01/01: website: Add Tatiana's GSoC report.

[Ricardo Wurmus]

rekado pushed a commit to branch master
in repository guix-artwork.

commit eb9a61be99d34c06200c06c3ea8ed1ac9a7853e1
Author: Ricardo Wurmus <address@hidden>
Date:   Tue Aug 14 13:50:52 2018 +0200

    website: Add Tatiana's GSoC report.
---
 website/posts/gsoc-report-2018.md             | 155 ++++++++++++++++++++++++++
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 website/static/blog/img/cuirass-wi-evals.png  | Bin 0 -> 41121 bytes
 website/static/blog/img/cuirass-wi-main.png   | Bin 0 -> 31306 bytes
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+title: GSoC 2018 report: Cuirass Web interface
+date: 2018-08-13 17:00
+author: Tatiana Sholokhova
+tags: Cuirass, GSoC, final report
+---
+
+For the last three months I have been working with the Guix team as a
+Google Summer of Code intern. The title of my project is "GNU Guix
+(Cuirass): Adding a web interface similar to the Hydra web interface".
+
+Cuirass is a continuous integration system which monitors the Guix git
+repository, schedules builds of Guix packages, and presents the build
+status of all Guix packages.  Before my project, Cuirass did not have
+a web interface. The goal of the project was to implement an interface
+for Cuirass which would allow a user to view the overall build
+progress, details about evaluations, build failures, etc.  The web
+interface of [Hydra](https://hydra.nixos.org/) is a good example of
+such a tool.
+
+In this post, I present a final report on the project. The Cuirass
+repository with the changes made during the project is located at
+[http://git.savannah.gnu.org/cgit/guix/guix-cuirass.git](http://git.savannah.gnu.org/cgit/guix/guix-cuirass.git).
 A
+working instance of the implemented interface is available at
+[https://berlin.guixsd.org/](https://berlin.guixsd.org/).  You can
+find more examples and demonstrations of the achieved results below.
+
+# About Cuirass
+
+Cuirass is designed to monitor a git repository containing Guix
+package definitions and build binaries from these package definitions.
+The state of planned builds is stored in a SQLite database. The key
+concepts of the Cuirass internal state are:
+
+- **Job specification**. Specifications state what has actually to be
+  done by Cuirass. A specification [is
+  
defined](https://www.gnu.org/software/guix/manual/en/html_node/Continuous-Integration.html)
+  by a Scheme data structure (an association list) which includes a
+  job name, repository URL, as well as the branch and a procedure
+  `proc` that specifies how this is to be built.
+
+- **Evaluation**. An evaluation is a high-level build actcion
+  related to a certain revision of a repository of a given
+  specification.  For each specification, Cuirass continuously
+  produces new evaluations which build different versions of the
+  project represented by revisions of the corresponding repository.
+  Derivations and builds (see below) each belong to a specific
+  evaluation.
+
+- **Derivation**. Derivations represent low-level build actions.  They
+  store such information as name of a build script and its arguments,
+  input and output of a build action, target system type, and
+  necessary environment variables.
+
+- **Build**. A build is a result of build actions that are prescribed
+  by a derivation.  This could be a failed build or a directory
+  containing the files that were generated by compiling a package.
+
+Besides the core which executes build actions and records their
+results in the database, Cuirass includes a web server which
+previously only responded to a handful of API requests with JSON
+containing information about the current status of builds.
+
+# Web interface
+
+The Cuirass web interface implemented during the project is served by
+the Cuirass web server whose functionality has been extended to
+generating HTML responses and serving static files.  General features
+of the interface are listed below.
+
+- The backend is written in Guile and implements request processing
+  procedures which parse request parameters and extract specific data
+  to be displayed from the database.
+
+- The frontend consists of HTML templates represented with [Guile
+  SXML](https://www.gnu.org/software/guile/manual/html_node/SXML.html)
+  and the [Bootstrap 4](https://getbootstrap.com/) CSS library.
+    
+- The appearance is minimalistic. Every page includes only specific
+  content information and basic navigation tools.
+
+- The interface is lightweight and widely accessible.  It does not use
+  JavaScript which makes it available to users who do not want to have
+  JavaScript running in the browser.
+
+## Structure
+
+Let's review the structure of the interface and take a look at the
+information you can find in it.  Note that the web-interface
+screenshots presented below were obtained with synthetic data loaded
+into Cuirass database.
+
+### Main page
+
+The main page is accessible on the root request endpoint (`/`).  The
+main page displays a list of all the specifications stored in the
+Cuirass database.  Each entry of the list is a clickable link which
+leads to a page about the evaluations of the corresponding
+specification (see below).
+
+Here is an example view of the main page.
+
+![Main page 
screenshot](https://www.gnu.org/software/guix/static/blog/img/cuirass-wi-main.png)
+
+### Evaluations list
+
+The evaluations list of a given specification with name `<name>` is
+located at `/jobset/<name>/`.  On this page, you can see a list of
+evaluations of the given project starting from the most recent ones.
+You can navigate to older evaluations using the pagination buttons at
+the bottom of the page.  In the table, you can find the following
+information:
+
+- The ID of the evaluation which is clickable and leads to a page with
+  information about all builds of the evaluation (see below).
+
+- List of commits corresponding to the evaluation.
+
+- Build summary of the evaluation: number of succeeded (green), failed
+  (red), and scheduled (grey) builds of this evaluation.  You can open
+  the list of builds with a certain status by clicking on one of these
+  three links.
+
+Here is a possible view of the evaluations list page:
+
+![Screenshoot of evaluations 
list](https://www.gnu.org/software/guix/static/blog/img/cuirass-wi-evals.png)
+
+### Builds list
+
+The builds list of a evaluation with ID `<id>` is located at
+`/eval/<id>/`.  On this page, you can see a list of builds of the
+given evaluation ordered by their stop time starting from the most
+recent one.  Similarly to the evaluation list, there are pagination
+buttons located at the bottom of the page.  For each build in the
+list, there is information about the build status (succeeded, failed,
+or scheduled), stop time, nixname (name of the derivation), system, and
+also a link to the corresponding build log.  As said above, it is
+possible to filter builds with a certain status by clicking on the
+status link in the evaluations list.
+
+![Screenshot of builds 
list](https://www.gnu.org/software/guix/static/blog/img/cuirass-wi-builds.png)
+
+# Summary
+
+Cuirass now has the web interface which makes it possible for users to
+get an overview on the status of Guix package builds in a
+user-friendly way.  As the result of my GSoC internship, the core of
+the web interface was developed.  Now there are several possibilities
+for future improvements and I would like to welcome everyone to
+contribute.
+
+It was a pleasure for me to work with the Guix team.  I would like to
+thank you all for this great experience!  Special thanks to my GSoC
+mentors: Ricardo Wurmus, Ludovic Courtès, and Gábor Boskovits, and
+also to Clément Lassieur and Danny Milosavljevic for their guidance
+and help throughout the project.
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