Add create_swapfile task

README.md

@@ -42,6 +42,7 @@ See `defaults/main.yml`
   - role: marvel-nccr.aiida-cws
     vars:
       aiida_timezone_name: Europe/Zurich  # to set a certain timezone for AiiDA
+      aiida_create_swapfile: true  # create a swapfile for RAM overflow, non-containers only
       aiida_allow_mpi_on_root: true  # containers only
 ```
 
@@ -54,7 +55,7 @@ If you want to install SLURM and use it as the scheduler, you can use e.g.:
   - role: marvel-nccr.aiida-cws
     vars:
       aiida_timezone_name: Europe/Zurich
-      aiida_allow_mpi_on_root: true
+      aiida_create_swapfile: true
       aiida_conda_code_computer: local_slurm_conda
 ```
 
@@ -226,7 +227,7 @@ Please direct inquiries regarding Quantum Mobile and associated ansible roles to
 - jupyter lab launcher
 - rest api service
 - check everything still works with non-root user install
-- understand set up of `swapfile` (doesn't seem to work on docker), plus other steps from `marvel-nccr.simulationbase`
+- migrate tasks from `marvel-nccr.simulationbase` (understand `hostname.yml`, which is non-container only, and `clean.yml`)
 - Get <https://github.com/quanshengwu/wannier_tools> on Conda, to replace `marvel-nccr.wannier_tools`
 
 - run code tests (how to check success <https://github.com/aiidateam/aiida-common-workflows/issues/289>?):

defaults/main.yml

@@ -7,6 +7,7 @@ aiida_release_notes: "${HOME}/aiida_release_notes.ini"
 aiida_temp_folder: /tmp
 aiida_data_folder_temp: "${HOME}/.local/share/aiida"
 aiida_allow_mpi_on_root: false  # should only be set for containers
+aiida_create_swapfile: false
 aiida_apt_packages:
 - vim    # required for manual verdi code/computer setup
 - ssh    # required by MPI

tasks/create_swapfile.yml

@@ -0,0 +1,32 @@
+# When the computer doesn't have enough RAM to hold everything it needs,
+# it can move some it doesn't need immediately to the hard drive.
+# It's incredibly slow, but it's usually considered better than the computer crashing.
+# This is required by many simulation codes.
+# see: https://www.techtarget.com/searchwindowsserver/definition/swap-file-swap-space-or-pagefile
+# note this can not be added in a container, since there the underlying OS handles memory
+
+- name: "Check if swapfile exists"
+  stat: path=/swapfile
+  register: swapfile_stat
+
+- block:
+
+  - name: "Create swapfile"
+    become: true
+    command: "dd if=/dev/zero of=/swapfile bs=1M count=1024"
+
+  - name: "Make the swapfile a valid swap"
+    become: true
+    command: "mkswap /swapfile"
+
+  - name: "Use the swapfile"
+    become: true
+    command: "swapon /swapfile"
+
+  - name: "Put a line in fstab to ensure swap is used at boot time"
+    become: true
+    lineinfile:
+      path: "/etc/fstab"
+      line: "/swapfile swap swap defaults 0 0"
+
+  when: not swapfile_stat.stat.exists

tasks/shared.yml

@@ -19,6 +19,10 @@
     name: "{{ aiida_timezone_name }}"
   when: aiida_timezone_name is defined
 
+- name: Setup swapfile RAM "overspill"
+  include_tasks: create_swapfile.yml
+  when: aiida_create_swapfile
+
 - name: Set user environmental variables
   # OMP_NUM_THREADS: https://github.com/marvel-nccr/quantum-mobile/issues/187
   # MAMBA_NO_BANNER: https://github.com/mamba-org/mamba/issues/587#issuecomment-762998474