feat: implement in-process-flagd provider

providers/flagd-in-process/README.md

@@ -0,0 +1,65 @@
+# In-process Flagd Provider
+
+This provider implements parts of the functionality of [Flagd](https://github.com/open-feature/flagd), and follows its
+specification for [in-process providers](https://github.com/open-feature/flagd/blob/main/docs/other_resources/in-process-providers/specification.md).
+
+## Setup
+To use flagd with the [OpenFeature SDK](https://github.com/open-feature/go-sdk) set the provider to the `openfeature` global singleton as shown below (using default values which align with those of `flagd`)
+```go
+openfeature.SetProvider(inprocessflagd.NewProvider())
+```  
+You may also provide additional options to configure the provider client
+```go
+WithSourceURI("localhost:8015")                  // sets the source URI
+inprocessflagd.FromEnv()                         // sets the provider configuration from environment variables
+inprocessflagd.WithSocketPath(string)            // no default, when set a unix socket connection is used (only available for GRPC)
+inprocessflagd.WithTLS(certPath string)          // default of false, if certPath is not given, system certs are used
+inprocessflagd.WithLogger(logger)                // sets a custom logger (see logging section)
+inprocessflagd.WithOtelInterceptor(bool)         // enable or disable OpenTelemetry interceptor for flagd communication
+```
+for example:
+```go
+package main
+
+import (
+	inprocessflagd "github.com/open-feature/go-sdk-contrib/providers/flagd-in-process/pkg"
+   	"github.com/open-feature/go-sdk/pkg/openfeature"
+)
+
+func main() {
+    openfeature.SetProvider(inprocessflagd.NewProvider(
+		inprocessflagd.WithSourceURI("localhost:8015"),
+		inprocessflagd.WithSourceProviderType(inprocessflagd.SourceTypeGrpc),
+    ))
+}
+```
+
+### Using inprocessflagd.FromEnv()  
+By default the flagd provider will read non-empty environment variables to set its own configuration with the lowest priority. Use the `flagd.FromEnv()` option as an argument for the `flagd.NewProvider()` method to give environment variables a higher priority.
+
+| Option name                 | Environment variable name             | Type    | Options      | Default                                |
+| --------------------------- | ------------------------------------- | ------- | ------------ | -------------------------------------- |
+| host                        | FLAGD_PROXY_HOST                      | string  |              | localhost                              |
+| port                        | FLAGD_PROXY_PORT                      | number  |              | 8013                                   |
+| tls                         | FLAGD_PROXY_TLS                       | boolean |              | false                                  |
+| socketPath                  | FLAGD_PROXY_SOCKET_PATH               | string  |              |                                        |
+| certPath                    | FLAGD_PROXY_SERVER_CERT_PATH          | string  |              |                                        |
+| sourceURI                   | FLAGD_SOURCE_URI                      | string  |              |                                        |
+| sourceProviderType          | FLAGD_SOURCE_PROVIDER_TYPE            | string  |              | grpc                                   |
+| sourceSelector              | FLAGD_SOURCE_SELECTOR                 | string  |              |                                        |
+| maxSyncRetries              | FLAGD_MAX_SYNC_RETRIES                | int     |              | 0 (0 means unlimited)                  |
+| maxSyncRetryInterval        | FLAGD_MAX_SYNC_RETRY_INTERVAL         | int     |              | 60s                                    |
+
+In the event that another configuration option is passed to the `flagd.NewProvider()` method, such as `WithSourceURI("localhost:8015")` then priority is decided by the order in which the options are passed to the constructor from lowest to highest priority.
+
+e.g. below the values set by `FromEnv()` overwrite the value set by `WithSourceURI("localhost:8015")`.
+```go
+openfeature.SetProvider(flagd.NewProvider(
+        flagd.WithSourceURI("localhost:8015"),
+        flagd.FromEnv(),
+    ))
+```
+
+## License
+
+Apache 2.0 - See [LICENSE](./../../LICENSE) for more information.

providers/flagd-in-process/go.mod

@@ -0,0 +1,111 @@
+module github.com/open-feature/go-sdk-contrib/providers/flagd-in-process
+
+go 1.20
+
+require (
+	buf.build/gen/go/open-feature/flagd/grpc/go v1.3.0-20230710190440-2333a9579c1a.1
+	buf.build/gen/go/open-feature/flagd/protocolbuffers/go v1.31.0-20230720212818-3675556880a1.1
+	github.com/golang/mock v1.6.0
+	github.com/open-feature/flagd/core v0.6.5
+	github.com/open-feature/go-sdk v1.6.0
+	github.com/stretchr/testify v1.8.4
+	google.golang.org/grpc v1.58.0
+	google.golang.org/protobuf v1.31.0
+)
+
+require (
+	buf.build/gen/go/open-feature/flagd/bufbuild/connect-go v1.9.0-20230720212818-3675556880a1.1 // indirect
+	github.com/beorn7/perks v1.0.1 // indirect
+	github.com/bufbuild/connect-go v1.10.0 // indirect
+	github.com/bufbuild/connect-opentelemetry-go v0.4.0 // indirect
+	github.com/cenkalti/backoff/v4 v4.2.1 // indirect
+	github.com/cespare/xxhash/v2 v2.2.0 // indirect
+	github.com/davecgh/go-spew v1.1.1 // indirect
+	github.com/diegoholiveira/jsonlogic/v3 v3.3.0 // indirect
+	github.com/emicklei/go-restful/v3 v3.10.1 // indirect
+	github.com/evanphx/json-patch/v5 v5.6.0 // indirect
+	github.com/fsnotify/fsnotify v1.6.0 // indirect
+	github.com/go-logr/logr v1.2.4 // indirect
+	github.com/go-logr/stdr v1.2.2 // indirect
+	github.com/go-openapi/jsonpointer v0.19.6 // indirect
+	github.com/go-openapi/jsonreference v0.20.2 // indirect
+	github.com/go-openapi/swag v0.22.3 // indirect
+	github.com/gogo/protobuf v1.3.2 // indirect
+	github.com/golang/groupcache v0.0.0-20210331224755-41bb18bfe9da // indirect
+	github.com/golang/protobuf v1.5.3 // indirect
+	github.com/google/gnostic-models v0.6.8 // indirect
+	github.com/google/go-cmp v0.5.9 // indirect
+	github.com/google/gofuzz v1.2.0 // indirect
+	github.com/google/uuid v1.3.0 // indirect
+	github.com/grpc-ecosystem/grpc-gateway/v2 v2.16.0 // indirect
+	github.com/imdario/mergo v0.3.13 // indirect
+	github.com/josharian/intern v1.0.0 // indirect
+	github.com/json-iterator/go v1.1.12 // indirect
+	github.com/klauspost/cpuid/v2 v2.2.4 // indirect
+	github.com/mailru/easyjson v0.7.7 // indirect
+	github.com/matttproud/golang_protobuf_extensions v1.0.4 // indirect
+	github.com/mitchellh/copystructure v1.2.0 // indirect
+	github.com/mitchellh/reflectwalk v1.0.2 // indirect
+	github.com/modern-go/concurrent v0.0.0-20180306012644-bacd9c7ef1dd // indirect
+	github.com/modern-go/reflect2 v1.0.2 // indirect
+	github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822 // indirect
+	github.com/open-feature/open-feature-operator v0.2.36 // indirect
+	github.com/open-feature/schemas v0.2.8 // indirect
+	github.com/pkg/errors v0.9.1 // indirect
+	github.com/pmezard/go-difflib v1.0.0 // indirect
+	github.com/prometheus/client_golang v1.16.0 // indirect
+	github.com/prometheus/client_model v0.4.0 // indirect
+	github.com/prometheus/common v0.44.0 // indirect
+	github.com/prometheus/procfs v0.10.1 // indirect
+	github.com/robfig/cron v1.2.0 // indirect
+	github.com/rs/cors v1.10.0 // indirect
+	github.com/rs/xid v1.5.0 // indirect
+	github.com/spf13/pflag v1.0.5 // indirect
+	github.com/twmb/murmur3 v1.1.8 // indirect
+	github.com/xeipuuv/gojsonpointer v0.0.0-20190905194746-02993c407bfb // indirect
+	github.com/xeipuuv/gojsonreference v0.0.0-20180127040603-bd5ef7bd5415 // indirect
+	github.com/xeipuuv/gojsonschema v1.2.0 // indirect
+	github.com/zeebo/xxh3 v1.0.2 // indirect
+	go.opentelemetry.io/otel v1.17.0 // indirect
+	go.opentelemetry.io/otel/exporters/otlp/otlpmetric v0.40.0 // indirect
+	go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetricgrpc v0.40.0 // indirect
+	go.opentelemetry.io/otel/exporters/otlp/otlptrace v1.17.0 // indirect
+	go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracegrpc v1.17.0 // indirect
+	go.opentelemetry.io/otel/exporters/prometheus v0.40.0 // indirect
+	go.opentelemetry.io/otel/metric v1.17.0 // indirect
+	go.opentelemetry.io/otel/sdk v1.17.0 // indirect
+	go.opentelemetry.io/otel/sdk/metric v0.40.0 // indirect
+	go.opentelemetry.io/otel/trace v1.17.0 // indirect
+	go.opentelemetry.io/proto/otlp v1.0.0 // indirect
+	go.uber.org/multierr v1.11.0 // indirect
+	go.uber.org/zap v1.25.0 // indirect
+	golang.org/x/crypto v0.13.0 // indirect
+	golang.org/x/exp v0.0.0-20230522175609-2e198f4a06a1 // indirect
+	golang.org/x/mod v0.12.0 // indirect
+	golang.org/x/net v0.15.0 // indirect
+	golang.org/x/oauth2 v0.10.0 // indirect
+	golang.org/x/sync v0.3.0 // indirect
+	golang.org/x/sys v0.12.0 // indirect
+	golang.org/x/term v0.12.0 // indirect
+	golang.org/x/text v0.13.0 // indirect
+	golang.org/x/time v0.3.0 // indirect
+	gomodules.xyz/jsonpatch/v2 v2.4.0 // indirect
+	google.golang.org/appengine v1.6.7 // indirect
+	google.golang.org/genproto/googleapis/api v0.0.0-20230711160842-782d3b101e98 // indirect
+	google.golang.org/genproto/googleapis/rpc v0.0.0-20230711160842-782d3b101e98 // indirect
+	gopkg.in/inf.v0 v0.9.1 // indirect
+	gopkg.in/yaml.v2 v2.4.0 // indirect
+	gopkg.in/yaml.v3 v3.0.1 // indirect
+	k8s.io/api v0.28.1 // indirect
+	k8s.io/apiextensions-apiserver v0.28.0 // indirect
+	k8s.io/apimachinery v0.28.1 // indirect
+	k8s.io/client-go v0.28.1 // indirect
+	k8s.io/component-base v0.28.1 // indirect
+	k8s.io/klog/v2 v2.100.1 // indirect
+	k8s.io/kube-openapi v0.0.0-20230717233707-2695361300d9 // indirect
+	k8s.io/utils v0.0.0-20230406110748-d93618cff8a2 // indirect
+	sigs.k8s.io/controller-runtime v0.16.1 // indirect
+	sigs.k8s.io/json v0.0.0-20221116044647-bc3834ca7abd // indirect
+	sigs.k8s.io/structured-merge-diff/v4 v4.2.3 // indirect
+	sigs.k8s.io/yaml v1.3.0 // indirect
+)