Colcon Dashboard

A live web dashboard for colcon build. It shows how many packages are done, building, ready, waiting, or failed. It draws the dependency graph and colors each node as the build moves through it. Each package gets its own log pane, so logs never mix.

The server is one Python file. It uses only the standard library. It works on any colcon workspace, because it reads the events.log and logger_all.log files that colcon writes under log/ for every build.

Install

The package has two parts: the colcon-dashboard command, and a colcon plugin that can start the dashboard when colcon build runs.

On Ubuntu, install the apt package from the PPA. This is the official method. It puts the plugin in the same Python environment as the apt colcon, where colcon finds it:

sudo add-apt-repository ppa:xmfcx/colcon-dashboard
sudo apt install python3-colcon-dashboard

For other setups, install from PyPI into the environment that runs colcon:

• colcon in a virtualenv or a conda environment: pip install colcon-dashboard in that environment.
• colcon installed with pipx: pipx inject colcon-common-extensions colcon-dashboard.
• For the colcon-dashboard command alone, without the plugin: pipx install colcon-dashboard.

To install from a checkout, replace the package name with the path to this repository.

Quick start

Run a build with the dashboard switched on. The plugin starts it and prints its address:

$ colcon build --event-handlers dashboard+
[colcon-dashboard] dashboard: http://127.0.0.1:8635/

The plugin stays off by default, so a plain colcon build starts no server.

For daily use, turn it on once. Pick one of these:

Add this line to your ~/.bashrc:

export COLCON_DASHBOARD=1

Or enable the handler in ~/.colcon/defaults.yaml:

build:
  event-handlers: [dashboard+]

After that, every colcon build starts the dashboard, or reuses the one that already runs for the workspace. The command line toggle wins over the environment default in both directions.

Each workspace gets exactly one server, on a stable port derived from the workspace path. A second colcon build reuses it, and a file lock refuses duplicate servers. The server keeps running after the build, so the page stays available for the next build and for post-mortems.

You can also run it by hand, with or without the plugin:

colcon-dashboard ~/projects/autoware          # start, or print the running URL
colcon-dashboard ~/projects/autoware --stop   # stop this workspace's server
colcon-dashboard --list                       # all running servers
colcon-dashboard --stop-all                   # stop every server

The server follows log/latest_build. If a new build starts in the same workspace, the page switches to it and shows a notice.

What the page shows

Header

The header shows the workspace path, the build id, a LIVE / COMPLETE / FAILED / STOPPED badge, and the parallel worker count.

The right side is the system strip. A colcon build can exhaust the machine, so pressure stays visible at all times:

• A per-core heatmap, one cell per core. Cell color runs from the idle gray to full blue at 100% use. Hover a cell for the exact number.
• CPU, RAM, and swap meters. A fill turns amber under pressure (CPU 85%, RAM 75%, swap 30%) and red near the limit (96%, 90%, 70%). At red the label also turns red and bold.
• Hover the CPU meter for the load average. Hover the RAM meter for the exact percentage.

Progress strip

The meter fills as the build advances: green for done, animated blue stripes for building, red for failed, orange for aborted.

The tiles count each state: done out of the total, building, ready, waiting (plus a blocked count after a failure), failed, aborted, and skipped. Elapsed time and the rate in packages per minute sit at the end.

Dependency graph

Every package in the build, laid out left to right by dependency depth. An edge points from a dependency to the package that needs it.

Node states combine color, border, and motion:

• Done: a green wash.
• Building: a blue box that slowly breathes, each node in its own rhythm. The box fills left to right with a deeper blue as make reports [ 42%] progress, and the label stays legible on top.
• Ready: a dashed blue border. All dependencies are done, and the package starts as soon as a worker becomes free.
• Next up: a slow pulse. This waiting package starts when the packages that build now finish, because no deeper dependency blocks it.
• Waiting: quiet gray. Skipped: gray with a struck label.
• Failed: solid red. Everything downstream of a failure turns red-dashed with red edges. This blast radius looks different from the packages that the stop only abandoned, which stay gray.
• Aborted: orange. The package was building when the build stopped.

Edges take color from their endpoints:

• Light green between two done packages: finished lineage.
• Solid blue into a building package, with droplets that flow along the edge at constant speed: the package consumes its finished dependencies.
• Dashed blue marching into a next-up package: what it waits for.
• Red along the failure cascade.

Interaction:

• Hover a node to see its state, phase, time, stderr count, and path, and to light its full dependency chain while the rest dims.
• Click a node to open its log pane.
• Drag to pan, scroll to zoom. Fit frames the whole graph. Frontier zooms to what builds now.
• This build / All packages switches between the build's packages and the whole workspace.
• When most package names share a prefix such as autoware_, the labels hide it. Tooltips keep the full name.

Layout modes

The layout menu picks one of three modes, and the choice persists:

• layered: the static left-to-right layout described above.
• force: a live spring simulation with the same left-to-right anchoring. Drag nodes to rearrange. The simulation cools and stops by itself.
• 3d: the build as a wavefront. Building packages share one central plane, finished discs stack to its left, and waiting discs queue to the right by dependency depth. Packages glide through the blue plane as the build advances. Left-drag orbits, shift-drag or right-drag or middle-drag pans, the wheel zooms, and the camera rotates by itself until the first grab.

Fit and Frontier drive the camera in every mode. In the force and 3D modes, a spread slider in the corner scales how far the simulation spreads the nodes.

Timeline

A Gantt chart of every started package, sorted by start time, with a time axis and a dashed now line. Bar colors match the graph states.

The chart makes the parallelism and the long serial chains visible. It auto-scrolls to the newest bars as they start. Scroll up to release, or use the ⤓ follow new toggle.

Log panes

The dock opens with a pinned build log tab: the whole build, as a terminal shows it, with Starting >>> and Finished <<< lines between every package's output. Click any package in the graph or the timeline to open its own tab next to it. Each tab has its own scrollback, so logs never interleave.

• A pane follows new output until you scroll up. The ⤓ follow button re-engages.
• Panes open at the tail for an instant start. ⤒ load all fetches the whole history in one click.
• Every line carries a timestamp: build-relative in the build log, job-relative in package panes. The 🕒 ts button hides them.
• The search box filters as you type: matching lines highlight, Enter and Shift+Enter step through them, and the search stays live while the log streams.
• A selector switches a package pane between the timestamped output, stdout+stderr, stderr, stdout, and the command log.
• ANSI colors render as in a terminal: the 16 classic colors, 256-color, and truecolor, with palettes tuned per theme. Uncolored lines that match error or warning patterns still get color.
• When a package fails, its pane opens by itself and a toast points to it.
• Drag the bar above the dock to resize it.

Theme

The page follows the system theme. The ◐ button cycles system, light, and dark. Every view recolors instantly, including the 3D canvas.

How it works

colcon writes a structured event stream to log/<build>/events.log. The server tails this file and reconstructs the exact job set from it. JobQueued events carry the full dependency closure of each job, as colcon resolved it. JobStarted, JobEnded, and JobSkipped events give the state machine. TimerEvent heartbeats give liveness, so the LIVE badge does not depend on process inspection.

The graph shows direct edges, not the full closure. The server computes the transitive reduction of colcon's per-job dependency sets. Package metadata (path, build type) and the edges of packages outside the current build come from a scan of the package.xml files in the workspace.

Per-package logs come from log/<build>/<package>/. The server serves them incrementally by byte offset, so an open pane costs one small request per second.

Options

API

Limits

• One server watches one workspace, and a lock enforces it. Each workspace gets its own server and port.
• The page follows the latest build. Finished builds stay readable until a new build starts.
• The server trusts the local workspace. Do not expose the port to an untrusted network.