* nixos/buildkite: drop user option
This reverts 8c6b1c3eaa.
Turns out, buildkite-agent has logic to write .ssh/known_hosts files and
only really works when $HOME and the user homedir are in sync.
On top of that, we provision ssh keys in /var/lib/buildkite-agent, which
doesn't work if that other users' homedir points elsewhere (we can cheat
by setting $HOME, but then getent and $HOME provide conflicting
results).
So after all, it's better to only run the system-wide buildkite agent as
the "buildkite-agent" user only - if one wants to run buildkite as
different users, systemd user services might be a better fit.
* nixosTests.buildkite-agent: add node with separate user and no ssh key
The current nixpkgs use elasticsearch-curator 5.8.1. As of version 5.7.0,
elasticsearch-curator supports elasticsearch 7, thus this change enables tests
with ES 7.
Updates required:
- Use vpc image format (new default, supported by Amazon)
- Pass full image filename to makeEc2Test
- Increase memory allocation for nixos-rebuild
- Set a networking.hostName for services.httpd
- Add appropriate escaping in literal userdata
While I'm here, try to make it fail fast.
This fixes the patch for nginx to clear the Last-Modified header if a
static file is served from the Nix store.
So far we only used the ETag from the store path, but if the
Last-Modified header is always set to "Thu, 01 Jan 1970 00:00:01 GMT",
Firefox and Chrome/Chromium seem to ignore the ETag and simply use the
cached content instead of revalidating.
Alongside the fix, this also adds a dedicated NixOS VM test, which uses
WebDriver and Firefox to check whether the content is actually served
from the browser's cache and to have a more real-world test case.
This is what I've suspected a while ago[1]:
> Heads-up everyone: After testing this in a few production instances,
> it seems that some browsers still get cache hits for new store paths
> (and changed contents) for some reason. I highly suspect that it might
> be due to the last-modified header (as mentioned in [2]).
>
> Going to test this with last-modified disabled for a little while and
> if this is the case I think we should improve that patch by disabling
> last-modified if serving from a store path.
Much earlier[2] when I reviewed the patch, I wrote this:
> Other than that, it looks good to me.
>
> However, I'm not sure what we should do with Last-Modified header.
> From RFC 2616, section 13.3.4:
>
> - If both an entity tag and a Last-Modified value have been
> provided by the origin server, SHOULD use both validators in
> cache-conditional requests. This allows both HTTP/1.0 and
> HTTP/1.1 caches to respond appropriately.
>
> I'm a bit nervous about the SHOULD here, as user agents in the wild
> could possibly just use Last-Modified and use the cached content
> instead.
Unfortunately, I didn't pursue this any further back then because
@pbogdan noted[3] the following:
> Hmm, could they (assuming they are conforming):
>
> * If an entity tag has been provided by the origin server, MUST
> use that entity tag in any cache-conditional request (using If-
> Match or If-None-Match).
Since running with this patch in some deployments, I found that both
Firefox and Chrome/Chromium do NOT re-validate against the ETag if the
Last-Modified header is still the same.
So I wrote a small NixOS VM test with Geckodriver to have a test case
which is closer to the real world and I indeed was able to reproduce
this.
Whether this is actually a bug in Chrome or Firefox is an entirely
different issue and even IF it is the fault of the browsers and it is
fixed at some point, we'd still need to handle this for older browser
versions.
Apart from clearing the header, I also recreated the patch by using a
plain "git diff" with a small description on top. This should make it
easier for future authors to work on that patch.
[1]: https://github.com/NixOS/nixpkgs/pull/48337#issuecomment-495072764
[2]: https://github.com/NixOS/nixpkgs/pull/48337#issuecomment-451644084
[3]: https://github.com/NixOS/nixpkgs/pull/48337#issuecomment-451646135
Signed-off-by: aszlig <aszlig@nix.build>
