@snyk/dep-graph

---

Snyk helps you find, fix and monitor for known vulnerabilities in your dependencies, both on an ad hoc basis and as part of your CI (Build) system.

Snyk dep-graph

This library provides a time and space efficient representation of a resolved package dependency graph, which can be used to construct, query and de/serialize dep-graphs.

The Graph

A directed graph, where a node represents a package instance and an edge from node foo to node bar means bar is a dependency of foo.

A package (name@version) can have several different nodes (i.e. instances) in the graph. This flexibility is useful for some ecosystems, for example:

• in npm due to conflict-resolutions by duplication. e.g. try to npm i tap@5.7 and then run npm ls and look for strip-ansi@3.0.1. You'll see that in some instances it depends on ansi-regex@2.0.0 while in others on ansi-regex@2.1.1.
• in maven due to "exclusion" rules. A dependency foo can be declared in the pom.xml such that some of it's sub-dependencies are excluded via the <exclusions> tag. If the same dependency is required elsewhere without (or with different) exclusions then foo can appear in the tree with different sub-trees.

This can also be used to break cycles in the graph, e.g.:

instead of:

A -> B -> C -> A

can have:

A -> B -> C -> A'

API Reference

DepGraph

Interface

A dep-graph instance can be queried using the following interface:

export interface DepGraph {
  readonly pkgManager: {
    name: string;
    version?: string;
    repositories?: Array<{
      alias: string;
    }>;
  };
  readonly rootPkg: {
    name: string;
    version?: string;
    purl?: string;
  };
  // all unique packages in the graph (including root package)
  getPkgs(): Array<{
    name: string;
    version?: string;
    purl?: string;
  }>;
  // all unique packages in the graph, except the root package
  getDepPkgs(): Array<{
    name: string;
    version?: string;
    purl?: string;
  }>;
  pkgPathsToRoot(pkg: Pkg): Array<Array<{
    name: string;
    version?: string;
    purl?: string;
  }>>;
  directDepsLeadingTo(pkg: Pkg): Array<{
    name: string;
    version?: string;
    purl?: string;
  }>;
  countPathsToRoot(pkg: Pkg): number;
  toJSON(): DepGraphData;
  equals(other: DepGraph, options?: { compareRoot?: boolean }): boolean;
}

DepGraphData

A dep-graph can be serialised into the following format:

export interface DepGraphData {
  schemaVersion: string;
  pkgManager: {
    name: string;
    version?: string;
    repositories?: Array<{
      alias: string;
    }>;
  };
  pkgs: Array<{
    id: string;
    info: {
      name: string;
      version?: string;
    purl?: string;
    };
  }>;
  graph: {
    rootNodeId: string;
    nodes: Array<{
      nodeId: string;
      pkgId: string;
      info?: {
        versionProvenance?: {
          type: string;
          location: string;
          property?: {
            name: string;
          };
        },
        labels?: {
          [key: string]: string | undefined;
        };
      };
      deps: Array<{
        nodeId: string;
      }>;
    }>;
  };
}

createFromJSON

DepGraphData can be used to construct a DepGraph instance using createFromJSON

DepGraphBuilder

DepGraphBuilder is used to create new DepGraph instances by adding packages and their connections.

  /**
   * Instantiates build for given package manager
   *
   * @param pkgManager - package manager for which dependcy graph is created
   * @param rootPkg - root package information
   *
   */
  public constructor(pkgManager: types.PkgManager, rootPkg?: types.PkgInfo)

  /**
   * Adds node to the graph. Every node represents logical instance of the package in the dependency graph.
   *
   * @param pkgInfo - name and version of the package
   * @param nodeId - identifier for node in the graph, e.g. `package@version`.
   *                 Must uniquely identify this "instance" of the package in the graph,
   *                 so may need to be more than `package@version` for many ecosystems.
   *                 If in doubt - ask a contributor!
   * @param nodeInfo - additional node info, e.g. for version provenance
   *
   */
  public addPkgNode(pkgInfo: types.PkgInfo, nodeId: string, nodeInfo?: types.NodeInfo)

  /**
   * Makes a connection between parent and its dependency.
   *
   * @param parentNodeId - id of the parent node
   * @param depNodeId - id of the dependency node
   *
   */
  public connectDep(parentNodeId: string, depNodeId: string)

  /**
   * Creates an instance of DepGraph
   *
   * @return DepGraph instance built from provided packages and their connections
   *
   */
  public build(): types.DepGraph

The legacy module

A DepTree is a legacy structure used by the Snyk CLI to represent dependency trees. Conversion functions in the legacy module ease the gradual migration of code that relies on the legacy format.

Legacy DepTree

A DepTree is a recursive structure that is quite similar to the output of npm list --json, and (omitting some details) looks like:

interface DepTree {
  name: string;
  version: string;
  dependencies?: {
    [depName: string]: DepTree
  };
}

The legacy conversion functions aim to maintain extra data that might be attached to the dep-tree and is dependant upon in code that wasn't yet updated to use solely dep-graphs:

• targetOS which exists on tree roots for Docker scans
• versionProvenance which might exist on the nodes of maven trees, storing information about the source manifest that caused the specfic version to be resolved