build: use SFTP for launchpad uploads (#19037)

* build: use sftp for launchpad uploads

* .travis.yml: configure sftp export

* build: update CI docs

(cherry picked from commit 3de19c8b31ab975eed1f7f276d31761f7f8b9af9)

4 files changed, 60 insertions, 21 deletions

diff --git a/.travis.yml b/.travis.yml
index f08083d3c..c34e3ea8a 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -68,8 +68,10 @@ matrix:
             - debhelper
             - dput
             - fakeroot
+            - python-bzrlib
+            - python-paramiko
       script:
-        - go run build/ci.go debsrc -signer "Go Ethereum Linux Builder <geth-ci@ethereum.org>" -upload ppa:ethereum/ethereum
+        - go run build/ci.go debsrc -upload ppa:ethereum/ethereum -sftp-user geth-ci -signer "Go Ethereum Linux Builder <geth-ci@ethereum.org>"
 
     # This builder does the Linux Azure uploads
     - if: type = push
diff --git a/build/ci-notes.md b/build/ci-notes.md
index f5b0e869d..ba27cdb1d 100644
--- a/build/ci-notes.md
+++ b/build/ci-notes.md
@@ -7,11 +7,18 @@ Canonical.
 Packages of develop branch commits have suffix -unstable and cannot be installed alongside
 the stable version. Switching between release streams requires user intervention.
 
+## Launchpad
+
 The packages are built and served by launchpad.net. We generate a Debian source package
 for each distribution and upload it. Their builder picks up the source package, builds it
 and installs the new version into the PPA repository. Launchpad requires a valid signature
-by a team member for source package uploads. The signing key is stored in an environment
-variable which Travis CI makes available to certain builds.
+by a team member for source package uploads.
+
+The signing key is stored in an environment variable which Travis CI makes available to
+certain builds. Since Travis CI doesn't support FTP, SFTP is used to transfer the
+packages. To set this up yourself, you need to create a Launchpad user and add a GPG key
+and SSH key to it. Then encode both keys as base64 and configure 'secret' environment
+variables `PPA_SIGNING_KEY` and `PPA_SSH_KEY` on Travis.
 
 We want to build go-ethereum with the most recent version of Go, irrespective of the Go
 version that is available in the main Ubuntu repository. In order to make this possible,
@@ -27,7 +34,7 @@ Add the gophers PPA and install Go 1.10 and Debian packaging tools:
 
     $ sudo apt-add-repository ppa:gophers/ubuntu/archive
     $ sudo apt-get update
-    $ sudo apt-get install build-essential golang-1.10 devscripts debhelper
+    $ sudo apt-get install build-essential golang-1.10 devscripts debhelper python-bzrlib python-paramiko
 
 Create the source packages:
 
diff --git a/build/ci.go b/build/ci.go
index d2f4ce4fe..14d97135b 100644
--- a/build/ci.go
+++ b/build/ci.go
@@ -441,11 +441,8 @@ func archiveBasename(arch string, archiveVersion string) string {
 func archiveUpload(archive string, blobstore string, signer string) error {
 	// If signing was requested, generate the signature files
 	if signer != "" {
-		pgpkey, err := base64.StdEncoding.DecodeString(os.Getenv(signer))
-		if err != nil {
-			return fmt.Errorf("invalid base64 %s", signer)
-		}
-		if err := build.PGPSignFile(archive, archive+".asc", string(pgpkey)); err != nil {
+		key := getenvBase64(signer)
+		if err := build.PGPSignFile(archive, archive+".asc", string(key)); err != nil {
 			return err
 		}
 	}
@@ -489,6 +486,7 @@ func doDebianSource(cmdline []string) {
 	var (
 		signer  = flag.String("signer", "", `Signing key name, also used as package author`)
 		upload  = flag.String("upload", "", `Where to upload the source package (usually "ppa:ethereum/ethereum")`)
+		sshUser = flag.String("sftp-user", "", `Username for SFTP upload (usually "geth-ci")`)
 		workdir = flag.String("workdir", "", `Output directory for packages (uses temp dir if unset)`)
 		now     = time.Now()
 	)
@@ -498,11 +496,7 @@ func doDebianSource(cmdline []string) {
 	maybeSkipArchive(env)
 
 	// Import the signing key.
-	if b64key := os.Getenv("PPA_SIGNING_KEY"); b64key != "" {
-		key, err := base64.StdEncoding.DecodeString(b64key)
-		if err != nil {
-			log.Fatal("invalid base64 PPA_SIGNING_KEY")
-		}
+	if key := getenvBase64("PPA_SIGNING_KEY"); len(key) > 0 {
 		gpg := exec.Command("gpg", "--import")
 		gpg.Stdin = bytes.NewReader(key)
 		build.MustRun(gpg)
@@ -523,12 +517,45 @@ func doDebianSource(cmdline []string) {
 				build.MustRunCommand("debsign", changes)
 			}
 			if *upload != "" {
-				build.MustRunCommand("dput", "--passive", "--no-upload-log", *upload, changes)
+				uploadDebianSource(*workdir, *upload, *sshUser, changes)
 			}
 		}
 	}
 }
 
+func uploadDebianSource(workdir, ppa, sshUser, changes string) {
+	// Create the dput config file.
+	dputConfig := filepath.Join(workdir, "dput.cf")
+	p := strings.Split(ppa, "/")
+	if len(p) != 2 {
+		log.Fatal("-upload PPA name must contain single /")
+	}
+	templateData := map[string]string{
+		"LaunchpadUser": p[0],
+		"LaunchpadPPA":  p[1],
+		"LaunchpadSSH":  sshUser,
+	}
+	if sshkey := getenvBase64("PPA_SSH_KEY"); len(sshkey) > 0 {
+		idfile := filepath.Join(workdir, "sshkey")
+		ioutil.WriteFile(idfile, sshkey, 0600)
+		templateData["IdentityFile"] = idfile
+	}
+	build.Render("build/dput-launchpad.cf", dputConfig, 0644, templateData)
+
+	// Run dput to do the upload.
+	dput := exec.Command("dput", "-c", dputConfig, "--no-upload-log", ppa, changes)
+	dput.Stdin = strings.NewReader("Yes\n") // accept SSH host key
+	build.MustRun(dput)
+}
+
+func getenvBase64(variable string) []byte {
+	dec, err := base64.StdEncoding.DecodeString(os.Getenv(variable))
+	if err != nil {
+		log.Fatal("invalid base64 " + variable)
+	}
+	return []byte(dec)
+}
+
 func makeWorkdir(wdflag string) string {
 	var err error
 	if wdflag != "" {
@@ -800,15 +827,10 @@ func doAndroidArchive(cmdline []string) {
 	os.Rename(archive, meta.Package+".aar")
 	if *signer != "" && *deploy != "" {
 		// Import the signing key into the local GPG instance
-		b64key := os.Getenv(*signer)
-		key, err := base64.StdEncoding.DecodeString(b64key)
-		if err != nil {
-			log.Fatalf("invalid base64 %s", *signer)
-		}
+		key := getenvBase64(*signer)
 		gpg := exec.Command("gpg", "--import")
 		gpg.Stdin = bytes.NewReader(key)
 		build.MustRun(gpg)
-
 		keyID, err := build.PGPKeyID(string(key))
 		if err != nil {
 			log.Fatal(err)
diff --git a/build/dput-launchpad.cf b/build/dput-launchpad.cf
new file mode 100644
index 000000000..3063c3c07
--- /dev/null
+++ b/build/dput-launchpad.cf
@@ -0,0 +1,8 @@
+[{{.LaunchpadUser}}/{{.LaunchpadPPA}}]
+fqdn = ppa.launchpad.net
+method = sftp
+incoming = ~{{.LaunchpadUser}}/ubuntu/{{.LaunchpadPPA}}/
+login = {{.LaunchpadSSH}}
+{{ if .IdentityFile }}
+  ssh_options = IdentityFile {{.IdentityFile}}
+{{ end }}