kargo: notify when a soak completes

♠ Previously. Problem statement: notify a Slack channel whenever Freight finishes soaking in an upstream Kargo Stage, without promoting it to the next environment. A soak does not finish a process. Once requiredSoakTime elapses, Kargo simply makes the Freight available downstream. There is no soak-complete event in the Kargo event list. Worakround: I made availability start a notification-only promotion. Relevant excerpt, with variable values omitted: metadata: name: notify-remaining-gardens-ready spec: requestedFreight: - origin: kind: Warehouse name: argocd sources: stages: - staging-gardens requiredSoakTime: 48h0m0s promotionTemplate: spec: steps: - uses: http config: method: POST url: https://slack.com/api/chat.postMessage responseContentType: application/json successExpression: response.status == 200 && response.body.ok == true failureExpression: response.status != 200 || response.body.ok != true body: |- ${{ quote({ "channel": vars.slackChannel, "username": "Kargo",…