grafana/pkg/cuectx/ctx.go
sam boyer 2a178bd73c
Introduce coremodels framework (extracted from intent-api) (#47653)
* Copy over most of coremodel from intent-api branch

* Fix import paths

* Fix incorrect provider name

* Add root compgen file, fixup componentroot.yaml

* go mod tidy

* Remove compgen for now

* Add dashboard coremodel

* Remove datasource coremodel, for now

* Tweak comments on dashboard struct model

* devenv: add dashboard testing directly

* Fixup dashboard schema for openness, heatmap

* Update Thema to tip

* Fix wire/registry references

* Fix hclog version
2022-04-14 14:54:35 -04:00

117 lines
3.1 KiB
Go

// Package cuectx provides a single, central CUE context (runtime) and Thema
// library that can be used uniformly across Grafana, and related helper
// functions for loading Thema lineages.
package cuectx
import (
"io"
"io/fs"
"path/filepath"
"testing/fstest"
"cuelang.org/go/cue"
"cuelang.org/go/cue/cuecontext"
"github.com/grafana/thema"
"github.com/grafana/thema/kernel"
"github.com/grafana/thema/load"
)
var ctx *cue.Context = cuecontext.New()
var lib thema.Library = thema.NewLibrary(ctx)
// ProvideCUEContext is a wire service provider of a central cue.Context.
func ProvideCUEContext() *cue.Context {
return ctx
}
// ProvideThemaLibrary is a wire service provider of a central thema.Library.
func ProvideThemaLibrary() thema.Library {
return lib
}
// JSONtoCUE attempts to decode the given []byte into a cue.Value, relying on
// the central Grafana cue.Context provided in this package.
//
// The provided path argument determines the name given to the input bytes if
// later CUE operations (e.g. Thema validation) produce errors related to the
// returned cue.Value.
//
// This is a convenience function for one-off JSON decoding. It's wasteful to
// call it repeatedly. Most use cases use cases should probably prefer making
// their own Thema/CUE decoders.
func JSONtoCUE(path string, b []byte) (cue.Value, error) {
return kernel.NewJSONDecoder(path)(ctx, b)
}
// LoadGrafanaInstancesWithThema loads CUE files containing a lineage
// representing some Grafana core model schema. It is expected to be used when
// implementing a thema.LineageFactory.
//
// This function primarily juggles paths to make CUE's loader happy. Provide the
// path from the grafana root to the directory containing the lineage.cue. The
// lineage.cue file must be the sole contents of the provided fs.FS.
//
// More details on underlying behavior can be found in the docs for github.com/grafana/thema/load.InstancesWithThema.
func LoadGrafanaInstancesWithThema(
path string,
cueFS fs.FS,
lib thema.Library,
opts ...thema.BindOption,
) (thema.Lineage, error) {
prefix := filepath.FromSlash(path)
fs, err := prefixWithGrafanaCUE(prefix, cueFS)
if err != nil {
return nil, err
}
inst, err := load.InstancesWithThema(fs, prefix)
// Need to trick loading by creating the embedded file and
// making it look like a module in the root dir.
if err != nil {
return nil, err
}
val := lib.Context().BuildInstance(inst)
lin, err := thema.BindLineage(val, lib, opts...)
if err != nil {
return nil, err
}
return lin, nil
}
func prefixWithGrafanaCUE(prefix string, inputfs fs.FS) (fs.FS, error) {
m := fstest.MapFS{
filepath.Join("cue.mod", "module.cue"): &fstest.MapFile{Data: []byte(`module: "github.com/grafana/grafana"`)},
}
prefix = filepath.FromSlash(prefix)
err := fs.WalkDir(inputfs, ".", (func(path string, d fs.DirEntry, err error) error {
if err != nil {
return err
}
if d.IsDir() {
return nil
}
f, err := inputfs.Open(path)
if err != nil {
return err
}
defer f.Close() // nolint: errcheck
b, err := io.ReadAll(f)
if err != nil {
return err
}
m[filepath.Join(prefix, path)] = &fstest.MapFile{Data: b}
return nil
}))
return m, err
}