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https://github.com/open-policy-agent/opa.git
synced 2026-08-13 03:42:35 -06:00
Add various GoDoc examples
This commit is contained in:
Torin Sandall
@@ -0,0 +1,55 @@
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// Copyright 2016 The OPA Authors. All rights reserved.
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// Use of this source code is governed by an Apache2
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// license that can be found in the LICENSE file.
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package ast_test
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import (
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"fmt"
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"github.com/open-policy-agent/opa/ast"
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)
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func ExampleCompiler_Compile() {
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// Define an input module that will be compiled.
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exampleModule := `
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package opa.example
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import data.foo
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import bar
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p[x] :- foo[x], not bar[x], x < min_x
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min_x = 100
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`
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// Parse the input module to obtain the AST representation.
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mod, err := ast.ParseModule("my_module", exampleModule)
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if err != nil {
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fmt.Println("Parse error:", err)
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}
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// Create a new compiler instance and compile the module.
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c := ast.NewCompiler()
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mods := map[string]*ast.Module{
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"my_module": mod,
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}
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if c.Compile(mods); c.Failed() {
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fmt.Println("Compile error:", c.FlattenErrors())
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}
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fmt.Println("Expr 1:", mod.Rules[0].Body[0])
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fmt.Println("Expr 2:", mod.Rules[0].Body[1])
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fmt.Println("Expr 3:", mod.Rules[0].Body[2])
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// Output:
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//
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// Expr 1: data.foo[x]
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// Expr 2: not bar[x]
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// Expr 3: lt(x, data.opa.example.min_x)
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}
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@@ -0,0 +1,42 @@
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// Copyright 2016 The OPA Authors. All rights reserved.
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// Use of this source code is governed by an Apache2
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// license that can be found in the LICENSE file.
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package repl_test
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import (
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"bytes"
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"fmt"
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"github.com/open-policy-agent/opa/repl"
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"github.com/open-policy-agent/opa/storage"
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)
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func ExampleREPL_OneShot() {
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// Setup dummy storage for the policy engine.
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ds := storage.NewDataStore()
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ps := storage.NewPolicyStore(ds, "")
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if err := ps.Open(storage.LoadPolicies); err != nil {
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fmt.Println("Open error:", err)
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}
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// Create a buffer that will receive REPL output.
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var buf bytes.Buffer
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// Create a new REPL.
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repl := repl.New(ds, ps, "", &buf, "json")
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// Define a rule inside the REPL.
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repl.OneShot("p :- a = [1, 2, 3, 4], a[_] > 3")
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// Query the rule defined above.
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repl.OneShot("p")
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// Inspect the output. Defining rules does not produce output so we only expect
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// output from the second line of input.
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fmt.Println(buf.String())
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// Output:
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// true
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}
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@@ -0,0 +1,182 @@
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// Copyright 2016 The OPA Authors. All rights reserved.
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// Use of this source code is governed by an Apache2
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// license that can be found in the LICENSE file.
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package storage_test
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import (
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"encoding/json"
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"fmt"
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"io/ioutil"
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"os"
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"path/filepath"
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"github.com/open-policy-agent/opa/storage"
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)
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func ExampleDataStore_Get() {
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// Define some dummy data to initialize the DataStore with.
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exampleData := `
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{
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"users": [
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{
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"name": "alice",
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"color": "red",
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"likes": ["clouds", "ships"]
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},
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{
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"name": "burt",
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"likes": ["cheese", "wine"]
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}
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]
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}
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`
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var d map[string]interface{}
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if err := json.Unmarshal([]byte(exampleData), &d); err != nil {
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fmt.Println("Unmarshal error:", err)
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}
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// Create the new DataStore with the dummy data.
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ds := storage.NewDataStoreFromJSONObject(d)
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// Read values out of the DataStore.
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v1, err1 := ds.Get([]interface{}{"users", float64(1), "likes", float64(1)})
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v2, err2 := ds.Get([]interface{}{"users", float64(0), "age"})
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// Inspect the return values.
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fmt.Println("v1:", v1)
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fmt.Println("err1:", err1)
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fmt.Println("v2:", v2)
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fmt.Println("err2:", err2)
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fmt.Println("err2 is not found:", storage.IsNotFound(err2))
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// Output:
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// v1: wine
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// err1: <nil>
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// v2: <nil>
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// err2: storage error (code: 1): bad path: [users 0 age], document does not exist
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// err2 is not found: true
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}
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func ExampleDataStore_Patch() {
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// Define some dummy data to initialize the DataStore with.
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exampleData := `
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{
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"users": [
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{
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"name": "alice",
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"color": "red",
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"likes": ["clouds", "ships"]
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},
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{
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"name": "burt",
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"likes": ["cheese", "wine"]
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}
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]
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}
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`
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var d1 map[string]interface{}
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if err := json.Unmarshal([]byte(exampleData), &d1); err != nil {
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fmt.Println("Unmarshal error:", err)
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}
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// Create the new DataStore with the dummy data.
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ds := storage.NewDataStoreFromJSONObject(d1)
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// Define dummy data to add to the DataStore.
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exampleAdd := `{
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"longitude": 82.501389,
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"latitude": -62.338889
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}`
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var d2 interface{}
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if err := json.Unmarshal([]byte(exampleAdd), &d2); err != nil {
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fmt.Println("Unmarshal error:", err)
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}
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// Write values into storage and read result.
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err0 := ds.Patch(storage.AddOp, []interface{}{"users", float64(0), "location"}, d2)
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v1, err1 := ds.Get([]interface{}{"users", float64(0), "location", "latitude"})
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err2 := ds.Patch(storage.ReplaceOp, []interface{}{"users", float64(1), "color"}, "red")
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// Inspect the return values.
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fmt.Println("err0:", err0)
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fmt.Println("v1:", v1)
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fmt.Println("err1:", err1)
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fmt.Println("err2:", err2)
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// Output:
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// err0: <nil>
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// v1: -62.338889
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// err1: <nil>
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// err2: storage error (code: 1): bad path: [users 1 color], document does not exist
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}
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func ExamplePolicyStore_Open() {
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// Define two example modules and write them to disk in a temporary directory.
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ex1 := `
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package opa.example
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p :- q.r != 0
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`
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ex2 := `
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package opa.example
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q = {"r": 100}
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`
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path, err := ioutil.TempDir("", "")
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if err != nil {
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fmt.Println("TempDir error:", err)
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}
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defer os.RemoveAll(path)
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if err = ioutil.WriteFile(filepath.Join(path, "ex1.rego"), []byte(ex1), 0644); err != nil {
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fmt.Println("WriteFile error:", err)
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}
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if err = ioutil.WriteFile(filepath.Join(path, "ex2.rego"), []byte(ex2), 0644); err != nil {
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fmt.Println("WriteFile error:", err)
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}
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// Create a new policy store and use the temporary directory for persistence.
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ds := storage.NewDataStore()
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ps := storage.NewPolicyStore(ds, path)
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// Open the policy store and load the existing modules.
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//
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// The LoadPolicies function provides a default implementation of callback
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// used to load the modules. If necessary, you can provide your own implementation
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// of the callback function to customize the policy store initialization.
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err = ps.Open(storage.LoadPolicies)
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if err != nil {
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fmt.Println("Open error:", err)
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}
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// Inspect one of the loaded policies.
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mod, err := ps.Get("ex1.rego")
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if err != nil {
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fmt.Println("Get error:", err)
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}
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fmt.Println("Expr:", mod.Rules[0].Body[0])
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// Output:
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// Expr: neq(data.opa.example.q.r, 0)
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}
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@@ -0,0 +1,101 @@
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// Copyright 2016 The OPA Authors. All rights reserved.
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// Use of this source code is governed by an Apache2
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// license that can be found in the LICENSE file.
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package topdown_test
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import (
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"fmt"
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"github.com/open-policy-agent/opa/ast"
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"github.com/open-policy-agent/opa/storage"
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"github.com/open-policy-agent/opa/topdown"
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)
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func ExampleEval() {
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// Define a dummy query and some data that the query will execute against.
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query, err := ast.CompileQuery("data.a[_] = x, x >= 2")
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if err != nil {
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fmt.Println("Compile error:", err)
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}
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ds := storage.NewDataStoreFromJSONObject(map[string]interface{}{
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"a": []interface{}{float64(1), float64(2), float64(3), float64(4)},
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})
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// Prepare the evaluation parameters. Evaluation executes against the policy engine's
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// storage. In this case, we seed the storage with a single array of number. Other parameters
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// such as globals, tracing configuration, etc. can be set on the context. See the Context
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// documentation for more details.
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ctx := topdown.NewContext(query, ds)
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result := []interface{}{}
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// Execute the query and provide a callbakc function to accumulate the results.
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err = topdown.Eval(ctx, func(ctx *topdown.Context) error {
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// Each variable in the query will have an associated "binding" in the context.
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x := ctx.Binding(ast.Var("x"))
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// The bindings are ast.Value types so we will convert to a native Go value here.
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v, err := topdown.ValueToInterface(x, ctx)
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if err != nil {
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return err
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}
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result = append(result, v)
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return nil
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})
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// Inspect the query result.
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fmt.Println("result:", result)
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fmt.Println("err:", err)
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// Output:
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// result: [2 3 4]
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// err: <nil>
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}
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func ExampleQuery() {
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// Define a dummy module with rules that produce documents that we will query below.
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mod, err := ast.CompileModule(`
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package opa.example
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p[x] :- q[x], not r[x]
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q[y] :- a = [1,2,3], y = a[_]
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r[z] :- b = [2,4], z = b[_]
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`)
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if err != nil {
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fmt.Println("Compile error:", err)
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}
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// Initialize the policy engine's storage.
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ds := storage.NewDataStore()
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ps := storage.NewPolicyStore(ds, "")
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if err := ps.Add("my_module", mod, nil, false); err != nil {
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fmt.Println("Add error:", err)
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}
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// Prepare the query parameters. Queries execute against the policy engine's storage and can
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// accept additional documents (which are referred to as "globals"). In this case we have no
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// additional documents.
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globals := storage.NewBindings()
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params := topdown.NewQueryParams(ds, globals, []interface{}{"opa", "example", "p"})
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// Execute the query against "p".
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v1, err1 := topdown.Query(params)
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// Inspect the result.
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fmt.Println("v1:", v1)
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fmt.Println("err1:", err1)
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// Output:
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// v1: [1 3]
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// err1: <nil>
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}
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