verifypr: update check and docs (#447)

Updates the `verifypr` to validate feature_set tag, also update docs and PR template.

category: misc
ticket: #381

.github/pull_request_template.md

@@ -4,6 +4,7 @@
    - 2️⃣ PR body: Replace 'body...' with detailed description of the change.
    - 3️⃣ category: pick one, delete the rest.
    - 4️⃣ ticket: Replace #000 with link to a GitHub issue (or 'none' if PR is trivial).
+   - 5️⃣ feature_set: pick one (or delete completely if not applicable).
 🧑‍🎓 Please review our contribution guide https://github.com/ObolNetwork/charon/blob/main/docs/contributing.md
    - 📜 Sign the Contributor License Agreement (CLA) when prompted.
    - 🌱 Starting with an issue, outlining the problem and proposed solution, is highly encouraged.
@@ -15,3 +16,4 @@ body...
 
 category: bug feature refactor docs test fixbuild misc
 ticket: #000
+feature_set: alpha beta stable

docs/branching.md

@@ -21,7 +21,7 @@ We follow [Trunk Based Development](https://trunkbaseddevelopment.com/) as a bra
 
 - Since a feature cannot be added as a single big merge of a big feature branch, tools and patterns are required that allow gradual controlled introduction of increment changes without breaking.
 - New code can be added as “dead code”. So not integrated into the actual program yet. Once it is properly complete, it can be integrated in a single PR.
-- Some features should however not be enabled straight into prod/mainnet, but should be tested in dev/devnet or staging/testnet first. This can be achieved by simple [feature switches](https://trunkbaseddevelopment.com/feature-flags/) (if statements) that integrate new features based on the environment (e.g. only enable feature X in testnet). TODO(corver): Add feature switch functionality.
+- Some features should however not be enabled straight into prod/mainnet, but should be rolled-out slowly being first tested in `alpha` (internal devnet only), then `beta` (internal and external testnet), and then only `stable` (enabled everywhere). This can be achieved by simple [feature switches](https://trunkbaseddevelopment.com/feature-flags/) (if statements) that enable features based on their `feature_set` status.
 - Another powerful pattern to gradually introduce change is [branching by abstraction](https://trunkbaseddevelopment.com/branch-by-abstraction/). This basically introduces an abstraction layer at the point where a new feature has to replace an old feature (like an interface). Using dependency injection, the new feature can be integrated during testing/staging while the old feature is still being used in production.
 - Note that both feature switches and/or abstraction layers used to roll out a feature should be removed once released to prod/main-net.
 

docs/contributing.md

@@ -85,7 +85,7 @@ Note: PRs can only be merged by obol-bulldozer bot. It is author's responsibilit
   - Ends with a list of tags (some required, others optional) (`^tag: value of this tag\n`):
   - `category`: required; one of: `refactor`, `bug`, `feature`, `docs`, `release`, `tidy`, `fixbuild`.
   - `ticket`: required; URL of the Github issue just a reference, E.g. `#123` or `none`.
-  - `phase`: optional; identifies the highest release cycle phase targeted by the change; `aplha`, `beta`, `gold`
+  - `feature_set`: optional; identifies the highest rollout status targeted by the change; `alpha`, `beta`, `stable`
 - Example:
 ```
 runner/tracer: add jaeger otel exporter
@@ -94,7 +94,7 @@ Adds the jaeger exporter to our opentelemetery infra.
 
 category: feature
 ticket: #206
-phase: gold
+feature_set: stable
 ```
 
 ### Dev tools, git hooks and linters.

testutil/verifypr/verifypr.go

@@ -133,6 +133,7 @@ func verifyBody(body string) error {
 		prevLineEmpty bool
 		foundCategory bool
 		foundTicket   bool
+		foundFeature  bool
 	)
 	for i, line := range strings.Split(body, "\n") {
 		if i == 0 && strings.TrimSpace(line) == "" {
@@ -204,6 +205,31 @@ func verifyBody(body string) error {
 			foundTicket = true
 		}
 
+		const featureTag = "feature_set:"
+		if strings.HasPrefix(line, featureTag) {
+			if foundFeature {
+				return errors.New("multiple ticket tag lines")
+			}
+
+			set := strings.TrimSpace(strings.TrimPrefix(line, featureTag))
+
+			if set == "" {
+				return errors.New("feature_set tag empty")
+			}
+
+			sets := map[string]bool{
+				"alpha":  true,
+				"beta":   true,
+				"stable": true,
+			}
+
+			if !sets[set] {
+				return errors.New("invalid feature_set tag not one of: alpha, beta, stable")
+			}
+
+			foundFeature = true
+		}
+
 		prevLineEmpty = strings.TrimSpace(line) == ""
 	}
 

testutil/verifypr/verifypr_internal_test.go

@@ -141,6 +141,22 @@ func TestBody(t *testing.T) {
 			Body:  "<!--\n\ncategory: bug\nticket: none",
 			Error: "instructions not deleted (markdown comments present)",
 		},
+		{
+			Body:  "Foo\n\ncategory: bug\nticket: none\nfeature_set: alpha",
+			Error: "",
+		},
+		{
+			Body:  "Foo\n\ncategory: bug\nticket: none\nfeature_set: beta",
+			Error: "",
+		},
+		{
+			Body:  "Foo\n\ncategory: bug\nticket: none\nfeature_set: stable",
+			Error: "",
+		},
+		{
+			Body:  "Foo\n\ncategory: bug\nticket: none\nfeature_set: bad set",
+			Error: "invalid feature_set tag not one of",
+		},
 	}
 	for i, test := range tests {
 		t.Run(fmt.Sprint(i), func(t *testing.T) {