[IOSP-543] Fix MergeBot deployment (#51)

* Made IDLE_BRANCH_QUEUE_CLEANUP_DELAY env optional

* Improve documentation

* Apply suggestions from code review

* Since they are optional, shouldn't throw anymore

Sources/App/Extensions/EnvironmentProperties.swift

@@ -3,44 +3,55 @@ import Bot
 
 extension Environment {
 
+    /// GitHub Webhook secret
     static func gitHubWebhookSecret() throws -> String {
         return try Environment.get("GITHUB_WEBHOOK_SECRET")
     }
 
+    /// GitHub Token
     static func gitHubToken() throws -> String {
         return try Environment.get("GITHUB_TOKEN")
     }
 
+    /// GitHub Organisation name (as seen in the github.com/<orgname>/* urls)
     static func gitHubOrganization() throws -> String {
         return try Environment.get("GITHUB_ORGANIZATION")
     }
 
+    /// URL of GitHub Repository to run the MergeBot on
     static func gitHubRepository() throws -> String {
         return try Environment.get("GITHUB_REPOSITORY")
     }
 
+    /// If set to YES/1/TRUE, the Merge Bot will require all GitHub status checks to pass before accepting to merge
+    /// Otherwise, only the GitHub status checks that are marked as "required" in the GitHub settings to pass
     static func requiresAllGitHubStatusChecks() throws -> Bool {
         guard let stringValue: String = Environment.get("REQUIRES_ALL_STATUS_CHECKS") else {
             return false // defaults to only consider required checks
         }
         return ["yes", "1", "true"].contains(stringValue.lowercased())
     }
 
-    static func statusChecksTimeout() throws -> TimeInterval? {
-        let value: String = try Environment.get("STATUS_CHECKS_TIMEOUT")
-        return TimeInterval(value)
+    /// Maximum time (in seconds) to wait for a status check to finish running and report a red/green status
+    /// Defaults to 5400 (90 minutes)
+    static func statusChecksTimeout() -> TimeInterval? {
+        let value: String? = Environment.get("STATUS_CHECKS_TIMEOUT")
+        return value.flatMap(TimeInterval.init)
     }
 
-    /// Delay to wait after a MergeService is back in idle state before destroying it
-    static func idleMergeServiceCleanupDelay() throws -> TimeInterval? {
-        let value: String = try Environment.get("IDLE_BRANCH_QUEUE_CLEANUP_DELAY")
-        return TimeInterval(value)
+    /// Delay (in seconds) to wait after a MergeService is back in idle state before killing it.
+    /// Defaults to 300 seconds (5 minutes)
+    static func idleMergeServiceCleanupDelay() -> TimeInterval? {
+        let value: String? = Environment.get("IDLE_BRANCH_QUEUE_CLEANUP_DELAY")
+        return value.flatMap(TimeInterval.init)
     }
 
+    /// The text of the GitHub label that you want to use to trigger the MergeBot and add a PR to the queue
     static func mergeLabel() throws -> PullRequest.Label {
         return PullRequest.Label(name: try Environment.get("MERGE_LABEL"))
     }
 
+    /// Comma-separated list of GitHub label names that you want to use to bump a PR's priority – and make it jump to the front of the queue
     static func topPriorityLabels() throws -> [PullRequest.Label] {
         let labelsList: String = try Environment.get("TOP_PRIORITY_LABELS")
         return labelsList.split(separator: ",").map { name in

Sources/App/configure.swift

@@ -46,8 +46,8 @@ private func makeDispatchService(with logger: LoggerProtocol, _ gitHubEventsServ
         integrationLabel: try Environment.mergeLabel(),
         topPriorityLabels: try Environment.topPriorityLabels(),
         requiresAllStatusChecks: try Environment.requiresAllGitHubStatusChecks(),
-        statusChecksTimeout: try Environment.statusChecksTimeout() ?? 90.minutes,
-        idleMergeServiceCleanupDelay: try Environment.idleMergeServiceCleanupDelay() ?? 5.minutes,
+        statusChecksTimeout: Environment.statusChecksTimeout() ?? 90.minutes,
+        idleMergeServiceCleanupDelay: Environment.idleMergeServiceCleanupDelay() ?? 5.minutes,
         logger: logger,
         gitHubAPI: gitHubAPI,
         gitHubEvents: gitHubEventsService