Cache rock build results for register-typed rocks

[weiiwang01]

Applicable spec:

Overview

Caching rock build results to speed up the CI pipeline.

The rocks are cached if they:

• Have been uploaded to the GitHub registry, which allows us to cache only a pointer to the registry location, thus not consuming cache storage space and speeding up the caching process
• Are not PaaS charms, because for PaaS charms the rock is usually the entire project, which changes more frequently and therefore benefits less from caching

The cache is invalidated and the rocks are rebuilt when:

• The contents of the rock directory have changed
• The cache is older than 1 week

Rationale

Workflow Changes

Checklist

• The contributing guide was applied
• The PR is tagged with appropriate label (urgent, trivial, complex)
• The changelog is updated with user-relevant changes in the format of keep a changelog v1.1.0

[Thanhphan1147]

Can we add an option to skip the cache and rebuild the rock regardless? since some rocks don't have everything pinned and the output can change from one build to the next even if the content has not changed.

[weiiwang01]

Can we add an option to skip the cache and rebuild the rock regardless? since some rocks don't have everything pinned and the output can change from one build to the next even if the content has not changed.

In that case you can go to cache setting page and delete the cache which will force it to rebuild the rock.

https://github.com/canonical/wordpress-k8s-operator/actions/caches

[github-actions]

Test results for commit 504507a

Test coverage for 504507a

Name           Stmts   Miss Branch BrPart  Cover   Missing
----------------------------------------------------------
src/charm.py       8      8      0      0     0%   8-25
----------------------------------------------------------
TOTAL              8      8      0      0     0%

Static code analysis report

Run started:2026-03-04 09:34:17.637488+00:00

Test results:
  No issues identified.

Code scanned:
  Total lines of code: 56
  Total lines skipped (#nosec): 0
  Total potential issues skipped due to specifically being disabled (e.g., #nosec BXXX): 0

Run metrics:
  Total issues (by severity):
  	Undefined: 0
  	Low: 0
  	Medium: 0
  	High: 0
  Total issues (by confidence):
  	Undefined: 0
  	Low: 0
  	Medium: 0
  	High: 0
Files skipped (0):

[github-actions]

Test results for commit 504507a

Test coverage for 504507a

Name           Stmts   Miss Branch BrPart  Cover   Missing
----------------------------------------------------------
src/charm.py       8      8      0      0     0%   8-25
----------------------------------------------------------
TOTAL              8      8      0      0     0%

Static code analysis report

Run started:2026-03-04 09:34:20.186936+00:00

Test results:
  No issues identified.

Code scanned:
  Total lines of code: 56
  Total lines skipped (#nosec): 0
  Total potential issues skipped due to specifically being disabled (e.g., #nosec BXXX): 0

Run metrics:
  Total issues (by severity):
  	Undefined: 0
  	Low: 0
  	Medium: 0
  	High: 0
  Total issues (by confidence):
  	Undefined: 0
  	Low: 0
  	Medium: 0
  	High: 0
Files skipped (0):

[github-actions]

Test results for commit 504507a

Test coverage for 504507a

Name           Stmts   Miss Branch BrPart  Cover   Missing
----------------------------------------------------------
src/charm.py       8      8      0      0     0%   8-25
----------------------------------------------------------
TOTAL              8      8      0      0     0%

Static code analysis report

Run started:2026-03-04 09:46:20.559258+00:00

Test results:
  No issues identified.

Code scanned:
  Total lines of code: 56
  Total lines skipped (#nosec): 0
  Total potential issues skipped due to specifically being disabled (e.g., #nosec BXXX): 0

Run metrics:
  Total issues (by severity):
  	Undefined: 0
  	Low: 0
  	Medium: 0
  	High: 0
  Total issues (by confidence):
  	Undefined: 0
  	Low: 0
  	Medium: 0
  	High: 0
Files skipped (0):

[github-actions]

Test results for commit 504507a

Test coverage for 504507a

Name           Stmts   Miss Branch BrPart  Cover   Missing
----------------------------------------------------------
src/charm.py       8      8      0      0     0%   8-25
----------------------------------------------------------
TOTAL              8      8      0      0     0%

Static code analysis report

Run started:2026-03-04 09:34:17.637488+00:00

Test results:
  No issues identified.

Code scanned:
  Total lines of code: 56
  Total lines skipped (#nosec): 0
  Total potential issues skipped due to specifically being disabled (e.g., #nosec BXXX): 0

Run metrics:
  Total issues (by severity):
  	Undefined: 0
  	Low: 0
  	Medium: 0
  	High: 0
  Total issues (by confidence):
  	Undefined: 0
  	Low: 0
  	Medium: 0
  	High: 0
Files skipped (0):

[github-actions]

Test results for commit 504507a

Test coverage for 504507a

Name           Stmts   Miss Branch BrPart  Cover   Missing
----------------------------------------------------------
src/charm.py       8      8      0      0     0%   8-25
----------------------------------------------------------
TOTAL              8      8      0      0     0%

Static code analysis report

Run started:2026-03-04 09:34:20.186936+00:00

Test results:
  No issues identified.

Code scanned:
  Total lines of code: 56
  Total lines skipped (#nosec): 0
  Total potential issues skipped due to specifically being disabled (e.g., #nosec BXXX): 0

Run metrics:
  Total issues (by severity):
  	Undefined: 0
  	Low: 0
  	Medium: 0
  	High: 0
  Total issues (by confidence):
  	Undefined: 0
  	Low: 0
  	Medium: 0
  	High: 0
Files skipped (0):

[github-actions]

Test results for commit 504507a

Test coverage for 504507a

Name           Stmts   Miss Branch BrPart  Cover   Missing
----------------------------------------------------------
src/charm.py       8      8      0      0     0%   8-25
----------------------------------------------------------
TOTAL              8      8      0      0     0%

Static code analysis report

Run started:2026-03-04 09:46:20.559258+00:00

Test results:
  No issues identified.

Code scanned:
  Total lines of code: 56
  Total lines skipped (#nosec): 0
  Total potential issues skipped due to specifically being disabled (e.g., #nosec BXXX): 0

Run metrics:
  Total issues (by severity):
  	Undefined: 0
  	Low: 0
  	Medium: 0
  	High: 0
  Total issues (by confidence):
  	Undefined: 0
  	Low: 0
  	Medium: 0
  	High: 0
Files skipped (0):