Merge pull request #406 from gedankenstuecke/add_r_description

add R DESCRIPTION support

docs/source/config_files.rst

@@ -96,6 +96,17 @@ We use ``apt.txt``, for example, to install LaTeX in our
 `example apt.txt for LaTeX <https://github.com/binder-examples/latex/blob/master/apt.txt>`_.
 
 
+``DESCRIPTION``
+~~~~~~~~~~~~~~~
+
+To install your repository like an R package, you may include a
+``DESCRIPTION`` file. repo2docker installs the package and dependencies
+ from the ``DESCRIPTION`` by running ``devtools:install_git(".")``.
+
+ You also need to have a ``runtime.txt`` file that is formatted as
+ ``r-<YYYY>-<MM>-<DD>``, where YYYY-MM-DD is a snapshot of MRAN that will be
+ used for your R installation.
+
 .. _postBuild:
 
 ``postBuild`` - Run code after installing the environment

repo2docker/buildpacks/r.py

@@ -69,7 +69,16 @@ class RBuildPack(PythonBuildPack):
         """
         # If no date is found, then self.checkpoint_date will be False
         # Otherwise, it'll be a date object, which will evaluate to True
-        return bool(self.checkpoint_date)
+        if self.checkpoint_date:
+            return True
+        description_R = 'DESCRIPTION'
+        if not os.path.exists('binder') and os.path.exists(description_R):
+            if not self.checkpoint_date:
+                # no R snapshot date set through runtime.txt
+                # set the R runtime to the latest date that is guaranteed to be on MRAN across timezones
+                self._checkpoint_date = datetime.date.today() - datetime.timedelta(days=2)
+                self._runtime = "r-{}".format(str(self._checkpoint_date))
+            return True
 
     def get_path(self):
         """
@@ -257,4 +266,13 @@ class RBuildPack(PythonBuildPack):
                 )
             ]
 
+        description_R = 'DESCRIPTION'
+        if not os.path.exists('binder') and os.path.exists(description_R):
+            assemble_scripts += [
+                (
+                    "${NB_USER}",
+                    'R --quiet -e "devtools::install_local(getwd())"'
+                )
+            ]
+
         return assemble_scripts

tests/r/description-file/DESCRIPTION

@@ -0,0 +1,7 @@
+Package: binderdescription
+Version: 0.1
+Date: 2018-09-18
+Title: Binder R DESCRIPTION support
+Description: Test that automatically building R packages works
+Author: Bastian Greshake Tzovaras <bgreshake@googlemail.com>
+Maintainer: Bastian Greshake Tzovaras <bgreshake@googlemail.com>

tests/r/description-file/NAMESPACE

@@ -0,0 +1,2 @@
+# Export all names
+exportPattern(".")

tests/r/description-file/R/print_something.R

@@ -0,0 +1,4 @@
+print_something <- function()
+  {
+    print('blah');
+  }

tests/r/description-file/README.md

@@ -0,0 +1,4 @@
+# Test that `repo2docker` will build an R package
+
+If a `DESCRIPTION` file is present along with an `R`-requiring `runtime.txt`
+, repo2docker should build the R package that is in the repository.

tests/r/description-file/verify

@@ -0,0 +1,2 @@
+#!/usr/bin/env Rscript
+library('binderdescription')