feat(conda): add licenses support for environment.yml files

docs/docs/coverage/os/conda.md

@@ -6,31 +6,38 @@ Trivy supports the following scanners for Conda packages.
 |:-------------:|:---------:|
 |     SBOM      |     ✓     |
 | Vulnerability |     -     |
-|    License    |   ✓[^1]   |
+|    License    |     ✓     |
 
 
-## SBOM
-Trivy detects packages that have been installed with `Conda`.
 
+## `<package>.json`
+### SBOM
+Trivy parses `<conda-root>/envs/<env>/conda-meta/<package>.json` files to find the dependencies installed in your env.
 
-### `<package>.json`
-Trivy parses `<conda-root>/envs/<env>/conda-meta/<package>.json` files to find the version and license for the dependencies installed in your env.
+### License
+The `<package>.json` files contain package license information.
+Trivy includes licenses for the packages it finds without having to parse additional files.
 
-### `environment.yml`[^2]
-Trivy supports parsing [environment.yml][environment.yml][^2] files to find dependency list.
+## `environment.yml`[^1]
+### SBOM
+Trivy supports parsing [environment.yml][environment.yml][^1] files to find dependency list.
 
-!!! note
-    License detection is currently not supported.
-
-`environment.yml`[^2] files supports [version range][env-version-range]. We can't be sure about versions for these dependencies.
-Therefore, you need to use `conda env export` command to get dependency list in `Conda` default format before scanning `environment.yml`[^2] file.
+`environment.yml`[^1] files supports [version range][env-version-range]. We can't be sure about versions for these dependencies.
+Therefore, you need to use `conda env export` command to get dependency list in `Conda` default format before scanning `environment.yml`[^1] file.
 
 !!! note
     For dependencies in a non-Conda format, Trivy doesn't include a version of them.
 
+### License
+Trivy parses `conda-meta/<package>.json` files at the [prefix] path.
+
+To correctly define licenses, make sure your `environment.yml`[^1] contains `prefix` field and `prefix` directory contains `package.json` files.
+
+!!! note 
+    To get correct `environment.yml`[^1] file and fill `prefix` directory - use `conda env export` command.
 
-[^1]: License detection is only supported for `<package>.json` files
-[^2]: Trivy supports both `yaml` and `yml` extensions.
+[^1]: Trivy supports both `yaml` and `yml` extensions.
 
 [environment.yml]: https://conda.io/projects/conda/en/latest/user-guide/tasks/manage-environments.html#sharing-an-environment
 [env-version-range]: https://docs.conda.io/projects/conda-build/en/latest/resources/package-spec.html#examples-of-package-specs
+[prefix]: https://conda.io/projects/conda/en/latest/user-guide/tasks/manage-environments.html#specifying-a-location-for-an-environment

pkg/dependency/parser/conda/environment/parse.go

@@ -16,6 +16,7 @@ import (
 
 type environment struct {
 	Entries []Entry `yaml:"dependencies"`
+	Prefix  string  `yaml:"prefix"`
 }
 
 type Entry struct {
@@ -27,6 +28,11 @@ type Dependency struct {
 	Line  int
 }
 
+type Packages struct {
+	Packages ftypes.Packages
+	Prefix   string
+}
+
 type Parser struct {
 	logger *log.Logger
 	once   sync.Once
@@ -39,10 +45,10 @@ func NewParser() *Parser {
 	}
 }
 
-func (p *Parser) Parse(r xio.ReadSeekerAt) ([]ftypes.Package, []ftypes.Dependency, error) {
+func (p *Parser) Parse(r xio.ReadSeekerAt) (Packages, error) {
 	var env environment
 	if err := yaml.NewDecoder(r).Decode(&env); err != nil {
-		return nil, nil, xerrors.Errorf("unable to decode conda environment.yml file: %w", err)
+		return Packages{}, xerrors.Errorf("unable to decode conda environment.yml file: %w", err)
 	}
 
 	var pkgs ftypes.Packages
@@ -58,7 +64,10 @@ func (p *Parser) Parse(r xio.ReadSeekerAt) ([]ftypes.Package, []ftypes.Dependenc
 	}
 
 	sort.Sort(pkgs)
-	return pkgs, nil, nil
+	return Packages{
+		Packages: pkgs,
+		Prefix:   env.Prefix,
+	}, nil
 }
 
 func (p *Parser) toPackage(dep Dependency) ftypes.Package {