rego

package
v0.15.1 Latest Latest
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 Go to latest Published: Nov 18, 2019 License: Apache-2.0 Imports: 19 Imported by: 611

Documentation

Overview

Package rego exposes high level APIs for evaluating Rego policies.

Index

Examples

Constants

This section is empty.

Variables

This section is empty.

Functions

func Compiler 

func Compiler(c *ast.Compiler) func(r *Rego)

Compiler returns an argument that sets the Rego compiler.

func DisableInlining added in v0.13.0 

func DisableInlining(paths []string) func(r *Rego)

DisableInlining adds a set of paths to exclude from partial evaluation inlining.

func Dump added in v0.10.0 

func Dump(w io.Writer) func(r *Rego)

Dump returns an argument that sets the writer to dump debugging information to.

func Function1 added in v0.14.0 

func Function1(decl *Function, f Builtin1) func(*Rego)

Function1 returns an option that adds a built-in function to the Rego object.

func Function2 added in v0.14.0 

func Function2(decl *Function, f Builtin2) func(*Rego)

Function2 returns an option that adds a built-in function to the Rego object.

func Function3 added in v0.14.0 

func Function3(decl *Function, f Builtin3) func(*Rego)

Function3 returns an option that adds a built-in function to the Rego object.

func Function4 added in v0.14.0 

func Function4(decl *Function, f Builtin4) func(*Rego)

Function4 returns an option that adds a built-in function to the Rego object.

func FunctionDecl added in v0.15.1 

func FunctionDecl(decl *Function) func(*Rego)

FunctionDecl returns an option that adds a custom-built-in function __declaration__. NO implementation is provided. This is used for non-interpreter execution envs (e.g., Wasm).

func FunctionDyn added in v0.14.0 

func FunctionDyn(decl *Function, f BuiltinDyn) func(*Rego)

FunctionDyn returns an option that adds a built-in function to the Rego object.

func Imports 

func Imports(p []string) func(r *Rego)

Imports returns an argument that adds a Rego import to the query's context.

func Input 

func Input(x interface{}) func(r *Rego)

Input returns an argument that sets the Rego input document. Input should be a native Go value representing the input document.

func Instrument added in v0.7.0 

func Instrument(yes bool) func(r *Rego)

Instrument returns an argument that enables instrumentation for diagnosing performance issues.

func Load added in v0.14.0 

func Load(paths []string, filter loader.Filter) func(r *Rego)

Load returns an argument that adds a filesystem path to load data and Rego modules from. Any file with a *.rego, *.yaml, or *.json extension will be loaded. The path can be either a directory or file, directories are loaded recursively. The optional ignore string patterns can be used to filter which files are used. The Load option can only be used once. Note: Loading files will require a write transaction on the store.

func LoadBundle added in v0.14.0 

func LoadBundle(path string) func(r *Rego)

LoadBundle returns an argument that adds a filesystem path to load a bundle from. The path can be a compressed bundle file or a directory to be loaded as a bundle. Note: Loading bundles will require a write transaction on the store.

func Metrics added in v0.4.9 

func Metrics(m metrics.Metrics) func(r *Rego)

Metrics returns an argument that sets the metrics collection.

func Module 

func Module(filename, input string) func(r *Rego)

Module returns an argument that adds a Rego module.

func Package 

func Package(p string) func(r *Rego)

Package returns an argument that sets the Rego package on the query's context.

func ParsedBundle added in v0.14.0 

func ParsedBundle(name string, b *bundle.Bundle) func(r *Rego)

ParsedBundle returns an argument that adds a bundle to be loaded.

func ParsedImports added in v0.7.0 

func ParsedImports(imp []*ast.Import) func(r *Rego)

ParsedImports returns an argument that adds Rego imports to the query's context.

func ParsedInput added in v0.7.0 

func ParsedInput(x ast.Value) func(r *Rego)

ParsedInput returns an argument that sets the Rego input document.

func ParsedModule added in v0.13.0 

func ParsedModule(module *ast.Module) func(*Rego)

ParsedModule returns an argument that adds a parsed Rego module. If a string module with the same filename name is added, it will override the parsed module.

func ParsedPackage added in v0.7.0 

func ParsedPackage(pkg *ast.Package) func(r *Rego)

ParsedPackage returns an argument that sets the Rego package on the query's context.

func ParsedQuery added in v0.7.0 

func ParsedQuery(q ast.Body) func(r *Rego)

ParsedQuery returns an argument that sets the Rego query.

func ParsedUnknowns added in v0.9.0 

func ParsedUnknowns(unknowns []*ast.Term) func(r *Rego)

ParsedUnknowns returns an argument that sets the values to treat as unknown during partial evaluation.

func PartialNamespace added in v0.7.0 

func PartialNamespace(ns string) func(r *Rego)

PartialNamespace returns an argument that sets the namespace to use for partial evaluation results. The namespace must be a valid package path component.

func PrintTrace added in v0.10.2 

func PrintTrace(w io.Writer, r *Rego)

PrintTrace is a helper function to write a human-readable version of the trace to the writer w.

func Query 

func Query(q string) func(r *Rego)

Query returns an argument that sets the Rego query.

func Runtime added in v0.10.0 

func Runtime(term *ast.Term) func(r *Rego)

Runtime returns an argument that sets the runtime data to provide to the evaluation engine.

func Store added in v0.5.0 

func Store(s storage.Store) func(r *Rego)

Store returns an argument that sets the policy engine's data storage layer.

If using the Load, LoadBundle, or ParsedBundle options then a transaction must also be provided via the Transaction() option. After loading files or bundles the transaction should be aborted or committed.

func Trace added in v0.10.2 

func Trace(yes bool) func(r *Rego)

Trace returns an argument that enables tracing on r.

func Tracer added in v0.5.3 

func Tracer(t topdown.Tracer) func(r *Rego)

Tracer returns an argument that adds a query tracer to r.

func Transaction added in v0.5.2 

func Transaction(txn storage.Transaction) func(r *Rego)

Transaction returns an argument that sets the transaction to use for storage layer operations.

Requires the store associated with the transaction to be provided via the Store() option. If using Load(), LoadBundle(), or ParsedBundle() options the transaction will likely require write params.

func Unknowns added in v0.7.0 

func Unknowns(unknowns []string) func(r *Rego)

Unknowns returns an argument that sets the values to treat as unknown during partial evaluation.

func UnsafeBuiltins added in v0.13.0 

func UnsafeBuiltins(unsafeBuiltins map[string]struct{}) func(r *Rego)

UnsafeBuiltins sets the built-in functions to treat as unsafe and not allow. This option is ignored for module compilation if the caller supplies the compiler. This option is always honored for query compilation. Provide an empty (non-nil) map to disable checks on queries.

Types

type Builtin1 added in v0.14.0 

type Builtin1 func(bctx BuiltinContext, op1 *ast.Term) (*ast.Term, error)

Builtin1 defines a built-in function that accepts 1 argument.

type Builtin2 added in v0.14.0 

type Builtin2 func(bctx BuiltinContext, op1, op2 *ast.Term) (*ast.Term, error)

Builtin2 defines a built-in function that accepts 2 arguments.

type Builtin3 added in v0.14.0 

type Builtin3 func(bctx BuiltinContext, op1, op2, op3 *ast.Term) (*ast.Term, error)

Builtin3 defines a built-in function that accepts 3 argument.

type Builtin4 added in v0.14.0 

type Builtin4 func(bctx BuiltinContext, op1, op2, op3, op4 *ast.Term) (*ast.Term, error)

Builtin4 defines a built-in function that accepts 4 argument.

type BuiltinContext added in v0.14.0 

type BuiltinContext = topdown.BuiltinContext

BuiltinContext contains additional attributes from the evaluator that built-in functions can use, e.g., the request context.Context, caches, etc.

type BuiltinDyn added in v0.14.0 

type BuiltinDyn func(bctx BuiltinContext, terms []*ast.Term) (*ast.Term, error)

BuiltinDyn defines a built-in function that accepts a list of arguments.

type CompileContext added in v0.11.0 

type CompileContext struct {
	// contains filtered or unexported fields
}

CompileContext contains options for Compile calls.

type CompileOption added in v0.11.0 

type CompileOption func(*CompileContext)

CompileOption defines a function to set options on Compile calls.

func CompilePartial added in v0.11.0 

func CompilePartial(yes bool) CompileOption

CompilePartial defines an option to control whether partial evaluation is run before the query is planned and compiled.

type CompileResult added in v0.10.0 

type CompileResult struct {
	Bytes []byte `json:"bytes"`
}

CompileResult represents the result of compiling a Rego query, zero or more Rego modules, and arbitrary contextual data into an executable.

type Errors 

type Errors []error

Errors represents a collection of errors returned when evaluating Rego.

func (Errors) Error 

func (errs Errors) Error() string

type EvalContext added in v0.11.0 

type EvalContext struct {
	// contains filtered or unexported fields
}

EvalContext defines the set of options allowed to be set at evaluation time. Any other options will need to be set on a new Rego object.

type EvalOption added in v0.11.0 

type EvalOption func(*EvalContext)

EvalOption defines a function to set an option on an EvalConfig

func EvalDisableInlining added in v0.13.0 

func EvalDisableInlining(paths []ast.Ref) EvalOption

EvalDisableInlining returns an argument that adds a set of paths to exclude from partial evaluation inlining.

func EvalInput added in v0.11.0 

func EvalInput(input interface{}) EvalOption

EvalInput configures the input for a Prepared Query's evaluation

func EvalInstrument added in v0.11.0 

func EvalInstrument(instrument bool) EvalOption

EvalInstrument enables or disables instrumenting for a Prepared Query's evaluation

func EvalMetrics added in v0.11.0 

func EvalMetrics(metric metrics.Metrics) EvalOption

EvalMetrics configures the metrics for a Prepared Query's evaluation

func EvalParsedInput added in v0.11.0 

func EvalParsedInput(input ast.Value) EvalOption

EvalParsedInput configures the input for a Prepared Query's evaluation

func EvalParsedUnknowns added in v0.11.0 

func EvalParsedUnknowns(unknowns []*ast.Term) EvalOption

EvalParsedUnknowns returns an argument that sets the values to treat as unknown during partial evaluation.

func EvalPartialNamespace added in v0.11.0 

func EvalPartialNamespace(ns string) EvalOption

EvalPartialNamespace returns an argument that sets the namespace to use for partial evaluation results. The namespace must be a valid package path component.

func EvalRuleIndexing added in v0.15.0 

func EvalRuleIndexing(enabled bool) EvalOption

EvalRuleIndexing will disable indexing optimizations for the evaluation. This should only be used when tracing in debug mode.

func EvalTracer added in v0.11.0 

func EvalTracer(tracer topdown.Tracer) EvalOption

EvalTracer configures a tracer for a Prepared Query's evaluation

func EvalTransaction added in v0.11.0 

func EvalTransaction(txn storage.Transaction) EvalOption

EvalTransaction configures the Transaction for a Prepared Query's evaluation

func EvalUnknowns added in v0.11.0 

func EvalUnknowns(unknowns []string) EvalOption

EvalUnknowns returns an argument that sets the values to treat as unknown during partial evaluation.

type ExpressionValue 

type ExpressionValue struct {
	Value    interface{} `json:"value"`
	Text     string      `json:"text"`
	Location *Location   `json:"location"`
}

ExpressionValue defines the value of an expression in a Rego query.

func (*ExpressionValue) String added in v0.10.2 

func (ev *ExpressionValue) String() string

type Function added in v0.14.0 

type Function struct {
	Name    string
	Decl    *types.Function
	Memoize bool
}

Function represents a built-in function that is callable in Rego.

type Location 

type Location struct {
	Row int `json:"row"`
	Col int `json:"col"`
}

Location defines a position in a Rego query or module.

type PartialQueries added in v0.9.0 

type PartialQueries struct {
	Queries []ast.Body    `json:"queries,omitempty"`
	Support []*ast.Module `json:"modules,omitempty"`
}

PartialQueries contains the queries and support modules produced by partial evaluation.

type PartialResult added in v0.7.0 

type PartialResult struct {
	// contains filtered or unexported fields
}

PartialResult represents the result of partial evaluation. The result can be used to generate a new query that can be run when inputs are known.

func (PartialResult) Rego added in v0.7.0 

func (pr PartialResult) Rego(options ...func(*Rego)) *Rego

Rego returns an object that can be evaluated to produce a query result.

type PrepareConfig added in v0.11.0 

type PrepareConfig struct {
	// contains filtered or unexported fields
}

PrepareConfig holds settings to control the behavior of the Prepare call.

type PrepareOption added in v0.11.0 

type PrepareOption func(*PrepareConfig)

PrepareOption defines a function to set an option to control the behavior of the Prepare call.

func WithNoInline added in v0.13.0 

func WithNoInline(paths []string) PrepareOption

WithNoInline adds a set of paths to exclude from partial evaluation inlining.

func WithPartialEval added in v0.11.0 

func WithPartialEval() PrepareOption

WithPartialEval configures an option for PrepareForEval which will have it perform partial evaluation while preparing the query (similar to rego.Rego#PartialResult)

type PreparedEvalQuery added in v0.11.0 

type PreparedEvalQuery struct {
	// contains filtered or unexported fields
}

PreparedEvalQuery holds the prepared Rego state that has been pre-processed for subsequent evaluations.

func (PreparedEvalQuery) Eval added in v0.11.0 

func (pq PreparedEvalQuery) Eval(ctx context.Context, options ...EvalOption) (ResultSet, error)

Eval evaluates this PartialResult's Rego object with additional eval options and returns a ResultSet. If options are provided they will override the original Rego options respective value. The original Rego object transaction will *not* be re-used. A new transaction will be opened if one is not provided with an EvalOption.

func (PreparedEvalQuery) Modules added in v0.14.0 

func (pq PreparedEvalQuery) Modules() map[string]*ast.Module

type PreparedPartialQuery added in v0.11.0 

type PreparedPartialQuery struct {
	// contains filtered or unexported fields
}

PreparedPartialQuery holds the prepared Rego state that has been pre-processed for partial evaluations.

func (PreparedPartialQuery) Modules added in v0.14.0 

func (pq PreparedPartialQuery) Modules() map[string]*ast.Module

func (PreparedPartialQuery) Partial added in v0.11.0 

func (pq PreparedPartialQuery) Partial(ctx context.Context, options ...EvalOption) (*PartialQueries, error)

Partial runs partial evaluation on the prepared query and returns the result. The original Rego object transaction will *not* be re-used. A new transaction will be opened if one is not provided with an EvalOption.

type Rego 

type Rego struct {
	// contains filtered or unexported fields
}

Rego constructs a query and can be evaluated to obtain results.

Example (Custom_function_caching) 
package main

import (
	"context"
	"fmt"
	"math/rand"

	"github.com/open-policy-agent/opa/ast"
	"github.com/open-policy-agent/opa/rego"
	"github.com/open-policy-agent/opa/topdown"
	"github.com/open-policy-agent/opa/types"
)

func main() {

	type builtinCacheKey string

	source := rand.NewSource(0)

	r := rego.New(
		// An example query that uses a custom function.
		rego.Query(`x = myrandom("foo"); y = myrandom("foo")`),

		// A custom function that uses caching.
		rego.FunctionDyn(
			&rego.Function{
				Name:    "myrandom",
				Memoize: true,
				Decl: types.NewFunction(
					types.Args(types.S), // one string input
					types.N,             // one number output
				),
			},
			func(_ topdown.BuiltinContext, args []*ast.Term) (*ast.Term, error) {
				return ast.IntNumberTerm(int(source.Int63())), nil
			},
		),
	)

	rs, err := r.Eval(context.Background())
	if err != nil {
		// handle error
	}

	fmt.Println("x:", rs[0].Bindings["x"])
	fmt.Println("y:", rs[0].Bindings["y"])

}

Output:


x: 8717895732742165505
y: 8717895732742165505
Example (Custom_functional_builtin) 
package main

import (
	"context"
	"fmt"
	"strings"

	"github.com/open-policy-agent/opa/ast"
	"github.com/open-policy-agent/opa/rego"
	"github.com/open-policy-agent/opa/types"
)

func main() {

	r := rego.New(
		// An example query that uses a custom function.
		rego.Query(`x = trim_and_split("/foo/bar/baz/", "/")`),

		// A custom function that trims and splits strings on the same delimiter.
		rego.Function2(
			&rego.Function{
				Name: "trim_and_split",
				Decl: types.NewFunction(
					types.Args(types.S, types.S), // two string inputs
					types.NewArray(nil, types.S), // variable-length string array output
				),
			},
			func(_ rego.BuiltinContext, a, b *ast.Term) (*ast.Term, error) {

				str, ok1 := a.Value.(ast.String)
				delim, ok2 := b.Value.(ast.String)

				// The function is undefined for non-string inputs. Built-in
				// functions should only return errors in unrecoverable cases.
				if !ok1 || !ok2 {
					return nil, nil
				}

				result := strings.Split(strings.Trim(string(str), string(delim)), string(delim))

				arr := make(ast.Array, len(result))
				for i := range result {
					arr[i] = ast.StringTerm(result[i])
				}

				return ast.NewTerm(arr), nil
			},
		),
	)

	rs, err := r.Eval(context.Background())
	if err != nil {
		// handle error
	}

	fmt.Println(rs[0].Bindings["x"])

}

Output:


[foo bar baz]

func New 

func New(options ...func(r *Rego)) *Rego

New returns a new Rego object.

func (*Rego) Compile added in v0.10.0 

func (r *Rego) Compile(ctx context.Context, opts ...CompileOption) (*CompileResult, error)

Compile returns a compiled policy query.

func (*Rego) Eval 

func (r *Rego) Eval(ctx context.Context) (ResultSet, error)

Eval evaluates this Rego object and returns a ResultSet.

Example (Compiler) 
package main

import (
	"context"
	"fmt"

	"github.com/open-policy-agent/opa/ast"
	"github.com/open-policy-agent/opa/rego"
)

func main() {

	ctx := context.Background()

	// Define a simple policy.
	module := `
		package example

		default allow = false

		allow {
			input.identity = "admin"
		}

		allow {
			input.method = "GET"
		}
	`

	// Compile the module. The keys are used as identifiers in error messages.
	compiler, err := ast.CompileModules(map[string]string{
		"example.rego": module,
	})

	// Create a new query that uses the compiled policy from above.
	rego := rego.New(
		rego.Query("data.example.allow"),
		rego.Compiler(compiler),
		rego.Input(
			map[string]interface{}{
				"identity": "bob",
				"method":   "GET",
			},
		),
	)

	// Run evaluation.
	rs, err := rego.Eval(ctx)

	if err != nil {
		// Handle error.
	}

	// Inspect results.
	fmt.Println("len:", len(rs))
	fmt.Println("value:", rs[0].Expressions[0].Value)

}

Output:


len: 1
value: true
Example (Errors) 
package main

import (
	"context"
	"fmt"

	"github.com/open-policy-agent/opa/ast"
	"github.com/open-policy-agent/opa/rego"
)

func main() {

	ctx := context.Background()

	r := rego.New(
		rego.Query("data.example.p"),
		rego.Module("example_error.rego",
			`package example

p = true { not q[x] }
q = {1, 2, 3} { true }`,
		))

	_, err := r.Eval(ctx)

	switch err := err.(type) {
	case ast.Errors:
		for _, e := range err {
			fmt.Println("code:", e.Code)
			fmt.Println("row:", e.Location.Row)
			fmt.Println("filename:", e.Location.File)
		}
	default:
		// Some other error occurred.
	}

}

Output:


code: rego_unsafe_var_error
row: 3
filename: example_error.rego
Example (Input) 
package main

import (
	"bytes"
	"context"
	"encoding/json"
	"fmt"

	"github.com/open-policy-agent/opa/rego"
)

func main() {

	ctx := context.Background()

	// Raw input data that will be used in evaluation.
	raw := `{"users": [{"id": "bob"}, {"id": "alice"}]}`
	d := json.NewDecoder(bytes.NewBufferString(raw))

	// Numeric values must be represented using json.Number.
	d.UseNumber()

	var input interface{}

	if err := d.Decode(&input); err != nil {
		panic(err)
	}

	// Create a simple query over the input.
	rego := rego.New(
		rego.Query("input.users[idx].id = user_id"),
		rego.Input(input))

	//Run evaluation.
	rs, err := rego.Eval(ctx)

	if err != nil {
		// Handle error.
	}

	// Inspect results.
	fmt.Println("len:", len(rs))
	fmt.Println("bindings.idx:", rs[1].Bindings["idx"])
	fmt.Println("bindings.user_id:", rs[1].Bindings["user_id"])

}

Output:


len: 2
bindings.idx: 1
bindings.user_id: alice
Example (MultipleBindings) 
package main

import (
	"context"
	"fmt"

	"github.com/open-policy-agent/opa/rego"
)

func main() {

	ctx := context.Background()

	// Create query that produces multiple bindings for variable.
	rego := rego.New(
		rego.Query(`a = ["ex", "am", "ple"]; x = a[_]; not p[x]`),
		rego.Package(`example`),
		rego.Module("example.rego", `package example

		p["am"] { true }
		`),
	)

	// Run evaluation.
	rs, err := rego.Eval(ctx)

	// Inspect results.
	fmt.Println("len:", len(rs))
	fmt.Println("err:", err)
	for i := range rs {
		fmt.Printf("bindings[\"x\"]: %v (i=%d)\n", rs[i].Bindings["x"], i)
	}

}

Output:


len: 2
err: <nil>
bindings["x"]: ex (i=0)
bindings["x"]: ple (i=1)
Example (MultipleDocuments) 
package main

import (
	"context"
	"fmt"

	"github.com/open-policy-agent/opa/rego"
)

func main() {

	ctx := context.Background()

	// Create query that produces multiple documents.
	rego := rego.New(
		rego.Query("data.example.p[x]"),
		rego.Module("example.rego",
			`package example

p = {"hello": "alice", "goodbye": "bob"} { true }`,
		))

	// Run evaluation.
	rs, err := rego.Eval(ctx)

	// Inspect results.
	fmt.Println("len:", len(rs))
	fmt.Println("err:", err)
	for i := range rs {
		fmt.Printf("bindings[\"x\"]: %v (i=%d)\n", rs[i].Bindings["x"], i)
		fmt.Printf("value: %v (i=%d)\n", rs[i].Expressions[0].Value, i)
	}

}

Output:


len: 2
err: <nil>
bindings["x"]: hello (i=0)
value: alice (i=0)
bindings["x"]: goodbye (i=1)
value: bob (i=1)
Example (Simple) 
package main

import (
	"context"
	"fmt"

	"github.com/open-policy-agent/opa/rego"
)

func main() {

	ctx := context.Background()

	// Create very simple query that binds a single variable.
	rego := rego.New(rego.Query("x = 1"))

	// Run evaluation.
	rs, err := rego.Eval(ctx)

	// Inspect results.
	fmt.Println("len:", len(rs))
	fmt.Println("bindings:", rs[0].Bindings)
	fmt.Println("err:", err)

}

Output:


len: 1
bindings: map[x:1]
err: <nil>
Example (SingleDocument) 
package main

import (
	"context"
	"fmt"

	"github.com/open-policy-agent/opa/rego"
)

func main() {

	ctx := context.Background()

	// Create query that produces a single document.
	rego := rego.New(
		rego.Query("data.example.p"),
		rego.Module("example.rego",
			`package example

p = ["hello", "world"] { true }`,
		))

	// Run evaluation.
	rs, err := rego.Eval(ctx)

	// Inspect result.
	fmt.Println("value:", rs[0].Expressions[0].Value)
	fmt.Println("err:", err)

}

Output:


value: [hello world]
err: <nil>
Example (Storage) 
package main

import (
	"context"
	"fmt"

	"github.com/open-policy-agent/opa/rego"
	"github.com/open-policy-agent/opa/storage/inmem"
	"github.com/open-policy-agent/opa/util"
)

func main() {

	ctx := context.Background()

	data := `{
        "example": {
            "users": [
                {
                    "name": "alice",
                    "likes": ["dogs", "clouds"]
                },
                {
                    "name": "bob",
                    "likes": ["pizza", "cats"]
                }
            ]
        }
    }`

	var json map[string]interface{}

	err := util.UnmarshalJSON([]byte(data), &json)
	if err != nil {
		// Handle error.
	}

	// Manually create the storage layer. inmem.NewFromObject returns an
	// in-memory store containing the supplied data.
	store := inmem.NewFromObject(json)

	// Create new query that returns the value
	rego := rego.New(
		rego.Query("data.example.users[0].likes"),
		rego.Store(store))

	// Run evaluation.
	rs, err := rego.Eval(ctx)
	if err != nil {
		// Handle error.
	}

	// Inspect the result.
	fmt.Println("value:", rs[0].Expressions[0].Value)

}

Output:


value: [dogs clouds]
Example (Tracer) 
package main

import (
	"context"
	"os"

	"github.com/open-policy-agent/opa/rego"
	"github.com/open-policy-agent/opa/topdown"
)

func main() {

	ctx := context.Background()

	buf := topdown.NewBufferTracer()

	// Create very simple query that binds a single variable, and enables tracing.
	rego := rego.New(
		rego.Query("x = 1"),
		rego.Tracer(buf),
	)

	// Run evaluation.
	rego.Eval(ctx)

	// Inspect results.
	topdown.PrettyTrace(os.Stdout, *buf)

}

Output:


Enter x = 1
| Eval x = 1
| Exit x = 1
Redo x = 1
| Redo x = 1
Example (Transactions) 
package main

import (
	"bytes"
	"context"
	"fmt"

	"github.com/open-policy-agent/opa/rego"
	"github.com/open-policy-agent/opa/storage"
	"github.com/open-policy-agent/opa/storage/inmem"
)

func main() {

	ctx := context.Background()

	// Create storage layer and load dummy data.
	store := inmem.NewFromReader(bytes.NewBufferString(`{
		"favourites": {
			"pizza": "cheese",
			"colour": "violet"
		}
	}`))

	// Open a write transaction on the store that will perform write operations.
	txn, err := store.NewTransaction(ctx, storage.WriteParams)
	if err != nil {
		// Handle error.
	}

	// Create rego query that uses the transaction created above.
	inside := rego.New(
		rego.Query("data.favourites.pizza"),
		rego.Store(store),
		rego.Transaction(txn),
	)

	// Create rego query that DOES NOT use the transaction created above. Under
	// the hood, the rego package will create it's own transaction to
	// ensure it evaluates over a consistent snapshot of the storage layer.
	outside := rego.New(
		rego.Query("data.favourites.pizza"),
		rego.Store(store),
	)

	// Write change to storage layer inside the transaction.
	err = store.Write(ctx, txn, storage.AddOp, storage.MustParsePath("/favourites/pizza"), "pepperoni")
	if err != nil {
		// Handle error.
	}

	// Run evaluation INSIDE the transaction.
	rs, err := inside.Eval(ctx)
	if err != nil {
		// Handle error.
	}

	fmt.Println("value (inside txn):", rs[0].Expressions[0].Value)

	// Run evaluation OUTSIDE the transaction.
	rs, err = outside.Eval(ctx)
	if err != nil {
		// Handle error.
	}

	fmt.Println("value (outside txn):", rs[0].Expressions[0].Value)

	if err := store.Commit(ctx, txn); err != nil {
		// Handle error.
	}

	// Run evaluation AFTER the transaction commits.
	rs, err = outside.Eval(ctx)
	if err != nil {
		// Handle error.
	}

	fmt.Println("value (after txn):", rs[0].Expressions[0].Value)

}

Output:


value (inside txn): pepperoni
value (outside txn): cheese
value (after txn): pepperoni

func (*Rego) Partial added in v0.9.0 

func (r *Rego) Partial(ctx context.Context) (*PartialQueries, error)

Partial runs partial evaluation on r and returns the result.

Example 
package main

import (
	"context"
	"fmt"

	"github.com/open-policy-agent/opa/rego"
)

func main() {

	ctx := context.Background()

	// Define a simple policy for example purposes.
	module := `package test

	allow {
		input.method = read_methods[_]
		input.path = ["reviews", user]
		input.user = user
	}

	allow {
		input.method = read_methods[_]
		input.path = ["reviews", _]
		input.is_admin
	}

	read_methods = ["GET"]
	`

	r := rego.New(rego.Query("data.test.allow == true"), rego.Module("example.rego", module))
	pq, err := r.Partial(ctx)
	if err != nil {
		// Handle error.
	}

	// Inspect result.
	for i := range pq.Queries {
		fmt.Printf("Query #%d: %v\n", i+1, pq.Queries[i])
	}

}

Output:


Query #1: "GET" = input.method; input.path = ["reviews", _]; input.is_admin
Query #2: "GET" = input.method; input.path = ["reviews", user3]; user3 = input.user

func (*Rego) PartialEval added in v0.7.0 

func (r *Rego) PartialEval(ctx context.Context) (PartialResult, error)

PartialEval has been deprecated and renamed to PartialResult.

func (*Rego) PartialResult added in v0.9.0 

func (r *Rego) PartialResult(ctx context.Context) (PartialResult, error)

PartialResult partially evaluates this Rego object and returns a PartialResult.

Example 
package main

import (
	"bytes"
	"context"
	"fmt"

	"github.com/open-policy-agent/opa/rego"
	"github.com/open-policy-agent/opa/storage/inmem"
)

func main() {

	ctx := context.Background()

	// Define a role-based access control (RBAC) policy that decides whether to
	// allow or deny requests. Requests are allowed if the user is bound to a
	// role that grants permission to perform the operation on the resource.
	module := `
		package example

		import data.bindings
		import data.roles

		default allow = false

		allow {
			user_has_role[role_name]
			role_has_permission[role_name]
		}

		user_has_role[role_name] {
			b = bindings[_]
			b.role = role_name
			b.user = input.subject.user
		}

		role_has_permission[role_name] {
			r = roles[_]
			r.name = role_name
			match_with_wildcard(r.operations, input.operation)
			match_with_wildcard(r.resources, input.resource)
		}

		match_with_wildcard(allowed, value) {
			allowed[_] = "*"
		}

		match_with_wildcard(allowed, value) {
			allowed[_] = value
		}
	`

	// Define dummy roles and role bindings for the example. In real-world
	// scenarios, this data would be pushed or pulled into the service
	// embedding OPA either from an external API or configuration file.
	store := inmem.NewFromReader(bytes.NewBufferString(`{
		"roles": [
			{
				"resources": ["documentA", "documentB"],
				"operations": ["read"],
				"name": "analyst"
			},
			{
				"resources": ["*"],
				"operations": ["*"],
				"name": "admin"
			}
		],
		"bindings": [
			{
				"user": "bob",
				"role": "admin"
			},
			{
				"user": "alice",
				"role": "analyst"
			}
		]
	}`))

	// Prepare and run partial evaluation on the query. The result of partial
	// evaluation can be cached for performance. When the data or policy
	// change, partial evaluation should be re-run.
	r := rego.New(
		rego.Query("data.example.allow"),
		rego.Module("example.rego", module),
		rego.Store(store),
	)

	pr, err := r.PartialEval(ctx)
	if err != nil {
		// Handle error.
	}

	// Define example inputs (representing requests) that will be used to test
	// the policy.
	examples := []map[string]interface{}{
		{
			"resource":  "documentA",
			"operation": "write",
			"subject": map[string]interface{}{
				"user": "bob",
			},
		},
		{
			"resource":  "documentB",
			"operation": "write",
			"subject": map[string]interface{}{
				"user": "alice",
			},
		},
		{
			"resource":  "documentB",
			"operation": "read",
			"subject": map[string]interface{}{
				"user": "alice",
			},
		},
	}

	for i := range examples {

		// Prepare and run normal evaluation from the result of partial
		// evaluation.
		r := pr.Rego(
			rego.Input(examples[i]),
		)

		rs, err := r.Eval(ctx)

		if err != nil || len(rs) != 1 || len(rs[0].Expressions) != 1 {
			// Handle erorr.
		} else {
			fmt.Printf("input %d allowed: %v\n", i+1, rs[0].Expressions[0].Value)
		}
	}

}

Output:


input 1 allowed: true
input 2 allowed: false
input 3 allowed: true

func (*Rego) PrepareForEval added in v0.11.0 

func (r *Rego) PrepareForEval(ctx context.Context, opts ...PrepareOption) (PreparedEvalQuery, error)

PrepareForEval will parse inputs, modules, and query arguments in preparation of evaluating them.

Example 
package main

import (
	"context"
	"fmt"

	"github.com/open-policy-agent/opa/rego"
)

func main() {
	ctx := context.Background()

	// Create a simple query
	r := rego.New(
		rego.Query("input.x == 1"),
	)

	// Prepare for evaluation
	pq, err := r.PrepareForEval(ctx)

	if err != nil {
		// Handle error.
	}

	// Raw input data that will be used in the first evaluation
	input := map[string]interface{}{"x": 2}

	// Run the evaluation
	rs, err := pq.Eval(ctx, rego.EvalInput(input))

	if err != nil {
		// Handle error.
	}

	// Inspect results.
	fmt.Println("initial result:", rs[0].Expressions[0])

	// Update input
	input["x"] = 1

	// Run the evaluation with new input
	rs, err = pq.Eval(ctx, rego.EvalInput(input))

	if err != nil {
		// Handle error.
	}

	// Inspect results.
	fmt.Println("updated result:", rs[0].Expressions[0])

}

Output:


initial result: false
updated result: true

func (*Rego) PrepareForPartial added in v0.11.0 

func (r *Rego) PrepareForPartial(ctx context.Context, opts ...PrepareOption) (PreparedPartialQuery, error)

PrepareForPartial will parse inputs, modules, and query arguments in preparation of partially evaluating them.

Example 
package main

import (
	"context"
	"fmt"

	"github.com/open-policy-agent/opa/rego"
)

func main() {

	ctx := context.Background()

	// Define a simple policy for example purposes.
	module := `package test

	allow {
		input.method = read_methods[_]
		input.path = ["reviews", user]
		input.user = user
	}

	allow {
		input.method = read_methods[_]
		input.path = ["reviews", _]
		input.is_admin
	}

	read_methods = ["GET"]
	`

	r := rego.New(
		rego.Query("data.test.allow == true"),
		rego.Module("example.rego", module),
	)

	pq, err := r.PrepareForPartial(ctx)
	if err != nil {
		// Handle error.
	}

	pqs, err := pq.Partial(ctx)
	if err != nil {
		// Handle error.
	}

	// Inspect result
	fmt.Println("First evaluation")
	for i := range pqs.Queries {
		fmt.Printf("Query #%d: %v\n", i+1, pqs.Queries[i])
	}

	// Evaluate with specified input
	exampleInput := map[string]string{
		"method": "GET",
	}

	// Evaluate again with different input and unknowns
	pqs, err = pq.Partial(ctx,
		rego.EvalInput(exampleInput),
		rego.EvalUnknowns([]string{"input.user", "input.is_admin", "input.path"}),
	)
	if err != nil {
		// Handle error.
	}

	// Inspect result
	fmt.Println("Second evaluation")
	for i := range pqs.Queries {
		fmt.Printf("Query #%d: %v\n", i+1, pqs.Queries[i])
	}

}

Output:


First evaluation
Query #1: "GET" = input.method; input.path = ["reviews", _]; input.is_admin
Query #2: "GET" = input.method; input.path = ["reviews", user3]; user3 = input.user
Second evaluation
Query #1: input.path = ["reviews", _]; input.is_admin
Query #2: input.path = ["reviews", user3]; user3 = input.user

type Result 

type Result struct {
	Expressions []*ExpressionValue `json:"expressions"`
	Bindings    Vars               `json:"bindings,omitempty"`
}

Result defines the output of Rego evaluation.

type ResultSet 

type ResultSet []Result

ResultSet represents a collection of output from Rego evaluation. An empty result set represents an undefined query.

type Vars 

type Vars map[string]interface{}

Vars represents a collection of variable bindings. The keys are the variable names and the values are the binding values.

func (Vars) WithoutWildcards added in v0.5.3 

func (v Vars) WithoutWildcards() Vars

WithoutWildcards returns a copy of v with wildcard variables removed.

Source Files

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