Add initial support for DS_EXPERIMENTAL_GRADLE_BUILTIN_PARSER to gemnasium-maven

Implementation plan

1. Add a new DS_EXPERIMENTAL_GRADLE_BUILTIN_PARSER environment variable to the gradle.Flags:

   Click to expand

   diff --git a/builder/gradle/gradle.go b/builder/gradle/gradle.go
   index 4cdf166..cb20920 100644
   --- a/builder/gradle/gradle.go
   +++ b/builder/gradle/gradle.go
   @@ -17,16 +17,18 @@ import (
    const (
           pathDefaultGradleBinary = "/opt/asdf/shims/gradle"
   
   -       flagGradleOpts       = "gradle-opts"
   -       flagGradleInitScript = "gradle-init-script"
   +       flagGradleOpts               = "gradle-opts"
   +       flagGradleInitScript         = "gradle-init-script"
   +       flagExperimentalGradleParser = "experimental-gradle-parser"
    )
   
    var errNoGradleWrapper = errors.New("cannot access gradle wrapper")
   
    // Builder generates dependency lists for gradle projects
    type Builder struct {
   -       GradleOpts       string
   -       GradleInitScript string
   +       GradleOpts               string
   +       GradleInitScript         string
   +       ExperimentalGradleParser bool
    }
   
    // Flags returns the CLI flags that configure the gradle command
   @@ -44,6 +46,12 @@ func (b Builder) Flags() []cli.Flag {
                           Value:   "gemnasium-gradle-plugin-init.gradle",
                           EnvVars: []string{"GRADLE_PLUGIN_INIT_PATH"},
                   },
   +               &cli.BoolFlag{
   +                       Name:    flagExperimentalGradleParser,
   +                       Usage:   "Enable experimental gradle parser",
   +                       Value:   false,
   +                       EnvVars: []string{"DS_EXPERIMENTAL_GRADLE_BUILTIN_PARSER"},
   +               },
           }
    }
   
   @@ -51,6 +59,7 @@ func (b Builder) Flags() []cli.Flag {
    func (b *Builder) Configure(c *cli.Context) error {
           b.GradleOpts = c.String(flagGradleOpts)
           b.GradleInitScript = c.String(flagGradleInitScript)
   +       b.ExperimentalGradleParser = c.Bool(flagExperimentalGradleParser)
           return nil
    }

2. Add a new init.gradle file to gemnasium-maven, and update the Dockerfile to copy this file to the / directory in the Docker image. This file must contain the following:

   allprojects { apply plugin: 'project-report' }

   This will enable the Project Report Plugin and allow us to export a JSON dependency list.

3. Add conditional logic to the --init-script argument to use the new DS_EXPERIMENTAL_GRADLE_BUILTIN_PARSER environment variable added in step 1. above.

   If the DS_EXPERIMENTAL_GRADLE_BUILTIN_PARSER environment variable is set to true, refer to the init.gradle initialization script added in step 2., and use the htmlDependencyReport task instead of the gemnasiumDumpDependencies task:

   Click to expand

   diff --git a/builder/gradle/gradle.go b/builder/gradle/gradle.go
   index 4cdf166..a7c8597 100644
   --- a/builder/gradle/gradle.go
   +++ b/builder/gradle/gradle.go
   @@ -77,7 +77,14 @@ func (b Builder) listDeps(input string) ([]string, error) {
   
           // run gemnasiumDumpDependencies gradle task
           args := strings.Fields(b.GradleOpts)
   -       args = append(args, "--init-script", b.GradleInitScript, "gemnasiumDumpDependencies")
   +       if b.ExperimentalGradleParser {
   +               initScript := "init.gradle"
   +               taskName := "htmlDependencyReport"
   +               args = []string{"--init-script", initScript, taskName}
   +       } else {
   +               args = append(args, "--init-script", b.GradleInitScript, "gemnasiumDumpDependencies")
   +       }
   +
           cmd := exec.Command(gradlewPath, args...)
           cmd.Dir = dir
           cmd.Env = os.Environ()

4. Create a new extractor in the gemnasium-maven exportpath package to parse the output of the htmlDependencyReport task executed above, to extract the paths to the JSON files for each sub-project. For example, assuming the output is the following:

   root@d04f6cdbcf81:/src# gradle --init-script init.gradle htmlDependencyReport
   
   > Task :htmlDependencyReport
   See the report at: file:///src/build/reports/project/dependencies/index.html
   
   > Task :mail:protocols:pop3:htmlDependencyReport
   See the report at: file:///src/mail/protocols/pop3/build/reports/project/dependencies/index.html
   
   > Task :plugins:openpgp-api-lib:openpgp-api:htmlDependencyReport
   See the report at: file:///src/plugins/openpgp-api-lib/openpgp-api/build/reports/project/dependencies/index.html

   We should obtain the following list of JSON files for the sub-projects:

   • build/reports/project/dependencies/root.js
   • mail/protocols/pop3/build/reports/project/dependencies/root.mail.protocols.pop3.js
   • plugins/openpgp-api-lib/openpgp-api/build/reports/project/dependencies/root.plugins.openpgp-api-lib.openpgp-api.js

5. Create a unit test for the extractor added in step 4. above.

/cc @thiagocsf @johncrowley