Drilldown

A panel can declare links: where it leads when a viewer wants to look closer. A link opens another dashboard in the same workspace, or stays on this one and sets a variable (“click to filter”). The viewer’s time range and variable picks go along, so landing on the host dashboard from the fleet overview keeps the window they were looking at.

Drilldown is being built in phases under #370. A link that only carries the view is followed from the panel’s menu. A link that reads what was clicked is followed by clicking a point, slice, cell or row (#373).

What a link is

A link is part of the spec, in the panel’s links array, so it is versioned, diffed and exported with everything else. Authors edit links in the editor’s Links section. See The shared IR for the fields.

{
  "title": "Host detail",
  "dashboard": "9b2c41d0-…",
  "carry": { "timeRange": true, "variables": true },
  "set": { "env": { "value": "prod" } }
}

• The target is an id. dashboard is the target’s id, never a URL. With no dashboard, the link stays on this dashboard.
• What it carries. By default the viewer’s current window and every pick go along. carry.timeRange: false lands on the target’s own default window; carry.variables: false lands on its own default picks.
• What it sets. set makes picks on arrival. A literal ({ "value": "prod" }) wins over a carried pick of the same name.

What a viewer sees

A panel with a link the viewer can follow shows a small link glyph in its header, and each link is an item in the panel’s ⋯ menu:

• A link to another dashboard is a real link to that dashboard’s page, opened in this tab or, with newTab, a new one.
• A self link sets the variables in place. The picker, the URL and the stream change as they would for a pick made by hand, and the page does not navigate.
• A link the viewer cannot follow is a disabled item that says the dashboard is not available. The page holds no href for it.

Clicking a datum

A link whose set reads a column ({ "column": "host" }), the series ({ "series": true }) or one label of the series or log line ({ "label": "instance" }) is a datum link. It needs to know what was clicked, so it is not in the panel’s menu. Instead the panel’s data is clickable:

• A chart. Click a point, bar, slice, cell, span or gauge. With one link, the click follows it. With several, a small list opens at the point, and Escape or a click outside closes it. A click that ends a time brush never follows a link.
• A table. Each row has a link control in a trailing cell; the row itself stays text to read and copy.
• A stat. The whole number is the control.
• The keyboard. Every chart has a visually hidden table of its rows. With datum links, each row there has the same link control, and the table shows itself over the chart while one has focus.

A click is mapped back to the result row the panel already holds (datumOf in src/lib/drilldown-datum.ts, one mapping per panel kind). No query runs. A column pick reads that column of the row. A series pick reads the series: the column a line, area or bar point belongs to, a slice’s label, a heatmap cell’s y value, a timeline’s lane or a gauge bar’s label. A value the row does not have, or one longer than a pick may be, leaves that variable unset, and the target falls back to its default.

On a PromQL panel (#388), an instant query’s table or pie has a column per label, so a column pick reads a label by name. A range query’s chart has one series per label set, named the way the Prometheus UI names a legend entry, up{instance="web-01:9100", job="node"}, and a series pick carries that whole name. A label pick reads one label out of it (seriesLabel in src/lib/drilldown.ts), so “click a host’s line, land on the host dashboard” needs no parsing in the link: { "host": { "label": "instance" } } sets host to web-01:9100. A series without that label leaves the pick unset.

On a LogQL logs panel (#565), each line’s row is its time, its message and every label it carries: its stream labels, its structured metadata and the fields a parser stage (| json, | logfmt) extracted. A label pick reads one of those from the clicked line (lineDatum in src/lib/drilldown-datum.ts), so { "pod": { "label": "pod" } } carries the clicked line’s pod into a pod dashboard. The time and the message are never labels; a label Loki returned as time or message is the column time_label or message_label, and is picked by that name. A line without the label, or with it empty, leaves the pick unset. In the editor’s link form, a label pick on a LogQL panel lists the labels the last preview returned. A LogQL metric query’s series are named as PromQL’s are, and a label pick reads them the same way.

A self datum link filters in place: clicking a host’s slice sets host on this dashboard, the picker and the URL follow, and the picker puts it back.

Who decides where a link may lead

The dashboard page resolves the targets on the server, on every load. A target is offered only when it:

1. exists and has not been deleted,
2. is in the same workspace as the dashboard the link is on, and
3. is one the viewer may view (can("dashboard:view")).

The browser builds hrefs only to the targets the server named. Nothing about the decision is read from the spec: an id in a link is a candidate, and a link never reaches across workspaces, even to a dashboard the viewer could open there.

An href carries the IR’s time expressions (now-6h) and var-* picks, never SQL and never a resolved instant. The target page treats it exactly like a URL typed by hand: the server resolves the window, and every pick is checked against the target’s own variable before anything runs with it. A pick the target does not allow falls back to its default, and a name it does not declare is ignored.

Where links do not appear

• A share link or embed shows no links. The other side has no session to open a dashboard with.
• Explore panels have none: a panel in an answer is on no dashboard. Add it to one and give it links in the editor.
• Templates. Saving a dashboard as a template keeps its self links and drops links to other dashboards, whose ids mean nothing where the template is used. A panel template keeps no links.
• Import. An imported file keeps its links. Ids from another instance resolve to nothing here, so those links show as unavailable; the import dialog says how many dashboards the file links to.

Deleting a dashboard leaves the links to it in place. They turn disabled.