feat(ops/besadii): Refactored tool to trigger sourcehut builds

Refactors //ops/sync-gcsr which was previously responsible for
synchronising the git repository between GCSR and the git.tazj.in cgit
instance to simply be responsible for triggering builds on sourcehut.

This program is intended to run as a git post-update hook.

Note: Not yet feature complete, as interpolation of concrete git
values and also sourcehut secrets is missing.

5 files changed, 127 insertions, 239 deletions

diff --git a/ops/besadii/default.nix b/ops/besadii/default.nix
new file mode 100644
index 000000000000..fc7b2286c7ee
--- /dev/null
+++ b/ops/besadii/default.nix
@@ -0,0 +1,8 @@
+# This program is used as a git post-update hook to trigger builds on
+# sourcehut.
+{ depot, ... }:
+
+depot.buildGo.program {
+  name = "besadii";
+  srcs = [ ./main.go ];
+}
diff --git a/ops/besadii/main.go b/ops/besadii/main.go
new file mode 100644
index 000000000000..e9feadd9538e
--- /dev/null
+++ b/ops/besadii/main.go
@@ -0,0 +1,119 @@
+// Copyright 2019 Google LLC.
+// SPDX-License-Identifier: Apache-2.0
+//
+// besadii is a small CLI tool that triggers depot builds on
+// builds.sr.ht
+//
+// It is designed to run as a post-update git hook on the server
+// hosting the depot.
+package main
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"io/ioutil"
+	"log"
+	"net/http"
+	"os"
+)
+
+// Represents a builds.sr.ht build object as described on
+// https://man.sr.ht/builds.sr.ht/api.md
+type Build struct {
+	Manifest string   `json:"manifest"`
+	Note     string   `json:"note"`
+	Tags     []string `json:"tags"`
+}
+
+// Represents a build trigger object as described on <the docs for
+// this are currently down>
+type Trigger struct {
+	Action    string `json:"action"`
+	Condition string `json:"condition"`
+	To        string `json:"to"`
+}
+
+// Represents a build manifest for sourcehut.
+type Manifest struct {
+	Image    string                `json:"image"`
+	Sources  []string              `json:"sources"`
+	Secrets  []string              `json:"secrets"`
+	Tasks    [](map[string]string) `json:"tasks"`
+	Triggers []Trigger             `json:"triggers"`
+}
+
+func prepareManifest(commit string) string {
+	m := Manifest{
+		Image:   "nixos/latest",
+		Sources: []string{"https://git.camden.tazj.in/"},
+
+		// secret for cachix/tazjin
+		Secrets: []string{"f7f02546-4d95-44f7-a98e-d61fdded8b5b"},
+
+		Tasks: [](map[string]string){
+			{"setup": `# sourcehut does not censor secrets in builds, hence this hack:
+echo -n 'export CACHIX_SIGNING_KEY=' >> ~/.buildenv
+cat ~/.cachix-tazjin >> ~/.buildenv
+nix-env -iA third_party.cachix -f git.tazj.in
+cachix use tazjin
+cd git.tazj.in
+git checkout ` + commit},
+
+			{"build": `cd git.tazj.in
+nix-build ci-builds.nix > built-paths`},
+
+			{"cache": `cd git.tazj.in
+cat built-paths | cachix push tazjin`},
+		},
+
+		Triggers: []Trigger{
+			Trigger{Action: "email", Condition: "failure", To: "mail@tazj.in"},
+		},
+	}
+
+	j, _ := json.Marshal(m)
+	return string(j)
+}
+
+// Trigger a build of a given branch & commit on builds.sr.ht
+func triggerBuild(branch, commit string) {
+	build := Build{
+		Manifest: prepareManifest(commit),
+		Note:     fmt.Sprintf("Build of 'master' at '%s'", commit),
+		Tags: []string{
+			"depot", branch,
+		},
+	}
+
+	body, _ := json.Marshal(build)
+	reader := ioutil.NopCloser(bytes.NewReader(body))
+
+	req, err := http.NewRequest("POST", "https://builds.sr.ht/api/jobs", reader)
+	if err != nil {
+		log.Fatalln("[ERROR] failed to create an HTTP request:", err)
+	}
+
+	req.Header.Add("Authorization", fmt.Sprintf("token %s", os.Getenv("SRHT_TOKEN")))
+	req.Header.Add("Content-Type", "application/json")
+
+	resp, err := http.DefaultClient.Do(req)
+	if err != nil {
+		// This might indicate a temporary error on the SourceHut side, do
+		// not fail the whole program.
+		log.Println("failed to send builds.sr.ht request:", err)
+		return
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != 200 {
+		respBody, err := ioutil.ReadAll(resp.Body)
+		log.Printf("received non-success response from builds.sr.ht: %s (%v)[%s]", respBody, resp.Status, err)
+	} else {
+		log.Println("triggered builds.sr.ht job for commit", commit)
+	}
+}
+
+func main() {
+	triggerBuild("master", "c5806a44a728d5a46878f54de7b695321a38559c")
+}
diff --git a/ops/sync-gcsr/default.nix b/ops/sync-gcsr/default.nix
deleted file mode 100644
index ea5d0594a871..000000000000
--- a/ops/sync-gcsr/default.nix
+++ /dev/null
@@ -1,14 +0,0 @@
-{ depot, ... }:
-
-depot.nix.buildGo.program {
-  name = "sync-gcsr";
-  srcs = [ ./main.go ];
-
-  deps = with depot.third_party; map (p: p.gopkg) [
-    gopkgs."gopkg.in".src-d.go-git
-  ];
-
-  x_defs = {
-    "main.BuildManifest" = "${./manifest.yaml}";
-  };
-}
diff --git a/ops/sync-gcsr/main.go b/ops/sync-gcsr/main.go
deleted file mode 100644
index 62c24a92cef0..000000000000
--- a/ops/sync-gcsr/main.go
+++ /dev/null
@@ -1,202 +0,0 @@
-// Copyright 2019 Google LLC.
-// SPDX-License-Identifier: Apache-2.0
-//
-// sync-gcsr implements a small utility that periodically mirrors a
-// remote Google Cloud Source Repository to a local file path.
-//
-// This utility is also responsible for triggering depot builds on
-// builds.sr.ht if a change is detected on the master branch.
-package main
-
-import (
-	"encoding/json"
-	"fmt"
-	"io/ioutil"
-	"log"
-	"net/http"
-	"os"
-	"time"
-	"bytes"
-
-	git "gopkg.in/src-d/go-git.v4"
-	"gopkg.in/src-d/go-git.v4/plumbing"
-	githttp "gopkg.in/src-d/go-git.v4/plumbing/transport/http"
-)
-
-// Path to the build manifest, added by Nix at compile time.
-var BuildManifest string
-
-// Represents a builds.sr.ht build object as described on
-// https://man.sr.ht/builds.sr.ht/api.md
-type Build struct {
-	Manifest string   `json:"manifest"`
-	Note     string   `json:"note"`
-	Tags     []string `json:"tags"`
-}
-
-func EnvOr(key, def string) string {
-	v := os.Getenv(key)
-	if v == "" {
-		return def
-	}
-
-	return v
-}
-
-// Trigger a build of master on builds.sr.ht
-func triggerBuild(commit string) {
-	manifest, err := ioutil.ReadFile(BuildManifest)
-	if err != nil {
-		log.Fatalln("[ERROR] failed to read sr.ht build manifest:", err)
-	}
-
-	build := Build{
-		Manifest: string(manifest),
-		Note:     fmt.Sprintf("Build of 'master' at '%s'", commit),
-		Tags: []string{
-			"depot", "master",
-		},
-	}
-
-	body, _ := json.Marshal(build)
-	reader := ioutil.NopCloser(bytes.NewReader(body))
-
-	req, err := http.NewRequest("POST", "https://builds.sr.ht/api/jobs", reader)
-	if err != nil {
-		log.Fatalln("[ERROR] failed to create an HTTP request:", err)
-	}
-
-	req.Header.Add("Authorization", fmt.Sprintf("token %s", os.Getenv("SRHT_TOKEN")))
-	req.Header.Add("Content-Type", "application/json")
-
-	resp, err := http.DefaultClient.Do(req)
-	if err != nil {
-		// This might indicate a temporary error on the SourceHut side, do
-		// not fail the whole program.
-		log.Println("failed to send builds.sr.ht request:", err)
-		return
-	}
-	defer resp.Body.Close()
-
-	if resp.StatusCode != 200 {
-		respBody, err := ioutil.ReadAll(resp.Body)
-		log.Printf("received non-success response from builds.sr.ht: %s (%v)[%s]", respBody, resp.Status, err)
-	} else {
-		log.Println("triggered builds.sr.ht job for commit", commit)
-	}
-}
-
-// ensure that all remote branches exist locally & are up to date.
-func updateBranches(auth *githttp.BasicAuth, repo *git.Repository) error {
-	origin, err := repo.Remote("origin")
-	if err != nil {
-		return err
-	}
-
-	refs, err := origin.List(&git.ListOptions{
-		Auth: auth,
-	})
-	if err != nil {
-		return err
-	}
-
-	for _, ref := range refs {
-		if !ref.Name().IsBranch() || ref.Type() != plumbing.HashReference {
-			continue
-		}
-
-		name := plumbing.NewBranchReferenceName(ref.Name().Short())
-
-		if current, err := repo.Storer.Reference(name); err == nil {
-			// Determine whether the reference has changed to skip
-			// unnecessary modifications.
-			if current.Hash() == ref.Hash() {
-				continue
-			}
-		}
-
-		branch := plumbing.NewHashReference(name, ref.Hash())
-
-		err := repo.Storer.SetReference(branch)
-		if err != nil {
-			return err
-		}
-
-		if ref.Name().Short() == "master" {
-			go triggerBuild(ref.Hash().String())
-		}
-
-		log.Println("Updated branch", ref.Name().String())
-	}
-
-	return nil
-}
-
-func updateRepo(auth *githttp.BasicAuth, repo *git.Repository, opts *git.FetchOptions) error {
-	err := repo.Fetch(opts)
-
-	if err == git.NoErrAlreadyUpToDate {
-		// nothing to do ...
-		return nil
-	} else if err != nil {
-		return err
-	}
-
-	log.Println("Fetched updates from remote, updating local branches")
-	return updateBranches(auth, repo)
-}
-
-func cloneRepo(dest, project, repo string, auth *githttp.BasicAuth) (*git.Repository, error) {
-	var cloneOpts = git.CloneOptions{
-		Auth: auth,
-		URL:  fmt.Sprintf("https://source.developers.google.com/p/%s/r/%s", project, repo),
-	}
-
-	handle, err := git.PlainClone(dest, true, &cloneOpts)
-
-	if err == git.ErrRepositoryAlreadyExists {
-		handle, err = git.PlainOpen(dest)
-	}
-
-	return handle, updateBranches(auth, handle)
-}
-
-func main() {
-	dest := EnvOr("SYNC_DEST", "/git/depot")
-	project := EnvOr("SYNC_PROJECT", "tazjins-infrastructure")
-	repo := EnvOr("SYNC_REPO", "depot")
-	user := os.Getenv("SYNC_USER")
-	pass := os.Getenv("SYNC_PASS")
-
-	log.Printf("Syncing repository '%s/%s' to destination '%s'", project, repo, dest)
-
-	var auth *githttp.BasicAuth
-	if user != "" && pass != "" {
-		auth = &githttp.BasicAuth{
-			Username: user,
-			Password: pass,
-		}
-		log.Println("Enabling basic authentication as user", user)
-	}
-
-	handle, err := cloneRepo(dest, project, repo, auth)
-
-	if err != nil {
-		log.Fatalf("Failed to clone repository: %s", err)
-	} else {
-		log.Println("Initiating update loop")
-	}
-
-	fetchOpts := git.FetchOptions{
-		Auth:  auth,
-		Force: true,
-	}
-
-	for {
-		if err = updateRepo(auth, handle, &fetchOpts); err != nil {
-			log.Fatalf("Failed to pull updated repository: %s", err)
-		}
-
-		time.Sleep(10 * time.Second)
-	}
-}
diff --git a/ops/sync-gcsr/manifest.yaml b/ops/sync-gcsr/manifest.yaml
deleted file mode 100644
index 3016c2ca57ee..000000000000
--- a/ops/sync-gcsr/manifest.yaml
+++ /dev/null
@@ -1,23 +0,0 @@
-image: nixos/latest
-sources:
-  - https://git.tazj.in/
-secrets:
-  # cachix/tazjin
-  - f7f02546-4d95-44f7-a98e-d61fdded8b5b
-tasks:
-  - setup: |
-      # sourcehut does not censor secrets in builds, hence this hack:
-      echo -n 'export CACHIX_SIGNING_KEY=' > cachix-preamble
-      cat cachix-preamble ~/.cachix-tazjin >> ~/.buildenv
-      nix-env -iA third_party.cachix -f git.tazj.in
-      cachix use tazjin
-  - build: |
-      cd git.tazj.in
-      nix-build ci-builds.nix > built-paths
-  - cache: |
-      cd git.tazj.in
-      cat built-paths | cachix push tazjin
-triggers:
-  - action: email
-    condition: failure
-    to: mail@tazj.in