Add skip_ssl_verify flag for certificate trust verification

[natalian98]

Applicable spec: n/a

Overview

This PR adds skip_ssl_verify as a new config option and smtp lib parameter.

Rationale

Some requirers of the smtp library need additional parameters for smtp configuration. One of them is skip_ssl_verify, which specifies if certificate trust verification is skipped in the integrated SMTP relay. This is a common config option which disables SSL verification, e.g. allowing the use of self-signed certificates.

Juju Events Changes

n/a

Module Changes

n/a

Library Changes

• added skip_ssl_verify flag

Checklist

• The charm style guide was applied
• The contributing guide was applied
• The changes are compliant with ISD054 - Managing Charm Complexity
• The documentation is generated using src-docs
• The documentation for charmhub is updated
• The PR is tagged with appropriate label (urgent, trivial, complex)

Can't add the trivial label as a non-maintainer

[arturo-seijas]

/canonical/self-hosted-runners/run-workflows 94e528b

[github-actions]

Test coverage for 94e528b

Name                                    Stmts   Miss Branch BrPart  Cover   Missing
-----------------------------------------------------------------------------------
lib/charms/smtp_integrator/v0/smtp.py     128      2     24      2    97%   336, 338
src/charm.py                               82      5     26      1    94%   91-93, 102-103
src/charm_state.py                         46      0      6      0   100%
-----------------------------------------------------------------------------------
TOTAL                                     256      7     56      3    97%

Static code analysis report

Run started:2024-08-13 09:12:33.313775

Test results:
  No issues identified.

Code scanned:
  Total lines of code: 913
  Total lines skipped (#nosec): 3
  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):

[yanksyoon]

LGTM!