Pack command output option is inconsistent
Metadata
Current evaluation
Pack command --output behaves inconsistently: paths outside the project root silently drop artifacts inside the build instance. Triaged bug (Jira CRAFT-4580); no fix found in current code, which still has the same --output handling.
Suggested action: keep open
Reason: The issue is labelled 'Status: Triaged' and 'Type: Bug' by maintainer cmatsuoka, and the reported behavior still exists in the code: PackCommand in craft_application/commands/lifecycle.py still defines --output with help 'Output directory for created packages.' and passes it to package.set_output_dir() with no validation or error for out-of-root paths. No commit in the history addresses this, so it remains a valid, open design/bug decision (error out vs. deprecate) rather than something to close.
Impact:
45
Quick Win:
18.0
Staleness:
75
Complexity:
60
Confidence:
80
Support Request:
5
Issue body
### Bug Description
The `pack` command offers the `--output` option as the "output directory for created packages." However it actually work in different ways:
- If output is specified as a subdirectory of the project root, it creates artifacts inside the directory (as described in the help message)
- If output is specified as a filename under the project root, it creates the artifact with the specified name.
- If output is specified as a directory or filename outside the project root, the artifact is created inside the build instance and it never appears in the host system.
The application should probably stop with an error instead of failing silently in cases where the artifact disappears, and clarify the `--output` behavior when multiple output artifacts are generated (if a directory is created then it should do the same when a single output artifact is generated). We can also consider deprecating this option in future releases.
### To Reproduce
```shell
$ mkdir /tmp/foo
$ cd /tmp/foo
$ snapcraft init
Go to https://docs.snapcraft.io/the-snapcraft-format/8337 for more information about the snapcraft.yaml format.
Successfully initialised project.
$ snapcraft pack --output=foo
Packed foo
$ mkdir bar
$ snapcraft pack --output=bar
Packed foo_0.1_amd64.snap
$ snapcraft pack --output=/tmp
Packed foo_0.1_amd64.snap
$ ls -l /tmp/foo_0.1_amd64.snap
ls: cannot access '/tmp/foo_0.1_amd64.snap': No such file or directory
$ snapcraft pack --output=/dirname/
Packed dirname
$ ls -l /dirname
ls: cannot access '/dirname': No such file or directory
```
### part yaml
```shell
```
### Relevant log output
```shell
:: 2025-05-23 09:41:29.948 Packing...
:: 2025-05-23 09:41:29.948 Reading snap metadata...
:: 2025-05-23 09:41:29.949 Running linters...
:: 2025-05-23 09:41:29.949 Running linter: classic
:: 2025-05-23 09:41:29.949 Running linter: library
:: 2025-05-23 09:41:29.951 pack_snap: output='/tmp', compression='xz'
:: 2025-05-23 09:41:29.951 pack_snap: check skeleton
:: 2025-05-23 09:41:29.966 Creating snap package...
:: 2025-05-23 09:41:29.966 Pack command: ['snap', 'pack', '--filename', 'foo_0.1_amd64.snap', '--compression', 'xz', PosixPath('/root/prime'), PosixPath('/tmp')]
:: 2025-05-23 09:41:30.026 Packed foo_0.1_amd64.snap
```
Evaluation history
| Date | Model | Scores | Action | Summary |
|---|---|---|---|---|
| qwen/qwen3.8-27b |
Impact:
45
Quick Win:
18.0
Staleness:
75
Complexity:
60
Confidence:
80
Support Request:
5
|
keep open | Pack command --output behaves inconsistently: paths outside the project root silently drop artifacts inside the build instance. Triaged bug (Jira CRAFT-4580); no fix found in current code, which still has the same --output handling. | |
| qwen/qwen3.6-35b-a3b |
Staleness:
90
Complexity:
40
Confidence:
85
Support Request:
10
|
keep open | Inconsistent snapcraft pack --output behavior causes silent failures when paths fall outside the project root. Triaged bug with over a year of inactivity and no follow-up. | |
| qwen3.6-35b-a3b-mtp-q6 |
Staleness:
90
Complexity:
40
Confidence:
75
Support Request:
5
|
keep open | Inconsistent behavior of snapcraft pack --output when paths are outside the project root, causing silent failures. Triaged bug with an internal ticket, but inactive for over a year. | |
| qwen3.6-35b-a3b-mtp-q6 |
Staleness:
85
Complexity:
35
Confidence:
80
Support Request:
10
|
keep open | Inconsistent snapcraft pack --output behavior fails silently when paths fall outside the project root. Triaged as a bug with an internal Jira ticket created, awaiting implementation. |
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Related issues
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