Merge pull request #44 from OpsLevel/eo/rego-read-file

Adding function to read files in policies

Author: eochoa260

.changes/unreleased/Feature-20220803-140502.yaml

@@ -0,0 +1,3 @@
+kind: Feature
+body: Add ability to read file contents with Rego
+time: 2022-08-03T14:05:02.946375-05:00

src/cmd/policy.go

@@ -1,11 +1,15 @@
 package cmd
 
 import (
+	"bufio"
 	"context"
 	"encoding/json"
 	"fmt"
+	"github.com/open-policy-agent/opa/ast"
 	"github.com/open-policy-agent/opa/rego"
-	"github.com/spf13/cobra"
+	"github.com/open-policy-agent/opa/types"
+	"github.com/rs/zerolog/log"
+	cobra "github.com/spf13/cobra"
 	"io/ioutil"
 	"os"
 	"path/filepath"
@@ -43,6 +47,12 @@ opslevel run policy -f policy.rego | jq
 			rego.Module("test.rego",
 				string(policy),
 			),
+			rego.Function1(
+				&rego.Function{
+					Name: "opslevel.read_file",
+					Decl: types.NewFunction(types.Args(types.S), types.S),
+				},
+				RegoFuncReadFile),
 			rego.Input(input),
 		)
 		rs, err := rego.Eval(context.Background())
@@ -54,6 +64,26 @@ opslevel run policy -f policy.rego | jq
 	},
 }
 
+func RegoFuncReadFile(ctx rego.BuiltinContext, a *ast.Term) (*ast.Term, error) {
+	if str, ok := a.Value.(ast.String); ok {
+		if _, err := os.Stat(string(str)); err != nil {
+			log.Warn().Msgf("%s", err)
+		} else {
+			file, err := os.Open(string(str))
+			defer file.Close()
+			cobra.CheckErr(err)
+
+			var lines []*ast.Term
+			scanner := bufio.NewScanner(file)
+			for scanner.Scan() {
+				lines = append(lines, ast.StringTerm(scanner.Text()))
+			}
+			return ast.ArrayTerm(lines...), nil
+		}
+	}
+	return nil, nil
+}
+
 func init() {
 	runCmd.AddCommand(policyCmd)