ostree-metadata commit API #1946

dbnicholson · 2019-10-16T21:05:47Z

There are 2 pieces of this PR:

Add an ostree_repo_regenerate_metadata API that rebuilds the summary and the ostree-metadata commit and signs them both. Currently the ostree-metadata commit is only created by the ostree summary CLI. This adds a way for callers to reliably generate it.
Add the local ref map to the ostree-metadata commit. This spawned out of discussion in https://lists.freedesktop.org/archives/flatpak/2019-October/001784.html and WIP: Work on authenticated downloads flatpak/flatpak#3167 (review). Essentially, it seems that since you can't trust the ref map in the peer's summary file, it should be included in the mirrored ostree-metadata commit like the additional summary metadata so that all you need from the peer's summary is a list of what mirrored refs it has.

~~I can split out the 2nd part, but I figured I'd put them both here for discussion.~~

openshift-ci-robot · 2019-10-16T21:06:08Z

Hi @dbnicholson. Thanks for your PR.

I'm waiting for a ostreedev or openshift member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

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cgwalters · 2019-10-17T13:14:58Z

/ok-to-test

cgwalters · 2019-10-17T13:15:40Z

/approve

openshift-ci-robot · 2019-10-17T13:15:46Z

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: cgwalters, dbnicholson

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alexlarsson · 2019-10-17T15:14:36Z

I don't really understand the local ref map. Is this only about the flatpak xa.cache issue, or do you actually expect ostree to use this? If so, how?

In a situation where you're pulling N refs from M different p2p remotes you'll end up pulling the ostree-metadata ref from one of those M different remotes. And the rest of the N refs from some "random" subset depending on what refs each node has in their respective summary file. If the ostree-metadata you end up with is more recent than some of the other peers, do you expect to fail pulling those refs? That seems like a bad idea to me.

dbnicholson · 2019-10-17T17:08:18Z

I don't really understand the local ref map. Is this only about the flatpak xa.cache issue, or do you actually expect ostree to use this? If so, how?

In a situation where you're pulling N refs from M different p2p remotes you'll end up pulling the ostree-metadata ref from one of those M different remotes. And the rest of the N refs from some "random" subset depending on what refs each node has in their respective summary file. If the ostree-metadata you end up with is more recent than some of the other peers, do you expect to fail pulling those refs? That seems like a bad idea to me.

The way I see it, you pull the ostree-metadata ref and the summary file from all of the p2p peers. That's how you reliably determine what subset of the remote each of them have. As I said in flatpak/flatpak#3167 (comment), since you can't verify the peer's summary file, the only source of verification it provides is the mirrored ostree-metadata file from the time when it mirrored from the remote. Having a copy of the remote's ref map in the ostree-metadata file allows you to verify that the commits in the peer are actually from the remote without fetching the commit objects from the peer.

However, I'm not the P2P expert.

alexlarsson · 2019-10-18T06:45:56Z

The way I see it, you pull the ostree-metadata ref and the summary file from all of the p2p peers. That's how you reliably determine what subset of the remote each of them have. As I said in flatpak/flatpak#3167 (comment), since you can't verify the peer's summary file, the only source of verification it provides is the mirrored ostree-metadata file from the time when it mirrored from the remote. Having a copy of the remote's ref map in the ostree-metadata file allows you to verify that the commits in the peer are actually from the remote without fetching the commit objects from the peer.

However, I'm not the P2P expert.

Well, that is not how any ostree code is written today. The unique identified for the ref (i.e. the ref name + the collection id) can with the current repo layout only be stored once (as refs/mirrors/$collection_id/$ref), and it is pulled like any other ref, ie. from the highest priority available peer. Now, in theory one could pull it from all, but that is not how any code today works.

But, the summary isn't really necessary to verify the the ref, because the commit itself is also signed, and it includes a timestamp so that we can know if the update is a downgrade or not. So, I don't see the point of verifying it with the original summary.

The reason that flapak needs this information is because it stores info related to the refs inside the ostree-metadata itself (rather than in the commit itself), and it then needs to know what commit this data is about. As such, having the commit map in the summary could help (although the form this has uses much more space than the solution i did for flatpak only, as it duplicates every ref in the table, as well as using asciified commit ids instead of raw and including all refs rather than the required ones only.

dbnicholson · 2019-11-13T15:47:47Z

Given that the last commit does not have good agreement, I'll break that out into a separate PR and leave this just for the new API to handle updating the summary and ostree-metadata commit in one shot.

rh-atomic-bot · 2019-11-21T14:14:27Z

☔ The latest upstream changes (presumably #1968) made this pull request unmergeable. Please resolve the merge conflicts.

openshift-ci-robot · 2019-11-21T14:14:34Z

@dbnicholson: PR needs rebase.

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dbnicholson · 2020-01-21T20:26:54Z

I rebased this on master now and dropped the "ref-map in ostree-metadata" commit. But I did add on an additional change I originally did in #490 to make the summary and summary.sig in a tmpdir before renaming. Although this doesn't solve a race (as #490 was trying to do), it does mean that you won't publish a summary without a matched summary.sig file.

jlebon · 2020-01-24T19:25:47Z

src/libostree/ostree-repo.c

+ */
+gboolean
+ostree_repo_regenerate_metadata (OstreeRepo     *self,
+                                 GVariant       *additional_metadata,


Maybe summary_additional_metadata to make it clear this goes in the summary file?

I think since the metadata goes in both the summary and the ostree-metadata commit then that's not entirely true. But I don't mind if it changes name.

jlebon · 2020-01-24T19:27:39Z

src/libostree/ostree-repo.c

+                                 const gchar   **key_ids,
+                                 const gchar    *homedir,
+                                 GCancellable   *cancellable,
+                                 GError        **error)


Whenever we add new extensible APIs, I lean towards adding a GVariant *options arg to help future proof it a bit more. WDYT?

Excellent suggestion. I did that and dropped the explicit GPG parameters. Instead, you specify them in options with or without non-GPG signing keys. There are other things I think could be added in the future. For example, flatpak has an option to only list a subset of refs in the summary. I think that was mostly done because flathub's summary file was getting enormous.

jlebon · 2020-01-24T19:46:53Z

src/libostree/ostree-repo.c

+    {
+      g_debug ("Deleting existing unmatched summary.sig file");
+      if (!ot_ensure_unlinked_at (self->repo_dir_fd, "summary.sig", error))
+        return glnx_prefix_error (error, "Unable to delete summary signature file: ");


A small improvement is hoisting this out of the if and up to before doing the summary rename. That way, if we're able to rename the summary but not the signature, we don't have to hope that we can remove the old one.

But if you remove the old summary before writing the new one, then you're left with no summary signature if there are errors. I think it's preferable to leave it the old signature in place until you know the new summary has been written.

I suppose if you've specified that you're going to create the new summary without a signature, then you might as well remove the old one, though. Like:

if (!signing) remove_old_signature() rename_new_summary() if (signing) if (!rename_new_signature()) remove_old_signature()

Is that what you meant? I think it makes sense either way, but I can see the advantage of doing it that way.

rh-atomic-bot · 2020-01-27T16:28:40Z

☔ The latest upstream changes (presumably #1957) made this pull request unmergeable. Please resolve the merge conflicts.

dbnicholson · 2023-01-27T23:57:50Z

I decided to dust off this PR this week. It's mostly the same as before (I'll respond to the original comments above). The main difference is that I changed the API to take a GVariant *options where the GPG keys and/or sign keys can be specified. I don't think non-GPG signing existed when I first started this.

The other thing I did was make the ostree-metadata commit generation an explicit internal API. Back when flatpak was in the ostree-metadata business, @pwithnall suggested that there should be public API in ostree to create the commit. Several years later, flatpak has dropped it and I don't think there's any intention of bringing it back. I don't know if there are any other users of that commit that would benefit from a public API now.

cgwalters

Only gave this a really superficial skim so far...having to context switch in a lot here 😄

Very superficially, seems sane.

cgwalters · 2023-01-30T23:25:11Z

src/libostree/ostree-repo.c

                                                ';', NULL, &read_values, error))
      return glnx_throw(error, "Unable to parse bls-append-except-default");
-


Could probably do this trailing-whitespace trimming in a prep patch.

Good point. I only noticed after the fact that my editor is now following the .editorconfig setting to do that.

It seemed weird to only strip the trailing whitespace in the files I was touching, so I went all the way and added a prep commit that does all the C files. I can split that out to a separate PR if you prefer.

My editor started following the configuration in .editorconfig and is applying this rule to many files I'm editing. Let's just get this over with and strip everything. This was done like so: git ls-files | grep '\.[ch]$' | xargs sed -ri 's/\s+$//'

Currently this is just a wrapper around regenerating and signing the summary in one call, but later it will be used to also generate the `ostree-metadata` commit if the repo has a collection ID.

Call `ostree_repo_regenerate_metadata` with the provided GPG and sign keys to generate and sign the summary in one call. This changes the handling when GPGME support is disabled but GPG keys are supplied. Instead of silently ignoring the option, it will now error. IMO that's better as callers would otherwise not know that the summary is not GPG signed.

If a commit is being made during summary generation, then it would trigger the summary to be generated again. That's either unwanted busy work or could result in an infinite loop. Add a boolean in `OstreeRepoTxn` to disable automatic summary generation as seen fit.

Rather than creating the `ostree-metadata` commit in the summary builtin, do it in the new `ostree_repo_regenerate_metadata` API. The commit contents are unchanged and the commit is generated before the summary as before. To keep from triggering an extra summary update, automatic summary updating is disabled in the transaction. Since the summary builtin was already using the new API, it will continue to generate the `ostree-metadata` commit when the repo has a collection ID. However, the `ostree_repo_regenerate_summary` API will still only generate the summary file as before.

Refactor the summary signing APIs to use internal versions where the directory fd containing the summary can be found. The existing signing APIs still uses the repo directory fd, but this will allow using a temporary directory for the summary and signature in the new metadata generating API.

Use a temporary directory for the summary and signature file in `ostree_repo_regenerate_metadata` so that the summary file isn't published if signing fails. This prevents publishing a summary without a signature file or leaving a mismatched signature file in place.

cgwalters

Nice!

cgwalters · 2023-02-09T13:24:51Z

/override continuous-integration/jenkins/pr-merge

openshift-ci · 2023-02-09T13:24:59Z

@cgwalters: Overrode contexts on behalf of cgwalters: continuous-integration/jenkins/pr-merge

In response to this:

/override continuous-integration/jenkins/pr-merge

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openshift-ci-robot requested review from mwleeds and rfairley October 16, 2019 21:05

openshift-ci-robot added size/L needs-ok-to-test labels Oct 16, 2019

dbnicholson mentioned this pull request Oct 16, 2019

WIP: Work on authenticated downloads flatpak/flatpak#3167

Merged

openshift-ci-robot added ok-to-test and removed needs-ok-to-test labels Oct 17, 2019

openshift-ci-robot added the approved label Oct 17, 2019

openshift-ci-robot added the needs-rebase label Nov 21, 2019

dbnicholson force-pushed the ostree-metadata-api branch from 50fc3ba to d61b9f9 Compare January 21, 2020 20:25

dbnicholson mentioned this pull request Jan 22, 2020

Narrow summary file race #490

Closed

jlebon reviewed Jan 24, 2020

View reviewed changes

dbnicholson mentioned this pull request Dec 3, 2021

repo: Change locking for summary regeneration to be shared #2493

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dbnicholson force-pushed the ostree-metadata-api branch from d61b9f9 to cbb7a39 Compare January 24, 2023 19:08

openshift-merge-robot removed the needs-rebase label Jan 24, 2023

dbnicholson force-pushed the ostree-metadata-api branch 2 times, most recently from 1499816 to 9f8df39 Compare January 27, 2023 23:51

cgwalters reviewed Feb 1, 2023

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dbnicholson and others added 7 commits February 7, 2023 14:50

repo: Add API to regenerate and sign repo metadata

1384267

Currently this is just a wrapper around regenerating and signing the summary in one call, but later it will be used to also generate the `ostree-metadata` commit if the repo has a collection ID.

dbnicholson force-pushed the ostree-metadata-api branch from 9f8df39 to 6f86693 Compare February 7, 2023 21:51

cgwalters approved these changes Feb 9, 2023

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cgwalters merged commit 8025a83 into ostreedev:main Feb 9, 2023

dbnicholson deleted the ostree-metadata-api branch February 13, 2023 19:33

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ostree-metadata commit API #1946

ostree-metadata commit API #1946

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		';', NULL, &read_values, error))
		return glnx_throw(error, "Unable to parse bls-append-except-default");

ostree-metadata commit API #1946

ostree-metadata commit API #1946

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