testcontainers / testcontainers/testcontainers-java
GenericContainer tries to talk to remote registry too soon (during instance initialization)
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Description
I'm running tests on a machine that doesn't currently have connectivity to the Docker Hub. Certainly, I expect TestContainer-based cases to fail in that case. So I have written a JUnit rule to conditionally disable these test cases when a certain configuration setting has been made, and write something like this in my test case:
public static ConditionalIgnore skip =
ConditionalIgnore.needsDocker(ConfigFactory.load("test"));
// VaultContainer is my own subclass of GenericContainer
public static VaultContainer VAULT = new VaultContainer();
@ClassRule
public static final RuleChain rules = RuleChain.outerRule(skip)
.around(VAULT);
The problem I'm seeing is, however, that this requires instantiating the VaultContainer class, which will call the GenericContainer constructors, and those constructors will actually try to talk to the Docker Hub:
Caused by: org.testcontainers.containers.ContainerFetchException: Can't get Docker image name from org.testcontainers.images.RemoteDockerImage@4a0952ab
at org.testcontainers.containers.GenericContainer.getDockerImageName(GenericContainer.java:711)
at org.testcontainers.containers.GenericContainer.setDockerImageName(GenericContainer.java:699)
at org.testcontainers.containers.GenericContainer.<init>(GenericContainer.java:145)
at com.progressfin.foundation.secret.VaultContainer.<init>(VaultContainer.java:33)
at com.progressfin.foundation.secret.VaultContainer.<init>(VaultContainer.java:29)
at com.progressfin.foundation.secret.VaultSecretsTest.<clinit>(VaultSecretsTest.java:30)
... 40 more
Caused by: org.testcontainers.shaded.com.github.dockerjava.api.exception.InternalServerErrorException: {"message":"Get https://registry-1.docker.io/v2/: read tcp 1.2.3.4:54526->4.3.2.1:443: read: connection reset by peer"}
The problem is here (line numbers don't match up because the stack trace is from 1.1.6):
There's a very interesting comment there ("Mimic old behavior where we resolve image once it's set") that tells us that this behavior is intentional. What I would suggest is that the behavior is at odds with the sort of uses that JUnit rules are meant to support; the test rule should arguably take no "risky" actions at all unless the Statement is actually invoked, i.e. in the GenericContainer.start() method, which already does call the getDockerImageName() method anyway. (And is it just me, or is it also weird that a String getter like getDockerImageName() would talk to the network?)
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Read core/src/main/java/org/testcontainers/containers/GenericContainer.java around the constructor, setDockerImageName(), getDockerImageName(), and start() entry points. Verify that constructing a container does not contact the remote registry, while startup still resolves the image; confirm the behavior with the relevant existing container tests.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- docker, java
- Domain
- testing
- Issue type
- Bug
- Difficulty
- 3/5
- Estimated time
- 1-2 days
- Activity status
- Stale
- Clarity
- Clearly specified
- Newbie friendliness
- 45/100