoming a Code Owner

A Code Owner is responsible for a component within Collector Contrib, as indicated by the CODEOWNERS file. That responsibility includes maintaining the component, responding to issues, and reviewing pull requests.

Sometimes a component may be in need of a new or additional Code Owner. A few reasons this situation may arise would be:

• The component was never assigned a Code Owner.
• A previous Code Owner stepped down.
• An existing Code Owner has become unresponsive. See unmaintained stability status.
• The existing Code Owners are actively looking for new Code Owners to help.

If you would like to help and become a Code Owner you must meet the following requirements:

1. Be a member of the OpenTelemetry organization.
2. (Code Owner Discretion) It is best to have resolved an issue related to the component, contributed directly to the component, and/or review component PRs. How much interaction with the component is required before becoming a Code Owner is up to any existing Code Owners.

Code Ownership is ultimately up to the judgement of the existing Code Owners and Collector Contrib Maintainers. Meeting the above requirements is not a guarantee to be granted Code Ownership.

To become a Code Owner, open a PR with the CODEOWNERS file modified, adding your GitHub username to the component's row. Be sure to tag the existing Code Owners, if any, within the PR to ensure they receive a notification.

Makefile Guidelines

When adding or modifying the Makefile's in this repository, consider the following design guidelines.

Make targets are organized according to whether they apply to the entire repository, or only to an individual module. The Makefile SHOULD contain "repo-level" targets. (i.e. targets that apply to the entire repo.) Likewise, Makefile.Common SHOULD contain "module-level" targets. (i.e. targets that apply to one module at a time.) Each module should have a Makefile at its root that includes Makefile.Common.

Module-level targets

Module-level targets SHOULD NOT act on nested modules. For example, running make lint at the root of the repo will only evaluate code that is part of the go.opentelemetry.io/collector module. This excludes nested modules such as go.opentelemetry.io/collector/component.

Each module-level target SHOULD have a corresponding repo-level target. For example, make golint will run make lint in each module. In this way, the entire repository is covered. The root Makefile contains some "for each module" targets that can wrap a module-level target into a repo-level target.

Repo-level targets

Whenever reasonable, targets SHOULD be implemented as module-level targets (and wrapped with a repo-level target). However, there are many valid justifications for implementing a standalone repo-level target.

1. The target naturally applies to the repo as a whole. (e.g. Building the collector.)
2. Interaction between modules would be problematic.
3. A necessary tool does not provide a mechanism for scoping its application. (e.g. porto cannot be limited to a specific module.)
4. The "for each module" pattern would result in incomplete coverage of the codebase. (e.g. A target that scans all file, not just .go files.)

Default targets

The default module-level target (i.e. running make in the context of an individual module), should run a substantial set of module-level targets for an individual module. Ideally, this would include all module-level targets, but exceptions should be made if a particular target would result in unacceptable latency in the local development loop.

The default repo-level target (i.e. running make at the root of the repo) should meaningfully validate the entire repo. This should include running the default common target for each module as well as additional repo-level targets.