renovate/docs/design-decisions.md

Design Decisions

This file documents the design choices as well as configuration options.

Stateless

No state storage is needed on renovate or the source code repository apart from what you see publicly (branches, Pull Requests). It, therefore, doesn't matter if you stop/restart the script and would even still work if you had it running from two different locations, as long as their configuration was the same.

API only

So far, nothing we need to do requires a full git clone of the repository. e.g. we do not need to perform a git clone of the entire repository. Therefore, all operations are performed via the API.

Synchronous Operation

The script current processes repositories, package files, and dependencies within them all synchronously.

• Greatly reduces the chance of hitting simultaneous API rate limits
• Simplifies logging

Note: Initial queries to NPM are done in parallel.

Multiple Configuration Methods

The script supports multiple configuration methods concurrently, and processed in order of priority. This allows examples such as token configured via environment variable and labels configured via target package.json.

Cascading Configuration

Configuration options applied per-package (e.g. with package rules) override those applied per package-type, which override those per-repository, which override those which are global (all repositories).

Automatic discovery of package.json locations

The default behaviour is to auto-discover all package.json locations in a repository and process them all. Doing so means that "monorepos" are supported by default. This can be overridden by the configuration option includePaths, where you list the file paths manually (e.g. limit to just package.json in the root of the repository).

Separate Branches per dependency

By default, renovate will maintain separate branches per-dependency. So if 20 dependencies need updating, there will be at least 20 branches/PRs. Although this may seem undesirable, it was considered even less desirable if all 20 were in the same Pull Request and it's up to the users to determine which dependency upgrade(s) caused the build to fail.

However, it's still possible to override the default branch and PR name templates in such a way to produce a single branch for all dependencies. The groupName configuration option can be used at a repository level (e.g. give it the value All) and then all dependency updates will be in the same branch/PR.

Separate Minor and Major PRs

renovate will create multiple branches/PRs if both major and minor branch upgrades are available. For example, if the current example is 1.6.0 and upgrades to 1.7.0 and 2.0.0 exist, then renovate will raise PRs for both the 1.x upgrade(s) and 2.x upgrade(s).

• It's often the case that projects can't upgrade major dependency versions immediately.
• It's also often the case that previous major versions continue receiving Minor or Patch updates.
• Projects should get Minor and Patch updates for their current Major release even if a new Major release exists

This can be overridden via the config option separateMajorMinor.

Branch naming

Branches are named like renovate/webpack-1.x instead of renovate/webpack-1.2.0.

• Branches often receive updates (e.g. new patches) before they're merged.
• Naming the branch like 1.x means its name still names sense if a 1.2.1 release happens

Note: Branch names are configurable using string templates.

Pull Request Recreation

By default, the script does not create a new PR if it finds an identical one already closed. This allows users to close unwelcome upgrade PRs and not worry about them being recreated every run. Typically this is most useful for major upgrades. This option is configurable.

Rebasing Unmergeable Pull Requests

With the default behaviour of one branch per dependency, it's often that case that a PR gets merge conflicts after an adjacent dependency update is merged. Although platforms often have a web interface for simple merge conflicts, this is still annoying to resolve manually.

renovate will rebase any unmergeable branches and add the latest necessary commit on top of the most recent master commit.

Note: renovate will only do this if the original branch hasn't been modified by anyone else.

Suppressing string templates from CLI

String templates (e.g. commit or PR name) are not configurable via CLI options, in order to not pollute the CLI help and make it unreadable. If you must configure via CLI, use an environment variable instead. e.g.

$ RENOVATE_BRANCH_NAME=foo renovate

Alternatively, consider using a Configuration File.

Logging and error levels

Renovate uses the following convention for log levels:

• logger.error should only be used for problems that are likely to be a Renovate bug or require Renovate improvements. These are the types of errors that Renovate administrators should be alerted to immediately
• logger.warn should be used for problems that might be a Renovate problem so should be checked periodically in batches
• For user problems (e.g. configuration errors), these should not warn or error on the server side and instead use logger.info