v1.0

Author: karmakaze

.gitignore

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+# Binaries for programs and plugins
+*.exe
+*.exe~
+*.dll
+*.so
+*.dylib
+
+# Test binary, build with `go test -c`
+*.test
+
+# Output of the go coverage tool, specifically when used with LiteIDE
+*.out

LICENSE

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+MIT License
+
+Copyright (c) 2018 Keith Kim
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

Makefile

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+# Go parameters
+OS_MACH=$(shell uname -s; uname -m)
+BINARY_NAME=vultrdata
+ifeq ($(OS_MACH),Linux x86_64)
+BINARY_LINUX=$(BINARY_NAME)
+else
+BINARY_LINUX=$(BINARY_NAME)-linux
+endif
+
+all: test build
+
+rebuild: delete-binary build
+
+rebuild-linux: delete-binary-linux build-linux
+
+delete-binary:
+	-rm $(BINARY_NAME) 2>/dev/null
+
+delete-binary-linux:
+	-rm $(BINARY_LINUX) 2>/dev/null
+
+build:
+	go build -o $(BINARY_NAME) -v
+
+build-linux:
+	CGO_ENABLED= GOOS=linux GOARCH=amd64 go build -o $(BINARY_LINUX) -v
+
+build-darwin:
+	CGO_ENABLED= GOOS=darwin GOARCH=amd64 go build -o $(BINARY_DARWIN) -v
+
+test:
+	go test -v ./...
+
+clean:
+	go clean
+	rm -f $(BINARY_NAME)
+	rm -f $(BINARY_LINUX)
+
+deploy-prod: build-linux
+	ssh prod "mv /opt/vultrdata/$(BINARY_NAME) /opt/vultrdata/$(BINARY_NAME)-old || true"
+	scp $(BINARY_LINUX) prod:/opt/vultrdata/$(BINARY_NAME)
+	ssh prod "sudo service vultrdata restart"
+
+run: deps
+	go run -race main.go
+
+deps:
+	go get github.com/kuangchanglang/graceful

README.md

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+# vultrdata
+
+Service to return sanitized data about the requesting instance.
+
+## Installation
+
+For systemd Linux systems:
+
+- Run `make deps build-linux`
+- Create the directory /opt/vultrdata
+- Copy `vultrdata-linux` to /opt/vultrdata/vultrdata
+  (or copy the file named `vultrdata` if make run on a Linux system)
+- Copy the file vultrdata.service to /etc/systemd/vultrdata.service
+- Edit that vultrdata.service file changing the API_KEY value as well as listen addr/port and/or removing --userdata option
+- On that system: `sudo systemctl daemon-reload`
+- On that system: `sudo systemctl enable vultrdata`
+- On that system: `sudo systemctl start vultrdata`
+
+It is recommended that the listen address is chosen to be on the internal network for security. When instances are created with internal networking enabled it usually has an additional address starting with 10. or possibly some other non-routing range.
+
+## Testing
+
+- `curl -si 'http://10.1.1.1:8888/'`
+  (Using whichever listen addr/port was chosen in vultrdata.service)
+- Run the same command from another instance which should return data for that instance different than the first

vultrdata.go

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+package main
+
+import (
+	"encoding/json"
+	"flag"
+	"fmt"
+	"io"
+	"io/ioutil"
+	"log"
+	"net/http"
+	"os"
+	"strconv"
+	"strings"
+	"time"
+
+	"github.com/kuangchanglang/graceful"
+)
+
+var (
+	httpClient = &http.Client{
+		Timeout: time.Second * 10,
+	}
+)
+
+var (
+	addr     = flag.String("addr", "0.0.0.0", "Listen address")
+	port     = flag.Int("port", 8888, "Listen port")
+	userdata = flag.Bool("userdata", false, "Also return 'userdata'")
+	apiKey   = ""
+)
+
+func instanceHandler(w http.ResponseWriter, r *http.Request) {
+	body, err := doApiRequest(w, r, "GET", "https://api.vultr.com/v1/server/list", nil)
+	if err != nil {
+		w.WriteHeader(http.StatusInternalServerError)
+		w.Header().Set("content-type", "text/plain")
+		w.Write([]byte(err.Error() + "\n"))
+		return
+	}
+
+	var subidData map[string]map[string]interface{}
+	err = json.Unmarshal(body, &subidData)
+	if err != nil {
+		w.WriteHeader(http.StatusInternalServerError)
+		w.Header().Set("content-type", "text/plain")
+		w.Write([]byte(err.Error() + "\n"))
+		return
+	}
+
+	remoteAddr := strings.Split(r.RemoteAddr, ":")[0]
+
+	found := findByIpAddress(subidData, remoteAddr)
+	if found == nil {
+		w.WriteHeader(http.StatusNotFound)
+		w.Header().Set("content-type", "text/plain")
+		w.Write([]byte(""))
+		return
+	}
+
+	delete(found, "default_password")
+	delete(found, "kvm_url")
+
+	if *userdata {
+		url := fmt.Sprintf("https://api.vultr.com/v1/server/get_user_data?SUBID=%v", found["SUBID"])
+		body, err = doApiRequest(w, r, "GET", url, nil)
+		if err != nil {
+			w.WriteHeader(http.StatusInternalServerError)
+			w.Header().Set("content-type", "text/plain")
+			w.Write([]byte(err.Error() + "\n"))
+			return
+		}
+		var kv map[string]string
+		json.Unmarshal(body, &kv)
+		if kv != nil {
+			if v, ok := kv["userdata"]; ok {
+				found["userdata"] = v
+			}
+		}
+	}
+
+	data, err := json.MarshalIndent(found, "", "  ")
+	if err != nil {
+		w.WriteHeader(http.StatusInternalServerError)
+		w.Header().Set("content-type", "text/plain")
+		w.Write([]byte(err.Error() + "\n"))
+		return
+	}
+
+	w.Header().Set("content-type", "application/json")
+	w.Write(data)
+}
+
+func doApiRequest(w http.ResponseWriter, r *http.Request, method, url string, body io.Reader) ([]byte, error) {
+	req, err := http.NewRequest(method, url, body)
+	if err != nil {
+		return nil, err
+	}
+
+	req.Header.Set("API-Key", apiKey)
+	resp, err := httpClient.Do(req)
+	if err != nil {
+		return nil, err
+	}
+
+	defer resp.Body.Close()
+	data, err := ioutil.ReadAll(resp.Body)
+	if err != nil {
+		return nil, err
+	}
+	return data, nil
+}
+
+func findByIpAddress(subidData map[string]map[string]interface{}, remoteAddr string) map[string]interface{} {
+	for _, data := range subidData {
+		for _, name := range []string{"internal_ip", "main_ip", "v6_main_ip"} {
+			value := data[name]
+			if s, ok := value.(string); ok {
+				if s == remoteAddr {
+					return data
+				}
+			}
+		}
+	}
+	return nil
+}
+
+func main() {
+	flag.Parse()
+
+	apiKey = os.Getenv("API_KEY")
+	if apiKey == "" {
+		fmt.Printf("Missing API_KEY environment variable.")
+		os.Exit(1)
+	}
+
+	http.HandleFunc("/", instanceHandler)
+
+	server := graceful.NewServer()
+
+	server.Register(*addr+":"+strconv.Itoa(*port), http.DefaultServeMux)
+	if graceful.IsWorker() {
+		log.Printf("Listening on %v:%d\n", *addr, *port)
+	}
+	if err := server.Run(); err != nil {
+		fmt.Printf("graceful.Server.Run: %v", err)
+	}
+}

vultrdata.service

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+[Unit]
+Description=Vultr Instance Data Service
+After=network.target
+
+[Service]
+User=ubuntu
+WorkingDirectory=/opt/vultrdata
+Restart=always
+Environment=API_KEY=____________________________________
+ExecStart=/opt/vultrdata/vultrdata --addr 127.0.0.1 --port 8888 --userdata
+
+[Install]
+WantedBy=multi-user.target