### Start flagd with Binary Installation

Source: https://github.com/open-feature/flagd/wiki/Examples-using-cURL

Start the flagd service using the downloaded configuration file when installed as a binary.

```shell
flagd start -f example_flags.json
```

--------------------------------

### Example Static Context Configuration

Source: https://github.com/open-feature/flagd/blob/main/docs/reference/flag-definitions.md

Shows how to start flagd with static context values using the -X flag. These values are included in all evaluations.

```shell
flagd start \
  --uri file:./flags.json \
  -X environment=production \
  -X region=us-east-1 \
  -X service=payment-api
```

--------------------------------

### Start flagd with Docker Installation

Source: https://github.com/open-feature/flagd/wiki/Examples-using-cURL

Start the flagd service using Docker, mounting the configuration file and exposing the necessary port.

```shell
docker run -p 8013:8013 -v $(pwd)/:/etc/flagd/ -it --pull=always ghcr.io/open-feature/flagd:latest start --uri file:./etc/flagd/example_flags.json
```

--------------------------------

### Download flagd example flags locally

Source: https://github.com/open-feature/flagd/blob/main/README.md

Download the example flags configuration file locally using wget. This allows for local modifications before starting flagd.

```sh
wget https://raw.githubusercontent.com/open-feature/flagd/main/samples/example_flags.flagd.json
```

--------------------------------

### Source Selector Examples

Source: https://github.com/open-feature/flagd/blob/main/docs/reference/selector-syntax.md

Examples showing how to select flags originating from specific sources using the source key.

```text
source=config/flags.json
```

```text
source=http://flag-server/config
```

```text
source=./local-flags.yaml
```

--------------------------------

### Full Flag Configuration Example

Source: https://github.com/open-feature/flagd/blob/main/docs/reference/flag-definitions.md

A comprehensive example of a fully configured flag, including state, variants, defaultVariant, targeting, and metadata.

```jsonc
{
  "$schema": "https://flagd.dev/schema/v0/flags.json",
  "flags": {
    "new-welcome-banner": {
      "state": "ENABLED",
      "variants": {
        "on": true,
        "off": false
      },
      "defaultVariant": "off",
      "targeting": {
        "if": [
          { "ends_with": [{ "var": "email" }, "@example.com"] },
          "on",
          "off"
        ]
      },
      "metadata": {
        "version": "17"
      }
    }
  },
  "metadata": {
    "team": "user-experience",
    "flagSetId": "ecommerce"
  }
}
```

--------------------------------

### flagd SEE ALSO

Source: https://github.com/open-feature/flagd/blob/main/docs/reference/flagd-cli/flagd.md

Lists related flagd subcommands. Use 'flagd start' to run the agent and 'flagd version' to check the installed version.

```bash
* [flagd start](flagd_start.md)	 - Start flagd
* [flagd version](flagd_version.md)	 - Print the version number of flagd
```

--------------------------------

### Starting flagd with multiple flag sources

Source: https://github.com/open-feature/flagd/blob/main/docs/architecture-decisions/multiple-flag-set-support(rejected).md

Demonstrates how to start the flagd service and configure it to load flag configurations from multiple sources using the `--uri` flag.

```shell
flagd start \
  --port 8013 \
  --uri file:etc/flagd/my-flags-1.json \
  --uri https://my-flags-2.com/flags
```

--------------------------------

### Starts-With Example Flag Configuration

Source: https://github.com/open-feature/flagd/blob/main/docs/reference/custom-operations/string-comparison-operation.md

Example of a flag configuration using the 'starts_with' operation to determine the 'headerColor' variant. Returns 'red' if the email starts with 'user@faas', otherwise 'green'.

```json
{
  "$schema": "https://flagd.dev/schema/v0/flags.json",
  "flags": {
    "headerColor": {
      "variants": {
        "red": "#FF0000",
        "blue": "#0000FF",
        "green": "#00FF00"
      },
      "defaultVariant": "blue",
      "state": "ENABLED",
      "targeting": {
        "if": [
          {
            "starts_with": [{"var": "email"}, "user@faas"]
          },
          "red", "green"
        ]
      }
    }
  }
}
```

--------------------------------

### Install flagd Go Binary

Source: https://github.com/open-feature/flagd/wiki/Home

Install the flagd Go binary using the go install command. Requires Go version 1.18 or above.

```bash
go install github.com/open-feature/flagd@latest
```

--------------------------------

### Run flagd Playground Development Environment

Source: https://github.com/open-feature/flagd/blob/main/playground-app/README.md

Execute this command from the project root to start the development server for the flagd playground. Ensure Node.js version 18 or newer is installed.

```bash
make playground-dev
```

--------------------------------

### Starting flagd with multiple sync sources

Source: https://github.com/open-feature/flagd/blob/main/docs/reference/sync-configuration.md

Demonstrates how to start the flagd daemon with a complex configuration of multiple sync sources using command-line arguments. This includes file, HTTP, and Kubernetes providers with various authentication and configuration options.

```sh
./bin/flagd start
--sources='[{"uri":"config/samples/example_flags.json","provider":"file"},
            {"uri":"config/samples/example_flags.json","provider":"fsnotify"},
            {"uri":"config/samples/example_flags.json","provider":"fileinfo"},
            {"uri":"http://my-flag-source/flags.json","provider":"http","authHeader":"Bearer bearer-dji34ld2l"},
            {"uri":"https://secure-remote/bearer-auth/flags.json","provider":"http","authHeader":"Bearer bearer-dji34ld2l"},
            {"uri":"https://secure-remote/basic-auth/flags.json","provider":"http","authHeader":"Basic dXNlcjpwYXNz"},
            {"uri":"default/my-flag-config","provider":"kubernetes"},
            {"uri":"grpc-source:8080","provider":"grpc"},
            {"uri":"my-flag-source:8080","provider":"grpc", "maxMsgSize": 5242880},
            {"uri":"envoy://localhost:9211/test.service", "provider":"grpc"},
            {"uri":"my-flag-source:8080","provider":"grpc", "certPath": "/certs/ca.cert", "tls": true, "providerID": "flagd-weatherapp-sidecar", "selector": "flagSetId=weatherapp"},
            {"uri":"gs://my-bucket/my-flag.json","provider":"gcs"},
            {"uri":"azblob://my-container/my-flag.json","provider":"azblob"},
            {"uri":"s3://my-bucket/my-flag.json","provider":"s3"}]'
```

--------------------------------

### Start flagd Service

Source: https://github.com/open-feature/flagd/blob/main/README.md

Instructions on how to start the flagd service using the command line or Docker, with options for specifying flag sources.

```APIDOC
## Start flagd

flagd can be started using the `flagd start` command. You can specify the port and the URI for the flag source.

### Command Line

```sh
flagd start \
  --port 8013 \
  --uri https://raw.githubusercontent.com/open-feature/flagd/main/samples/example_flags.flagd.json
```

### Docker

```sh
docker run \
  --rm -it \
  --name flagd \
  -p 8013:8013 \
  ghcr.io/open-feature/flagd:latest start \
  --uri https://raw.githubusercontent.com/open-feature/flagd/main/samples/example_flags.flagd.json
```

### Local File URI

To use a local file as the flag source, prefix the file path with `file:`.

```sh
flagd start \
  --port 8013 \
  --uri file:./example_flags.flagd.json
```

Or using Docker:

```sh
docker run \
  --rm -it \
  --name flagd \
  -p 8013:8013 \
  -v $(pwd):/etc/flagd \
  ghcr.io/open-feature/flagd:latest start \
  --uri file:./etc/flagd/example_flags.flagd.json
```

Multiple `--uri` parameters can be specified to retrieve flags from multiple sources simultaneously.
```

--------------------------------

### Kubernetes Sync Provider Configuration

Source: https://github.com/open-feature/flagd/wiki/Options

Example command to start flagd using the Kubernetes sync provider. This configuration requires specifying the sync provider and its arguments, including the FeatureFlagConfiguration resource name and namespace.

```shell
flagd start --sync-provider=kubernetes --sync-provider-args=featureflagconfiguration=my-example --sync-provider-args=namespace=default
```

--------------------------------

### flagd Start Command Help

Source: https://github.com/open-feature/flagd/wiki/Options

Lists all available command-line flags for starting the flagd service. These flags control various aspects of flagd's behavior, including ports, security, and sync providers.

```bash
  -b, --bearer-token string       Set a bearer token to use for remote sync
  -e, --evaluator string          Set an evaluator e.g. json (default "json")
  -h, --help                      help for start
  -p, --port int32                Port to listen on (default 8013)
  -m, --metrics-port int32        Port to set up metrics listener on (default 8014)
  -c, --server-cert-path string   Server side tls certificate path
  -k, --server-key-path string    Server side tls key path
  -a, --sync-provider-args        Sync provider arguments as key values separated by =
  -d, --socket-path string        Set the flagd socket path.
  -y, --sync-provider string      Set a sync provider e.g. filepath, remote or kubernetes (default "filepath")
  -f, --uri strings               Set a sync provider uri to read data from this can be a filepath or url. Using multiple providers is supported where collisions between flags with the same key, the later will be used.
  -C, --cors-origin strings       Set a CORS allow origin header, setting "*" will allow all origins (by default CORS headers are not set)
```

--------------------------------

### Starting flagd with CLI-based OAuth configuration

Source: https://github.com/open-feature/flagd/blob/main/docs/reference/sync-configuration.md

Demonstrates how to start flagd using the command line with OAuth enabled for HTTP synchronization. It includes client ID, client secret, and token URL configuration.

```sh
./bin/flagd start
--sources='[{ 
  "uri": "http://localhost:8180/flags", 
  "provider": "http", 
  "interval": 1,
  "timeoutS": 10,
  "oauth": { 
    "clientID": "test", 
    "clientSecret": "test", 
    "tokenURL": "http://localhost:8180/sso/oauth2/token" 
  }}]'
```

--------------------------------

### Start flagd with a local configuration file

Source: https://github.com/open-feature/flagd/blob/main/CONTRIBUTING.md

Manually start the flagd service using a local JSON file for flag configurations. Requires Go and curl.

```shell
go run main.go start -f file:../config/samples/example_flags.flagd.json
```

--------------------------------

### Source Selection Example (Legacy)

Source: https://github.com/open-feature/flagd/blob/main/docs/reference/selector-syntax.md

Example using curl to select flags from a specific source file, demonstrating backward compatibility.

```APIDOC
### Source Selection (Legacy)

```bash
# Select flags from a specific source (backward compatibility)
curl -H "Flagd-Selector: source=config/prod-flags.json" \
  http://localhost:8014/ofrep/v1/evaluate/flags
```
```

--------------------------------

### Start flagd with Docker Compose

Source: https://github.com/open-feature/flagd/blob/main/docs/quick-start.md

Execute the Docker Compose configuration to start the flagd service.

```shell
docker compose up
```

--------------------------------

### flagSetId Selector Examples

Source: https://github.com/open-feature/flagd/blob/main/docs/reference/selector-syntax.md

Examples demonstrating how to select flags belonging to specific flag sets using the flagSetId key.

```text
flagSetId=project-42
```

```text
flagSetId=dev-environment
```

```text
flagSetId=team-payments
```

--------------------------------

### Example Context Merge Priority Configuration

Source: https://github.com/open-feature/flagd/blob/main/docs/reference/flag-definitions.md

Demonstrates a scenario where static context and header-mapped context are configured, illustrating merge priority.

```shell
flagd start \
  --uri file:./flags.json \
  -X tier=basic \
  -H "X-User-Tier=tier"
```

--------------------------------

### Download Sample Flag Configuration

Source: https://github.com/open-feature/flagd/wiki/Examples-using-cURL

Use cURL to download the example flag configuration file.

```shell
curl https://raw.githubusercontent.com/open-feature/flagd/main/config/samples/example_flags.json -o example_flags.json
```

--------------------------------

### Start flagd command

Source: https://github.com/open-feature/flagd/blob/main/docs/reference/flagd-cli/flagd_start.md

This is the base command to start the flagd service. Various flags can be appended to configure its behavior.

```bash
flagd start [flags]
```

--------------------------------

### Initialize flagd workspace

Source: https://github.com/open-feature/flagd/blob/main/CONTRIBUTING.md

Run this command to set up the Go workspace for the flagd project. Ensure you have Go and make installed.

```shell
make workspace-init
```

--------------------------------

### Running flagd with Binary

Source: https://github.com/open-feature/flagd/blob/main/docs/reference/cheat-sheet.md

Examples for running flagd directly using the binary with different flag source configurations.

```APIDOC
## Running flagd with Binary

### Single flag source (local file)
```shell
flagd start --uri file:./cheat-sheet-flags.json
```

### Multiple flag sources
```shell
flagd start \
  --uri file:./cheat-sheet-flags.json \
  --uri file:./cheat-sheet-flags-payments.json
```

### HTTP source
```shell
flagd start --uri https://flagd.dev/assets/cheat-sheet-flags.json
```
```

--------------------------------

### Provider SDK Usage

Source: https://github.com/open-feature/flagd/blob/main/docs/reference/selector-syntax.md

Examples of how to configure the selector in various OpenFeature provider SDKs.

```APIDOC
### Provider SDK Usage

#### Go Provider

```go
import "github.com/open-feature/go-sdk-contrib/providers/flagd"

provider := flagd.NewProvider(
    flagd.WithHost("localhost"),
    flagd.WithPort(8013),
    flagd.WithSelector("flagSetId=user-service"),
)
```

#### Java Provider

```java
FlagdProvider provider = new FlagdProvider(
    FlagdOptions.builder()
        .host("localhost")
        .port(8013)
        .selector("flagSetId=payment-service")
        .build()
);
```

#### JavaScript Provider

```javascript
const provider = new FlagdProvider({
  host: 'localhost',
  port: 8013,
  selector: 'flagSetId=frontend-features'
});
```
```

--------------------------------

### Example flagd Service Status Output

Source: https://github.com/open-feature/flagd/wiki/systemd-Service

This is an example output from the `systemctl status flagd` command, showing the service details including its loaded status, active state, main process information, and recent log lines.

```text
  flagd.service - "A generic feature flag daemon"
     Loaded: loaded (/etc/systemd/system/flagd.service; disabled; vendor preset: enabled)
     Active: active (running) since Mon 2022-05-30 12:19:55 BST; 5min ago
   Main PID: 64610 (flagd)
      Tasks: 7 (limit: 4572)
     Memory: 1.4M
     CGroup: /system.slice/flagd.service
             └─64610 /usr/local/bin/flagd start -f=/etc/flagd/flags.json

May 30 12:19:55 foo systemd[1]: Started "A generic feature flag daemon".

```

--------------------------------

### Flagd Sync Selector Examples

Source: https://github.com/open-feature/flagd/blob/main/docs/architecture-decisions/decouple-flag-source-and-set.md

These examples demonstrate the extended selector syntax for selecting flags based on source and flag set ID. The semantic can be extended later for more complex filtering.

```yaml
selector: override
```

```yaml
selector: source=override
```

```yaml
selector: flagsetID=project-42
```

--------------------------------

### Provider Configuration: Source-Based Selector

Source: https://github.com/open-feature/flagd/blob/main/docs/guides/migrating-to-flag-sets.md

Example of a provider configuration using a source-based selector.

```yaml
selector: "config/my-flags.json"
```

--------------------------------

### Starts-With Operation Configuration

Source: https://github.com/open-feature/flagd/blob/main/docs/reference/specifications/custom-operations/string-comparison-operation-spec.md

Example of how the 'starts_with' property is configured within a targeting rule. It specifies the evaluation context property to check and the prefix to match.

```json
{
  "starts_with": [
    {"var": "email"},
    "user@faas"
  ]
}
```

--------------------------------

### Run flagd Binary (Multiple Local Flag Sources)

Source: https://github.com/open-feature/flagd/blob/main/docs/reference/cheat-sheet.md

Starts flagd directly from the binary with multiple local JSON files as flag sources.

```shell
flagd start \
  --uri file:./cheat-sheet-flags.json \
  --uri file:./cheat-sheet-flags-payments.json
```

--------------------------------

### Run flagd Binary (Single Local Flag Source)

Source: https://github.com/open-feature/flagd/blob/main/docs/reference/cheat-sheet.md

Starts flagd directly from the binary with a single local JSON file as the flag source.

```shell
flagd start --uri file:./cheat-sheet-flags.json
```

--------------------------------

### Rollout Operator Syntax Examples

Source: https://github.com/open-feature/flagd/blob/main/docs/architecture-decisions/rollout-operator.md

Demonstrates the different ways to define the 'rollout' operator, including shorthand, longhand, and with a custom 'bucketBy' expression.

```jsonc
// shorthand: roll from defaultVariant to "new"
{"rollout": [1704067200, 1706745600, "new"]}

// longhand: explicit from and to - from "old" to "new"
{"rollout": [1704067200, 1706745600, "old", "new"]}

// with custom bucketBy
{"rollout": [{"var": "email"}, 1704067200, 1706745600, "old", "new"]}
```

--------------------------------

### Run flagd Binary (HTTP Flag Source)

Source: https://github.com/open-feature/flagd/blob/main/docs/reference/cheat-sheet.md

Starts flagd directly from the binary, fetching flag definitions from a remote HTTP URL.

```shell
flagd start --uri https://flagd.dev/assets/cheat-sheet-flags.json
```

--------------------------------

### Start flagd with Envoy gRPC resolution

Source: https://github.com/open-feature/flagd/blob/main/docs/reference/sync-configuration.md

Use this command to start flagd with a custom gRPC target URI for Envoy proxy resolution. Ensure flagd is built with the appropriate flags enabled.

```shell
./bin/flagd start -x --uri envoy://localhost:9211/test.service
```

--------------------------------

### Running flagd with Docker

Source: https://github.com/open-feature/flagd/blob/main/docs/reference/cheat-sheet.md

Examples for running flagd using Docker with different flag source configurations (local file, multiple files, HTTP).

```APIDOC
## Running flagd with Docker

### Single flag source (local file)
```shell
docker run --rm -it \
  -p 8013:8013 \
  -p 8015:8015 \
  -p 8016:8016 \
  -v $(pwd):/flags \
  ghcr.io/open-feature/flagd:latest start \
  --uri file:./flags/cheat-sheet-flags.json
```

### Multiple flag sources
```shell
docker run --rm -it \
  -p 8013:8013 \
  -p 8015:8015 \
  -p 8016:8016 \
  -v $(pwd):/flags \
  ghcr.io/open-feature/flagd:latest start \
  --uri file:./flags/cheat-sheet-flags.json \
  --uri file:./flags/cheat-sheet-flags-payments.json
```

### HTTP source
```shell
docker run --rm -it \
  -p 8013:8013 \
  -p 8015:8015 \
  -p 8016:8016 \
  -v $(pwd):/flags \
  ghcr.io/open-feature/flagd:latest start \
  --uri https://flagd.dev/assets/cheat-sheet-flags.json
```
```

--------------------------------

### Example Header-Mapped Context Configuration

Source: https://github.com/open-feature/flagd/blob/main/docs/reference/flag-definitions.md

Illustrates configuring flagd to map HTTP/gRPC request headers to evaluation context keys using the -H flag.

```shell
flagd start \
  --uri file:./flags.json \
  -H "X-User-Id=userId" \
  -H "X-User-Tier=tier"
```

--------------------------------

### Flag Configuration: After Flag Set IDs

Source: https://github.com/open-feature/flagd/blob/main/docs/guides/migrating-to-flag-sets.md

Example of a flag configuration with a flagSetId added to metadata.

```json
{
  "metadata": {
    "flagSetId": "my-application"
  },
  "flags": {
    "feature-a": {
      "state": "ENABLED",
      "variants": {"on": true, "off": false},
      "defaultVariant": "on"
    }
  }
}
```

--------------------------------

### Configure Git for DCO Sign-off

Source: https://github.com/open-feature/flagd/blob/main/CONTRIBUTING.md

Set up your Git client with your legal name and email for DCO sign-offs. This is a one-time setup.

```shell
git config user.name <legal name>
git config user.email <email address you use for GitHub>
```

```shell
git config --global user.name <legal name>
git config --global user.email <email address you use for GitHub>
```

--------------------------------

### Rollout Operator Example

Source: https://github.com/open-feature/flagd/blob/main/docs/architecture-decisions/rollout-operator.md

Defines a linear rollout from 'off' to 'on' over a specified time window using the 'rollout' operator.

```jsonc
{"rollout": [1740000000, 1800000000, "off", "on"]}
```

--------------------------------

### Provider Configuration: Flag Set-Based Selector

Source: https://github.com/open-feature/flagd/blob/main/docs/guides/migrating-to-flag-sets.md

Example of a provider configuration using a flag set-based selector.

```yaml
selector: "flagSetId=my-application"
```

--------------------------------

### Starts-With ResolveString Command and Result (No Match)

Source: https://github.com/open-feature/flagd/blob/main/docs/reference/custom-operations/string-comparison-operation.md

Example command to resolve a string flag using 'starts_with' with a non-matching email, and its expected JSON result.

```shell
curl -X POST "localhost:8013/flagd.evaluation.v1.Service/ResolveString" -d '{"flagKey":"headerColor","context":{"email": "foo@bar.com"}}' -H "Content-Type: application/json"
```

```json
{"value":"#0000FF","reason":"TARGETING_MATCH","variant":"green"}
```

--------------------------------

### Starts-With ResolveString Command and Result (Match)

Source: https://github.com/open-feature/flagd/blob/main/docs/reference/custom-operations/string-comparison-operation.md

Example command to resolve a string flag using 'starts_with' with a matching email, and its expected JSON result.

```shell
curl -X POST "localhost:8013/flagd.evaluation.v1.Service/ResolveString" -d '{"flagKey":"headerColor","context":{"email": "user@faas.com"}}' -H "Content-Type: application/json"
```

```json
{"value":"#00FF00","reason":"TARGETING_MATCH","variant":"red"}
```

--------------------------------

### Run flagd-proxy Locally

Source: https://github.com/open-feature/flagd/blob/main/flagd-proxy/tests/loadtest/README.md

Starts the flagd-proxy service on port 8080. This is a prerequisite for running the load tests.

```bash
go run flagd-proxy/main.go start --port 8080
```

--------------------------------

### Return flag not found error

Source: https://github.com/open-feature/flagd/wiki/Examples-using-cURL

This example demonstrates the error response when the requested flag key does not exist in the configuration.

```APIDOC
## POST /schema.v1.Service/ResolveBoolean (Flag Not Found Error)

### Description
This scenario triggers a 'flag not found' error when the provided flag key does not match any configured flags.

### Method
POST

### Endpoint
`localhost:8013/schema.v1.Service/ResolveBoolean`

### Request Body
- **flagKey** (string) - Required - The key of a flag that does not exist (e.g., `aMissingFlag`).
- **context** (object) - Optional - The evaluation context.

### Request Example
```json
{
  "flagKey": "aMissingFlag",
  "context": {}
}
```

### Response
#### Error Response (404 Not Found)
- **code** (string) - Error code, e.g., `not_found`.
- **message** (string) - Error message, e.g., `FLAG_NOT_FOUND`.

#### Response Example
```json
{
  "code": "not_found",
  "message": "FLAG_NOT_FOUND"
}
```
```

--------------------------------

### Conventional PR Title Example

Source: https://github.com/open-feature/flagd/blob/main/CONTRIBUTING.md

Format your Pull Request titles according to conventional commit standards, starting with a type like 'docs:'.

```text
docs: some PR title here...
```

--------------------------------

### gRPC Header Precedence Example

Source: https://github.com/open-feature/flagd/blob/main/docs/reference/selector-syntax.md

Demonstrates how the gRPC metadata header takes precedence over the request body selector when both are provided.

```bash
grpcurl -H "Flagd-Selector: flagSetId=production" \
  -d '{"selector": "flagSetId=development"}' \
  localhost:8013 flagd.sync.v1.FlagSyncService/FetchAllFlags
```

--------------------------------

### Rollback Operator Example

Source: https://github.com/open-feature/flagd/blob/main/docs/architecture-decisions/rollout-operator.md

Implements a 'first in, last out' rollback initiated at the 50% mark using the 'rollback' operator. Requires a pivot time to define the rollback start.

```jsonc
{"rollback": [1740000000, 1800000000, 1770000000, "on", "off"]}
```

--------------------------------

### Setup grpcurl with flagd Proto Files

Source: https://github.com/open-feature/flagd/blob/main/docs/reference/cheat-sheet.md

Prepare to interact with the flagd gRPC API by cloning the repository to access the necessary proto files for serialization and deserialization.

```shell
# Clone the repo for proto files
git clone git@github.com:open-feature/flagd-schemas.git
PROTO_DIR="flagd-schemas/protobuf/"
```

--------------------------------

### Variants Property Example (String)

Source: https://github.com/open-feature/flagd/blob/main/docs/reference/flag-definitions.md

Example of the 'variants' property with string values. All variant values must be of the same type.

```jsonc
"variants": {
  "red": "c05543",
  "green": "2f5230",
  "blue": "0d507b"
}
```

--------------------------------

### Variants Property Example (Boolean)

Source: https://github.com/open-feature/flagd/blob/main/docs/reference/flag-definitions.md

Example of the 'variants' property with boolean values. All variant values must be of the same type.

```jsonc
"variants": {
  "on": true,
  "off": false
}
```

--------------------------------

### No Flag Set Selection Example

Source: https://github.com/open-feature/flagd/blob/main/docs/reference/selector-syntax.md

Example using curl to select flags that do not belong to any named flag set.

```APIDOC
### No Flag Set Selection

```bash
# Select flags that don't belong to any named flag set
curl -H "Flagd-Selector: flagSetId=" \
  http://localhost:8014/ofrep/v1/evaluate/flags
```
```

--------------------------------

### Start flagd with a local flag configuration file

Source: https://github.com/open-feature/flagd/blob/main/README.md

Run flagd as a standalone binary, using a local file for flag configurations. The `--uri` parameter should be prefixed with `file:`.

```sh
flagd start \
  --port 8013 \
  --uri file:./example_flags.flagd.json
```

--------------------------------

### Publish flagd Playground to Docs

Source: https://github.com/open-feature/flagd/blob/main/playground-app/README.md

Run this command from the project root to build the playground app and copy its output to the documentation directory.

```bash
make playground-publish
```

--------------------------------

### Current Fractional Calculation (Go)

Source: https://github.com/open-feature/flagd/blob/main/docs/architecture-decisions/high-precision-fractional-bucketing.md

Illustrates the current implementation of fractional bucketing in Go, which limits granularity to 1% increments.

```go
bucket := hashRatio * 100 // in range [0, 100]
```

--------------------------------

### Run flagd with TLS Configuration

Source: https://github.com/open-feature/flagd/blob/main/test/integration/README.md

Start the flagd binary with TLS enabled, specifying the certificate and key files. This prepares flagd to accept TLS connections.

```shell
./bin/flagd start -f file:test-harness/symlink_testing-flags.json -c ./localhost.crt -k ./localhost.key
```

--------------------------------

### Flag Set Selection Example

Source: https://github.com/open-feature/flagd/blob/main/docs/reference/selector-syntax.md

Example using curl to select flags from the 'payments' flag set via the Flagd-Selector header.

```APIDOC
### Flag Set Selection

```bash
# Select flags from the "payments" flag set
curl -H "Flagd-Selector: flagSetId=payments" \
  http://localhost:8014/ofrep/v1/evaluate/flags
```
```

--------------------------------

### State Property Example

Source: https://github.com/open-feature/flagd/blob/main/docs/reference/flag-definitions.md

Example of the 'state' property, which must be either 'ENABLED' or 'DISABLED'. When disabled, flagd returns a successful evaluation with reason=DISABLED.

```jsonc
"state": "ENABLED"
```

--------------------------------

### Default Variant Example (String)

Source: https://github.com/open-feature/flagd/blob/main/docs/reference/flag-definitions.md

Example of 'defaultVariant' set to 'red' for a flag with string variants. This variant is used unless targeting rules override it.

```jsonc
"variants": {
  "red": "c05543",
  "green": "2f5230",
  "blue": "0d507b"
},
"defaultVariant": "red"
```

--------------------------------

### Default Variant Example (Boolean)

Source: https://github.com/open-feature/flagd/blob/main/docs/reference/flag-definitions.md

Example of 'defaultVariant' set to 'off' for a flag with boolean variants. This variant is used unless targeting rules override it.

```jsonc
"variants": {
  "on": true,
  "off": false
},
"defaultVariant": "off"
```

--------------------------------

### ResolveString Command Example

Source: https://github.com/open-feature/flagd/blob/main/docs/reference/custom-operations/fractional-operation.md

Example curl commands to resolve a string flag using fractional evaluation. The context, specifically the 'email' field, determines the variant.

```shell
curl -X POST "localhost:8013/flagd.evaluation.v1.Service/ResolveString" -d '{"flagKey":"headerColor","context":{"email": "foo@bar.com"}}' -H "Content-Type: application/json"
```

```json
{"value":"#0000FF","reason":"TARGETING_MATCH","variant":"blue"}
```

```shell
curl -X POST "localhost:8013/flagd.evaluation.v1.Service/ResolveString" -d '{"flagKey":"headerColor","context":{"email": "foo@test.com"}}' -H "Content-Type: application/json"
```

```json
{"value":"#00FF00","reason":"TARGETING_MATCH","variant":"green"}
```

--------------------------------

### flagd ResolveString API Response Example

Source: https://github.com/open-feature/flagd/blob/main/README.md

Example JSON response when resolving a string flag. It includes the resolved value, the reason for the resolution, and the specific variant returned.

```json
{
  "value": "val1",
  "reason": "DEFAULT",
  "variant":"key1"
}
```

--------------------------------

### Ends-With Example Flag Configuration

Source: https://github.com/open-feature/flagd/blob/main/docs/reference/custom-operations/string-comparison-operation.md

Example of a flag configuration using the 'ends_with' operation to determine the 'headerColor' variant. Returns 'red' if the email ends with 'faas.com', otherwise 'green'.

```json
{
  "$schema": "https://flagd.dev/schema/v0/flags.json",
  "flags": {
    "headerColor": {
      "variants": {
        "red": "#FF0000",
        "blue": "#0000FF",
        "green": "#00FF00"
      },
      "defaultVariant": "blue",
      "state": "ENABLED",
      "targeting": {
        "if": [
          {
            "ends_with": [{"var": "email"}, "faas.com"]
          },
          "red", "green"
        ]
      }
    }
  }
}
```

--------------------------------

### Docker Compose for Local OTEL Collector Setup

Source: https://github.com/open-feature/flagd/blob/main/docs/reference/monitoring.md

A docker-compose configuration to set up a local OpenTelemetry collector with Jaeger and Prometheus. This setup allows for local testing and development of telemetry export and visualization.

```yaml
services:
  jaeger:
    image: cr.jaegertracing.io/jaegertracing/jaeger:2.8.0
    restart: always
    ports:
      - "16686:16686"
      - "14268"
      - "14250"
  # Collector
  otel-collector:
    image: otel/opentelemetry-collector:0.129.1
    restart: always
    command: [ "--config=/etc/otel-collector-config.yaml" ]
    volumes:
      - ./otel-collector-config.yaml:/etc/otel-collector-config.yaml
    ports:
      - "1888:1888"   # pprof extension
      - "8888:8888"   # Prometheus metrics exposed by the collector
      - "8889:8889"   # Prometheus exporter metrics
      - "13133:13133" # health_check extension
      - "4317:4317"   # OTLP gRPC receiver
      - "55679:55679" # zpages extension
    depends_on:
      - jaeger
  prometheus:
    container_name: prometheus
    image: prom/prometheus:v2.53.5
    restart: always
    volumes:
      - ./prometheus.yaml:/etc/prometheus/prometheus.yml
    ports:
      - "9090:9090"
```

--------------------------------

### Start flagd using Docker with a local flag configuration

Source: https://github.com/open-feature/flagd/blob/main/README.md

Run flagd as a Docker container, mounting the current directory to `/etc/flagd` and using a local file for flag configurations. This requires WSL on Windows.

```sh
docker run \
  --rm -it \
  --name flagd \
  -p 8013:8013 \
  -v $(pwd):/etc/flagd \
  ghcr.io/open-feature/flagd:latest start \
  --uri file:./etc/flagd/example_flags.flagd.json
```

--------------------------------

### OFREP Response Metadata Example

Source: https://github.com/open-feature/flagd/blob/main/docs/reference/specifications/providers.md

Example JSON structure for an OFREP response, illustrating the 'metadata' field which includes reflected selector information such as 'flagSetId', 'team', and 'version'. This provides transparency on how flags were queried.

```json
{
  "value": true,
  "reason": "TARGETING_MATCH",
  "variant": "on",
  "metadata": {
    "flagSetId": "payment-service",
    "team": "payments",
    "version": "1.2.0"
  }
}
```

--------------------------------

### Start flagd with Filepath Sync

Source: https://github.com/open-feature/flagd/blob/main/docs/concepts/syncs.md

Use the file path sync provider to read and watch a local file for feature flag updates. For production, a symbolic link is recommended for atomic modifications.

```shell
flagd start --uri file:etc/featureflags.json
```

--------------------------------

### Example Custom Target String for Envoy

Source: https://github.com/open-feature/flagd/blob/main/docs/reference/specifications/proposal/rfc-grpc-custom-name-resolver.md

This example shows a custom target string format that utilizes an Envoy sidecar proxy for name resolution. The provider uses the endpoint name as the authority and connects to a specified host and port.

```text
envoy://localhost:9211/flagd-sync.service
```

--------------------------------

### Go Implementation of Fractional Evaluation

Source: https://github.com/open-feature/flagd/blob/main/docs/reference/specifications/custom-operations/fractional-operation-spec.md

A simplified Go implementation demonstrating the logic for fractional evaluation distribution. The 'values' parameter contains the targeting rule, and 'data' holds the evaluation context.

```go
type fractionalEvaluationDistribution struct {
    variant    string
    weight int
}

/*
    values: contains the targeting rule object; e.g.:
        [
          {"var":"email"},
          [
            "red",
            50
          ],
          [
            "blue",
            20
          ],
          [
            "green",
            30
          ]
        ]
    
    data: contains the evaluation context; e.g.:
        {

```

--------------------------------

### JavaScript Fractional Bucketing Example

Source: https://github.com/open-feature/flagd/blob/main/docs/architecture-decisions/high-precision-fractional-bucketing.md

This JavaScript example shows how to perform fractional bucketing using `BigInt` to handle potentially large numbers resulting from the multiplication. It converts the hash to `BigInt` and uses `BigInt` arithmetic for the calculation. Ensure `totalWeight` is a `BigInt` and the sum of variant weights does not exceed `Number.MAX_SAFE_INTEGER`.

```javascript
const hash = murmur3_32(value);  // Number
const bucket = (BigInt(hash) * BigInt(totalWeight)) >> 32n;
```

--------------------------------

### Invalid Variants Configuration

Source: https://github.com/open-feature/flagd/blob/main/docs/reference/flag-definitions.md

An example of an invalid 'variants' configuration where values are of mixed types.

```jsonc
"variants": {
  "on": true,
  "off": "false"
}
```

--------------------------------

### Run flagd with Docker (Single Local Flag Source)

Source: https://github.com/open-feature/flagd/blob/main/docs/reference/cheat-sheet.md

Starts flagd using Docker with a single local JSON file as the flag source. Ensure the flag file is mounted into the container.

```shell
docker run --rm -it \
  -p 8013:8013 \
  -p 8015:8015 \
  -p 8016:8016 \
  -v $(pwd):/flags \
  ghcr.io/open-feature/flagd:latest start \
  --uri file:./flags/cheat-sheet-flags.json
```

--------------------------------

### Configuring FlagdProvider with a selector

Source: https://github.com/open-feature/flagd/blob/main/docs/architecture-decisions/multiple-flag-set-support(rejected).md

Shows how to instantiate the `FlagdProvider` with options, including specifying a `selector` for a flag set. The `selector` argument will be used to pass the `flagSetId` instead of a source file name.

```java
final FlagdProvider flagdProvider =
        new FlagdProvider(FlagdOptions.builder()
                .resolverType(Config.Evaluator.IN_PROCESS)
                .host("localhost")
                .port(8015)
                .selector("myFlags.json")
                .build());
```

--------------------------------

### Flag Configuration: Before Flag Set IDs

Source: https://github.com/open-feature/flagd/blob/main/docs/guides/migrating-to-flag-sets.md

Example of a flag configuration without a flagSetId.

```json
{
  "flags": {
    "feature-a": {
      "state": "ENABLED",
      "variants": {"on": true, "off": false},
      "defaultVariant": "on"
    }
  }
}
```

--------------------------------

### Invalid Default Variant Configuration

Source: https://github.com/open-feature/flagd/blob/main/docs/reference/flag-definitions.md

An example of an invalid 'defaultVariant' configuration where the specified variant does not exist.

```jsonc
"variants": {
  "red": "c05543",
  "green": "2f5230",
  "blue": "0d507b"
},
"defaultVariant": "purple"
```

--------------------------------

### Configure sync provider sources

Source: https://github.com/open-feature/flagd/blob/main/docs/reference/flagd-cli/flagd_start.md

Use the -s or --sources flag to provide a JSON array of SourceConfig objects, defining where flagd should fetch feature flags from. Each source requires a 'uri' and 'provider'.

```bash
flagd start -s "[{ \"uri\": \"file:///path/to/flags.yaml\", \"provider\": \"local\" }]"
```

--------------------------------

### Flag Set Organization: By Team

Source: https://github.com/open-feature/flagd/blob/main/docs/guides/migrating-to-flag-sets.md

Example YAML showing flag set organization by team.

```yaml
flagSetId: "frontend-team"   # Frontend features
flagSetId: "backend-team"    # Backend features
```

--------------------------------

### Flag Set Organization: By Environment

Source: https://github.com/open-feature/flagd/blob/main/docs/guides/migrating-to-flag-sets.md

Example YAML showing flag set organization by environment.

```yaml
flagSetId: "development"     # Dev-specific flags
flagSetId: "production"      # Production flags
```

--------------------------------

### Invalid Default Variant Configuration

Source: https://github.com/open-feature/flagd/wiki/Feature-Flag-Configurations

An example of an invalid configuration where the defaultVariant does not match any of the defined variants.

```json
"variants": {
  "red": "c05543",
  "green": "2f5230",
  "blue": "0d507b"
},
"defaultVariant": "purple"
```

--------------------------------

### Analyze Heap Profile in UI Mode

Source: https://github.com/open-feature/flagd/blob/main/test/loadtest/README.MD

Use the go pprof tool to analyze the heap profile data from the running flagd instance via its pprof endpoint. This command starts a web server for UI-based analysis.

```bash
go tool pprof --http=:9090  http://localhost:6060/debug/pprof/heap
```

--------------------------------

### YAML configuration for flagd sync sources

Source: https://github.com/open-feature/flagd/blob/main/docs/reference/sync-configuration.md

An example of configuring flagd synchronization sources using a YAML file. This demonstrates various providers like file, http, kubernetes, grpc, gcs, azblob, and s3, along with specific configurations for each.

```yaml
sources:
  - uri: config/samples/example_flags.json
    provider: file
  - uri: config/samples/example_flags.json
    provider: fsnotify
  - uri: config/samples/example_flags.json
    provider: fileinfo
  - uri: http://my-flag-source/flags.json
    provider: http
    authHeader: "Bearer bearer-dji34ld2l"
  - uri: default/my-flag-config
    provider: kubernetes
  - uri: my-flag-source:8080
    provider: grpc
  - uri: my-flag-source:8080
    provider: grpc
    maxMsgSize: 5242880
  - uri: envoy://localhost:9211/test.service
    provider: grpc
  - uri: my-flag-source:8080
    provider: grpc
    certPath: /certs/ca.cert
    tls: true
    providerID: flagd-weatherapp-sidecar
    selector: "flagSetId=weatherapp"
  - uri: gs://my-bucket/my-flag.json
    provider: gcs
  - uri: azblob://my-container/my-flags.json
    provider: azblob
  - uri: s3://my-bucket/my-flags.json
    provider: s3
```

--------------------------------

### Flag Configuration with SemVer Targeting

Source: https://github.com/open-feature/flagd/blob/main/docs/reference/custom-operations/semver-operation.md

Example flag configuration demonstrating how to use the semver operation within targeting rules to conditionally serve variants based on a version string. The 'red' variant is served if the 'version' property is >= '1.0.0'.

```json
{
  "$schema": "https://flagd.dev/schema/v0/flags.json",
  "flags": {
    "headerColor": {
      "variants": {
        "red": "#FF0000",
        "blue": "#0000FF",
        "green": "#00FF00"
      },
      "defaultVariant": "blue",
      "state": "ENABLED",
      "targeting": {
        "if": [
          {
            "sem_ver": [{"var": "version"}, ">=", "1.0.0"]
          },
          "red", "green"
        ]
      }
    }
  }
}
```

--------------------------------

### Flag Set Organization: By Application/Service

Source: https://github.com/open-feature/flagd/blob/main/docs/guides/migrating-to-flag-sets.md

Example YAML showing flag set organization by application or service.

```yaml
flagSetId: "user-service"    # All user-related flags
flagSetId: "payment-service" # All payment-related flags
```

--------------------------------

### Resolve an integer value

Source: https://github.com/open-feature/flagd/wiki/Examples-using-cURL

This example demonstrates resolving an integer flag. Note that the response value is a string.

```APIDOC
## POST /schema.v1.Service/ResolveInt

### Description
Resolves an integer flag. Note: The resolved value is returned as a string.

### Method
POST

### Endpoint
`localhost:8013/schema.v1.Service/ResolveInt`

### Request Body
- **flagKey** (string) - Required - The key of the flag to resolve.
- **context** (object) - Optional - The evaluation context.

### Request Example
```json
{
  "flagKey": "myIntFlag",
  "context": {}
}
```

### Response
#### Success Response (200)
- **value** (string) - The resolved integer value of the flag, returned as a string.
- **reason** (string) - The reason for the resolution.
- **variant** (string) - The variant of the flag that was resolved.

#### Response Example
```json
{
  "value": "1",
  "reason": "DEFAULT",
  "variant": "one"
}
```
```