3.0 migration guide by jan--f · Pull Request #15099 · prometheus/prometheus

jan--f · 2024-10-04T14:41:38Z

Just a first outline of the 3.0 migration guide. Looking forward to feedback!

Signed-off-by: Jan Fajerski <jfajersk@redhat.com>

tjhop · 2024-10-06T23:05:07Z

docs/stability.md

+    function](https://github.com/prometheus/prometheus/issues/2458)
+  * Remote remote read and the remote read endpoint
+* Server-side HTTPS and basic authentication
+* Service discovery integrations, with the exception of `static_configs` and `file_sd_configs`


Should HTTP SD be included in this list now as well?

tjhop · 2024-10-06T23:08:10Z

docs/migration.md

+- Some previously deprecated feature flags have been removed. Check that you no 
+  longer pass any of the following to `--enable-feature`: `promql-at-modifier`
+  `promql-negative-offset`, `remote-write-receiver`, 
+  `new-service-discovery-manager`, `expand-external-labels`, 
+  `no-default-scrape-port`.


I think this would be easier to follow with the options as a proper list

Yes. And state that you can still pass in these flags, just that they don't do anything anymore, and that a warning will be logged.

roidelapluie · 2024-10-07T08:54:44Z

We should remove references to 2.0 and link to the 2.55 docs to migrate from prom1 to prom2. STABILITY should only contain 3.0 stuff.

we should mention that it is only possible to rollback to 2.55 because of indexing change.

beorn7

Great start.

Left some comments and ideas.

beorn7 · 2024-10-08T14:48:21Z

docs/migration.md

+
+## PromQL
+
+- Regular expressions in PromQL not match newline characters.


not → now

But maybe also explain this better. IIRC this is about . that did not match newline before but now does, while you could of course create a regexp matching the newline character even in the old world (just not by using .).

As this is a migration guide, we should maybe provide a few examples (old regexp now also matches this other string, here is what you have to do to keep the old behavior).

beorn7 · 2024-10-08T14:51:11Z

docs/migration.md

+- Regular expressions in PromQL not match newline characters.
+- Lookback and range selectors are left open and right closed (previously left 
+  closed and right closed). This mostly means that the result size of range 
+  selectors is more predictable.


We need to explain more details, like that this is happening with "perfect" alignment, most typically happening in tests, so you probably have to change a lot of tests, but not a lot in practice.

With the special caveat of sub queries. As some frontends create nicely aligned queries (like Grafana), and sub-queries are internally always aligned to multiples of their step size, you will get this a lot with sub queries.

beorn7 · 2024-10-08T14:53:27Z

docs/migration.md

+  closed and right closed). This mostly means that the result size of range 
+  selectors is more predictable.
+- The `holt_winters` function has been renamed to `double_exponential_smoothing` 
+  and is now guarded by the `experimental_promql` feature flag.


The flag is called promql-experimental-functions.

We need to say things more clearly, along these lines:

If you want to keep using holt_winters, you have to do both of these things:

Rename holt_winters to double_exponential_smoothing in your query.

Make sure to pass --enable-feature=promql-experimental-functions.

(Wordsmithing still required.)

beorn7 · 2024-10-08T14:54:24Z

docs/migration.md

+- Some previously deprecated feature flags have been removed. Check that you no 
+  longer pass any of the following to `--enable-feature`: `promql-at-modifier`
+  `promql-negative-offset`, `remote-write-receiver`, 
+  `new-service-discovery-manager`, `expand-external-labels`, 
+  `no-default-scrape-port`.


Yes. And state that you can still pass in these flags, just that they don't do anything anymore, and that a warning will be logged.

beorn7 · 2024-10-08T14:55:26Z

docs/migration.md

+  `new-service-discovery-manager`, `expand-external-labels`, 
+  `no-default-scrape-port`.
+
+## PromQL


I think each point in the list below needs to be an own paragraph (or even subsection with heading) with examples and concrete migration steps (see comments below for inspiration).

docs/migration.md

beorn7 · 2024-10-08T15:11:46Z

Going through Prometheus 3.0 (view) should give more inspiration what to add here (and looking at the changelog, and making sure that all is consistent with each other).

Some things I have spotted:

UTF-8 support in name is now always on (might be surprising for some that special characters might show up in names now).
The whole "we won't interfere with you scrape ports anymore" thing, i.e. if people still want to see the default HTTP or HTTPS port, they have to specify it in their scrape config (and vice versa: if they don't want to see it, they must not specify it).

docs/migration.md

beorn7 · 2024-10-09T11:10:22Z

#15092 should be mentioned, too, i.e. the whole "selectors are actually expected to return matching results". This will only affect a few, but because it is so subtle, I would still call it out. Mostly for people who use "remote read hacks" (i.e. the whole "let's put a MySQL query in a label selector", maybe even with a hint how to still make the hack work (by adding a corresponding label to the result)).

jan--f · 2024-10-09T12:58:14Z

Thanks everyone so far. I'll address the feedback later this week, until then please keep it coming.

Signed-off-by: Jan Fajerski <jfajersk@redhat.com>

jan--f · 2024-10-11T14:05:48Z

Here is a first update according to reviews. There are some formatting warts to fix..

I'm still unsure about the "regex match \n" examples. its tricky to strike the right balance between accurate and succinct.

Happt to incorporate feedback via PRs against https://github.com/jan--f/prometheus/tree/3.0-migration too.

jan--f · 2024-10-11T14:06:19Z

Oh and I still want to add links to issues and PRs.

docs/stability.md

docs/migration.md

ywwg · 2024-10-16T14:39:43Z

docs/migration.md

+### UTF-8 names
+Prometheus v3 supports UTF-8 in metrics and label names. This means metrics and 
+label names can change after upgrading according to what is exposed by 
+endpoints.


I need to expand this to explain how to adjust configs to disallow utf8. Should I do that here or in a subsequent PR?

You can either create a PR against https://github.com/jan--f/prometheus/tree/3.0-migration or we merge this soon and then incremental improvements can be parallelized in p/p.

Signed-off-by: Jan Fajerski <jfajersk@redhat.com>

Signed-off-by: Owen Williams <owen.williams@grafana.com>

bwplotka · 2024-10-18T07:33:54Z

docs/migration.md

+the Prometheus 3.0 release contains a number of backwards incompatible changes.
+This document offers guidance on migrating from Prometheus 2.x to Prometheus 3.0 and newer versions.

 ## Flags


Can we add # Configuration

#15178 got renamed. While native histograms were experimental, it's worth mentioning the rename?

docs/migration.md

docs/migration: details on enabling legacy name validation

docs/migration.md

beorn7 · 2024-10-23T22:04:19Z

The change to log/slog should be mentioned as it changes the logging format.

old:

ts=2024-10-23T22:01:06.074Z caller=main.go:627 level=info msg="No time or size retention was set so using the default time retention" duration=15d
ts=2024-10-23T22:01:06.074Z caller=main.go:671 level=info msg="Starting Prometheus Server" mode=server version="(version=, branch=, revision=91d80252c3e528728b0f88d254dd720f6be07cb8-modified)"
ts=2024-10-23T22:01:06.074Z caller=main.go:676 level=info build_context="(go=go1.23.0, platform=linux/amd64, user=, date=, tags=unknown)"
ts=2024-10-23T22:01:06.074Z caller=main.go:677 level=info host_details="(Linux 5.15.0-124-generic #134-Ubuntu SMP Fri Sep 27 20:20:17 UTC 2024 x86_64 gigafips (none))"

new:

time=2024-10-24T00:03:07.542+02:00 level=INFO source=/home/beorn/go/src/github.com/prometheus/prometheus/cmd/prometheus/main.go:640 msg="No time or size retention was set so using the default time retention" duration=15d
time=2024-10-24T00:03:07.542+02:00 level=INFO source=/home/beorn/go/src/github.com/prometheus/prometheus/cmd/prometheus/main.go:681 msg="Starting Prometheus Server" mode=server version="(version=, branch=, revision=7c7116fea8343795cae6da42960cacd0207a2af8)"
time=2024-10-24T00:03:07.542+02:00 level=INFO source=/home/beorn/go/src/github.com/prometheus/prometheus/cmd/prometheus/main.go:686 msg="operational information" build_context="(go=go1.23.0, platform=linux/amd64, user=, date=, tags=unknown)" host_details="(Linux 5.15.0-124-generic #134-Ubuntu SMP Fri Sep 27 20:20:17 UTC 2024 x86_64 gigafips (none))" fd_limits="(soft=1048576, hard=1048576)" vm_limits="(soft=unlimited, hard=unlimited)"

beorn7 · 2024-10-23T22:05:31Z

Scrape config option scrape_classic_histograms is now called always_scrape_classic_histograms.

Signed-off-by: Jan Fajerski <jfajersk@redhat.com>

jan--f · 2024-10-24T11:44:43Z

Ok I addressed all recent comments. I would like to merge the current state if there are no glaring errors so its included in the RC release due at the end of this week.

Further additions and fixes can be added after that.

Signed-off-by: Jan Fajerski <jfajersk@redhat.com>

docs/migration.md

Signed-off-by: Jan Fajerski <jfajersk@redhat.com>

jesusvazquez

LGTM!

jan--f added 2 commits October 4, 2024 16:39

docs: 2 to 3 migration guide

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Signed-off-by: Jan Fajerski <jfajersk@redhat.com>

docs/stability: add 3.0 section

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docs/migration: address first review round

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Signed-off-by: Jan Fajerski <jfajersk@redhat.com>

jan--f force-pushed the 3.0-migration branch from f680fce to 6a12eee Compare October 11, 2024 14:02

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ywwg mentioned this pull request Oct 16, 2024

Epic: Implement UTF-8 character support for label and metric names #13095

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alexgreenbank mentioned this pull request Oct 17, 2024

scrape: provide a fallback format #15136

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jan--f and others added 2 commits October 17, 2024 16:36

Second review round

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Signed-off-by: Jan Fajerski <jfajersk@redhat.com>

docs/migration: details on enabling legacy name validation

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Merge pull request #5 from ywwg/owilliams/3.0-migration

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docs/migration: details on enabling legacy name validation

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jan--f added 2 commits October 24, 2024 10:23

migration: address more comments

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Signed-off-by: Jan Fajerski <jfajersk@redhat.com>

migration: add log format and le normalization

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Signed-off-by: Jan Fajerski <jfajersk@redhat.com>

migration: add new enable_http2 default for remote write

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jan--f enabled auto-merge October 25, 2024 09:40

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migration: fix typo

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Signed-off-by: Jan Fajerski <jfajersk@redhat.com>

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jan--f merged commit f131cdd into prometheus:main Oct 25, 2024

julienduchesne pushed a commit to julienduchesne/prometheus that referenced this pull request Dec 13, 2024

3.0 migration guide (prometheus#15099)

a1bcab5


		## PromQL

		- Regular expressions in PromQL not match newline characters.

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