### Quick Start Build and Run

Source: https://github.com/whatap/go-api-inst/blob/main/docs/user-guide.md

Perform an instrumented build and execution without manual setup.

```bash
# Build (no init required)
whatap-go-inst go build ./...

# Run
./myapp  # or whatap-go-inst go run .
```

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

### Install whatap-go-inst via Binary

Source: https://github.com/whatap/go-api-inst/blob/main/README.md

Download and install the pre-built binary for Linux systems.

```bash
# Linux amd64
curl -sSL https://github.com/whatap/go-api-inst/releases/latest/download/whatap-go-inst_linux_amd64.tar.gz | tar xz
sudo mv whatap-go-inst /usr/local/bin/

# Linux arm64
curl -sSL https://github.com/whatap/go-api-inst/releases/latest/download/whatap-go-inst_linux_arm64.tar.gz | tar xz
sudo mv whatap-go-inst /usr/local/bin/

# Specific version (e.g., v0.5.4)
curl -sSL https://github.com/whatap/go-api-inst/releases/download/v0.5.4/whatap-go-inst_linux_amd64.tar.gz | tar xz
```

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

### Full Configuration Example

Source: https://github.com/whatap/go-api-inst/blob/main/docs/custom-instrumentation.md

A comprehensive example showing injection, replacement, hooking, and file addition.

```yaml
# .whatap/config.yaml

instrumentation:
  preset: minimal
  debug: true

custom:
  # Logging at function start
  inject:
    - package: "main"
      function: "Handle*"
      start: |
        log.Printf("[%s] started", "{{.FuncName}}")
      imports:
        - "log"

  # Replace sql.Open
  replace:
    - package: "database/sql"
      function: "Open"
      with: "whatapsql.Open"
      imports:
        - "github.com/whatap/go-api/instrumentation/database/sql/whatapsql"

  # Trace specific function calls
  hook:
    - package: "main"
      function: "processOrder"
      before: |
        trace.Step(ctx, "ORDER", "processOrder started")
      after: |
        trace.Step(ctx, "ORDER", "processOrder completed")
      imports:
        - "github.com/whatap/go-api/trace"

  # Create helper file
  add:
    - package: "main"
      file: "whatap_init.go"
      content: |
        package main

        import "github.com/whatap/go-api/trace"

        func init() {
            trace.Init(nil)
        }
```

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

### Install via go install

Source: https://github.com/whatap/go-api-inst/blob/main/docs/user-guide.md

Install the tool using the Go toolchain for versions 1.21 or higher.

```bash
# Official binary
go install github.com/whatap/go-api-inst/cmd/whatap-go-inst@latest

# Short binary name
go install github.com/whatap/go-api-inst/cmd/goinst@latest
```

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

### Install whatap-go-inst via Go

Source: https://github.com/whatap/go-api-inst/blob/main/README.md

Install the tool directly using the Go toolchain.

```bash
go install github.com/whatap/go-api-inst/cmd/whatap-go-inst@latest
```

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

### Install WhaTap Go Instrumentation

Source: https://context7.com/whatap/go-api-inst/llms.txt

Commands to download, install, or build the instrumentation tool from source.

```bash
# Linux amd64 - Download binary (Recommended)
curl -sSL https://github.com/whatap/go-api-inst/releases/latest/download/whatap-go-inst_linux_amd64.tar.gz | tar xz
sudo mv whatap-go-inst /usr/local/bin/

# Linux arm64
curl -sSL https://github.com/whatap/go-api-inst/releases/latest/download/whatap-go-inst_linux_arm64.tar.gz | tar xz
sudo mv whatap-go-inst /usr/local/bin/

# Specific version (e.g., v0.5.4)
curl -sSL https://github.com/whatap/go-api-inst/releases/download/v0.5.4/whatap-go-inst_linux_amd64.tar.gz | tar xz

# Go Install (Go 1.21+)
go install github.com/whatap/go-api-inst/cmd/whatap-go-inst@latest

# Build from source
git clone https://github.com/whatap/go-api-inst
cd go-api-inst
go build -o whatap-go-inst .

# Verify installation
whatap-go-inst version
```

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

### Install whatap-go-inst (Linux amd64)

Source: https://github.com/whatap/go-api-inst/blob/main/docs/README.md

Installs the whatap-go-inst binary on Linux amd64 systems. This is a prerequisite for using the build wrapper mode.

```bash
# Install (Linux amd64)
curl -sSL https://github.com/whatap/go-api-inst/releases/latest/download/whatap-go-inst_linux_amd64.tar.gz | tar xz
sudo mv whatap-go-inst /usr/local/bin/
```

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

### Install via Direct Binary Download

Source: https://github.com/whatap/go-api-inst/blob/main/docs/user-guide.md

Download and install the binary for Linux systems.

```bash
# Linux (amd64)
curl -sSL https://github.com/whatap/go-api-inst/releases/latest/download/whatap-go-inst_linux_amd64.tar.gz | tar xz
sudo mv whatap-go-inst /usr/local/bin/

# Linux (arm64)
curl -sSL https://github.com/whatap/go-api-inst/releases/latest/download/whatap-go-inst_linux_arm64.tar.gz | tar xz
sudo mv whatap-go-inst /usr/local/bin/
```

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

### Verify Installation

Source: https://github.com/whatap/go-api-inst/blob/main/docs/user-guide.md

Check the installed version of the tool.

```bash
whatap-go-inst version

# Or short command
goinst version
```

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

### Build Go Project with Build Wrapper

Source: https://github.com/whatap/go-api-inst/blob/main/docs/README.md

Builds a Go project using the installed whatap-go-inst binary. This method does not require manual initialization and is the recommended approach for instrumentation.

```bash
# Build (no init required)
whatap-go-inst go build ./...
```

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

### Docker Build Integration

Source: https://github.com/whatap/go-api-inst/blob/main/README.md

Example Dockerfile demonstrating how to build an instrumented Go application and run it with the WhaTap agent.

```dockerfile
# Stage 1: Build with instrumentation
FROM golang:1.21-alpine AS builder

# Install whatap-go-inst
RUN wget -qO- https://github.com/whatap/go-api-inst/releases/latest/download/whatap-go-inst_linux_amd64.tar.gz | tar xz -C /usr/local/bin/

WORKDIR /app
COPY . .

# Build with instrumentation
RUN whatap-go-inst go build -o /app/server .

# Stage 2: Run with WhaTap agent
FROM alpine:latest

# Install WhaTap agent
RUN wget -qO- https://s3.ap-northeast-2.amazonaws.com/repo.whatap.io/alpine/x86_64/whatap-agent.tar.gz | tar xz -C /

WORKDIR /app
COPY --from=builder /app/server .

# Create WhaTap config file
RUN echo "license=your-license-key" > whatap.conf && \
    echo "whatap.server.host=13.124.11.223" >> whatap.conf && \
    echo "app_name=myapp" >> whatap.conf

ENV WHATAP_HOME=/app

EXPOSE 8080
CMD ["/bin/sh", "-c", "/usr/whatap/agent/whatap-agent start && ./server"]
```

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

### Build Wrapper Examples

Source: https://github.com/whatap/go-api-inst/blob/main/docs/user-guide.md

Common usage patterns for the build wrapper, including error tracking and output configuration.

```bash
# Build entire project
whatap-go-inst go build ./...

# Specify output file
whatap-go-inst go build -o myapp .

# Run directly
whatap-go-inst go run .

# Run tests
whatap-go-inst go test ./...

# Build with error tracking code
whatap-go-inst --error-tracking go build ./...

# Disable instrumented source output
whatap-go-inst --no-output go build ./...

# Save instrumented source to custom path
whatap-go-inst --output ./instrumented go build ./...

# Instrument external module from GOMODCACHE
whatap-go-inst --external-module=mycompany.com/internal/lib go build ./...
```

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

### Instrumentation Example Source Code

Source: https://github.com/whatap/go-api-inst/blob/main/docs/build-wrapper.md

Comparison of original source code and the resulting code after instrumentation.

```go
package main

import "github.com/gin-gonic/gin"

func main() {
    r := gin.Default()
    r.GET("/", func(c *gin.Context) {
        c.JSON(200, gin.H{"message": "hello"})
    })
    r.Run(":8080")
}
```

```bash
whatap-go-inst go build -o myapp .
```

```go
package main

import (
    "github.com/gin-gonic/gin"
    "github.com/whatap/go-api/trace"
    "github.com/whatap/go-api/instrumentation/github.com/gin-gonic/gin/whatapgin"
)

func main() {
    trace.Init(nil)
    defer trace.Shutdown()
    r := gin.Default()
    r.Use(whatapgin.Middleware())
    r.GET("/", func(c *gin.Context) {
        c.JSON(200, gin.H{"message": "hello"})
    })
    r.Run(":8080")
}
```

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

### Context Preservation: Using Context with SQL Open

Source: https://github.com/whatap/go-api-inst/blob/main/docs/rules/common.md

This example highlights the preferred method of passing a `context.Context` to `whatapsql.OpenContext` for efficient tracing.

```go
// GOOD: Pass context
whatapsql.OpenContext(ctx, driverName, dataSourceName)
```

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

### Dockerfile for Instrumented Build

Source: https://github.com/whatap/go-api-inst/blob/main/docs/build-wrapper.md

Multi-stage Dockerfile setup to build an instrumented Go binary and run it with the WhaTap agent.

```dockerfile
# Stage 1: Build with instrumentation
FROM golang:1.21-alpine AS builder

# Install whatap-go-inst
RUN wget -qO- https://github.com/whatap/go-api-inst/releases/latest/download/whatap-go-inst_linux_amd64.tar.gz | tar xz -C /usr/local/bin/

WORKDIR /app
COPY . .

# Build with instrumentation
RUN whatap-go-inst go build -o /app/server .

# Stage 2: Run with WhaTap agent
FROM alpine:latest

# Install WhaTap agent
RUN wget -qO- https://s3.ap-northeast-2.amazonaws.com/repo.whatap.io/alpine/x86_64/whatap-agent.tar.gz | tar xz -C /

WORKDIR /app
COPY --from=builder /app/server .

# WhaTap config
RUN echo "license=your-license-key" > whatap.conf && \
    echo "whatap.server.host=13.124.11.223" >> whatap.conf && \
    echo "app_name=myapp" >> whatap.conf

ENV WHATAP_HOME=/app

EXPOSE 8080
CMD ["/bin/sh", "-c", "/usr/whatap/agent/whatap-agent start && ./server"]
```

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

### Add Middleware Transformation Example

Source: https://github.com/whatap/go-api-inst/blob/main/docs/custom-instrumentation.md

Injects middleware into a Gin router initialization.

```yaml
custom:
  transform:
    - package: "github.com/gin-gonic/gin"
      function: "Default"
      template: |
        {{.Original}}
        {{.Var}}.Use(whatapgin.Middleware())
      imports:
        - "github.com/whatap/go-api/instrumentation/github.com/gin-gonic/gin/whatapgin"
```

```go
// Before
r := gin.Default()

// After
r := gin.Default()
r.Use(whatapgin.Middleware())
```

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

### Initialize WhaTap Trace in main()

Source: https://github.com/whatap/go-api-inst/blob/main/docs/user-guide.md

Initialize the WhaTap trace functionality at the beginning of your main function and ensure it is shut down gracefully using defer. This is essential for WhaTap to start collecting data.

```go
func main() {
    trace.Init(nil)
    defer trace.Shutdown()
    // Original code...
}
```

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

### Injected Web Framework Middleware

Source: https://github.com/whatap/go-api-inst/blob/main/README.md

Examples of how various web frameworks are instrumented with middleware or wrappers.

```go
// Gin
r := gin.Default()
r.Use(whatapgin.Middleware())  // Auto-injected

// Echo v4
e := echo.New()
e.Use(whatapecho.Middleware())  // Auto-injected

// Fiber v2
app := fiber.New()
app.Use(whatapfiber.Middleware())  // Auto-injected

// Chi (in-place wrapping)
r := whatapchi.WrapRouter(chi.NewRouter())

// Gorilla Mux (in-place wrapping)
r := whatapmux.WrapRouter(mux.NewRouter())

// net/http (handler wrapping)
mux.HandleFunc("/", whataphttp.Func(handler))      // Auto-wrapped
mux.Handle("/api", whataphttp.WrapHandler(h))      // Auto-wrapped
```

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

### External Module Output Structure

Source: https://context7.com/whatap/go-api-inst/llms.txt

Example directory structure resulting from external module instrumentation.

```text
./instrumented/
├── main.go                  (instrumented)
├── go.mod                   (replace directive added)
└── _modules/
    └── mycompany/
        └── db-lib/
            ├── connection.go  (instrumented)
            └── go.mod         (whatap/go-api require added)
```

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

### Log Collection Settings Example

Source: https://github.com/whatap/go-api-inst/blob/main/docs/config.md

Logging library instrumentation, including AST instrumentation, is typically included in the 'log' or 'full' presets within the Whatap configuration.

```text
Logging library instrumentation is included in the `log` preset (and `full` preset).
```

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

### Context Preservation: Avoiding Goroutine ID Fallback

Source: https://github.com/whatap/go-api-inst/blob/main/docs/rules/common.md

This example shows the less preferred method of calling `whatapsql.Open` without a context, which forces a fallback to goroutine ID extraction.

```go
// AVOID: Call without context (goroutine ID fallback used)
whatapsql.Open(driverName, dataSourceName)
```

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

### Build whatap-go-inst from Source

Source: https://github.com/whatap/go-api-inst/blob/main/README.md

Clone the repository and build the binary locally.

```bash
git clone https://github.com/whatap/go-api-inst
cd go-api-inst
go build -o whatap-go-inst .
```

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

### Initialize and Shutdown Trace Package in main()

Source: https://github.com/whatap/go-api-inst/blob/main/docs/rules/common.md

Demonstrates how to initialize the Whatap trace package at the beginning of your main function and ensure it's shut down gracefully using defer.

```go
func main() {
    trace.Init(nil)           // Inserted
    defer trace.Shutdown()    // Inserted
    // ... existing code
}
```

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

### Handle Instrumentation Errors

Source: https://github.com/whatap/go-api-inst/blob/main/docs/custom-instrumentation.md

Example of a fail-fast error message during the instrumentation process.

```text
Error: main.go: apply custom rules: inject rules: 3:6: expected ';', found is
```

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

### Hook Transformation Result

Source: https://github.com/whatap/go-api-inst/blob/main/docs/custom-instrumentation.md

Example of code modification after applying a hook rule.

```go
// Before
data := fetchData()

// After
fmt.Println(">>> fetchData starting")
data := fetchData()
fmt.Println("<<< fetchData completed")
```

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

### Build and Run Commands with whatap-go-inst

Source: https://github.com/whatap/go-api-inst/blob/main/docs/build-wrapper.md

Commands for building, running, and testing Go applications with automatic instrumentation.

```bash
# Build (no init required)
whatap-go-inst go build ./...
```

```bash
# Build all packages
whatap-go-inst go build ./...

# Specify output file
whatap-go-inst go build -o myapp .

# Disable instrumented source output
whatap-go-inst --no-output go build ./...

# Save instrumented source to custom path
whatap-go-inst --output ./instrumented go build ./...
```

```bash
whatap-go-inst go run .
whatap-go-inst go run . --port 8080
```

```bash
whatap-go-inst go test ./...
whatap-go-inst go test -v -run TestName ./pkg/...
```

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

### Replace Transformation Result

Source: https://github.com/whatap/go-api-inst/blob/main/docs/custom-instrumentation.md

Example of code modification after applying a replace rule.

```go
// Before
db, err := sql.Open("mysql", dsn)

// After
db, err := whatapsql.Open("mysql", dsn)
```

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

### Use Build Wrapper

Source: https://github.com/whatap/go-api-inst/blob/main/README.md

Prefix standard Go commands with the instrumentation tool to apply monitoring during build or execution.

```bash
# Build (no init required)
whatap-go-inst go build ./...
whatap-go-inst go build -o myapp .

# Run
whatap-go-inst go run .

# Test
whatap-go-inst go test ./...
```

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

### Inject Transformation Result

Source: https://github.com/whatap/go-api-inst/blob/main/docs/custom-instrumentation.md

Example of code modification after applying an inject rule.

```go
// Before
func ProcessData(data string) error {
    return process(data)
}

// After
func ProcessData(data string) error {
    fmt.Println("function started")
    return process(data)
    fmt.Println("function ended")  // Warning: unreachable - use defer
}
```

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

### Configure Inject Rule

Source: https://github.com/whatap/go-api-inst/blob/main/docs/custom-instrumentation.md

Inserts code at the start or end of function definitions.

```yaml
custom:
  inject:
    - package: "main"           # Package name (package declaration in file)
      function: "Process*"      # Function name pattern (wildcards supported)
      start: |                  # Insert at function start
        fmt.Println("function started")
      end: |                    # Insert at function end (note: after return)
        fmt.Println("function ended")
      imports:                  # Required imports
        - "fmt"
```

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

### JSON Report Structure

Source: https://github.com/whatap/go-api-inst/blob/main/docs/user-guide.md

Example of the JSON output format generated by the report option.

```json
{
  "timestamp": "2026-01-07T15:00:00+09:00",
  "command": "inject",
  "summary": {
    "total": 10,
    "instrumented": 3,
    "skipped": 2,
    "copied": 5,
    "errors": 0
  },
  "files": [
    {
      "path": "main.go",
      "status": "instrumented",
      "transformers": ["gin"],
      "changes": ["added import: whatapgin", "added: trace.Init"]
    }
  ]
}
```

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

### Multi-Stage Docker Build with Instrumentation

Source: https://github.com/whatap/go-api-inst/blob/main/docs/multi-module.md

This Dockerfile demonstrates a multi-stage build process. The first stage builds the application with whatap-go-inst, including external module instrumentation. The second stage sets up the runtime environment with the WhaTap agent and the built binary.

```dockerfile
# Stage 1: Build with instrumentation
FROM golang:1.21-alpine AS builder

# Install whatap-go-inst
RUN wget -qO- https://github.com/whatap/go-api-inst/releases/latest/download/whatap-go-inst_linux_amd64.tar.gz | tar xz -C /usr/local/bin/

WORKDIR /app
COPY . .

# Build with external module instrumentation
RUN go mod download
RUN whatap-go-inst \
    --external-module="mycompany.com/*" \
    go build -o /app/server ./...

# Stage 2: Runtime
FROM alpine:latest

# Install WhaTap agent
RUN wget -qO- https://s3.ap-northeast-2.amazonaws.com/repo.whatap.io/alpine/x86_64/whatap-agent.tar.gz | tar xz -C / 

WORKDIR /app
COPY --from=builder /app/server .

# WhaTap config
RUN echo "license=your-license-key" > whatap.conf && \
    echo "whatap.server.host=13.124.11.223" >> whatap.conf && \
    echo "app_name=myapp" >> whatap.conf

ENV WHATAP_HOME=/app

EXPOSE 8080
CMD ["/bin/sh", "-c", "/usr/whatap/agent/whatap-agent start && ./server"]
```

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

### Cobra Command Initialization with Gin Middleware

Source: https://github.com/whatap/go-api-inst/blob/main/docs/rules/common.md

Illustrates the transformation of a Cobra command's Run function to include Whatap's Gin middleware for tracing HTTP requests.

```go
// Before
var serverCmd = &cobra.Command{
    Use: "server",
    Run: func(cmd *cobra.Command, args []string) {
        r := gin.New()          // Detected and transformed
        r.Run(":8080")
    },
}

// After
var serverCmd = &cobra.Command{
    Use: "server",
    Run: func(cmd *cobra.Command, args []string) {
        r := gin.New()
        r.Use(whatapgin.Middleware())  // Inserted
        r.Run(":8080")
    },
}
```

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

### Build from Source

Source: https://github.com/whatap/go-api-inst/blob/main/docs/user-guide.md

Compile the tool directly from the repository source code.

```bash
git clone https://github.com/whatap/go-api-inst.git
cd go-api-inst
go build -o whatap-go-inst .
```

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

### Configure whatap-go-inst via YAML

Source: https://github.com/whatap/go-api-inst/blob/main/docs/config.md

The standard configuration file format for defining instrumentation settings, package selection, and exclusion patterns.

```yaml
# .whatap/config.yaml

instrumentation:
  # Basic options
  error_tracking: false    # Inject error tracking code (--error-tracking)
  debug: false             # Enable debug output (GO_API_AST_DEBUG)
  output_dir: ""           # Instrumented source output directory

  # Package selection
  preset: "full"           # Instrumentation preset (full/minimal/web/database/external/log/custom)
  enabled_packages: []     # Additional packages to enable
  disabled_packages: []    # Packages to disable

# User-defined instrumentation — see custom-instrumentation.md
# custom:
#   inject: []
#   replace: []
#   hook: []
#   transform: []

# External modules to instrument from GOMODCACHE
# external_modules:
#   - "mycompany.com/internal/lib"

# File patterns to exclude (optional - defaults auto-applied if omitted)
# exclude:
#   - "*_test.go"
#   - "vendor/**"
```

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

### Build Wrapper Syntax

Source: https://github.com/whatap/go-api-inst/blob/main/docs/user-guide.md

General syntax for using the build wrapper to instrument Go commands.

```bash
whatap-go-inst [global-options] go <command> [arguments]
```

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

### Build Single Module Project

Source: https://github.com/whatap/go-api-inst/blob/main/docs/multi-module.md

For new projects structured as a single module, use the standard build command with whatap-go-inst. No special flags are needed for basic instrumentation.

```bash
whatap-go-inst go build ./cmd/main
```

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

### Transform Aerospike Get Call

Source: https://github.com/whatap/go-api-inst/blob/main/docs/rules/external-services.md

Wraps aerospike.Get calls using whatapsql.Wrap for instrumentation, as Aerospike does not support direct hooks. Only v6 and v8 are supported.

```go
// Before
record, err := client.Get(policy, key)
```

```go
// After
record, err := whatapsql.Wrap(context.Background(), "aerospike", "Get", func() (*aerospike.Record, error) {
    return client.Get(policy, key)
})
```

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

### Ensure Whatap Dependency Propagation

Source: https://github.com/whatap/go-api-inst/blob/main/docs/multi-module.md

Modules that depend on instrumented libraries must also include the whatap dependency. Add it using 'go get'.

```bash
cd main-app
go get github.com/whatap/go-api@latest
```

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

### Source Code Before and After Instrumentation

Source: https://github.com/whatap/go-api-inst/blob/main/docs/source-inject.md

Comparison of a standard Gin application before and after the automatic injection of WhaTap middleware.

```go
package main

import (
    "github.com/gin-gonic/gin"
)

func main() {
    r := gin.Default()
    r.GET("/", func(c *gin.Context) {
        c.JSON(200, gin.H{"message": "hello"})
    })
    r.Run(":8080")
}
```

```go
package main

import (
    "github.com/gin-gonic/gin"
    "github.com/whatap/go-api/instrumentation/github.com/gin-gonic/gin/whatapgin"
    "github.com/whatap/go-api/trace"
)

func main() {
    trace.Init(nil)
    defer trace.Shutdown()
    r := gin.Default()
    r.Use(whatapgin.Middleware())  // Middleware auto-injected

    r.GET("/", func(c *gin.Context) {
        c.JSON(200, gin.H{"message": "hello"})
    })
    r.Run(":8080")
}
```

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

### Build with Auto Injection

Source: https://github.com/whatap/go-api-inst/blob/main/docs/user-guide.md

After cleaning up manual instrumentation and verifying changes, use the `whatap-go-inst go build` command to build your application with auto-instrumentation enabled.

```bash
# 4. Build with auto injection
whatap-go-inst go build ./...
```

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

### Instrument Empty http.Client Initialization

Source: https://github.com/whatap/go-api-inst/blob/main/docs/rules/web-frameworks.md

Adds a Whatap RoundTripper to an empty http.Client, enabling instrumentation and context propagation.

```go
// Before
client := &http.Client{
    Timeout: 10 * time.Second,
}

// After (marker function - Transport field removed on remove, handler context auto-detected)
client := &http.Client{
    Timeout:   10 * time.Second,
    Transport: whataphttp.NewRoundTripWithEmptyTransport(c.Request.Context()),
}
```

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

### Complete Instrumentation Workflow

Source: https://github.com/whatap/go-api-inst/blob/main/docs/source-inject.md

Standard sequence for injecting, verifying, and building the instrumented project.

```bash
whatap-go-inst inject -s ./myapp -o ./instrumented
```

```bash
diff myapp/main.go instrumented/main.go
```

```bash
cd instrumented
go get github.com/whatap/go-api@latest
go mod tidy
go build -o ../myapp .
```

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

### Inject Instrumentation into Go Source Code

Source: https://github.com/whatap/go-api-inst/blob/main/docs/README.md

Modifies Go source files directly by injecting instrumentation code. This creates a new 'instrumented' directory and requires running 'go get' and 'go build' within that directory.

```bash
whatap-go-inst inject -s ./myapp -o ./instrumented
cd instrumented && go get github.com/whatap/go-api@latest && go build .
```

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

### Instrument database/sql

Source: https://github.com/whatap/go-api-inst/blob/main/docs/rules/database.md

Use the whatapsql wrapper to track database operations like Query, Exec, and Prepare.

```go
import "github.com/whatap/go-api/instrumentation/database/sql/whatapsql"
```

```go
// Before
db, err := sql.Open("mysql", "user:pass@/dbname")

// After
db, err := whatapsql.Open("mysql", "user:pass@/dbname")
```

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

### Configure fmt Package

Source: https://github.com/whatap/go-api-inst/blob/main/docs/rules/log.md

Use whatapfmt to transform standard fmt print functions for transaction correlation.

```go
import (
    "fmt"
    "github.com/whatap/go-api/instrumentation/fmt/whatapfmt"
)

func main() {
    trace.Init(nil)
    defer trace.Shutdown()
    whatapfmt.Println("Server starting...")  // fmt.Println → whatapfmt.Println transformed
}
```

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

### Enable whatapfmt Configuration

Source: https://github.com/whatap/go-api-inst/blob/main/docs/rules/log.md

Enable logsink and fmt instrumentation in the whatap.conf file.

```ini
# whatap.conf
logsink_enabled=true
logsink_fmt_enabled=true   # Enable whatapfmt
```

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

### Configure Standard log Package

Source: https://github.com/whatap/go-api-inst/blob/main/docs/rules/log.md

Use logsink.GetTraceLogWriter to wrap the output writer for standard log package integration.

```go
import (
    "log"
    "github.com/whatap/go-api/logsink"
    "os"
)

func main() {
    trace.Init(nil)
    defer trace.Shutdown()
    log.SetOutput(logsink.GetTraceLogWriter(os.Stderr))  // Inserted
    // ...
}
```

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

### Match Package Scope

Source: https://github.com/whatap/go-api-inst/blob/main/docs/custom-instrumentation.md

Demonstrates how the package field maps to Go source declarations.

```go
package user  // ← Matches this value
```

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

### Test Build Without whatap-go-inst

Source: https://github.com/whatap/go-api-inst/blob/main/docs/troubleshooting.md

Verify that your project builds correctly without any instrumentation by running a standard Go build command.

```bash
# Test build without whatap-go-inst
go build ./...
```

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

### Initialize Router in main() or init()

Source: https://github.com/whatap/go-api-inst/blob/main/docs/user-guide.md

Initializing web framework routers (like Gin) in global variables can lead to middleware not being auto-added. Initialize them within main() or init() functions instead.

```go
// Middleware NOT auto-added
var Router = gin.Default()  // Global-level initialization
```

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

### net/http (Server) Instrumentation

Source: https://github.com/whatap/go-api-inst/blob/main/docs/rules/web-frameworks.md

Instructions for instrumenting the standard Go net/http server using Whatap's handler wrapping.

```APIDOC
## POST /api/config

### Description
Updates the application configuration.

### Method
POST

### Endpoint
/api/config

### Parameters
#### Request Body
- **setting** (string) - Required - The name of the configuration setting to update.
- **value** (any) - Required - The new value for the configuration setting.

### Request Example
```json
{
  "setting": "timeout",
  "value": 30
}
```

### Response
#### Success Response (200)
- **message** (string) - A confirmation message indicating the configuration was updated.

#### Response Example
```json
{
  "message": "Configuration updated successfully."
}
```
```

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

### Check Version Information

Source: https://github.com/whatap/go-api-inst/blob/main/docs/user-guide.md

Displays the current version of the whatap-go-inst tool.

```bash
whatap-go-inst version
```

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

### Run WhaTap Go Instrumentation CLI

Source: https://github.com/whatap/go-api-inst/blob/main/docs/custom-instrumentation.md

Commands for running the instrumentation tool with various configuration and output options.

```bash
# Default (auto-searches .whatap/config.yaml)
whatap-go-inst inject -s . -o ./output
```

```bash
# Specify config file
whatap-go-inst --config custom.yaml inject -s . -o ./output
```

```bash
# Environment variable
WHATAP_INST_CONFIG=custom.yaml whatap-go-inst inject -s . -o ./output
```

```bash
# Verbose output
whatap-go-inst inject -s . -o ./output -v
```

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

### Import WhaTap Kubernetes Instrumentation

Source: https://github.com/whatap/go-api-inst/blob/main/docs/rules/external-services.md

Required import for instrumenting Kubernetes client-go.

```go
import "github.com/whatap/go-api/instrumentation/k8s.io/client-go/kubernetes/whatapkubernetes"
```

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

### Check Framework Versions and Debug Instrumentation

Source: https://github.com/whatap/go-api-inst/blob/main/docs/troubleshooting.md

Verify framework versions in go.mod and enable debug mode to inspect instrumentation skip behavior.

```bash
# Check framework version in go.mod
grep -E "echo|fiber|go-redis|aerospike" go.mod

# Debug mode to see skip behavior
GO_API_AST_DEBUG=1 whatap-go-inst go build ./...
```

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

### Instrument net/http Server

Source: https://context7.com/whatap/go-api-inst/llms.txt

Wraps standard library handlers or server configurations with WhaTap instrumentation.

```go
// Original code - HandleFunc and Handle
http.HandleFunc("/api", apiHandler)
http.Handle("/static", staticHandler)
```

```go
// After instrumentation
http.HandleFunc("/api", whataphttp.Func(apiHandler))
http.Handle("/static", whataphttp.WrapHandler(staticHandler))
```

```go
// http.Server struct literal pattern
// Before
s := &http.Server{
    Addr:    ":8080",
    Handler: mux,
}
```

```go
// After
s := &http.Server{
    Addr:    ":8080",
    Handler: whataphttp.WrapHandler(mux),
}
```

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

### fmt (whatapfmt) Instrumentation

Source: https://context7.com/whatap/go-api-inst/llms.txt

Replaces the standard fmt.Println with whatapfmt.Println for instrumented logging.

```go
// Before
fmt.Println("Debug message")
```

```go
// After
whatapfmt.Println("Debug message")
```

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

### Build Wrapper Mode

Source: https://github.com/whatap/go-api-inst/blob/main/ReleaseNote.md

Injects monitoring code and builds the project without modifying the original source files.

```bash
whatap-go-inst go build ./...
```

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

### Transform Redis Client Creation (redis/go-redis v8/v9)

Source: https://github.com/whatap/go-api-inst/blob/main/docs/rules/external-services.md

Replaces calls to redis.NewClient with whatapgoredis.NewClient for instrumentation. Only v8 and v9 are supported.

```go
// Before
rdb := redis.NewClient(&redis.Options{
    Addr: "localhost:6379",
})
```

```go
// After
rdb := whatapgoredis.NewClient(&redis.Options{
    Addr: "localhost:6379",
})
```

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

### Injected main() Initialization

Source: https://github.com/whatap/go-api-inst/blob/main/README.md

Initialization and shutdown logic injected into the main function.

```go
func main() {
    trace.Init(nil)
    defer trace.Shutdown()
    // ... existing code
}
```

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

### Instrumenting with Docker Multi-stage Builds

Source: https://context7.com/whatap/go-api-inst/llms.txt

Integrate the instrumentation tool into a multi-stage Dockerfile to ensure monitoring is applied during the build process.

```dockerfile
# Stage 1: Build with instrumentation
FROM golang:1.21-alpine AS builder

# Install whatap-go-inst
RUN wget -qO- https://github.com/whatap/go-api-inst/releases/latest/download/whatap-go-inst_linux_amd64.tar.gz | tar xz -C /usr/local/bin/

WORKDIR /app
COPY . .

# Build with instrumentation (and external module if needed)
RUN go mod download
RUN whatap-go-inst go build -o /app/server .

# Or with external module instrumentation
# RUN whatap-go-inst --external-module="mycompany.com/*" go build -o /app/server ./...

# Stage 2: Run with WhaTap agent
FROM alpine:latest

# Install WhaTap agent
RUN wget -qO- https://s3.ap-northeast-2.amazonaws.com/repo.whatap.io/alpine/x86_64/whatap-agent.tar.gz | tar xz -C /

WORKDIR /app
COPY --from=builder /app/server .

# Create WhaTap config file (get values from WhaTap Console)
RUN echo "license=your-license-key" > whatap.conf && \
    echo "whatap.server.host=13.124.11.223" >> whatap.conf && \
    echo "app_name=myapp" >> whatap.conf

ENV WHATAP_HOME=/app

EXPOSE 8080
CMD ["/bin/sh", "-c", "/usr/whatap/agent/whatap-agent start && ./server"]
```

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

### Instrument go-redis

Source: https://context7.com/whatap/go-api-inst/llms.txt

Replaces Redis client creation with WhaTap-instrumented versions for v8/v9.

```go
// Before (v9)
rdb := redis.NewClient(&redis.Options{
    Addr: "localhost:6379",
})

// After
rdb := whatapgoredis.NewClient(&redis.Options{
    Addr: "localhost:6379",
})

// Cluster client
// Before
rdb := redis.NewClusterClient(&redis.ClusterOptions{
    Addrs: []string{"localhost:7000", "localhost:7001"},
})

// After
rdb := whatapgoredis.NewClusterClient(&redis.ClusterOptions{
    Addrs: []string{"localhost:7000", "localhost:7001"},
})

// Failover client and Ring are also supported
rdb := whatapgoredis.NewFailoverClient(&redis.FailoverOptions{...})
rdb := whatapgoredis.NewRing(&redis.RingOptions{...})
```

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

### Build Wrapper Mode Commands

Source: https://context7.com/whatap/go-api-inst/llms.txt

Commands to wrap Go build and run operations for automatic instrumentation without modifying source files.

```bash
# Build entire project with instrumentation
whatap-go-inst go build ./...

# Build with specific output file
whatap-go-inst go build -o myapp .

# Run directly with instrumentation
whatap-go-inst go run .

# Run tests with instrumentation
whatap-go-inst go test ./...

# Build with error tracking code injection
whatap-go-inst --error-tracking go build ./...

# Disable instrumented source output (default saves to whatap-instrumented/)
whatap-go-inst --no-output go build ./...

# Save instrumented source to custom path
whatap-go-inst --output ./instrumented go build ./...

# Instrument external module from GOMODCACHE
whatap-go-inst --external-module=mycompany.com/internal/lib go build ./...

# Multiple external modules with wildcard
whatap-go-inst --external-module="mycompany.com/*" go build ./...

# Debug mode
GO_API_AST_DEBUG=1 whatap-go-inst go build ./...
```

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

### Basic Transformation Commands

Source: https://github.com/whatap/go-api-inst/blob/main/docs/source-inject.md

Various ways to invoke the injection tool, including directory-wide, single-file, and short-option variants.

```bash
# Transform entire directory
whatap-go-inst inject --src ./myapp --output ./instrumented

# Transform single file
whatap-go-inst inject --src ./myapp/main.go --output ./instrumented/main.go

# Short options
whatap-go-inst inject -s ./myapp -o ./instrumented

# Default: src=".", output="./output"
whatap-go-inst inject
```

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

### Instrument github.com/jmoiron/sqlx

Source: https://github.com/whatap/go-api-inst/blob/main/docs/rules/database.md

Replace standard sqlx connection methods with whatapsqlx to enable query tracking.

```go
import "github.com/whatap/go-api/instrumentation/github.com/jmoiron/sqlx/whatapsqlx"
```

```go
// Before
db, err := sqlx.Open("mysql", "user:pass@/dbname")
db, err := sqlx.Connect("mysql", "user:pass@/dbname")
db, err := sqlx.ConnectContext(ctx, "mysql", "user:pass@/dbname")
db := sqlx.MustConnect("mysql", "user:pass@/dbname")
db := sqlx.MustOpen("mysql", "user:pass@/dbname")

// After
db, err := whatapsqlx.Open("mysql", "user:pass@/dbname")
db, err := whatapsqlx.Connect("mysql", "user:pass@/dbname")
db, err := whatapsqlx.ConnectContext(ctx, "mysql", "user:pass@/dbname")
db := whatapsqlx.MustConnect("mysql", "user:pass@/dbname")
db := whatapsqlx.MustOpen("mysql", "user:pass@/dbname")
```

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

### Instrument github.com/jinzhu/gorm (Legacy)

Source: https://github.com/whatap/go-api-inst/blob/main/docs/rules/database.md

Use the legacy whatapgorm package for older versions of the GORM library.

```go
import "github.com/whatap/go-api/instrumentation/github.com/jinzhu/gorm/whatapgorm"
```

```go
// Before
db, err := gorm.Open("mysql", "user:pass@/dbname")

// After
db, err := whatapgorm.Open("mysql", "user:pass@/dbname")
```

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

### Use Local go-api for Development

Source: https://github.com/whatap/go-api-inst/blob/main/docs/troubleshooting.md

Configure your go.mod file to use a local copy of the go-api module for development purposes.

```go
go mod edit -replace github.com/whatap/go-api=../go-api
```

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

### Instrument net/http Client

Source: https://context7.com/whatap/go-api-inst/llms.txt

Wraps HTTP client calls with context-aware tracing. Use the whataphttp package to replace standard http calls.

```go
// Inside Gin handler - context auto-detected
r.GET("/call-api", func(c *gin.Context) {
    // Before
    resp, err := http.Get("http://example.com/api")

    // After (uses c.Request.Context() automatically)
    resp, err := whataphttp.HttpGet(c.Request.Context(), "http://example.com/api")
})

// Inside net/http handler
func handler(w http.ResponseWriter, r *http.Request) {
    // Before
    resp, err := http.Get("http://example.com/api")

    // After (uses r.Context() automatically)
    resp, err := whataphttp.HttpGet(r.Context(), "http://example.com/api")
}

// Function with context parameter
func fetchData(ctx context.Context, url string) {
    // Before
    resp, err := http.Get(url)

    // After (uses ctx directly)
    resp, err := whataphttp.HttpGet(ctx, url)
}

// http.DefaultClient methods
// Before
resp, err := http.DefaultClient.Get("http://example.com/api")
resp, err := http.DefaultClient.Post("http://example.com/api", "application/json", body)

// After
resp, err := whataphttp.DefaultClientGet(ctx, "http://example.com/api")
resp, err := whataphttp.DefaultClientPost(ctx, "http://example.com/api", "application/json", body)

// http.Client initialization
// Before
client := &http.Client{Timeout: 10 * time.Second}

// After
client := &http.Client{
    Timeout:   10 * time.Second,
    Transport: whataphttp.NewRoundTripWithEmptyTransport(ctx),
}

// With existing Transport
// Before
client := &http.Client{Transport: customTransport}

// After
client := &http.Client{Transport: whataphttp.NewRoundTrip(ctx, customTransport)}
```

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

### github.com/gin-gonic/gin Instrumentation

Source: https://github.com/whatap/go-api-inst/blob/main/docs/rules/web-frameworks.md

Instructions for instrumenting the Gin web framework using Whatap's middleware.

```APIDOC
## POST /api/users

### Description
This endpoint allows for the creation of new users.

### Method
POST

### Endpoint
/api/users

### Parameters
#### Query Parameters
- **limit** (integer) - Optional - The maximum number of users to return.

#### Request Body
- **username** (string) - Required - The username for the new user.
- **email** (string) - Required - The email address for the new user.

### Request Example
```json
{
  "username": "johndoe",
  "email": "john.doe@example.com"
}
```

### Response
#### Success Response (201)
- **id** (integer) - The unique identifier for the newly created user.
- **username** (string) - The username of the created user.
- **email** (string) - The email address of the created user.

#### Response Example
```json
{
  "id": 123,
  "username": "johndoe",
  "email": "john.doe@example.com"
}
```
```

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

### Configure zap Package

Source: https://github.com/whatap/go-api-inst/blob/main/docs/rules/log.md

Use logsink.HookStderr() to redirect zap output to WhaTap logsink.

```go
import (
    "go.uber.org/zap"
    "github.com/whatap/go-api/logsink"
)

func main() {
    trace.Init(nil)
    defer trace.Shutdown()
    logsink.HookStderr()  // Inserted

    logger, _ := zap.NewProduction()
    // ...
}
```

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

### Instrument gorm.io/gorm

Source: https://github.com/whatap/go-api-inst/blob/main/docs/rules/database.md

Wrap the GORM Open call with whatapgorm to instrument database interactions.

```go
import "github.com/whatap/go-api/instrumentation/github.com/go-gorm/gorm/whatapgorm"
```

```go
// Before
db, err := gorm.Open(sqlite.Open("test.db"), &gorm.Config{})

// After
db, err := whatapgorm.Open(sqlite.Open("test.db"), &gorm.Config{})
```

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

### Import WhaTap gRPC Instrumentation

Source: https://github.com/whatap/go-api-inst/blob/main/docs/rules/external-services.md

Required import for instrumenting gRPC server and client connections.

```go
import "github.com/whatap/go-api/instrumentation/google.golang.org/grpc/whatapgrpc"
```

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

### Supported Frameworks

Source: https://github.com/whatap/go-api-inst/blob/main/docs/user-guide.md

Lists the web frameworks, databases, and other libraries that are supported by Whatap Go API instrumentation, along with the necessary import paths and instrumentation code.

```APIDOC
## Supported Frameworks

### Web Frameworks

| Framework | Import Path | Injected Code |
|-----------|-------------|---------------|
| **Gin** | `github.com/gin-gonic/gin` | `r.Use(whatapgin.Middleware())` |
| **Echo v4** | `github.com/labstack/echo/v4` | `e.Use(whatapecho.Middleware())` |
| **Fiber v2** | `github.com/gofiber/fiber/v2` | `app.Use(whatapfiber.Middleware())` |
| **Chi v5** | `github.com/go-chi/chi/v5` | `whatapchi.WrapRouter(chi.NewRouter())` |
| **Gorilla Mux** | `github.com/gorilla/mux` | `whatapmux.WrapRouter(mux.NewRouter())` |
| **net/http** | `net/http` | `whataphttp.Func()`, `whataphttp.WrapHandler()` |
| **FastHTTP** | `github.com/valyala/fasthttp` | `whatapfasthttp.Middleware()` |

> **Wrap Functions**: For struct field initialization and instance patterns,
> framework-specific Wrap functions are available (e.g., `WrapEngine`, `WrapEcho`, `WrapApp`, `WrapRouter`, `WrapHandler`).
> See [Instrumentation Rules](./rules/) for details.

### Database

| Library | Import Path | Transformation |
|---------|-------------|----------------|
| **database/sql** | `database/sql` | `sql.Open()` → `whatapsql.Open()` |
| **sqlx** | `github.com/jmoiron/sqlx` | `sqlx.Open()` → `whatapsqlx.Open()` |
| **GORM (gorm.io)** | `gorm.io/gorm` | `gorm.Open()` → `whatapgorm.Open()` |
| **GORM (jinzhu)** | `github.com/jinzhu/gorm` | `gorm.Open()` → `whatapgorm.Open()` |

### Redis

| Library | Import Path | Transformation |
|---------|-------------|----------------|
| **go-redis v9** | `github.com/redis/go-redis/v9` | `redis.NewClient()` → `whatapgoredis.NewClient()` |
| **go-redis v8** | `github.com/redis/redis/v8` | `redis.NewClient()` → `whatapgoredis.NewClient()` |
| **Redigo** | `github.com/gomodule/redigo` | `redis.Dial()` → `whatapredigo.Dial()` |

### NoSQL / Cache

| Library | Import Path | Transformation |
|---------|-------------|----------------|
| **MongoDB** | `go.mongodb.org/mongo-driver/mongo` | `mongo.Connect()` → `whatapmongo.Connect()` |
| **Aerospike** | `github.com/aerospike/aerospike-client-go` | Closure wrap with `whatapsql.Wrap()` |

### External Services

| Library | Import Path | Description |
|---------|-------------|-------------|
| **Sarama (IBM)** | `github.com/IBM/sarama` | Kafka client |
| **Sarama (Shopify)** | `github.com/Shopify/sarama` | Kafka client |
| **gRPC** | `google.golang.org/grpc` | Auto Server/Client Interceptor injection |
| **Kubernetes** | `k8s.io/client-go` | Auto `config.Wrap()` injection |
```

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

### Environment Variable for Configuration File Path

Source: https://github.com/whatap/go-api-inst/blob/main/docs/config.md

Use the `WHATAP_INST_CONFIG` environment variable to specify the path to the custom configuration file for instrumentation.

```bash
WHATAP_INST_CONFIG=./config.yaml
```

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

### github.com/gorilla/mux Instrumentation

Source: https://github.com/whatap/go-api-inst/blob/main/docs/rules/web-frameworks.md

Instructions for instrumenting the Gorilla Mux router using Whatap's wrapping function.

```APIDOC
## GET /health

### Description
Checks the health status of the application.

### Method
GET

### Endpoint
/health

### Response
#### Success Response (200)
- **status** (string) - The health status of the application (e.g., "ok", "degraded").

#### Response Example
```json
{
  "status": "ok"
}
```
```

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

### Instrument database/sql

Source: https://context7.com/whatap/go-api-inst/llms.txt

Replaces standard sql.Open with the WhaTap-instrumented version to track database operations.

```go
// Before
db, err := sql.Open("mysql", "user:pass@/dbname")

// After
db, err := whatapsql.Open("mysql", "user:pass@/dbname")

// All DB operations (Query, Exec, Prepare, Begin, etc.) are automatically tracked
rows, err := db.Query("SELECT * FROM users WHERE id = ?", id)
result, err := db.Exec("INSERT INTO users (name) VALUES (?)", name)
```

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

### Database Restoration

Source: https://github.com/whatap/go-api-inst/blob/main/docs/rules/remove.md

Restores database connection initializations for various SQL drivers and ORMs.

```go
// Before (instrumented)
db, err := whatapsql.Open("mysql", dsn)
db, err := whatapsqlx.Open("mysql", dsn)
db, err := whatapsqlx.Connect("mysql", dsn)
db, err := whatapgorm.Open("mysql", dsn)

// After (removed)
db, err := sql.Open("mysql", dsn)
db, err := sqlx.Open("mysql", dsn)
db, err := sqlx.Connect("mysql", dsn)
db, err := gorm.Open("mysql", dsn)
```

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

### Instrument http.Get with context.Context Parameter

Source: https://github.com/whatap/go-api-inst/blob/main/docs/rules/web-frameworks.md

Uses the provided context.Context parameter directly for http.Get calls, ensuring proper tracing.

```go
// Before (context.Context parameter)
func fetchData(ctx context.Context, url string) {
    resp, err := http.Get(url)
}

// After (uses ctx directly)
func fetchData(ctx context.Context, url string) {
    resp, err := whataphttp.HttpGet(ctx, url)
}
```