Minimum viable product

Is able to take 2 flags:
 -command       'some command string' (mandatory)
 -identity-file <id_rsa file>

Still to do:
 - read hosts from a file
 - flag to select which subset of hosts to run command on

Signed-off-by: Blaine Gardner <[email protected]>

.gitignore

@@ -0,0 +1 @@
+vendor/

Gopkg.toml

@@ -0,0 +1,30 @@
+# Gopkg.toml example
+#
+# Refer to https://golang.github.io/dep/docs/Gopkg.toml.html
+# for detailed Gopkg.toml documentation.
+#
+# required = ["github.com/user/thing/cmd/thing"]
+# ignored = ["github.com/user/project/pkgX", "bitbucket.org/user/project/pkgA/pkgY"]
+#
+# [[constraint]]
+#   name = "github.com/user/project"
+#   version = "1.0.0"
+#
+# [[constraint]]
+#   name = "github.com/user/project2"
+#   branch = "dev"
+#   source = "github.com/myfork/project2"
+#
+# [[override]]
+#   name = "github.com/x/y"
+#   version = "2.4.0"
+#
+# [prune]
+#   non-go = false
+#   go-tests = true
+#   unused-packages = true
+
+
+[prune]
+  go-tests = true
+  unused-packages = true

cmd/octopus/octopus.go

@@ -0,0 +1,163 @@
+// Package octopus is a commandline tool for running the same command on multiple remote hosts in
+// parallel.
+package main
+
+import (
+	"bytes"
+	"flag"
+	"fmt"
+	"io/ioutil"
+	"log"
+	"os"
+	"strings"
+
+	"golang.org/x/crypto/ssh"
+)
+
+const (
+	noHostNameText = "! could not get hostname !"
+)
+
+// Each of octopus's tentacles is a remote connection to a host executing the command
+type tentacle struct {
+	host     string
+	hostname string
+	stdout   *bytes.Buffer
+	err      error
+}
+
+func main() {
+	identityFile := flag.String("identity-file", "~/.ssh/id_rsa",
+		"identity file used to authenticate to remote hosts")
+	command := flag.String("command", "", "(required) command to execute on remote hosts")
+	flag.Parse()
+
+	if strings.Trim(*command, " \t") == "" {
+		fmt.Printf("ERROR! '-command' must be specified\n\n")
+		flag.PrintDefaults()
+		os.Exit(1)
+	}
+
+	key, err := ioutil.ReadFile(*identityFile)
+	if err != nil {
+		log.Fatalf("unable to read private key: %v", err)
+	}
+
+	signer, err := ssh.ParsePrivateKey(key)
+	if err != nil {
+		log.Fatalf("unable to parse private key: %v", err)
+	}
+
+	config := &ssh.ClientConfig{
+		User: "root",
+		Auth: []ssh.AuthMethod{
+			ssh.PublicKeys(signer),
+		},
+		HostKeyCallback: ssh.InsecureIgnoreHostKey(),
+	}
+
+	hosts := []string{"10.86.1.87", "10.86.1.103"}
+	tentacles := make(chan tentacle, len(hosts))
+
+	for i := 0; i < len(hosts); i++ {
+		go runCommand(hosts[i], *command, config, tentacles)
+	}
+
+	numErrors := 0
+
+	for range hosts {
+		t := <-tentacles
+		err := t.print()
+		if err != nil {
+			numErrors++
+		}
+	}
+
+	os.Exit(numErrors)
+}
+
+func runCommand(host, command string, config *ssh.ClientConfig, out chan<- tentacle) {
+	t := tentacle{
+		host:     host,
+		hostname: "",
+		err:      fmt.Errorf("run command failed"),
+	}
+	defer func() { out <- t }()
+
+	client, err := ssh.Dial("tcp", fmt.Sprintf("%s:22", t.host), config)
+	if err != nil {
+		t.err = fmt.Errorf("%v: %v", t.err, err)
+		return
+		// log.Fatal("Failed to dial: ", err)
+	}
+
+	hn := make(chan tentacle)
+	go getHostname(client, hn)
+
+	session, err := client.NewSession()
+	if err != nil {
+		t.err = fmt.Errorf("%v: %v", t.err, err)
+		// log.Fatal("Failed to create session: ", err)
+	}
+	defer session.Close()
+
+	t.stdout = new(bytes.Buffer)
+	stderr := new(bytes.Buffer)
+	session.Stdout = t.stdout
+	session.Stderr = stderr
+	err = session.Run(command)
+
+	if err != nil {
+		t.err = fmt.Errorf("%v: %v\n\n%s\n\n%s", t.err, err, strings.TrimRight(stderr.String(), "\n"), "")
+	} else {
+		t.err = nil
+	}
+
+	tn := <-hn
+	t.hostname = tn.hostname
+	return
+}
+
+func getHostname(client *ssh.Client, out chan<- tentacle) {
+	defer close(out)
+
+	t := tentacle{
+		hostname: noHostNameText,
+	}
+	defer func() { out <- t }()
+
+	session, err := client.NewSession()
+	if err != nil {
+		t.err = fmt.Errorf("%v: %v", t.err, err)
+		return
+	}
+	defer session.Close()
+
+	t.stdout = new(bytes.Buffer)
+	stderr := new(bytes.Buffer)
+	session.Stdout = t.stdout
+	session.Stderr = stderr
+	err = session.Run("hostname")
+	if err == nil {
+		t.hostname = strings.TrimRight(t.stdout.String(), "\n")
+	}
+
+	return
+}
+
+func (t *tentacle) print() error {
+	fmt.Println("-----")
+	fmt.Println(t.hostname)
+	if t.hostname == noHostNameText {
+		fmt.Println(t.host)
+	}
+	fmt.Printf("-----\n\n")
+	o := strings.TrimRight(t.stdout.String(), "\n")
+	if o != "" {
+		fmt.Printf("%s\n\n", o)
+	}
+	if t.err != nil {
+		fmt.Printf("Error: %v", t.err)
+	}
+	return t.err
+}