Goals:

1. Improve operability in the Hydrator Studio (Improvements to logs, metrics, debuggability)
2. Improve usability in the Hydrator Studio (Redesign of bottom panel, etc)

Checklist

• User stories documented (Bhooshan)
• User stories reviewed (Nitin/Sree)
• Design documented (Bhooshan/Brady)
• Design reviewed (Nitin/Sree)

Use Cases:

Use Case 1: Improve Log Viewer

Problems with current Log Viewer

• Doesn't cater to usual developer interactions with logs - tail'ing (with log file monitoring -f) or less'ing (viewing the log) or downloading
• Hard to distinguish between two log lines
• Exception stack traces are virtually un-readable
• Virtually no formatting in the UI - almost rendered as the logs appear from the backend, which is not ideal to an end-user
• No search (even at the UI level)
• No way to download logs
• No way to distinguish whether logs are live or past
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User Stories:

• As a Hydrator/CDAP user, I want to be able to view my pipeline logs from both currently running pipelines as well as past pipelines to effectively debug the pipeline during failures
• As a Hydrator/CDAP user, I want to clearly know if the logs I am viewing are being updated live or are from a past run
• As a Hydrator/CDAP user, I want greater emphasis on the most important part of logs - the messages
• As a Hydrator user, I do not want logs to be flooded with stack traces. I want the ability to suppress them individually and as a whole
• As a Hydrator/CDAP user, I want the ability to download complete log files
  
• As a Hydrator/CDAP user, I want to view a summary of the logs I'm viewing (the number of messages, the number of errors, the number of warnings)
• As a Hydrator/CDAP user, I want to be able to filter logs by the lowest log level
• As a Hydrator/CDAP user, I want to be able to filter logs by keywords
• As a Hydrator/CDAP user, I want to be able to view a larger number of log events with a single-line summary for each, with the capability to drill down into particular events as desired
• As a Hydrator/CDAP user, I want to be able to view logs in the selected time range. I want to be able to dynamically change the time range for which I want to view logs, with context about how that time range maps to the duration of the program/service run.
• As a Hydrator/CDAP user, I want to be able to be able to maximize the log viewer to full screen size and restore it to original size as required.

   Possible solutions

• Tabular view: Columns for date, Class Name/Thread Name, Log Level, Log Line
• Alternate row background colors
• Vertically expandable with scrolling
• Searchable (Filter-able) columns
• Clear demarcation of rows
• Snippet with expand - especially for stack traces
• Picking only 1 or more log level -INFO, DEBUG, WARN, ERROR, ALL
• Ability to view and download raw logs if required
• Ability to view and expand only the "content" column of a log line

Use Case 2: Bottom Panel

Problems with current Bottom Panel

• Constant back-and forth between DAG and bottom panel - click on a node, then view the bottom panel - not very intuitive
• Reserved real-estate for configurations that are not commonly updated
• Schema available in both bottom panel as well as the DAG
• Reduced "prominance" for both the DAG as well as the bottom panel, since you're not using the full available space ever
• Restricted space in the bottom panel for logs, pipeline configuration, node configuration, etc
• Association between a DAG and its bottom panel is not always clear enough

User Stories:

• As a Hydrator Product Team, I want to better plan the Hydrator real-estate so it is not statically allocated for configurations/views that are not commonly used/mandatory to be updated for creating pipelines
• e.g. Pipeline configurations like post run actions, engine, schedule
• As a Hydrator Product Team, I want to better design the Hydrator UI to lay more emphasis on the DAG
• As a Hydrator user, I do not want to switch back-and-forth between the DAG and the bottom panel repeatedly for building my pipeline
  • I should be able to provide node-level details right near the node
  • I should be able to simultaneously view details for multiple nodes both while editing a pipeline as well as viewing it.
• As a Hydrator user, I want to be able to build my pipeline incrementally. I want mandatory information to be more obvious.
• Build the pipeline with mandatory fields only to start off
• Incrementally add schedule, post run actions, etc
• As a Hydrator Product Team, I want remove the disparity between the pipeline detail view and the studio view. This will facilitate the move towards being able to edit a pipeline after publishing
  • e.g. Reference is unavailable in the pipeline details view
    
• As a Hydrator user, I want the messaging regarding multiple runs from the Hydrator UI to be clearer.
• Does Hydrator only always show the last run?
• If so, what is the "History" view for
• As a Hydrator Product Team, I want to reduce duplication
  • The console is not very useful today, it just shows messages. Can it be reconciled with the notification center?
• As a Hydrator user, I want related actions to appear together. 
  • e.g. "Export" is available in the bottom panel, but other pipeline controls are in the top bar.
• As a Hydrator Product team, I want to bring Jump buttons to Hydrator to make them the primary method of viewing entities in different contexts across CDAP, Hydrator and Tracker
  • Jump from pipeline details view in Hydrator to program details view in CDAP
  • Jump actions for source/sink in Hydrator:
    • View in Dataset Details page in CDAP
    • View in entity details page in Tracker
    • Explore Dataset (if possible) in CDAP

Use Case 2: Debuggability/Testing

User Stories:

Design:

Proposed Log Viewer:

Composed of two main views:

1. Viewing current logs along with monitoring (Live)
   1. Similar to tail -f
   2. Starts off with 50 lines
   3. Shows newer logs as they become available towards the end
   4. Users can see newer logs if they are 'scroll-positioned' at the last log line
   5. Scroll position is retained if users are at any position other than the last log line
   6. Previous button
2. Viewing logs within a specified time range (Not Live)
   1. Similar in behavior to less, so its not live, but allows the following capabilities
   2. Time range selector
   3. Previous/Next buttons
   4. Download button

Common to both views:

1. Compact view: A log line is a single line, so you see more logs (even though they are partial) at once.
2. Expanded view: A log line contains the entire content, including message and stack trace
3. Suppress stack trace: The stack trace in a log line can be suppressed by clicking something
4. 1, 2, and 3 can be achieved either for all logs, or for an individual log line
5. Logs are tabular, consisting of columns: Timestamp, Log Level, Origin (includes thread name, class name and line number - but these can be split into separate columns if there is a requirement), Message (contains stack trace too).
6. Error/Warn level logs have some sort of highlighting (a symbol next to the log level?)
7. Log level column has a dropbox with checkboxes to select only a particular log level - ALL, DEBUG, INFO, WARN, ERROR
8. The message column can be expanded to the full width of the table, thereby hiding other columns. This operation can be reversed. 
9. Search box that allows filtering log lines with the search text

Backend support:

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Work Streams:

 Tech Debt

• Simplify Config Store
• Simplify DAG component ~ Ajai's hack
  

Moving hard-coding/logic to backend

• Drafts
• Default plugin version
• For a stage, define whether it can accept an Input, Output or both
• Single APIs for status/logs/metrics for hydrator pipelines

New features

• Preview
• Log Viewer