`devcontainer up --mount` rejects `type=image` and mount options such as `subpath`
维护者通常 1 天内回复
评估
- 难度
- 4/5
- 预计耗时
- 3-5 天
- 新手友好度
- 35/100
- Issue 类型
- 功能
- 描述清晰度
- 描述清楚
- 活跃度
- 停滞
- 技术栈
- docker, docker-compose, typescript
调研方向
Trace how the --mount flag is validated and converted, then compare it with how string mounts from devcontainer.json reach the runtime. Check the Docker Compose path, where mounts use short syntax, and define a clear rejection for unsupported mount forms there. Done means runtime string mounts are passed through for supported runtimes, existing bind/volume behavior remains covered, and the linked pull request is reviewed for overlap.
由索引模型根据 Issue 内容生成。
描述
What I want to do
I keep my personal tools (neovim, Claude Code) in a Nix-built OCI image and mount its /nix read-only into a team's dev container with an image mount. The team's devcontainer.json stays untouched, so the mount has to come from the command line:
devcontainer up --docker-path podman --workspace-folder . \
--mount "type=image,source=localhost/devtools:latest,target=/nix,subpath=/nix"
Podman (since 5.1) and Docker Engine (since 28, with the containerd image store) support --mount type=image. Docker spells the option image-subpath instead of subpath.
What happens
The CLI exits with:
Unmatched argument format: mount must match type=<bind|volume>,source=<source>,target=<target>[,external=<true|false>]
The same string works as an entry in mounts in devcontainer.json. The CLI passes string mounts to podman run verbatim, and with --log-level trace I see:
podman run ... --mount type=image,source=localhost/devtools:latest,target=/nix,subpath=/nix ...
Inside the container, /nix is a read-only overlay, and nvim --version and claude --version run from it. So the runtime handles the mount fine; only the --mount flag refuses it.
Why
In 0.89.0 the flag goes through two steps:
- A fixed regex validates it:
/^type=(bind|volume),source=([^,]+),target=([^,]+)(?:,external=(true|false))?$/. Any other type or option fails, includingreadonly. - The value is parsed into a mount object, and the object is serialized back as
type=...,src=...,dst=.... Options outside these three fields would be lost even if the regex allowed them.
The object form follows the spec's Mount schema (type is bind or volume, additionalProperties: false).
Proposal
When the --mount value does not match the bind/volume form, pass it to the container runtime as a string, the same way string entries in devcontainer.json mounts are handled today. The bind/volume parsing and external= keep working as now.
That covers type=image, subpath / image-subpath, readonly, volume-subpath, tmpfs and future runtime options without the CLI having to know each one. The runtime reports an invalid string itself.
For Docker Compose configs the string cannot be passed through as-is, since mounts are converted to the short source:target syntax there. Rejecting a non-bind/volume --mount with a clear error on the Compose path would be enough.
Workaround
--override-config with a full copy of the team's devcontainer.json plus the string mount. The copy has to be regenerated whenever the team changes their file, because --override-config replaces the config instead of merging it.
Environment
- @devcontainers/cli 0.89.0
- Podman 6.1.4, rootless, Debian 13 (Linux 6.12, x86_64)
Related
- devcontainers/spec#781: the Feature
Mountschema rejects--mountoptions such asvolume-subpath - devcontainers/spec#511: no way to declare a read-only mount in object form
- devcontainers/cli#881 and devcontainers/cli#1314:
readonlyis dropped when mounts are converted
- 主要语言
- TypeScript
- 星标
- 3k
- 派生
- 473
- 平均合并
- 10 小时 31 分钟
- 30 天内合并 PR
- 9
环境准备
在浏览器里用你自己的 GitHub 账号启动这个项目的开发容器。
- 没有 Dockerfile 或 Docker Compose 文件
- 没有 Pull Request 模板
- 阅读贡献指南
从这里开始
- 先读完整个 Issue，再读项目的贡献指南。
- 在 Issue 下留言说明你要接手 —— 这能避免两个人做同样的事。
- Fork 仓库，在一个分支上完成修改。
- 提交 Pull Request，并在描述里引用这个 Issue 编号。
devcontainers/cli 的其他 Issue
-
难度 2/5 1-3 小时 新手友好度 82/100
devcontainers/cli#1325 ·
维护者通常 1 天内回复
-
难度 1/5 1 小时以内 新手友好度 92/100
devcontainers/cli#1203 ·
维护者通常 1 天内回复
-
难度 1/5 1-3 小时 新手友好度 68/100
devcontainers/cli#1178 · 1 条评论 ·
维护者通常 1 天内回复
-
up hangs after compose up -d on a cold start (Node 26, Compose 5.6)可能已有人在做 @v-Kaniska244 今天认领。 未关闭
难度 4/5 3-5 天 新手友好度 48/100
devcontainers/cli#1354 · 已指派 1 人 ·
维护者通常 1 天内回复
-
SELinux labelling does not get disabled when using Podman machines可能已有人在做 @darshpatel1052 于 6 天前认领。 未关闭
难度 3/5 1-2 天 新手友好度 40/100
devcontainers/cli#1347 · 1 条评论 ·
维护者通常 1 天内回复
查看 devcontainers/cli 的全部 Issue
相似的 Issue
-
fehler
难度 2/5 1-3 小时 新手友好度 66/100
维护者通常 1 天内回复
-
难度 2/5 1-3 小时 新手友好度 76/100
Azure/azure-functions-nodejs-extensions#180 ·
维护者通常 1 天内回复
-
bug good first issue help wanted
难度 2/5 1-3 小时 新手友好度 88/100
laaielichter/Threesmith#28 ·
维护者通常 1 天内回复
-
难度 2/5 1-3 小时 新手友好度 67/100
维护者通常 2 天内回复
-
难度 2/5 1-3 小时 新手友好度 72/100
streaming-video-technology-alliance/common-media-library#611 ·
维护者通常 1 天内回复