host_check

README.md

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+# Purpose
+
+This Go binary performs basic network diagnostics on a set of hostnames, useful for checking connectivity to dependency containers.
+
+## Usage
+
+1. **Build:**
+   ```bash
+   ./build.sh
+   ```
+
+2. **Set Environment Variables:**
+   * **HOSTNAMES:** Comma-separated list of hostnames to check (e.g., `database,redis-server,api.example.com`)
+   * **FAIL_ON_ERROR** (optional): Set to "true" to exit the program immediately upon the first ping failure.
+   * **COMMAND** (optional):  Set to "entrypoint.sh" to execute an additional script on each host.
+   * **ERROR_COMMAND** (optional): A command to execute if a ping failure occurs, useful for automated error reporting (e.g., `go-glitch report-error <hostname> 'Ping failed'`). 
+
+3. **Run:**
+   ```bash
+   ./host_check
+   ```
+
+## Output
+
+For each hostname:
+
+* **DNS Resolution:** Success or failure, with resolved IPs if successful.
+* **Ping:** Success or failure, with ping statistics if successful.
+* **Custom Script:** Output of the `entrypoint.sh` script, if executed.
+* **Error Reporting:** Output of the `ERROR_COMMAND`, if set and a ping failure occurs.
+
+## Example
+
+To check connectivity to "db-container" and "webserver", execute an `entrypoint.sh` script, and report errors to go-glitch:
+
+```bash
+export HOSTNAMES="db-container,webserver"
+export COMMAND="entrypoint.sh"
+export ERROR_COMMAND="go-glitch report-error <hostname> 'Ping failed'"
+./host_check 
+``` 
+
+**Important:** 
+* Make sure you have a `build.sh` script in your project directory to handle the Go compilation process.
+* You'll need an `entrypoint.sh` script if you want to leverage the `COMMAND` functionality.
+
+Let me know if you'd like any other adjustments to your README! 
+

build.sh

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+#!/bin/bash
+
+# Default architecture
+DEFAULT_ARCH="linux/amd64"
+
+# Supported architectures (adjust as needed)
+ARCHITECTURES=("linux/amd64" "linux/arm64" "linux/arm/v7")
+
+# Build function (Updated)
+build_binary() {
+    os=$1
+    arch=$2
+    output_name="host_check"
+
+    if [[ "$os/$arch" != "$DEFAULT_ARCH" ]]; then
+        output_name="${output_name}_${os}_${arch}"
+    fi
+
+    # Create the dist folder if it doesn't exist
+    mkdir -p dist
+
+    echo "Building for ${os}/${arch} -> dist/${output_name}"
+    GOOS=${os} GOARCH=${arch} go build -o dist/${output_name} . 
+}
+
+# Main Build Process (Updated)
+for arch in "${ARCHITECTURES[@]}"; do
+    IFS='/' read -r -a parts <<< "$arch" 
+    os=${parts[0]}
+    arch=${parts[1]}
+
+    # Ensure module files are present in the current directory
+    if [ ! -f "go.mod" ] || [ ! -f "go.sum" ]; then
+        echo "Error: 'go.mod' and/or 'go.sum' not found in the current directory."
+        echo "Make sure you're in the root of your Go module before running the build."
+        exit 1
+    fi
+
+    build_binary $os $arch
+done
+

host_check.go

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+package main
+
+import (
+    "fmt"
+    "net"
+    "os"
+    "os/exec"
+    "strings"
+)
+
+func main() {
+    // ... (Hostname handling as before) ...
+
+    failOnError := os.Getenv("FAIL_ON_ERROR") == "true"
+    commandStr := os.Getenv("COMMAND")
+    errorCommandStr := os.Getenv("ERROR_COMMAND") // Fetch error command
+
+    for _, host := range hosts {
+        // ... (DNS Resolution as before) ...
+
+        // Ping
+        pingCmd := exec.Command("ping", "-c", "3", host)
+        pingOutput, err := pingCmd.Output()
+        if err != nil {
+            fmt.Println("Ping Failed:", err)
+            if failOnError {
+                os.Exit(1) // Exit with error code
+            }
+
+            // Execute error command if specified
+            if errorCommandStr != "" {
+                cmdParts := strings.Fields(errorCommandStr)
+                cmd := exec.Command(cmdParts[0], cmdParts[1:]...)
+                cmdOutput, cmdErr := cmd.Output()
+                if cmdErr != nil {
+                    fmt.Println("Error Command Execution Failed:", errorCommandStr, cmdErr)
+                } else {
+                    fmt.Println("Error Command Output:\n", string(cmdOutput))
+                }
+            }
+        } else {
+            fmt.Println("Ping Output:\n", string(pingOutput))
+        }
+
+        // Execute additional command if specified
+        if commandStr != "" {
+            cmdParts := strings.Fields(commandStr) // Split on spaces
+            cmd := exec.Command(cmdParts[0], cmdParts[1:]...)
+            cmdOutput, err := cmd.Output()
+            if err != nil {
+                fmt.Println("Command Execution Failed:", cmdStr, err)
+            } else {
+                fmt.Println("Command Output:\n", string(cmdOutput))
+            }
+        }
+    }
+}
+