website: sync commits to github

Fixes issue #708

Change-Id: I0e081724134ab08c736b00bd2ebe81eb9028ace7

website/camweb.go

@@ -656,6 +656,9 @@ func main() {
 		}
 	}
 	readTemplates()
+	if err := initGithubSyncing(); err != nil {
+		log.Fatalf("error setting up syncing to github: %v")
+	}
 	go runDemoBlobserverLoop()
 
 	mux := http.DefaultServeMux

website/email.go

@@ -241,6 +241,11 @@ func pollCommits(dir string) {
 			}
 		}
 	}
+	if githubSSHKey != "" {
+		if err := syncToGithub(dir, hashes[0]); err != nil {
+			log.Printf("Failed to push to github: %v")
+		}
+	}
 }
 
 func recentCommits(dir string) (hashes []string, err error) {

website/github.go

@@ -0,0 +1,122 @@
+/*
+Copyright 2016 The Camlistore Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+     http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package main
+
+import (
+	"fmt"
+	"io/ioutil"
+	"log"
+	"net/http"
+	"os"
+	"os/user"
+	"path/filepath"
+
+	"go4.org/wkfs"
+)
+
+const githubSSHKeyGCS = "/gcs/camlistore-website-resource/id_github_camlistorebot_push"
+
+var githubSSHKey string // Also used to detect whether we do the syncs to github
+
+func githubSSHConfig(filename string) string {
+	return `
+Host github.com
+  User git
+  IdentityFile ` + filename + `
+  IdentitiesOnly yes
+`
+}
+
+func initGithubSyncing() error {
+	if !inProd {
+		return nil
+	}
+	keyData, err := wkfs.ReadFile(githubSSHKeyGCS)
+	if err != nil {
+		log.Print("Not syncing to github, because no ssh key found.")
+		return nil
+	}
+	u, err := user.Current()
+	if err != nil {
+		return fmt.Errorf("can't look up user: %v", err)
+	}
+	dir, err := ioutil.TempDir("", "ssh")
+	if err != nil {
+		return fmt.Errorf("failed to create temp dir for github SSH key: %v", err)
+	}
+	keyFile := filepath.Join(dir, "id_github_camlistorebot_push")
+	if err := ioutil.WriteFile(keyFile, keyData, 0600); err != nil {
+		return fmt.Errorf("failed to create temp github SSH key: %v", err)
+	}
+	if err := os.MkdirAll(filepath.Join(u.HomeDir, ".ssh"), 0700); err != nil {
+		return fmt.Errorf("failed to create ssh config dir %v: %v", filepath.Join(u.HomeDir, ".ssh"), err)
+	}
+	if err := ioutil.WriteFile(
+		filepath.Join(u.HomeDir, ".ssh", "id_github_camlistorebot_push"),
+		[]byte(githubSSHConfig(keyFile)),
+		0600); err != nil {
+		return fmt.Errorf("failed to create github SSH config: %v", err)
+	}
+	githubSSHKey = keyFile
+	return nil
+}
+
+// githubHEAD returns the hash of the HEAD commit on the github repo.
+// The gerritHEAD argument is used as an optimization in the request to github:
+// if it is found as the HEAD commit, the request is not counted in our
+// non-authenticated requests quota.
+func githubHEAD(gerritHEAD string) (string, error) {
+	const (
+		headAPI  = "https://api.github.com/repos/camlistore/camlistore/commits/HEAD"
+		mimeType = "application/vnd.github.VERSION.sha"
+	)
+	req, err := http.NewRequest("GET", headAPI, nil)
+	if err != nil {
+		return "", err
+	}
+	req.Header.Add("If-None-Match", `"`+gerritHEAD+`"`)
+	req.Header.Add("Accept", mimeType)
+	resp, err := http.DefaultClient.Do(req)
+	if err != nil {
+		return "", err
+	}
+	defer resp.Body.Close()
+	if resp.StatusCode == http.StatusNotModified {
+		return gerritHEAD, nil
+	}
+	ghCommit, err := ioutil.ReadAll(resp.Body)
+	if err != nil {
+		return "", err
+	}
+	return string(ghCommit), nil
+}
+
+func syncToGithub(dir, gerritHEAD string) error {
+	gh, err := githubHEAD(gerritHEAD)
+	if err != nil {
+		return fmt.Errorf("error looking up the github HEAD commit: %v", err)
+	}
+	if gh == gerritHEAD {
+		return nil
+	}
+	cmd := execGit(dir, "push", "git@github.com:camlistore/camlistore.git", "master:master")
+	out, err := cmd.CombinedOutput()
+	if err != nil {
+		return fmt.Errorf("error running git push to github: %v\n%s", err, out)
+	}
+	return nil
+}