software: singularity added example workflow for building a container.

software/singularity.rst

@@ -466,6 +466,46 @@ Only changes made in mounted files and folders
 will persist. (see `Container Architecture <arch_>`_)
 
 
+Example Building Workflow: Building a custom R container
+--------------------------------------------------------
+
+ 1. Build a sandbox from Singularity Hub Container.
+
+ .. code-block:: shell
+
+    singularity build -s r-sandbox shub://MPIB/singularity-r:3.4.4
+
+ 2. Work on changes. Test Functionality
+
+  .. code-block:: shell
+
+    sudo singularity shell -w r-sandbox
+    # Install R package.
+    R -e 'install.packages("ggplot2", repos="http://cran.uni-muenster.de")'
+    # Do something in R to see if it works as expected.
+
+ 3. Documenting changes in recipe file.
+
+ .. code-block:: shell
+
+    Bootstrap: shub
+    From: MPIB/singularity-r:3.4.4
+
+    %post
+    R -e 'install.packages("ggplot2", repos="http://cran.uni-muenster.de")'
+    # Saved into file called Singularity.3.4.4.ggplot2
+
+ 4. Repeat 2 and 3 till satisfied with the environment.
+
+ 5. Build Container or commit it to GitHub to let Singularity Hub build it.
+
+ .. code-block:: shell
+
+    sudo singularity build R-3-ggplot2 Singularity.3.4.4.ggplot2
+    # Oder
+    git add Singularity.3.4.4.ggplot2
+    git commit -m "Added recipe to create r 3.4.4 with ggplot2 installed"
+    git push
 
 Singularity Documentation
 -------------------------