Add ViewDashboard action for external dashboard integration (#537)

## What
Adds a "View Dashboard" button to the backfill run page that redirects
to external dashboard providers. Follows the same provider pattern as
the existing ViewLogsAction.

## Why
Enables integrators to link backfill runs to external
monitoring/observability dashboards, providing a consistent way to view
runtime metrics and health data alongside logs.

Co-authored-by: Claude Sonnet 4.5 <noreply@anthropic.com>

Author: emilydespas

service-self-backfill/src/test/kotlin/app/cash/backfila/service/selfbackfill/BackfilaSelfBackfillDevelopmentService.kt

@@ -4,6 +4,7 @@ import app.cash.backfila.client.BackfilaCallbackConnector
 import app.cash.backfila.client.BackfilaCallbackConnectorProvider
 import app.cash.backfila.client.BackfilaDefaultEndpointConfigModule
 import app.cash.backfila.client.ForConnectors
+import app.cash.backfila.dashboard.ViewDashboardUrlProvider
 import app.cash.backfila.dashboard.ViewLogsUrlProvider
 import app.cash.backfila.protos.clientservice.GetNextBatchRangeRequest
 import app.cash.backfila.protos.clientservice.GetNextBatchRangeResponse
@@ -52,6 +53,7 @@ internal fun main(args: Array<String>) {
         bind<MiskCaller>().annotatedWith<DevelopmentOnly>()
           .toInstance(MiskCaller(user = "testfila"))
         bind<ViewLogsUrlProvider>().to<DevelopmentViewLogsUrlProvider>()
+        bind<ViewDashboardUrlProvider>().to<DevelopmentViewDashboardUrlProvider>()
 
         newMapBinder<String, BackfilaCallbackConnectorProvider>(ForConnectors::class)
           .permitDuplicates().addBinding("DEV")
@@ -130,3 +132,9 @@ internal class DevelopmentViewLogsUrlProvider : ViewLogsUrlProvider {
     return "/"
   }
 }
+
+internal class DevelopmentViewDashboardUrlProvider : ViewDashboardUrlProvider {
+  override fun getUrl(session: Session, backfillRun: DbBackfillRun): String {
+    return "/"
+  }
+}

service/src/main/kotlin/app/cash/backfila/dashboard/BackfilaWebActionsModule.kt

@@ -18,6 +18,7 @@ class BackfilaWebActionsModule() : KAbstractModule() {
     install(WebActionModule.create<GetBackfillStatusAction>())
     install(WebActionModule.create<UpdateBackfillAction>())
     install(WebActionModule.create<ViewLogsAction>())
+    install(WebActionModule.create<ViewDashboardAction>())
     install(WebActionModule.create<EditPartitionCursorAction>())
     install(WebActionModule.create<EditPartitionCursorHandlerAction>())
     install(WebActionModule.create<SearchBackfillNamesAction>())

service/src/main/kotlin/app/cash/backfila/dashboard/ViewDashboardAction.kt

@@ -0,0 +1,47 @@
+package app.cash.backfila.dashboard
+
+import app.cash.backfila.service.persistence.BackfilaDb
+import app.cash.backfila.service.persistence.DbBackfillRun
+import java.net.HttpURLConnection
+import javax.inject.Inject
+import misk.exceptions.BadRequestException
+import misk.hibernate.Id
+import misk.hibernate.Session
+import misk.hibernate.Transacter
+import misk.hibernate.loadOrNull
+import misk.security.authz.Authenticated
+import misk.web.Get
+import misk.web.PathParam
+import misk.web.Response
+import misk.web.ResponseBody
+import misk.web.actions.WebAction
+import misk.web.toResponseBody
+import okhttp3.Headers
+
+interface ViewDashboardUrlProvider {
+  fun getUrl(session: Session, backfillRun: DbBackfillRun): String
+}
+
+class ViewDashboardAction @Inject constructor(
+  @BackfilaDb private val transacter: Transacter,
+  private val viewDashboardUrlProvider: ViewDashboardUrlProvider,
+) : WebAction {
+  @Get("/backfills/{id}/view-dashboard")
+  @Authenticated(allowAnyUser = true)
+  fun viewDashboard(
+    @PathParam id: Long,
+  ): Response<ResponseBody> {
+    val url = getUrl(id)
+    return Response(
+      body = "go to $url".toResponseBody(),
+      statusCode = HttpURLConnection.HTTP_MOVED_TEMP,
+      headers = Headers.headersOf("Location", url),
+    )
+  }
+
+  fun getUrl(id: Long) = transacter.transaction { session ->
+    val backfillRun = session.loadOrNull<DbBackfillRun>(Id(id))
+      ?: throw BadRequestException("backfill $id doesn't exist")
+    viewDashboardUrlProvider.getUrl(session, backfillRun)
+  }
+}

service/src/main/kotlin/app/cash/backfila/ui/pages/BackfillShowAction.kt

@@ -3,6 +3,7 @@ package app.cash.backfila.ui.pages
 import app.cash.backfila.dashboard.EditPartitionCursorAction
 import app.cash.backfila.dashboard.GetBackfillStatusAction
 import app.cash.backfila.dashboard.GetBackfillStatusResponse
+import app.cash.backfila.dashboard.ViewDashboardAction
 import app.cash.backfila.dashboard.ViewLogsAction
 import app.cash.backfila.service.persistence.BackfillState
 import app.cash.backfila.ui.actions.BackfillShowButtonHandlerAction
@@ -59,6 +60,7 @@ class BackfillShowAction @Inject constructor(
   private val getBackfillStatusAction: GetBackfillStatusAction,
   private val dashboardPageLayout: DashboardPageLayout,
   private val viewLogsAction: ViewLogsAction,
+  private val viewDashboardAction: ViewDashboardAction,
   private val backfillShowButtonHandlerAction: BackfillShowButtonHandlerAction,
   private val httpCall: ActionScoped<HttpCall>,
 ) : WebAction {
@@ -514,6 +516,14 @@ class BackfillShowAction @Inject constructor(
         href = viewLogsAction.getUrl(id),
       ),
     ),
+    DescriptionListRow(
+      label = "Dashboard",
+      description = "",
+      button = Link(
+        label = VIEW_DASHBOARD_BUTTON_LABEL,
+        href = viewDashboardAction.getUrl(id),
+      ),
+    ),
   ) + if (parameters?.isNotEmpty() == true) {
     listOf(
       DescriptionListRow(
@@ -628,6 +638,21 @@ class BackfillShowAction @Inject constructor(
                 href = button.href
                 target = "_blank"
 
+                button(
+                  classes = "rounded-md font-medium text-indigo-600 hover:text-indigo-500",
+                ) {
+                  type = ButtonType.submit
+                  +button.label
+                }
+              }
+            }
+          } else if (button.label == VIEW_DASHBOARD_BUTTON_LABEL) {
+            span("ml-4 flex-shrink-0") {
+              // View dashboard button will link to external dashboard provider
+              a {
+                href = button.href
+                target = "_blank"
+
                 button(
                   classes = "rounded-md font-medium text-indigo-600 hover:text-indigo-500",
                 ) {
@@ -836,5 +861,6 @@ class BackfillShowAction @Inject constructor(
     const val DELETE_STATE_BUTTON_LABEL = "Delete"
     const val UPDATE_BUTTON_LABEL = "Update"
     const val VIEW_LOGS_BUTTON_LABEL = "View Logs"
+    const val VIEW_DASHBOARD_BUTTON_LABEL = "View Dashboard"
   }
 }

service/src/test/kotlin/app/cash/backfila/development/BackfilaDevelopmentService.kt

@@ -4,6 +4,7 @@ import app.cash.backfila.client.BackfilaCallbackConnector
 import app.cash.backfila.client.BackfilaCallbackConnectorProvider
 import app.cash.backfila.client.BackfilaDefaultEndpointConfigModule
 import app.cash.backfila.client.ForConnectors
+import app.cash.backfila.dashboard.ViewDashboardUrlProvider
 import app.cash.backfila.dashboard.ViewLogsUrlProvider
 import app.cash.backfila.development.DevServiceConstants.Companion.BACKFILA_PORT
 import app.cash.backfila.protos.clientservice.GetNextBatchRangeRequest
@@ -56,6 +57,7 @@ fun main(args: Array<String>) {
         install(MiskWebModule(webConfig))
         multibind<MiskCallerAuthenticator>().to<FakeCallerAuthenticator>()
         bind<ViewLogsUrlProvider>().to<DevelopmentViewLogsUrlProvider>()
+        bind<ViewDashboardUrlProvider>().to<DevelopmentViewDashboardUrlProvider>()
 
         // Example custom link that shows up in navbar
         install(
@@ -154,6 +156,12 @@ internal class DevelopmentViewLogsUrlProvider : ViewLogsUrlProvider {
   }
 }
 
+internal class DevelopmentViewDashboardUrlProvider : ViewDashboardUrlProvider {
+  override fun getUrl(session: Session, backfillRun: DbBackfillRun): String {
+    return "/${backfillRun.service.registry_name}/${backfillRun.service.variant}/${backfillRun.id}/dashboard"
+  }
+}
+
 class DevServiceConstants {
   companion object {
     const val BACKFILA_PORT = 8080