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Initial version of CEL resource expressions.
CEL for Receiver notification filtering This introduces CEL for filtering CEL resources in a Receiver. Users can define a CEL expression that is applied as a filter for resources that are identified for notification. A CEL expression that returns false means that a resource will not be annotated. Signed-off-by: Kevin McDermott <[email protected]>
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,172 @@ | ||
| package server | ||
|
|
||
| import ( | ||
| "encoding/json" | ||
| "fmt" | ||
| "mime" | ||
| "net/http" | ||
| "strings" | ||
|
|
||
| "github.com/google/cel-go/cel" | ||
| "github.com/google/cel-go/checker/decls" | ||
| "github.com/google/cel-go/common/types" | ||
| "github.com/google/cel-go/common/types/ref" | ||
| "github.com/google/cel-go/common/types/traits" | ||
| celext "github.com/google/cel-go/ext" | ||
| "sigs.k8s.io/controller-runtime/pkg/client" | ||
| ) | ||
|
|
||
| func newCELEvaluator(expr string, req *http.Request) (resourcePredicate, error) { | ||
| env, err := makeCELEnv() | ||
| if err != nil { | ||
| return nil, err | ||
| } | ||
| parsed, issues := env.Parse(expr) | ||
| if issues != nil && issues.Err() != nil { | ||
| return nil, fmt.Errorf("failed to parse expression %v: %w", expr, issues.Err()) | ||
| } | ||
|
|
||
| checked, issues := env.Check(parsed) | ||
| if issues != nil && issues.Err() != nil { | ||
| return nil, fmt.Errorf("expression %v check failed: %w", expr, issues.Err()) | ||
| } | ||
|
|
||
| prg, err := env.Program(checked, cel.EvalOptions(cel.OptOptimize)) | ||
| if err != nil { | ||
| return nil, fmt.Errorf("expression %v failed to create a Program: %w", expr, err) | ||
| } | ||
|
|
||
| body := map[string]any{} | ||
| // Only decodes the body for the expression if the body is JSON. | ||
| // Technically you could generate several resources without any body. | ||
| if isJSONContent(req) { | ||
| if err := json.NewDecoder(req.Body).Decode(&body); err != nil { | ||
| return nil, fmt.Errorf("failed to parse request body as JSON: %s", err) | ||
| } | ||
| } | ||
|
|
||
| return func(obj client.Object) (*bool, error) { | ||
| data, err := clientObjectToMap(obj) | ||
| if err != nil { | ||
| return nil, err | ||
| } | ||
|
|
||
| out, _, err := prg.Eval(map[string]any{ | ||
| "resource": data, | ||
| "request": body, | ||
| }) | ||
| if err != nil { | ||
| return nil, fmt.Errorf("expression %v failed to evaluate: %w", expr, err) | ||
| } | ||
|
|
||
| v, ok := out.(types.Bool) | ||
| if !ok { | ||
| return nil, fmt.Errorf("expression %q did not return a boolean value", expr) | ||
| } | ||
|
|
||
| result := v.Value().(bool) | ||
|
|
||
| return &result, nil | ||
| }, nil | ||
| } | ||
|
|
||
| func makeCELEnv() (*cel.Env, error) { | ||
| mapStrDyn := decls.NewMapType(decls.String, decls.Dyn) | ||
| return cel.NewEnv( | ||
| celext.Strings(), | ||
| celext.Encoders(), | ||
| notifications(), | ||
| cel.Declarations( | ||
| decls.NewVar("resource", mapStrDyn), | ||
| decls.NewVar("request", mapStrDyn), | ||
| )) | ||
| } | ||
|
|
||
| func isJSONContent(r *http.Request) bool { | ||
| contentType := r.Header.Get("Content-type") | ||
| for _, v := range strings.Split(contentType, ",") { | ||
| t, _, err := mime.ParseMediaType(v) | ||
| if err != nil { | ||
| break | ||
| } | ||
| if t == "application/json" { | ||
| return true | ||
| } | ||
| } | ||
|
|
||
| return false | ||
| } | ||
|
|
||
| func notifications() cel.EnvOption { | ||
| r, err := types.NewRegistry() | ||
| if err != nil { | ||
| panic(err) // TODO: Do something better? | ||
| } | ||
|
|
||
| return cel.Lib(¬ificationsLib{registry: r}) | ||
| } | ||
|
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| type notificationsLib struct { | ||
| registry *types.Registry | ||
| } | ||
|
|
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| // LibraryName implements the SingletonLibrary interface method. | ||
| func (*notificationsLib) LibraryName() string { | ||
| return "flux.notifications.lib" | ||
| } | ||
|
|
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| // CompileOptions implements the Library interface method. | ||
| func (l *notificationsLib) CompileOptions() []cel.EnvOption { | ||
| listStrDyn := cel.ListType(cel.DynType) | ||
| opts := []cel.EnvOption{ | ||
| cel.Function("first", | ||
| cel.MemberOverload("first_list", []*cel.Type{listStrDyn}, cel.DynType, | ||
| cel.UnaryBinding(listFirst))), | ||
| cel.Function("last", | ||
| cel.MemberOverload("last_list", []*cel.Type{listStrDyn}, cel.DynType, | ||
| cel.UnaryBinding(listLast))), | ||
| } | ||
|
|
||
| return opts | ||
| } | ||
|
|
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| // ProgramOptions implements the Library interface method. | ||
| func (*notificationsLib) ProgramOptions() []cel.ProgramOption { | ||
| return []cel.ProgramOption{} | ||
| } | ||
|
|
||
| func listLast(val ref.Val) ref.Val { | ||
| l := val.(traits.Lister) | ||
| sz := l.Size().Value().(int64) | ||
|
|
||
| if sz == 0 { | ||
| return types.NullValue | ||
| } | ||
|
|
||
| return l.Get(types.Int(sz - 1)) | ||
| } | ||
|
|
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| func listFirst(val ref.Val) ref.Val { | ||
| l := val.(traits.Lister) | ||
| sz := l.Size().Value().(int64) | ||
|
|
||
| if sz == 0 { | ||
| return types.NullValue | ||
| } | ||
|
|
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| return l.Get(types.Int(0)) | ||
| } | ||
|
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| func clientObjectToMap(v client.Object) (map[string]any, error) { | ||
| b, err := json.Marshal(v) | ||
| if err != nil { | ||
| return nil, fmt.Errorf("failed to marshal PartialObjectMetadata from resource for CEL expression: %w", err) | ||
| } | ||
|
|
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| var result map[string]any | ||
| if err := json.Unmarshal(b, &result); err != nil { | ||
| return nil, fmt.Errorf("failed to unmarshal PartialObjectMetadata from resource for CEL expression: %w", err) | ||
| } | ||
|
|
||
| return result, nil | ||
| } |
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