[Bug]: override tag not supported

[meck-gd]

Module

Core

Testcontainers version

1.21.4

Using the latest Testcontainers version?

Yes

Host OS

Linux

Host Arch

x64

Docker version

Client: Docker Engine - Community
 Version:           29.2.1
 API version:       1.53
 Go version:        go1.25.6
 Git commit:        a5c7197
 Built:             Mon Feb  2 17:17:09 2026
 OS/Arch:           linux/amd64
 Context:           default

Server: Docker Engine - Community
 Engine:
  Version:          29.2.1
  API version:      1.53 (minimum version 1.44)
  Go version:       go1.25.6
  Git commit:       6bc6209
  Built:            Mon Feb  2 17:17:09 2026
  OS/Arch:          linux/amd64
  Experimental:     false
 containerd:
  Version:          v2.2.1
  GitCommit:        dea7da592f5d1d2b7755e3a161be07f43fad8f75
 runc:
  Version:          1.3.4
  GitCommit:        v1.3.4-0-gd6d73eb8
 docker-init:
  Version:          0.19.0
  GitCommit:        de40ad0

What happened?

I'm trying to use an override compose file that looks like this:

volumes:
  data-mongodb:

services:
  flask:
    ports: !override
      - "5000:5000"

  mongodb:
    volumes: !override
      - "data-mongodb:/data/db"

The !override tag is not supported and its presence causes a parsing exception.

Relevant log output

Caused by: java.lang.IllegalArgumentException: Unable to parse YAML file from <snip>/docker-compose.integrationtest.yml
	at org.testcontainers.containers.ParsedDockerComposeFile.<init>(ParsedDockerComposeFile.java:63)
	at java.base/java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:197)
	at java.base/java.util.Spliterators$ArraySpliterator.forEachRemaining(Spliterators.java:992)
	at java.base/java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:509)
	at java.base/java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:499)
	at java.base/java.util.stream.ReduceOps$ReduceOp.evaluateSequential(ReduceOps.java:921)
	at java.base/java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234)
	at java.base/java.util.stream.ReferencePipeline.collect(ReferencePipeline.java:682)
	at org.testcontainers.containers.DockerComposeFiles.<init>(DockerComposeFiles.java:18)
	at org.testcontainers.containers.ComposeDelegate.<init>(ComposeDelegate.java:91)
	at org.testcontainers.containers.ComposeContainer.<init>(ComposeContainer.java:85)
	at org.testcontainers.containers.ComposeContainer.<init>(ComposeContainer.java:77)
	at org.testcontainers.containers.ComposeContainer.<init>(ComposeContainer.java:73)
	at org.codehaus.groovy.vmplugin.v8.IndyInterface.fromCache(IndyInterface.java:321)
	... 9 more
Caused by: could not determine a constructor for the tag !override
 in 'reader', line 14, column 12:
        ports: !override
               ^

	at org.testcontainers.shaded.org.yaml.snakeyaml.constructor.SafeConstructor$ConstructUndefined.construct(SafeConstructor.java:620)
	at org.testcontainers.shaded.org.yaml.snakeyaml.constructor.BaseConstructor.constructObjectNoCheck(BaseConstructor.java:270)
	at org.testcontainers.shaded.org.yaml.snakeyaml.constructor.BaseConstructor.constructObject(BaseConstructor.java:253)
	at org.testcontainers.containers.ParsedDockerComposeFile$1.constructObject(ParsedDockerComposeFile.java:56)
	at org.testcontainers.shaded.org.yaml.snakeyaml.constructor.BaseConstructor.constructMapping2ndStep(BaseConstructor.java:581)
	at org.testcontainers.shaded.org.yaml.snakeyaml.constructor.SafeConstructor.constructMapping2ndStep(SafeConstructor.java:213)
	at org.testcontainers.shaded.org.yaml.snakeyaml.constructor.BaseConstructor.constructMapping(BaseConstructor.java:557)
	at org.testcontainers.shaded.org.yaml.snakeyaml.constructor.SafeConstructor$ConstructYamlMap.construct(SafeConstructor.java:600)

Additional Information

No response