[Bug 1799251] Re: mount options for /run should be the same as initramfs tools

[Dimitri John Ledkov]

** Description changed:

  mount options for /run should be the same as initramfs tools
+ 
+ [Impact]
+ 
+  * /run is mounted with different options on initrd boots, and initrd-
+ less boots. For consistency it should be the same
+ 
+  * In particular, this causes overuse of RAM on hosts with dense
+ deployment of containers. Specifically, runtime journald takes up at
+ most 10% or /run, which is capped at 10% of ram, thus 1% of total RAM.
+ However, on initrd-less boots (like lxd launch ubuntu-daily:foo), /run
+ takes up all of RAM, and thus run-time journal is now capped at 10% of
+ RAM. Which is really bad when one deploys more than 10 containers...
+ 
+ [Test Case]
+ 
+  * Check total RAM on the host with `free -h`
+  * lxd launch ubuntu-daily:release
+  * In that container check the size of /run with `df -h | grep '/run$'`
+  * /run should roughly be 1/10th of the total RAM.
+ 
+ [Regression Potential]
+ 
+  * /run is meant to be small, and it is small on systems booted with
+ initrd and everything works fine there. Reducing the default size of
+ /run in the containers should not have averse impacts. The most notable
+ change is that runtime journald is now capped 10x smaller in the
+ containers, to the same size as on the hosts. If that is not enough, one
+ should $ sudo mkdir /var/log/journal to have a larger persistent
+ journal.
+ 
+ [Other Info]
+  
+  * This issue got escalated as affecting production deployments in the Canonical datacentre.

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https://bugs.launchpad.net/bugs/1799251

Title:
  mount options for /run should be the same as initramfs tools

Status in systemd package in Ubuntu:
  Fix Committed
Status in systemd source package in Xenial:
  New
Status in systemd source package in Bionic:
  New
Status in systemd source package in Cosmic:
  In Progress

Bug description:
  mount options for /run should be the same as initramfs tools

  [Impact]

   * /run is mounted with different options on initrd boots, and initrd-
  less boots. For consistency it should be the same

   * In particular, this causes overuse of RAM on hosts with dense
  deployment of containers. Specifically, runtime journald takes up at
  most 10% or /run, which is capped at 10% of ram, thus 1% of total RAM.
  However, on initrd-less boots (like lxd launch ubuntu-daily:foo), /run
  takes up all of RAM, and thus run-time journal is now capped at 10% of
  RAM. Which is really bad when one deploys more than 10 containers...

  [Test Case]

   * Check total RAM on the host with `free -h`
   * lxd launch ubuntu-daily:release
   * In that container check the size of /run with `df -h | grep '/run$'`
   * /run should roughly be 1/10th of the total RAM.

  [Regression Potential]

   * /run is meant to be small, and it is small on systems booted with
  initrd and everything works fine there. Reducing the default size of
  /run in the containers should not have averse impacts. The most
  notable change is that runtime journald is now capped 10x smaller in
  the containers, to the same size as on the hosts. If that is not
  enough, one should $ sudo mkdir /var/log/journal to have a larger
  persistent journal.

  [Other Info]
   
   * This issue got escalated as affecting production deployments in the Canonical datacentre.

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