renovate/docs/development/adding-a-package-manager.md

Adding a Package Manager

This document explains how to add a new package manager.

Code structure

Code for package managers goes in the lib/modules/manager/* directory. The package manager code is often tightly coupled to the datasource code in lib/modules/datasource/*.

Versioning logic like Semver or PEP 440 goes in lib/modules/versioning/*.

Common application logic for Renovate, not specific to particular managers, usually lives under lib/workers/*.

Manager requirements

The manager's index.ts file supports the following values or functions:

Value/function	Optional	Async
bumpPackageVersion	yes
extractPackageFile		yes
extractAllPackageFiles	yes	yes
getRangeStrategy	yes
categories	yes
supportsLockFileMaintenance	yes
updateArtifacts	yes	yes
updateDependency	yes
updateLockedDependency	yes

bumpPackageVersion (optional)

Use this function to allow version bumps of updated packages. For example:

• to increase the version of a Maven module if a package has been updated
• to bump the Helm chart version, if a subchart version has been updated

extractPackageFile(content, packageFile, config) (async, semi-mandatory)

This function is mandatory, unless you use extractAllPackageFiles instead. It takes as arguments the file's content and optionally the file's full file pathname and config. The function returns an array of detected or extracted dependencies, including the:

• dependency name
• dependency type (dependencies, devDependencies, etc)
• currentValue
• versioning used (like SemVer, PEP 440)

The extractPackageFile function doesn't need to fully understand the file or syntax that it gets. It needs to understand enough to extract a correct list of dependencies.

In general, we extract all dependencies from each dependency file, even if they have values we don't support.

If the function reads parts of a dependency file that it can't parse, it should give a skipReason message to the extractPackageFile function. Make sure the skipReason message is helpful to someone reading the logs.

If extractPackageFile is passed a file which is a "false match", so not a package file, or a file with no dependencies then it can return null. Downstream this results in the file being ignored and removed from the list of package files.

extractAllPackageFiles(packageFiles) (async, optional)

Normally a package manager parses or extracts all package files in parallel, and can thus use the extractPackageFile function. If the package manager you're adding works in serial, use this function instead.

For example the npm and Yarn package manager must process the package.json and package-lock or yarn.lock files together. This allows features like Workspaces to work. This means that for npm or Yarn we need to iterate through all package files after the initial parsing.

As another example, in order for Gradle to extract dependencies Renovate must first call a command via a child process.

The extractAllPackageFiles function takes an array of filenames as input. It returns an array of filenames and dependencies.

If you implement extractAllPackageFiles the manager must export as well either updateDependency or extractPackageFile.

getRangeStrategy(config) (optional)

Write this optional function if you want the manager to support "auto" range strategies. For example, pinning or not pinning a dependency, depending on other values in the package file.

The npm manager uses the getRangeStrategy function to pin devDependencies but not dependencies, unless the package file is detected as an app.

If left undefined, then a default getRangeStrategy will be used that always returns "replace".

supportsLockFileMaintenance (optional)

Set to true if this package manager needs to update lock files in addition to package files.

updateArtifacts (async, optional)

Use updateArtifacts to run binaries that in turn will update files. We often use updateArtifacts to update lock files indirectly.

To directly update dependencies in lock files: use updateLockedDependency instead.

updateArtifacts gets triggered:

• after a dependency update (for a package file), or
• during lockfileMaintenance

updateDependency (optional)

Use updateDependency if both conditions apply:

• the manager can't be updated to use the standard replacing mechanism
• a custom replacement has to be provided

updateLockedDependency (optional)

Use updateLockedDependency to directly update dependencies in lock files.

Package files and Lock files

A special Renovate term is "package files". Package files have human-readable dependency definitions, for example:

• npm's package.json file
• Maven's pom.xml file
• Docker's Dockerfile

Some package managers may also have "lock files", like npm's package-lock.json.

If a repository has a lock file, then Renovate must update the package file and the matching lock file in the same commit. This prevents creating "broken" updates for users and generating frustration with Renovate.

Focus on getting lock file syncing working

When you develop a new package manager, which supports lockfiles, focus on getting lock file synchronization working.

Supporting lock file synchronization usually means that Renovate runs a third-party tool, like npm or poetry. The third-party tool then updates the lock file for Renovate.

Avoid reverse engineering lock file formats

Let a third-party package manager (npm, poetry, etc.) update the lockfile. Avoid "reverse engineering" lock file formats, where Renovate manually updates the lock file.

Only "reverse engineer" lock file formats as a last resort.

Add third-party tools to Containerbase first

Add third-party package manager tools to Containerbase first.

Here are the various ways in approximate order in which lock file awareness should be added to a manager:

Lock file maintenance

The goal of lock file maintenance is to update all locked dependencies (including transitive dependencies) to the latest possible version, without changing ranges defined in package files.

There are two ways to update lock files:

• Call a command like <tool> update to update all locked dependencies (plus transitive dependencies), updating the whole lock file where possible
• Delete the lock file, then call a command like <tool> install to create a new lockfile

If you can, use the <tool> update method, as that keeps platform-specific information.

Keep platform-specific information

Lock files may have platform-specific information (e.g. amd64, arm64). If you delete the lock file, and then create a new lock file with <tool> install, the platform-specific information is lost.

If you can, use the <tool> update method instead!

Lock file updating after a package file change

Updating lock files after a package file changes is a fundamental feature. This means you often need to build it first, when adding new package manager to Renovate.

Add a updateArtifacts() function, that "syncs" the lock file to the package file changes made by Renovate. This way, both files can be updated in the same commit.

Usually, the flow is like this:

1. Renovate directly changes the version or constraint in the package file,
2. Renovate calls a tool command like <tool> install, <tool> lock, etc.
3. If the tool command changes the lock file (which it usually should!), then Renovate commits the changed lock file and the package file

Locked version extracting and dependency pinning

The next step is for the manager's "extract" feature to return a lockedVersion for dependencies, whenever a lock file exists. To do this, the manager needs to:

1. Parse the lock file
2. Match each dependency from the package file to its entry in the lock file
3. Add the matched version as lockedVersion

Once lockedVersion is provided, Renovate should be able to "pin" constraints/ranges into exact versions, if the user configures as such (e.g. rangeStrategy=pin), however Renovate won't automatically be able to make lockfile-only updates.

Lock file-only updates

updateArtifacts()

End users often want, or need to:

• preserve constraints in their package file (like ^1.0.0)
• and want Renovate to update their lock file when a new versions is available (e.g. updating from a locked value of 1.1.0 to 1.1.1)

In this case, the Renovate package manager must extract the lockedVersion as described above!

Detect if updates satisfy isLockFileUpdate=true

In addition to this, the manager needs to add logic to updateArtifacts() to detect if any of the updates it has been passed satisfy isLockFileUpdate=true.

If any lock file-only updates have been passed, then the manager typically needs to run specific commands to update/bump the locked version for one specific dependency only. This functionality is manager-specific, and depends heavily on the capabilities of the third-party tool. A mix of the following approaches are used in Renovate, from best to worst:

• Renovate calls a tool command to specifically update the dependency in question to the specific version, e.g. <tool> update <dependency name>@<new version>
• Renovate manually updates the locked version in the lock file it needs updated, then calls a <tool> install command to "fix" up the remaining parts (hashes, transitive dependencies, etc). This is good, if it works, but it is prone to breaking in future releases if the maintainers of the tool do not know people are using their package manager in this manner, even if it works unintentionally.
• Renovate calls a tool command similar to the first approach, except the tool does not support specific versions, e.g. <tool> update <dependency name>. This approach can be problematic because Renovate might want to update to e.g. v1.1.1 but instead the tool finds a newer v1.1.2 and that's what the user gets instead

Difficult cases

A further complication is that sometimes:

• dependencies must be upgraded together
• there are peer dependency problems
• or there is some other conflict

In those cases it's best if the tool supports creating a list of dependencies to update, and the tool then updates all dependencies at once.

updateLockedDependency()

The updateLockedDependency() method is optional for managers. But we recommend that any manager which supports rangeStrategy=update-lockfile also implements the updateLockedDependency() method.

The goal of the updateLockedDependency() method is to return quickly if a dependency is already updated. This way, Renovate only runs tool commands when there is a dependency to update.

The simplest logic for updateLockedDependency() is:

1. Parse the existing lock file
2. If the locked version of the dependency is already updated to the version specified: return { status: 'already-updated' }
3. Else: return { status: 'unsupported' }

An example of this can be seen in the composer manager source code for updateLockedDependency().