Use lazy logging instead of f-strings in logger calls by pankajastro · Pull Request #2672 · astronomer/astronomer-cosmos

pankajastro · 2026-05-13T15:22:52Z

The codebase predominantly uses lazy logging
(logger.info("msg %s", arg)) but ~47 call sites across 15 files still embedded f-strings into the log message. Eager formatting defeats the point of lazy logging: the message is built even when the log level filters the record out, and structured-log handlers that key on record.msg can no longer match on the format template.

Convert every logger.{info,warning,error,debug,exception}(f"...") in cosmos/ to the lazy form, fixing one mixed-style call in cosmos/operators/_watcher/base.py that interpolated self.__class__.__name__ via f-string while using %s for other arguments.

Update tests/plugin/test_cluster_policy.py to assert against the new format-string + args calling convention.

No behaviour change.

Copilot

Pull request overview

This PR standardizes Cosmos’ logging style by replacing eager f-string interpolation in logger calls with lazy %s formatting, preserving the format template in record.msg and avoiding unnecessary string construction when logs are filtered out.

Changes:

Converted remaining logger.{debug,info,warning}(f"...") call sites in cosmos/ to lazy logging (logger.info("...", arg)).
Fixed one mixed-style watcher log message to be fully lazy-formatted.
Updated tests/plugin/test_cluster_policy.py assertions to match the new (msg_template, *args) logging convention.

Reviewed changes

Copilot reviewed 15 out of 15 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
tests/plugin/test_cluster_policy.py	Updates mock logger assertions to expect format string + args.
cosmos/versioning.py	Converts warning about broken symlink targets to lazy logging.
cosmos/plugin/cluster_policy.py	Converts queue-setting info log to lazy logging.
cosmos/operators/virtualenv.py	Converts virtualenv lock acquisition/release logs to lazy logging.
cosmos/operators/local.py	Converts XCom push info log to lazy logging.
cosmos/operators/_watcher/base.py	Converts fallback/retry logs to fully lazy logging (including class name).
cosmos/listeners/dag_run_listener.py	Converts telemetry decompression warning to lazy logging.
cosmos/dbt/selector.py	Converts “selector not found” warning to lazy logging.
cosmos/dbt/project.py	Converts several project/package helper logs to lazy logging.
cosmos/dbt/parser/project.py	Converts parser warnings to lazy logging.
cosmos/dbt/graph.py	Converts cache-related debug/info logs to lazy logging (including multi-arg performance logs).
cosmos/core/graph/entities.py	Converts “adding entity” info log to lazy logging.
cosmos/converter.py	Converts performance/debug/warning logs in converter to lazy logging.
cosmos/cache.py	Converts cache versioning and deletion logs to lazy logging.
cosmos/airflow/graph.py	Converts conversion debug logs to lazy logging.

Comments suppressed due to low confidence (1)

cosmos/cache.py:469

The log message has a double space before the %s placeholder ("for %s"). Consider removing the extra space to avoid inconsistent log templates between similar messages.

    logger.info("Delete the Cosmos cache stored remotely that hasn't been used for  %s", max_age_last_usage)

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Copilot

Pull request overview

Copilot reviewed 15 out of 15 changed files in this pull request and generated 2 comments.

Comments suppressed due to low confidence (1)

cosmos/cache.py:469

There appears to be an unintended double space before the "%s" placeholder ("for %s"). Consider removing the extra space to keep log output consistent and easier to search.

    logger.info("Delete the Cosmos cache stored remotely that hasn't been used for  %s", max_age_last_usage)

Copilot

Pull request overview

Copilot reviewed 16 out of 16 changed files in this pull request and generated 1 comment.

Copilot

Pull request overview

Copilot reviewed 16 out of 16 changed files in this pull request and generated no new comments.

codecov · 2026-05-13T16:22:34Z

Codecov Report

❌ Patch coverage is 93.75000% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 98.03%. Comparing base (4867faf) to head (eca00b8).

Files with missing lines	Patch %	Lines
cosmos/core/graph/entities.py	0.00%	1 Missing ⚠️
cosmos/dbt/parser/project.py	50.00%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2672   +/-   ##
=======================================
  Coverage   98.03%   98.03%           
=======================================
  Files         105      105           
  Lines        7843     7843           
=======================================
  Hits         7689     7689           
  Misses        154      154

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The codebase predominantly uses lazy logging (logger.info("msg %s", arg)) but ~47 call sites across 15 files still embedded f-strings into the log message. Eager formatting defeats the point of lazy logging: the message is built even when the log level filters the record out, and structured-log handlers that key on record.msg can no longer match on the format template. Convert every `logger.{info,warning,error,debug,exception}(f"...")` in cosmos/ to the lazy form, fixing one mixed-style call in cosmos/operators/_watcher/base.py that interpolated self.__class__.__name__ via f-string while using %s for other arguments. Update tests/plugin/test_cluster_policy.py to assert against the new format-string + args calling convention. No behaviour change. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>

Fix the remaining double space in the remote cache deletion log template, and switch the virtualenv lock log messages to self.log so they pick up the Airflow task context (task_id/dag_id) like the rest of the operator. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

The two dag-versioning tests asserted on the eagerly-formatted log message, which no longer holds now that converter.py uses lazy logging. Inspect the format string and args separately so the tests match the new calling convention. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>

tatiana

Thanks, @pankajastro , looks great.

Follow-up to #2672. The original sweep caught ~47 single-line logger.X(f"...") sites but missed two patterns: 1. Multi-line calls of the form logger.exception( f"..." ) in cosmos/plugin/airflow3.py (three sites) and cosmos/dbt/parser/output.py (one site). The original regex required the f-string on the same line as the logger call. 2. self.log.X(f"...") calls in operators that inherit Airflow's LoggingMixin. These never matched the original logger.X(f"...") pattern even though they violate the lazy logging rule identically. Affects azure_container_instance, docker, kubernetes, aws_ecs, gcp_cloud_run_job, and virtualenv operators. Also converts one eager percent-interpolation call in cosmos/cache.py ("%s" % repr(e)) that used %-formatting instead of an f-string and so was outside the scope of #2672. No behaviour change. --------- Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com> Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>

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pankajastro and others added 6 commits May 14, 2026 15:06

Potential fix for pull request finding

a8827b0

Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>

Potential fix for pull request finding

9a9506c

Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>

Potential fix for pull request finding

eca00b8

Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>

pankajastro force-pushed the lazy-log-formatting branch from 79d13a2 to eca00b8 Compare May 14, 2026 09:36

pankajastro temporarily deployed to internal May 14, 2026 09:36 — with GitHub Actions Inactive

tatiana approved these changes May 14, 2026

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pankajastro merged commit b8614e2 into main May 14, 2026
124 of 125 checks passed

pankajastro deleted the lazy-log-formatting branch May 14, 2026 14:20

pankajastro mentioned this pull request May 14, 2026

Convert remaining f-string logger calls to lazy form #2680

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pankajastro self-assigned this May 20, 2026

pankajastro modified the milestones: Cosmos 1.14.2, Cosmos 1.15.0 May 20, 2026

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Use lazy logging instead of f-strings in logger calls#2672

Use lazy logging instead of f-strings in logger calls#2672
pankajastro merged 6 commits into
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lazy-log-formatting

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pankajastro commented May 13, 2026

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