Keep values tagged with !override when parsing compose files

[srivathsav01]

Fixes #12094

ParsedDockerComposeFile (used to find the images ComposeDelegate#pullImages pre-pulls) handled the !override tag exactly like !reset and replaced the tagged value with null. In Compose, !override means the value replaces the one from previous files, so Testcontainers pre-pulled the base file's image instead of the overriding one.

Changes

• !override-tagged nodes are now constructed as if they were untagged: mappings as maps, sequences as lists, scalars using the regular YAML resolver. The value from the later file then wins in the existing DockerComposeFiles merge. !reset still returns null. Only the standard SafeConstructor tags are used, so arbitrary-class deserialization is still rejected (shouldRejectDeserializationOfArbitraryClasses still passes).
• A service definition that is not a map is now skipped with continue instead of stopping the parsing of all remaining services with break.
• A file without a services element is parsed as the legacy v1 format, where every top-level element is a service. Top-level elements of newer formats (version, name, include, networks, volumes, configs, secrets) and extension fields (x-*) are now skipped in that case. Before, break on the first non-map element (such as version) mostly hid the problem. With continue, an extension field such as x-common: {image: busybox:1.36} would otherwise be pre-pulled as if it were a service. (The same already happened before whenever such a field came before version.)
• Quoted scalars tagged with !override keep their string type (implicit typing only applies to plain scalars, as for untagged values).

Before / after, using DockerComposeFiles#getDependencyImages():

                                          2.0.5                   this PR
image: !override postgres:16              [postgres:15]           [postgres:16]
db: !override {image: postgres:16}        [postgres:15]           [postgres:16]
  + following service redis:6 -> redis:7  [redis:6, postgres:15]  [redis:7, postgres:16]

Tests

• DockerComposeFilesTest#shouldGetDependencyImagesWhenOverridingWithOverrideTag: base + override file using !override on a whole service and on an image, followed by a normally merged service.
• ParsedDockerComposeFileValidationTest#shouldObtainImageNamesFromOverrideTag: !override values are kept.
• ParsedDockerComposeFileValidationTest#shouldIgnoreImageNamesRemovedWithResetTag: !reset behaviour is unchanged.
• ParsedDockerComposeFileValidationTest#shouldContinueAfterServiceWithUnknownStructure: services after an unexpected one are still parsed.
• ParsedDockerComposeFileValidationTest#shouldIgnoreTopLevelElementsWithoutServicesElement: in a file without services, version, networks and x-* entries are not treated as services. The existing shouldObtainImageNamesV1 still passes, so real v1 files keep working.
• ParsedDockerComposeFileValidationTest#shouldKeepQuotedValuesTaggedWithOverrideAsStrings: quoted !override values stay strings.

All new tests except the !reset one fail without this change. ./gradlew :testcontainers:test --tests "*ParsedDockerComposeFileValidationTest" --tests "*DockerComposeFilesTest" :testcontainers:checkstyleMain :testcontainers:checkstyleTest :testcontainers:spotlessCheck passes.

Summary by CodeRabbit

• Bug Fixes
  • Docker Compose files using !override now apply overridden values correctly, including service images and values with inferred YAML types.
  • Compose parsing continues after invalid service entries, so later valid services are still processed.
  • Values marked with !reset remain null and are excluded from service image results.
• Compatibility
  • Legacy-format service detection skips recognized Compose top-level elements and x- extension fields, rather than treating them as services.
  • Top-level data without a services element is no longer interpreted as service definitions.

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Reviewing files that changed from the base of the PR and between 1de0789 and 9759638.

📒 Files selected for processing (2)

• core/src/main/java/org/testcontainers/containers/ParsedDockerComposeFile.java
• core/src/test/java/org/testcontainers/containers/ParsedDockerComposeFileValidationTest.java

🚧 Files skipped from review as they are similar to previous changes (2)

• core/src/test/java/org/testcontainers/containers/ParsedDockerComposeFileValidationTest.java
• core/src/main/java/org/testcontainers/containers/ParsedDockerComposeFile.java

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📝 Walkthrough

Walkthrough

The parser now retains values tagged with !override, continues to map !reset to null, and handles legacy Compose top-level elements and non-map service definitions during extraction. Tests cover image selection and service parsing.

Changes

Compose image parsing

Layer / File(s)	Summary
Parse Compose override values core/src/main/java/org/testcontainers/containers/ParsedDockerComposeFile.java, core/src/test/java/org/testcontainers/containers/ParsedDockerComposeFileValidationTest.java, core/src/test/java/org/testcontainers/containers/DockerComposeFilesTest.java, core/src/test/resources/docker-compose-imagename-overriding-tag-*.yml	The YAML constructor resolves and constructs !override nodes according to their underlying type. !reset nodes still construct as null. Tests check parsed images and image selection across Compose files.
Extract legacy-format services core/src/main/java/org/testcontainers/containers/ParsedDockerComposeFile.java, core/src/test/java/org/testcontainers/containers/ParsedDockerComposeFileValidationTest.java	The parser skips known Compose top-level elements and x- entries in legacy-format files. It skips non-map service definitions and continues processing later services.

Priority: ➖ Normal

Estimated code review effort: 2 (Simple) | ~15 minutes

Change: Bug fix · Severity of issue fixed: Medium

Suggested reviewers: eddumelendez

Merge Risk: ⚪ Minimal · up to 97596

The change makes Compose image discovery use values tagged with !override and keeps parsing after unexpected service definitions. No actionable merge-blocking risk was identified.

Security Architecture Review

Security architecture risk: 🔵 Low · up to 1de07

The change makes pre-pulling follow Compose override values more closely. It retains safe YAML construction and uses the existing image-pull path, but the effect depends on who can supply Compose files in a deployment.

Retained concerns
No architecture-level concerns identified.

Security review details

Security Blast Radius

• inferred — An image named through !override can now be fetched through the existing pre-pull path. The visible effect is confined to dependency images derived from the Compose files supplied to that invocation; deployment-specific file ownership is not established.

Trust Boundaries and Controls

• inferred — The new syntax changes which configured image reaches pre-pull, not who may configure an image: ordinary service image strings already reached that path. SafeConstructor remains the YAML construction control.

Resilience and Maintainability Implications

• observed — The existing pre-pull loop catches an individual image-fetch exception and continues, limiting a failed prefetch's effect on startup.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 14 functions across 3 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Linked Issues check	✅ Passed	The changes satisfy the coding requirements in [#12094]. !override mappings, sequences, and scalars are constructed with their YAML types, so image and service override values remain available to de…
Out of Scope Changes check	✅ Passed	The changes remain within Compose parsing and dependency-image discovery scope. Skipping known top-level Compose fields and x-* extensions prevents false service detection in legacy v1 parsing. The …
Title check	✅ Passed	The title clearly and concisely identifies the main change: preserving values tagged with !override during Compose parsing.
Description check	✅ Passed	The description explains the bug, the expected !override and !reset behavior, related parsing changes, linked issue #12094, test coverage, and validation commands.

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✨ Finishing Touches 💡 1

🛠️ Fix failing CI checks 💡

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Actionable comments posted: 1

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Inline comments:
Review comments at
@core/src/main/java/org/testcontainers/containers/ParsedDockerComposeFile.java:
- Line 107: Update the scalar `!override` resolution in
`ParsedDockerComposeFile` to preserve the node’s scalar style: resolve quoted
scalars as `Tag.STR` and apply implicit typing only to plain scalars. Ensure
quoted values such as `"true"` remain strings so the override image is retained.

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ℹ️ Review info

⚙️ Run configuration

Configuration used: Repository UI

Review profile: CHILL

Plan: Advanced

Run ID: f9418f77-289f-4b18-a85a-4ed269bf1463

📥 Commits

Reviewing files that changed from the base of the PR and between 8e54951 and 1de0789.

📒 Files selected for processing (5)

• core/src/main/java/org/testcontainers/containers/ParsedDockerComposeFile.java
• core/src/test/java/org/testcontainers/containers/DockerComposeFilesTest.java
• core/src/test/java/org/testcontainers/containers/ParsedDockerComposeFileValidationTest.java
• core/src/test/resources/docker-compose-imagename-overriding-tag-a.yml
• core/src/test/resources/docker-compose-imagename-overriding-tag-b.yml

Included review availability: This review used your included allowance. Your plan provides up to 8 included reviews per hour; 7 remain after this review.