Directories

Structure and Environment

The snippet below represents the structure of the flatimage temporary files directory located in /tmp/fim, the corresponding environment variable is shown between [].

/tmp/fim [FIM_DIR_GLOBAL]
    ├── app
    │    └── app_id [FIM_DIR_APP]
    │        ├── bin [FIM_DIR_APP_BIN]
    │        └── instance
    │            └── instance_id [FIM_DIR_INSTANCE]
    │                └── mount [FIM_DIR_MOUNT]
    │                    ├── layers
    │                    │   ├── 0
    │                    │   ├── 1
    │                    │   ├── ...
    │                    │   └── n
    │                    └── overlayfs
    │
    └── run [FIM_DIR_RUNTIME]
        └── host [FIM_DIR_RUNTIME_HOST]

The app Directory

• /tmp/fim/app is a directory containing data of flatimage applications, each application has its own id that represents a specific build, for example, 119216d_20241019145954 is a build of commit 119216d from 2024-10-19 (YYYY-MM-DD) built at 14h 59m 54s.
• /tmp/fim/app/app_id is used to store binaries and create instances of flatimage applications.
• /tmp/fim/app/app_id/bin contains static binaries for the current flatimage build.
• /tmp/fim/app/app_id/instance contains instances of the current flatimage build, these instances share the binaries located in /tmp/fim/app/app_id/bin.
• /tmp/fim/app/app_id/instance/instance_id contains the read-only layer mountpoints and overlayfs mountpoint over all the layers from 0 to n. The id for the instance_id directory is generated from a call to mkdtemp with the template XXXXXX.

The run Directory

The run directory contains read-only access to the host filesystem, it is only accessible from inside the container and can be used to create symlinks for libraries, sockets and more. This directory is used by the gpu permission to symlink nvidia drivers.