I've been conducting a systematic evaluation of Snyk CLI for integrating security scanning into our CI/CD pipelines, specifically focusing on its container image analysis capabilities. My current workflow involves scanning locally built Docker images before pushing them to a registry, and I've encountered a persistent and frustrating issue: the `snyk container test` command is failing silently under specific conditions. The process exits with a code 0 (success) even when the scan demonstrably does not complete, providing no actionable error output.
I have methodically replicated the issue across three different environments. The failure mode is consistent when the local image, built via `docker build`, is quite large (approximately 4.2 GB). The command I'm executing is:
```bash
snyk container test my-app:local --file=Dockerfile --json > snyk_scan_results.json
```
The observed behavior is as follows:
* The CLI initializes, prints "Analyzing container dependencies," and then appears to hang indefinitely.
* After approximately 90 seconds, the process terminates without an error message.
* The exit code is `0`.
* The output file (`snyk_scan_results.json`) is created but contains only an empty JSON structure or is completely empty.
* CPU and network activity for the Docker daemon cease.
For comparison, here is the successful behavior with a smaller image (~800 MB):
* The CLI initializes and prints "Analyzing container dependencies."
* A progress indicator is shown, and the process continues for 45-60 seconds.
* It terminates with exit code `0` or `1` (depending on findings), and the JSON file contains the full vulnerability report.
My diagnostic steps so far include:
* Confirmed Docker daemon is accessible and the image exists locally via `docker images`.
* Run with `--debug` and `--verbose` flags. The debug output stops abruptly at the dependency analysis stage.
* Increased Docker daemon logs to `debug` level, observing no errors, only layer extraction steps.
* Verified available disk space on `/tmp` and Docker's storage volume.
* Tested with multiple Snyk CLI versions (1.1252.0, 1.1248.0).
The core of the problem is the silent failure. A non-zero exit code and a clear error message (e.g., regarding timeouts, memory constraints, or layer extraction failures) would allow for scripting retries or alternative actions. This is critical for automated pipelines.
My questions for the community are:
* Has anyone encountered similar silent failures with large local images?
* Are there known, but undocumented, resource constraints (memory, timeout) within the Snyk CLI for local image analysis?
* Is there a method to surface more granular logs from the underlying container analysis engine?
* As a workaround, would pushing the large image to a local repository (like a local Docker registry) and testing from there be more reliable than scanning the local Docker daemon storage directly?
Any insights into the internal process or configuration tweaks would be greatly appreciated. I will update this thread with any findings from my continued investigation.
— Amanda
Data > opinions
That's a particularly gnarly kind of issue, isn't it? A silent failure with an exit code of 0 completely undermines the reliability you need for automation. It makes troubleshooting feel like guessing.
Your systematic replication across environments is really valuable for pinning this down. The 4.2 GB detail strongly suggests a resource constraint issue, maybe a timeout or memory limit inside the CLI that isn't being surfaced to the user. Before you go deeper into Snyk's own debugging, have you checked the Docker daemon logs on those machines during the attempted scan? Sometimes the CLI's interaction with the Docker API to export and analyze that large image layer can fail on that side without Snyk catching it properly.
Also, for your immediate workflow, you could experiment with using `--debug` flag if you haven't already. While it might not fix the silent exit, it sometimes buries a more telling message in the verbose output before the process ends.
Stay curious.