feat: add layout lib for Grafana dashboard (#22)

.editorconfig

@@ -0,0 +1,11 @@
+root = true
+
+[*]
+charset = utf-8
+end_of_line = lf
+indent_size = 2
+tab_width = 2
+indent_style = space
+insert_final_newline = true
+max_line_length = 80
+trim_trailing_whitespace = true

terraform/monitoring/dashboard.jsonnet

@@ -1,4 +1,7 @@
-local lib = import 'lib.libsonnet';
+local layout = import 'layout.libsonnet';
+local full_width = layout.full_width;
+local half_width = layout.half_width;
+local height    = 8;
 
 local grafana = import 'grafonnet/grafana.libsonnet';
 local dashboard = grafana.dashboard;
@@ -7,8 +10,8 @@ local statPanel = grafana.statPanel;
 local prometheus = grafana.prometheus;
 
 local ds_prometheus = {
-    type: 'prometheus',
-    uid: std.extVar('prometheus_uid'),
+  type: 'prometheus',
+  uid: std.extVar('prometheus_uid'),
 };
 
 dashboard.new(
@@ -19,98 +22,80 @@ dashboard.new(
   graphTooltip = 'shared_crosshair',
 )
 .addAnnotation(
-    annotation.default +
-    {
-        iconColor: 'rgba(0, 211, 255, 1)',
-    }
+  annotation.default {
+    iconColor: 'rgba(0, 211, 255, 1)',
+  }
 )
-.addPanel(
+.addPanels(
+  layout.generate_grid([
     statPanel.new(
-        title = 'Received Items per Hour',
-        description = 'The number of items received from relay',
-        datasource = ds_prometheus,
-        reducerFunction = 'lastNotNull',
+      title = 'Received Items per Hour',
+      description = 'The number of items received from relay',
+      datasource = ds_prometheus,
+      reducerFunction = 'lastNotNull',
     )
     .addTarget(prometheus.target(
-        expr = 'sum(rate(received_items{}[1h]))',
-        legendFormat = 'Received Items',
-        datasource = ds_prometheus,
-    )),
-    gridPos = {
-        x:  0, y:  0,
-        w: 10, h:  8
-    },
-)
-.addPanel(
+      expr = 'sum(rate(received_items{}[1h]))',
+      legendFormat = 'Received Items',
+      datasource = ds_prometheus,
+    ))
+    { gridPos: { w: half_width, h: height } },
+
     statPanel.new(
-        title = 'Stored Items per Hour',
-        description = 'The number of items actually stored in the database',
-        datasource = ds_prometheus,
-        reducerFunction = 'lastNotNull',
+      title = 'Stored Items per Hour',
+      description = 'The number of items actually stored in the database',
+      datasource = ds_prometheus,
+      reducerFunction = 'lastNotNull',
     )
     .addTarget(prometheus.target(
-        expr = 'sum(rate(stored_items{}[1h]))',
-        legendFormat = 'Stored Items',
-        datasource = ds_prometheus,
-    )),
-    gridPos = {
-        x: 10, y:  0,
-        w: 10, h:  8
-    },
-)
-.addPanel(
+      expr = 'sum(rate(stored_items{}[1h]))',
+      legendFormat = 'Stored Items',
+      datasource = ds_prometheus,
+    ))
+    { gridPos: { w: half_width, h: height } },
+
     statPanel.new(
-        title = 'Get Queries per Hour',
-        description = 'The number of items retrieval queries',
-        datasource = ds_prometheus,
-        reducerFunction = 'lastNotNull',
+      title = 'Get Queries per Hour',
+      description = 'The number of items retrieval queries',
+      datasource = ds_prometheus,
+      reducerFunction = 'lastNotNull',
     )
     .addTarget(prometheus.target(
-        expr = 'sum(rate(get_queries{}[1h]))',
-        legendFormat = '"Get" Queries',
-        datasource = ds_prometheus,
-    )),
-    gridPos = {
-        x:  0, y:  8,
-        w: 10, h:  8
-    },
-)
-.addPanel(
+      expr = 'sum(rate(get_queries{}[1h]))',
+      legendFormat = '"Get" Queries',
+      datasource = ds_prometheus,
+    ))
+    { gridPos: { w: half_width, h: height } },
+
     statPanel.new(
-        title = 'Served Items per Hour',
-        description = 'The number of messages served to clients',
-        datasource = ds_prometheus,
-        reducerFunction = 'lastNotNull',
+      title = 'Served Items per Hour',
+      description = 'The number of messages served to clients',
+      datasource = ds_prometheus,
+      reducerFunction = 'lastNotNull',
     )
     .addTarget(prometheus.target(
-        expr = 'sum(rate(served_items{}[1h]))',
-        legendFormat = '"Get" Queries',
-        datasource = ds_prometheus,
-    )),
-    gridPos = {
-        x: 10, y:  8,
-        w: 10, h:  8
-    },
-)
-.addPanel(
+      expr = 'sum(rate(served_items{}[1h]))',
+      legendFormat = '"Get" Queries',
+      datasource = ds_prometheus,
+    ))
+    { gridPos: { w: half_width, h: height } },
+
     statPanel.new(
-        title = 'Registrations per Hour',
-        description = 'The number of registrations retrievals',
-        datasource = ds_prometheus,
-        reducerFunction = 'lastNotNull',
+      title = 'Registrations per Hour',
+      description = 'The number of registrations retrievals',
+      datasource = ds_prometheus,
+      reducerFunction = 'lastNotNull',
     )
     .addTarget(prometheus.target(
-        expr = 'sum(rate(cached_registrations{}[1h]))',
-        legendFormat = 'Cache hits',
-        datasource = ds_prometheus,
+      expr = 'sum(rate(cached_registrations{}[1h]))',
+      legendFormat = 'Cache hits',
+      datasource = ds_prometheus,
     ))
     .addTarget(prometheus.target(
-        expr = 'sum(rate(fetched_registrations{}[1h]))',
-        legendFormat = 'Cache misses',
-        datasource = ds_prometheus,
-    )),
-    gridPos = {
-        x:  0, y:  16,
-        w: 20, h:  8
-    },
+      expr = 'sum(rate(fetched_registrations{}[1h]))',
+      legendFormat = 'Cache misses',
+      datasource = ds_prometheus,
+    ))
+    { gridPos: { w: full_width, h: height } },
+  ])
 )

terraform/monitoring/layout.libsonnet

@@ -0,0 +1,93 @@
+local grid_width = 24;
+
+{
+  full_width: grid_width,
+  half_width: grid_width / 2,
+  quarter_width: grid_width / 4,
+  heighth_width: grid_width / 8,
+
+  /**
+   * @name utils.generate_grid
+   *
+   * Generate Grafana grid, based on panels size.
+   * Should be called only once with the list of all panels that will be added.
+   * It puts panels from left to right, until there is a free space, and then uses new line.
+   * Line step on a new line break is the height of the last panel in a previous line.
+   * You can use rows as line breaks.
+   * For complex structures you can insert panels with pre-set position,
+   * but you must be careful to not introduce conflicts.
+   * If there are conflicts in grid, Grafana will solve them on import.
+   * Grafana's negative gravity will also be applied on import, it is not computed here.
+   * You should be careful with using both this and dynamic repeating with variables:
+   * static generator do not know about dynamic repeating,
+   * so Grafana conflict solver will be applied on import.
+   *
+   * @param panels List of panels (their width and height must be set in gridPos)
+   *
+   * @return List of panels with computed grid positions
+   */
+  generate_grid(panels):: [
+    el {
+      gridPos: {
+        x: el.gridPos.x,
+        y: el.gridPos.y,
+        h: el.gridPos.h,
+        w: el.gridPos.w,
+      },
+    }
+    for el in std.foldl(function(_panels, p) (
+      local i = std.length(_panels);
+      local prev = (if i == 0 then null else _panels[i - 1]);
+
+      if i == 0 then
+        _panels + [p { gridPos: {
+          x: 0,
+          y: 0,
+          h: p.gridPos.h,
+          w: p.gridPos.w,
+          x_cursor: p.gridPos.w,
+          y_cursor: 0,
+        } }]
+      else
+        local line_break = prev.gridPos.x_cursor + p.gridPos.w > grid_width;
+
+        _panels + [p { gridPos: {
+          x:
+            if std.objectHas(p.gridPos, 'x') then
+              p.gridPos.x
+            else if line_break then
+              0
+            else
+              prev.gridPos.x_cursor,
+
+          y:
+            if std.objectHas(p.gridPos, 'y') then
+              p.gridPos.y
+            else if line_break then
+              prev.gridPos.y_cursor + prev.gridPos.h
+            else
+              prev.gridPos.y_cursor,
+
+              h: p.gridPos.h,
+
+              w: p.gridPos.w,
+
+              x_cursor:
+                if std.objectHas(p.gridPos, 'x') then
+                  p.gridPos.x + p.gridPos.w
+                else if line_break then
+                  p.gridPos.w
+                else
+                  prev.gridPos.x_cursor + p.gridPos.w,
+
+              y_cursor:
+                if std.objectHas(p.gridPos, 'y') then
+                  p.gridPos.y
+                else if line_break then
+                  prev.gridPos.y_cursor + prev.gridPos.h
+                else
+                  prev.gridPos.y_cursor,
+        } }]
+    ), panels, [])
+  ],
+}

terraform/monitoring/terraform.tf

@@ -14,5 +14,5 @@ terraform {
 }
 
 provider "jsonnet" {
-  jsonnet_path = "./lib/,./grafonnet"
+  jsonnet_path = "./grafonnet"
 }