Add -n/--tail support to lstk logs#359
Open
gtsiolis wants to merge 1 commit into
Open
Conversation
gtsiolis
added
semver: minor
docs: needed
gtsiolis
force-pushed
the
pro-358-support-n-tail-n-in-lstk-logs
branch
4 times, most recently
from
July 9, 2026 07:11
cff248a to
b3e7ad8
Compare
gtsiolis
force-pushed
the
pro-358-support-n-tail-n-in-lstk-logs
branch
4 times, most recently
from
July 17, 2026 13:47
80c342e to
52b13c3
Compare
gtsiolis
marked this pull request as ready for review
July 17, 2026 13:48
gtsiolis
force-pushed
the
pro-358-support-n-tail-n-in-lstk-logs
branch
from
July 20, 2026 07:16
52b13c3 to
a8809b2
Compare
gtsiolis
force-pushed
the
pro-358-support-n-tail-n-in-lstk-logs
branch
from
July 21, 2026 07:08
a8809b2 to
a3a8697
Compare
skyrpex
requested changes
Jul 21, 2026
Contributor
There was a problem hiding this comment.
The tail value is computed before filtering, so the output is confusing in some scenarios. For example, when the latest log entries are of type INFO:
$ ./bin/lstk logs --verbose
emulator |
emulator | LocalStack version: 2026.6.3
emulator | LocalStack build date: 2026-07-15
emulator | LocalStack build git hash: 7bf63b7c4
emulator |
emulator | 2026-07-21T12:19:57.291 INFO --- [ MainThread] l.p.c.b.licensingv2 : Successfully activated cached license cc9b6903-7df5-4afb-9d50-f27d7c
9a4cf5:enterprise from /var/lib/localstack/cache/license.json 🔑✅
emulator | 2026-07-21T12:20:00.115 INFO --- [ MainThread] l.p.c.extensions.plugins : loaded 0 extensions
emulator | Ready.
emulator | 2026-07-21T12:20:02.016 INFO --- [et.reactor-2] localstack.request.http : GET /_localstack/pods/state/metamodel => 200
emulator | 2026-07-21T12:20:02.017 INFO --- [et.reactor-1] localstack.request.http : GET /_localstack/pods/state/metamodel => 200
emulator | 2026-07-21T12:20:02.017 INFO --- [et.reactor-0] localstack.request.http : GET /_localstack/pods/state/metamodel => 200
emulator | 2026-07-21T12:20:02.024 INFO --- [et.reactor-1] localstack.request.http : GET /_localstack/pods/state/metamodel => 200
emulator | 2026-07-21T12:20:02.025 INFO --- [et.reactor-2] localstack.request.http : GET /_localstack/pods/state/metamodel => 200
emulator | 2026-07-21T12:20:02.026 INFO --- [et.reactor-0] localstack.request.http : GET /_localstack/pods/state/metamodel => 200For reference, this is the $ ./bin/lstk logs output:
emulator |
emulator | LocalStack version: 2026.6.3
emulator | LocalStack build date: 2026-07-15
emulator | LocalStack build git hash: 7bf63b7c4
emulator |
emulator | 2026-07-21T12:19:57.291 INFO --- [ MainThread] l.p.c.b.licensingv2 : Successfully activated cached license cc9b6903-7df5-4afb-9d50-f27d7c
9a4cf5:enterprise from /var/lib/localstack/cache/license.json 🔑✅
emulator | 2026-07-21T12:20:00.115 INFO --- [ MainThread] l.p.c.extensions.plugins : loaded 0 extensions
emulator | Ready.
Now, if I run ./bin/lstk logs --tail 1 the output is empty as it's tailed on the full set first, and then filtered afterwards. What I expect, as a user, is the following:
$ ./bin/lstk logs --tail 1
emulator | Ready.
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
2 participants
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
Motivation
DevRel parity report: the Python CLI supports
localstack logs -n 20to inspect the last N log lines, whilelstk logsonly offered all-or-follow — cumbersome on a busy emulator and a migration papercut.-n, --tail(defaultall) is also the exact convention ofdocker logs,docker compose logs, andnerdctl logs.Changes
-n, --tailtolstk logs(string, default"all", wording identical todocker logs); validated at the command boundary — non-negative integer orallcontainer.Logs/ui.RunLogsintoruntime.StreamLogs, which previously hardcodedTail: "all"--follow --tail Nshows the last N lines and then streams (handled natively by the Docker API)MockRuntimefor theStreamLogssignature changeTail applies to raw log lines before the noise filter (docker semantics), so
--tail 20can display fewer than 20 lines unless-vis passed.Tests
--tail/-nlimit output, default shows all lines, invalid values are rejected with a helpful error, and--follow --tailstarts from the tail--tail 0,--tail all, over-count values, and combined-fn 3Closes PRO-358