# How to Access Application and VM Boot Logs for Debugging Container Issues > Debug container issues by accessing application and VM boot logs. Learn to use container logs seamlessly for efficient troubleshooting in the apple/container repository. - Repository: [Apple/container](https://github.com/apple/container) - Tags: how-to-guide - Published: 2026-06-20 --- **Use `container logs ` to stream application STDIO and `container logs --boot ` to retrieve VM bootstrap logs when debugging issues in the apple/container ecosystem.** Effective debugging of containerized workloads requires visibility into both the application layer and the underlying virtualization stack. The apple/container repository provides native CLI commands to access standard output streams from OCI containers and low-level boot logs from the hosting VM. This guide demonstrates how to access application and VM boot logs for debugging container issues using the official Container CLI. ## Retrieving Application Logs (STDIO) The primary interface for accessing container output is the `container logs` command, which streams the STDIO files of the container's main process. ### Viewing Complete Log History To retrieve the full application log file for a specific container, execute the logs command with the container identifier: ```bash container logs my-web-server ``` ### Limiting Output to Recent Entries When investigating recent failures, use the `-n` flag to restrict output to the last N lines. This behaves similarly to the standard `tail -n` utility: ```bash container logs -n 100 my-web-server ``` ### Real-Time Log Streaming For active debugging sessions, the `--follow` (`-f`) flag enables real-time streaming of new log entries as they are written: ```bash container logs --follow my-web-server ``` ## Accessing VM Boot Logs Application logs capture container output, but initialization failures often manifest in the VM bootstrap process. The container runtime uses a minimal init daemon (`vminitd`) that writes its own log file. To retrieve these low-level boot logs, use the `--boot` flag: ```bash container logs --boot my-web-server ``` According to the source code in [`Sources/ContainerResource/Container/Bundle.swift`](https://github.com/apple/container/blob/main/Sources/ContainerResource/Container/Bundle.swift) (lines 37-40), the `--boot` flag directs the CLI to open the bundle's boot-log file defined by `Bundle.bootlog`, which resolves to `vminitd.log` within the container's bundle directory. This file contains the initialization sequence of the micro-VM hosting the container. ## Debugging Container Machine Logs For workflows utilizing the higher-level "machine" abstraction, the same logging interface applies through the `container machine logs` command. ### Machine Application Logs To access STDIO logs from a container machine: ```bash container machine logs dev-machine ``` ### Machine Boot Logs To retrieve the VM boot log for a container machine, combine the machine command with the `--boot` flag: ```bash container machine logs --boot dev-machine ``` As implemented in [`Sources/ContainerCommands/Machine/MachineLogs.swift`](https://github.com/apple/container/blob/main/Sources/ContainerCommands/Machine/MachineLogs.swift) (lines 29-60), the machine logs command supports the same output-limiting and follow flags as the standard container logs interface. ## Implementation Details The CLI routes log requests to dedicated service layers that handle file system interactions. In [`Sources/Services/ContainerAPIService/Server/Containers/ContainersService.swift`](https://github.com/apple/container/blob/main/Sources/Services/ContainerAPIService/Server/Containers/ContainersService.swift) (lines 726-760), the service reads log files directly from the container bundle and returns file handles to the CLI for streaming. This architecture ensures efficient access to both application STDIO streams and the `vminitd` boot logs without requiring direct filesystem access to the host. ## Summary - Use `container logs ` to access application STDIO output from the container's main process - Append `-n ` to limit output to recent lines, or `--follow` to stream new entries in real-time - Use `container logs --boot ` to retrieve the VM boot log (`vminitd.log`) from the container bundle - For container machines, use `container machine logs` with the same flags, including `--boot` for VM initialization logs - Log files are read from the bundle directory via the Container API service, ensuring consistent access patterns ## Frequently Asked Questions ### What is the difference between application logs and VM boot logs? Application logs contain the STDIO streams (stdout and stderr) produced by the container's main OCI process. VM boot logs, accessed via the `--boot` flag, contain the initialization sequence of the `vminitd` daemon that runs inside the micro-VM before the container starts. These boot logs are essential for debugging VM-level failures that occur before the application executes. ### Where are the VM boot logs stored on the filesystem? The VM boot logs are stored as `vminitd.log` within the container's bundle directory. According to the `Bundle` implementation in [`Sources/ContainerResource/Container/Bundle.swift`](https://github.com/apple/container/blob/main/Sources/ContainerResource/Container/Bundle.swift), the `Bundle.bootlog` property references this file at `…/vminitd.log` inside the bundle structure. ### Can I follow boot logs in real-time like application logs? Yes. Combine the `--boot` and `--follow` flags to stream the VM boot log as it is being written. This is particularly useful when initializing new containers or diagnosing slow boot sequences: ```bash container logs --boot --follow my-web-server ``` ### Do these commands work with container machines as well? Yes. The `container machine logs` command supports both application and boot log access. Omit the `--boot` flag to view the container's STDIO logs, or include it to view the VM boot log for the machine instance, as defined in [`Sources/ContainerCommands/Machine/MachineLogs.swift`](https://github.com/apple/container/blob/main/Sources/ContainerCommands/Machine/MachineLogs.swift).