Upgrades Hydra to the latest master/flake branch. To perform this
upgrade, it's needed to do a non-trivial db-migration which provides a
massive performance-improvement[1].
The basic ideas behind multi-step upgrades of services between NixOS versions
have been gathered already[2]. For further context it's recommended to
read this first.
Basically, the following steps are needed:
* Upgrade to a non-breaking version of Hydra with the db-changes
(columns are still nullable here). If `system.stateVersion` is set to
something older than 20.03, the package will be selected
automatically, otherwise `pkgs.hydra-migration` needs to be used.
* Run `hydra-backfill-ids` on the server.
* Deploy either `pkgs.hydra-unstable` (for Hydra master) or
`pkgs.hydra-flakes` (for flakes-support) to activate the optimization.
The steps are also documented in the release-notes and in the module
using `warnings`.
`pkgs.hydra` has been removed as latest Hydra doesn't compile with
`pkgs.nixStable` and to ensure a graceful migration using the newly
introduced packages.
To verify the approach, a simple vm-test has been added which verifies
the migration steps.
[1] https://github.com/NixOS/hydra/pull/711
[2] https://github.com/NixOS/nixpkgs/pull/82353#issuecomment-598269471
After upgrading to NixOS 20.03, I've got the following warning:
nginx: [warn] could not build optimal types_hash, you should increase either types_hash_max_size: 2048 or types_hash_bucket_size: 64; ignoring types_hash_bucket_size
The documentation states that "if nginx emits the message requesting
to increase either hash max size or hash bucket size then the first
parameter should first be increased" (aka types_hash_max_size).
In 19.03, the size of mime.types was around 100 entries. In 20.03, we
are around 900 entries. This is due to ff0148d868 which makes nginx
use mailcap mime.types.
In ff0148d868, nginx configuration was modified to use mime.types
from mailcap package as it is more complete. However, there are two
places where mime.types is included in configuration. When the user
was setting `cfg.httpConfig`, the mime.types from nginx was still
used. This commit fix that by moving the common snippet in a variable
of its own and ensure it is used at both places.
While our ETag patch works pretty fine if it comes to serving data off
store paths, it unfortunately broke something that might be a bit more
common, namely when using regexes to extract path components of
location directives for example.
Recently, @devhell has reported a bug with a nginx location directive
like this:
location ~^/\~([a-z0-9_]+)(/.*)?$" {
alias /home/$1/public_html$2;
}
While this might look harmless at first glance, it does however cause
issues with our ETag patch. The alias directive gets broken up by nginx
like this:
*2 http script copy: "/home/"
*2 http script capture: "foo"
*2 http script copy: "/public_html/"
*2 http script capture: "bar.txt"
In our patch however, we use realpath(3) to get the canonicalised path
from ngx_http_core_loc_conf_s.root, which returns the *configured* value
from the root or alias directive. So in the example above, realpath(3)
boils down to the following syscalls:
lstat("/home", {st_mode=S_IFDIR|0755, st_size=4096, ...}) = 0
lstat("/home/$1", 0x7ffd08da6f60) = -1 ENOENT (No such file or directory)
During my review[1] of the initial patch, I didn't actually notice that
what we're doing here is returning NGX_ERROR if the realpath(3) call
fails, which in turn causes an HTTP 500 error.
Since our patch actually made the canonicalisation (and thus additional
syscalls) necessary, we really shouldn't introduce an additional error
so let's - at least for now - silently skip return value if realpath(3)
has failed.
However since we're using the unaltered root from the config we have
another issue, consider this root:
/nix/store/...-abcde/$1
Calling realpath(3) on this path will fail (except if there's a file
called "$1" of course), so even this fix is not enough because it
results in the ETag not being set to the store path hash.
While this is very ugly and we should fix this very soon, it's not as
serious as getting HTTP 500 errors for serving static files.
I added a small NixOS VM test, which uses the example above as a
regression test.
It seems that my memory is failing these days, since apparently I *knew*
about this issue since digging for existing issues in nixpkgs, I found
this similar pull request which I even reviewed:
https://github.com/NixOS/nixpkgs/pull/66532
However, since the comments weren't addressed and the author hasn't
responded to the pull request, I decided to keep this very commit and do
a follow-up pull request.
[1]: https://github.com/NixOS/nixpkgs/pull/48337
Signed-off-by: aszlig <aszlig@nix.build>
Reported-by: @devhell
Acked-by: @7c6f434c
Acked-by: @yorickvP
Merges: https://github.com/NixOS/nixpkgs/pull/80671
Fixes: https://github.com/NixOS/nixpkgs/pull/66532
