fix: redact database password from tracing span output

[ctron]

Add HideString newtype that wraps a Debug value and replaces all occurrences of a given string with "***" in the Debug output. Use it in the #[instrument] on Database::new to prevent the password from leaking through the url field in tracing spans.

Summary by Sourcery

Redact sensitive database passwords from tracing spans when constructing a Database instance.

Enhancements:

• Introduce a generic HideString debug wrapper that masks a specified substring as "***" in Debug output.
• Apply the HideString wrapper to the database configuration in Database::new tracing instrumentation to prevent password leakage.
• Expose the new redact module from the common crate for reuse across the codebase.

Tests:

• Add unit and rstest-based tests verifying HideString redacts sensitive values in strings and structured types like URLs.

[sourcery-ai]

Reviewer's Guide

Introduces a generic HideString debug wrapper to redact sensitive substrings (like DB passwords) from Debug output and wires it into Database::new tracing instrumentation so database URLs in spans no longer expose passwords.

Sequence diagram for Database::new tracing with HideString redaction

sequenceDiagram
    actor Caller
    participant Database
    participant tracing

    Caller->>Database: new(database)
    activate Database
    Database->>tracing: HideString(database, database.password.0)
    tracing-->>Database: span_created_with_redacted_database_field
    Database-->>Caller: Result<Database>
    deactivate Database

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File-Level Changes

Change	Details	Files
Redact database password from tracing span output for Database::new.	Extend #[instrument] on Database::new to skip the database argument from automatic capture. Add a custom span field database that uses the HideString wrapper to redact the password from the database config when logging. Keep error logging level configuration unchanged while enhancing span safety.	common/src/db/mod.rs
Expose a new redact module and generic HideString Debug wrapper for redacting substrings from Debug output.	Export a new redact module from the common crate so it can be used elsewhere. Implement the HideString<'a, T: Debug> wrapper type that formats its inner value via Debug and replaces all occurrences of a target substring with "". Handle the empty hide-string case by delegating directly to the wrapped Debug impl without allocation or replacement. Add rstest-based tests to verify redaction behavior for plain strings and for a config struct containing a reqwest::Url and password, ensuring passwords in URLs and fields are replaced with "".	common/src/lib.rs common/src/redact.rs

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[sourcery-ai]

Hey - I've left some high level feedback:

• The HideString Debug implementation allocates a String and does a full replace on every call; if this will be used in hot paths it may be worth constraining it to cheaper, more structured redaction (e.g., only extracting/redacting the URL field or using a custom formatter instead of format!).
• Using a plain replace on the debug output means any occurrence of the password substring (including in non-sensitive fields) will be masked; consider clarifying that this behavior is intentional or narrowing the redaction to known sensitive parts of the structure.

Prompt for AI Agents

Please address the comments from this code review:

## Overall Comments
- The `HideString` `Debug` implementation allocates a `String` and does a full replace on every call; if this will be used in hot paths it may be worth constraining it to cheaper, more structured redaction (e.g., only extracting/redacting the URL field or using a custom formatter instead of `format!`).
- Using a plain `replace` on the debug output means any occurrence of the password substring (including in non-sensitive fields) will be masked; consider clarifying that this behavior is intentional or narrowing the redaction to known sensitive parts of the structure.

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 71.31%. Comparing base (b5c7762) to head (4758f86).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2415      +/-   ##
==========================================
+ Coverage   71.28%   71.31%   +0.03%     
==========================================
  Files         449      450       +1     
  Lines       27146    27161      +15     
  Branches    27146    27161      +15     
==========================================
+ Hits        19352    19371      +19     
+ Misses       6662     6652      -10     
- Partials     1132     1138       +6     

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[trustify-ci-bot]

Successfully created backport PR for release/0.5.z:

• fix: redact database password from tracing span output [Backport release/0.5.z] #2418