Timeline and time travel
The timeline at the bottom of the StackState UI allows you to travel back in time to the state of the topology at a specific point in the past. You can then navigate through all telemetry available for the selected topology snapshot. Health and events charts in the timeline give an overview of the state of the topology during the selected telemetry interval.
The telemetry interval specifies the time window for which events, metrics and traces are available in the StackState perspectives. It runs from left to right on the timeline.
The selected telemetry interval can be either relative (live mode), or set to a custom telemetry interval (time travel mode). By default, the telemetry interval is set to a relative telemetry interval - in live mode and showing telemetry from the last hour. You can zoom in/out or set a custom telemetry interval to view telemetry from a specific point in time.
The telemetry interval can be set in the following ways:
- Zoom in
Click and drag on the timeline to set a custom telemetry interval on your selection
- Zoom out
Click the magnifying glass to double the size of the telemetry interval
- Use the telemetry interval jumper arrows
Click the time jumper arrows to move the telemetry interval backwards or forwards through time
- Set a relative or custom telemetry interval
Use the popup "Set the telemetry interval" to specify a telemetry interval
The topology and all telemetry displayed in StackState are based on a snapshot of the IT infrastructure. The moment from which this snapshot is taken is specified by the topology time. By default, StackState is in live mode with the topology time set to the current time. You can time travel to a previous state of the topology by selecting a custom topology time.
On the timeline, the selected topology time is indicated by the playhead - a black line with the current topology time at the top. It is also specified in the Topology time box at the top of the timeline.
The topology time can be set in the following ways:
- Click on the timeline
Click anywhere on the timeline to set the topology time to that moment
- Use the topology time jumper arrows
Click the topology time jumper arrows to move the topology time backwards or forwards in time to the next set of events
- Set a custom topology time
Use the popup "Set the topology time" to specify a topology time
- Click a timestamp
Click a timestamp to jump to that specific topology time
If the selected topology time is a time outside the currently selected telemetry interval, the message "The topology time is out of the current telemetry interval" will be displayed and the Topology time box at the top of the timeline will be highlighted black. As the timeline shows the telemetry interval from left to right, the playhead indicating the current topology time will not be visible on the timeline.
Topology time outside telemetry interval
You can still browse topology and telemetry as expected:
- In all perspectives, telemetry is displayed that was generated in the selected telemetry interval and relates to the topology elements that existed at the selected topology time.
To stop time travelling and return the topology time to live mode, click Go live or BACK TO LIVE at the top of the screen.
The health state of a view during the selected telemetry interval is displayed as a color in the timeline Health line.
When health state information is not available, a gray line is displayed.
Health state not available
The Events line in the timeline shows a bar chart with the number of events generated at each point in time. This helps you to see moments in the past with a lot of activity. Note that only events generated by topology elements that existed at the selected topology time are displayed.
To zoom in on an event bar of interest, click and drag to select a smaller telemetry interval around it on the timeline.
Click and drag to select a telemetry interval
In each of the StackState perspectives, you can either be in live mode or in the past. In live mode, StackState will constantly poll for new data. When you time travel through topology or telemetry, you are effectively working with a snapshot of your infrastructure. The data available is based on two selections:
Let's imagine a concrete scenario:
- You received an event notification saying that your payment processing application is not able to process any payments right now, and your customers aren't being served.
- In StackState, you can go to the moment in time when the components that make up the CRITICAL path of payment processing turned to a CRITICAL state. That moment corresponds to the point in time for which you will fetch the snapshot of your IT infrastructure - the topology time.
- You can then select to see the hours that preceded that moment in order to fetch the telemetry that will hopefully point you to the root cause of your problem - the telemetry interval.
StackState will enter time travel mode whenever a custom topology time is selected, the Pause button is clicked, or a custom telemetry interval is set for the telemetry interval. When StackState is in time travel mode:
- You are effectively working with a snapshot of your infrastructure.
- Telemetry is available for components that were part of the topology at the selected topology time only.
- If a relative telemetry interval was selected in live mode, this is frozen as a custom telemetry interval relative to the moment at which time travelling began.
To stop time travelling and return to live mode, click Go live or BACK TO LIVE at the top of the screen.