tree 1bc2e79cffe7c0d8a2a8b3d1596867493db2b7f5
parent fdc3a2473e4ebfd77db342252e1088882e01b2d6
author Serge Bazanski <serge@monogon.tech> 1649326386 +0200
committer Sergiusz Bazanski <serge@monogon.tech> 1650355560 +0000

scripts: devcontainer: mount tmpfs on /tmp

This makes tests generally faster, but most importantly, it
significantly deflakes etcd-heavy tests, especially when run with
--runs_per_test=many. Without this, the underlying FS is overlayfs-fuse,
which has very little iops to spare, to the point where etcd servers in
tests will take hundreds of seconds because of iops starvation.

Some cherrypicked figures:

Before:

//metropolis/installer/test:installer                                    PASSED in 30.8s
//metropolis/pkg/event/etcd:etcd_test                                    PASSED in 14.6s

After:
//metropolis/installer/test:installer                                    PASSED in 18.9s
//metropolis/pkg/event/etcd:etcd_test                                    PASSED in 6.1s

This has the downside of possibly eating more RAM on developer machines,
but RAM is cheap. Importantly, our test suite seems to not leak things
into /tmp (other than some leftover empty directories), so RAM usage
within the build container shouldn't balloon.

This is also something that's irrelevant for CI, as CI doesn't use
scripts/{build,destroy}_container.sh.

Change-Id: Iae12f6fdd5b48685f17f1466f2695f3707a0dd62
Reviewed-on: https://review.monogon.dev/c/monogon/+/653
Reviewed-by: Leopold Schabel <leo@nexantic.com>