refactor: more robust SSH connection handling

README.md

@@ -196,7 +196,8 @@ Host varia.zone
 
 `distribusi-go` will read the `User` and `Port` values from this configuration.
 It won't try to parse private key files or prompt for passwords, it will simply
-interface with `ssh-agent` which handles all that.
+interface with `ssh-agent` which handles all that. If there is no
+`~/.ssh/config` entry, default values will be attempted.
 
 If all else fails, try `-d/--debug` for extra help figuring out what SSH
 connection details are used. You can [open a ticket] and we can try and help.

distribusi.go

@@ -15,6 +15,7 @@ import (
 	"net/http"
 	"os"
 	"os/exec"
+	"os/user"
 	"path"
 	"path/filepath"
 	"sort"
@@ -915,19 +916,24 @@ func scpPublish(c *cli.Context, root, pubTarget string) error {
 	split := strings.Split(pubTarget, ":")
 	server, remotePath := split[0], split[1]
 
-	logrus.Debugf("parsed server: %s remotePath: %s from %s", server, remotePath, pubTarget)
+	logrus.Debugf("parsed server: %s, remotePath: %s from %s", server, remotePath, pubTarget)
 
-	if hostname := ssh_config.Get(server, "Hostname"); hostname == "" {
-		return fmt.Errorf("missing Hostname entry for %s in ~/.ssh/config, cannot continue", server)
-	}
+	sshUser := ssh_config.Get(server, "User")
+	if sshUser == "" {
+		logrus.Debugf("no ssh user discovered for %s, using system user as default", server)
 
-	user := ssh_config.Get(server, "User")
-	port := ssh_config.Get(server, "Port")
+		sysUser, err := user.Current()
+		if err != nil {
+			return fmt.Errorf("unable to determine current system user")
+		}
+
+		sshUser = sysUser.Username
+	}
 
-	logrus.Debugf("read user: %s, port: %s for %s in ~/.ssh/config", user, port, server)
+	sshPort := ssh_config.Get(server, "Port")
 
 	sshConf := &ssh.ClientConfig{
-		User:            user,
+		User:            sshUser,
 		HostKeyCallback: ssh.InsecureIgnoreHostKey(), // awful, i know
 		Timeout:         5 * time.Second,
 	}
@@ -936,22 +942,24 @@ func scpPublish(c *cli.Context, root, pubTarget string) error {
 	if identityFile != "" && identityFile != "~/.ssh/identity" {
 		sshAgent, err := net.Dial("unix", os.Getenv("SSH_AUTH_SOCK"))
 		if err != nil {
-			return err
+			return fmt.Errorf("unable to connect to local ssh-agent, is it running?")
 		}
 
 		agentCl := agent.NewClient(sshAgent)
 		authMethod := ssh.PublicKeysCallback(agentCl.Signers)
 		sshConf.Auth = []ssh.AuthMethod{authMethod}
 
-		logrus.Debugf("read identityFile: %s for %s in ~/.ssh/config, using ssh-agent for auth", identityFile, server)
+		logrus.Debugf("choosing ssh key: %s to connect to %s using ssh-agent", identityFile, server)
+	} else {
+		logrus.Debugf("no ssh key discovered for %s", server)
 	}
 
-	logrus.Debug("attempting to construct SSH client for publishing logic")
+	logrus.Debugf("connecting with user: %s, port: %s to connect to %s", sshUser, sshPort, server)
 
-	serverAndPort := fmt.Sprintf("%s:%s", server, port)
+	serverAndPort := fmt.Sprintf("%s:%s", server, sshPort)
 	scpClient, err := scp.NewClient(serverAndPort, sshConf, &scp.ClientOption{})
 	if err != nil {
-		return err
+		return fmt.Errorf("unable to make SSH connection to %s, have you configured your SSH client?", server)
 	}
 	defer scpClient.Close()
 
@@ -963,7 +971,7 @@ func scpPublish(c *cli.Context, root, pubTarget string) error {
 	fmt.Printf(fmt.Sprintf("publishing %s to %s...", filepath.Base(root), server))
 
 	if err := scpClient.CopyDirToRemote(root, remotePath, opts); err != nil {
-		return err
+		return fmt.Errorf("woops, publishing failed, saw this error: %s", err.Error())
 	}
 
 	fmt.Println(" done!")