fix(mongodb): replica set initialization & connection handling by ttruongatl · Pull Request #2984 · testcontainers/testcontainers-go

ttruongatl · 2025-02-15T01:25:17Z

What does this PR do?

This PR addresses critical issues in the MongoDB container module regarding replica set initialization, host IP detection, and connection string formation. In addition, it expands test coverage by verifying change stream functionality when a replica set is configured.

Replica Set Initialization Reliability:
The previous implementation initialized the replica set using the container’s internal IP and a hardcoded port (27017). This approach caused issues when custom host port mappings were applied (e.g., mapping container port 27017 to host port 52120) because the advertised address was incorrect. Furthermore, the old code did not reliably wait for MongoDB to be fully ready before issuing the rs.initiate command, leading to intermittent failures that went undetected by tests.
This PR introduces a waitForMongoReady helper, which waits for MongoDB’s readiness (using a ping command) before retrieving the host and mapped port and issuing the replica set initialization command with the correct values.
Accurate Host IP Detection:
Previously, using Unix sockets defaulted to "localhost," which often broke replica set functionality since that address isn't externally reachable. This PR introduces a helper, getLocalNonLoopbackIP, to obtain a non-loopback IPv4 address—and if that fails, it falls back to "host.docker.internal"—ensuring the connection string advertises an externally accessible IP.
Enhanced Connection String Formation:
The ConnectionString method has been updated to dynamically build the connection URI. When a replica set is configured, it now appends the appropriate query parameter (e.g., ?replicaSet=rs0) so that clients can connect properly. Previously, the tests did not verify this because the connection string did not accurately reflect the replica set configuration.
Expanded Testing with Change Streams:
The test suite has been extended to include change stream tests for containers configured with a replica set. If the connection string contains a replica set parameter, the tests now create a change stream on a collection, insert a document, and verify that the change event reflects an insert operation. This ensures that the replica set functionality is not only initialized correctly but also operational in terms of change stream processing.

Why is it important?

Without these enhancements, the replica set configuration might not work correctly—especially in CI or Docker host environments where custom port mappings are common. The shortcomings of the old code meant that, even though tests passed, the replica set functionality (and thus features like change streams) was not truly exercised. This PR improves reliability and test coverage, ensuring that integration tests can now fully validate replica set behavior.

How to test this PR:

git clone git@github.com:ttruongatl/testcontainers-go.git
cd modules/mongodb
make test

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stevenh

Thanks for the PR, here's some initial feedback.

stevenh

Thanks for the updates, just done another quick pass.

mdelapenya

I just left a few non-blocking comments. Will approve once discussed, thanks!

stevenh

Sorry a little miss-understanding on a previous suggestion, should be good to go after this.

Co-authored-by: Steven Hartland <stevenmhartland@gmail.com>

Co-authored-by: Manuel de la Peña <social.mdelapenya@gmail.com>

Co-authored-by: Steven Hartland <stevenmhartland@gmail.com>

stevenh

Looks good to me

stevenh · 2025-02-17T21:28:21Z

@ttruongatl looks like the file needs a format, likely just a spacing change from one of my suggestions.

ttruongatl · 2025-02-17T22:40:32Z

@stevenh I've fixed the lint check issues. PTAL! Thank you.

…pbackIP function

…ialization-and-connection-handling

mdelapenya

LGTM, thanks!

* main: fix(mongodb): replica set initialization & connection handling (testcontainers#2984)

* main: chore: bump golangci-lint to v2 (testcontainers#3082) chore(gcloud): deprecate old gcp containers, creating subpackages for them (testcontainers#3063) fix(mongodb): replica set initialization & connection handling (testcontainers#2984) chore(deps): bump docker/setup-docker-action from 4.2.0 to 4.3.0 (testcontainers#3077) chore(deps): bump github/codeql-action from 3.28.12 to 3.28.13 (testcontainers#3078) chore(deps): bump tj-actions/changed-files from 45.0.4 to 46.0.3 (testcontainers#3076) docs: add dependabot configuration (testcontainers#3074) chore(deps): replace `golang.org/x/exp/slices` with stdlib (testcontainers#3075) fix(dind): use docker image load (testcontainers#3073)

* main: fix(mssql): reduce flakiness in tests (testcontainers#3084) chore: bump golangci-lint to v2 (testcontainers#3082) chore(gcloud): deprecate old gcp containers, creating subpackages for them (testcontainers#3063) fix(mongodb): replica set initialization & connection handling (testcontainers#2984)

* main: (91 commits) chore(deps): bump github/codeql-action from 3.28.13 to 3.28.15 (testcontainers#3097) chore(deps): bump golang.org/x/crypto from 0.31.0 to 0.37.0 (testcontainers#3098) feat(aerospike): add Aerospike module (testcontainers#3094) security(compose): upgrade github.com/docker/compose/v2 to fix security vulnerability (testcontainers#3095) feat: add more functional options to the modules API (testcontainers#3070) chore(deps): bump golang.org/x/net in /modules/arangodb (testcontainers#3087) feat: add arangodb module (testcontainers#3083) chore(deps): bump actions/upload-artifact from 4.6.0 to 4.6.2 (testcontainers#3086) chore(deps): bump SonarSource/sonarqube-scan-action from 5.0.0 to 5.1.0 (testcontainers#3085) feat: add socat container (testcontainers#3071) fix(mssql): reduce flakiness in tests (testcontainers#3084) chore: bump golangci-lint to v2 (testcontainers#3082) chore(gcloud): deprecate old gcp containers, creating subpackages for them (testcontainers#3063) fix(mongodb): replica set initialization & connection handling (testcontainers#2984) chore(deps): bump docker/setup-docker-action from 4.2.0 to 4.3.0 (testcontainers#3077) chore(deps): bump github/codeql-action from 3.28.12 to 3.28.13 (testcontainers#3078) chore(deps): bump tj-actions/changed-files from 45.0.4 to 46.0.3 (testcontainers#3076) docs: add dependabot configuration (testcontainers#3074) chore(deps): replace `golang.org/x/exp/slices` with stdlib (testcontainers#3075) fix(dind): use docker image load (testcontainers#3073) ...

ttruongatl requested a review from a team as a code owner February 15, 2025 01:25

ttruongatl changed the title ~~[MongoDB] Improve Replica Set Initialization & Connection Handling~~ fix(replica): Mongodb Replica Set Initialization & Connection Handling Feb 15, 2025

ttruongatl changed the title ~~fix(replica): Mongodb Replica Set Initialization & Connection Handling~~ fix(replica): mongodb replica set initialization & connection handling Feb 15, 2025

stevenh requested changes Feb 15, 2025

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ttruongatl requested a review from stevenh February 16, 2025 20:33

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ttruongatl requested a review from stevenh February 17, 2025 02:29

mdelapenya reviewed Feb 17, 2025

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ttruongatl requested a review from mdelapenya February 17, 2025 14:17

stevenh requested changes Feb 17, 2025

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Comment thread modules/mongodb/mongodb.go

Comment thread modules/mongodb/mongodb.go Outdated

ttruongatl requested a review from stevenh February 17, 2025 16:36

ttruongatl and others added 18 commits February 17, 2025 14:34

[MongoDB] Improve Replica Set Initialization & Connection Handling

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Co-authored-by: Steven Hartland <stevenmhartland@gmail.com>

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ttruongatl force-pushed the thanhtruong/improve-MongoDB-Replica-Set-Initialization-and-connection-handling branch from 7966110 to 37cb2c5 Compare February 17, 2025 19:34

stevenh previously approved these changes Feb 17, 2025

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Fix lint

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ttruongatl dismissed stevenh’s stale review via deb1fbd February 17, 2025 22:39

ttruongatl requested a review from stevenh February 17, 2025 22:40

stevenh previously approved these changes Feb 18, 2025

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mdelapenya reviewed Feb 25, 2025

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Comment thread modules/mongodb/mongodb.go Outdated

Refactor MongoDB replica set initiation and remove unused localNonLoo…

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…pbackIP function

ttruongatl dismissed stevenh’s stale review via 6e93a1d March 29, 2025 12:10

Merge branch 'main' into thanhtruong/improve-MongoDB-Replica-Set-Init…

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…ialization-and-connection-handling

mdelapenya reviewed Mar 31, 2025

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Comment thread modules/mongodb/mongodb.go Outdated

refactor(mongodb): remove unused waitForMongoReady function

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mdelapenya changed the title ~~fix(replica): mongodb replica set initialization & connection handling~~ fix(mongodb): replica set initialization & connection handling Apr 2, 2025

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mdelapenya merged commit 675acc3 into testcontainers:main Apr 2, 2025
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mdelapenya added a commit to mdelapenya/testcontainers-go that referenced this pull request Apr 2, 2025

Merge branch 'main' into bump-golangci-lint

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* main: fix(mongodb): replica set initialization & connection handling (testcontainers#2984)

mdelapenya added the bug An issue with the library label Apr 3, 2025

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