[Feat]: Annotations for charts

[shyamvalsan]

Problem

As a user, I want to add annotations to charts which "explain a pattern or spike", "ask a question about something I see on chart", "add context to an anomaly", "highlight real world events such as a prod rollout" etc. and I also want to share this with other users in my space. There is no way to do this in Netdata currently.

Description

There must be a simple and intuitive way for users to annotate a specific timeline of the chart and add their comments which can be saved in a way similar to chart settings and be made available to the user/room/space.

Based on this setting, other users would see the annotations as a vertical line on the chart that visually stands out and on hovering will see the comment added by the other user.

Annotations will also influence other features such as Netdata Insights by using the additional context while creating reports.

Annotations should have an option to share with other users in the space via email, so user can make annotation and click share - so the other user will receive an email with the annotation and a link to this chart. Sort of similar to how we do it for Insights report sharing.

Importance

must have

Value proposition

1. Make Netdata more useful for collaborative troubleshooting
2. Improve shareability and make Netdata more friendly for team-wide use
3. Allow external context (provided by user) to make the observability more meaningful

Proposed implementation

FE

• Visually the annotations should look something like this.
• Comments will be hidden until hover but the lines will clearly indicate that annotations exist in this part of the chart
• Annotation save can be done similarly to chart settings saving

BE

• Store annotations similar to how we do chart settings saving

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