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Changelog

[Unreleased]

Added

  • Added devtool build --ssh-keys flag to support fetching from private git repositories.
  • Added option to configure block device flush.
  • Added --new-pid-ns flag to the Jailer in order to spawn the Firecracker process in a new PID namespace.
  • Added API metrics for GET, PUT and PATCH requests on /mmds endpoint.
  • Added --describe-snapshot flag to Firecracker to fetch the data format version of a snapshot state file provided as argument.
  • Added --no-seccomp parameter for disabling the default seccomp filters.
  • Added --seccomp-filter parameter for supplying user-provided, custom filters.
  • Added the seccompiler binary that is used to compile JSON seccomp filters into serialized BPF for Firecracker consumption.
  • Snapshotting support for GICv2 enabled guests.
  • Added devtool install to deploy built binaries in /usr/local/bin or a given path.

Changed

  • Changed Docker images repository from DockerHub to Amazon ECR.
  • Fixed off-by-one error in virtio-block descriptor address validation.
  • Changed the PATCH request on /balloon/statistics to schedule the first statistics update immediately after processing the request.
  • Deprecated the --seccomp-level parameter. It will be removed in a future release. Using it logs a runtime warning.
  • Experimental gnu libc builds no longer use a default seccomp filter.

Fixed

  • Fixed non-compliant check for the RTC device ensuring a fixed 4-sized data buffer.
  • Unnecessary interrupt assertion was removed from the RTC. However, a dummy interrupt is still allocated for snapshot compatibility reasons.
  • Fixed the SIGPIPE signal handler so Firecracker no longer exits. The signal is still recorded in metrics and logs.
  • Fixed ballooning API definitions by renaming all fields which mentioned "MB" to use "MiB" instead.
  • Snapshot related host files (vm-state, memory, block backing files) are now flushed to their backing mediums as part of the CreateSnapshot operation.
  • Fixed the SSBD mitigation not being enabled on aarch64 with the provided prod-host-setup.md.

[0.24.0]

Added

  • Added optional resume_vm field to /snapshot/load API call.
  • Added support for block rate limiter PATCH.
  • Added devtool test -c|--cpuset-cpus flag for cpus confinement when tests run.
  • Added devtool test -m|--cpuset-mems flag for memory confinement when tests run.
  • Added the virtio traditional memory ballooning device.
  • Added a mechanism to handle vCPU/VMM errors that result in process termination.
  • Added incremental guest memory snapshot support.
  • Added aarch64 snapshot support.

Changed

  • Change the information provided in DescribeInstance command to provide microVM state information (Not started/Running/Paused) instead of whether it's started or not.
  • Removed the jailer --extra-args parameter. It was a noop, having been replaced by the -- separator for extra arguments.
  • Changed the output of the --version command line parameter to include a list of supported snapshot data format versions for the firecracker binary.
  • Increased the maximum number of virtio devices from 11 to 19.
  • Added a new check that prevents creating v0.23 snapshots when more than 11 devices are attached.
  • If the stdout buffer is full and non-blocking, the serial writes no longer block. Any new bytes will be lost, until the buffer is freed. The device also logs these errors and increments the uart.error_count metric for each lost byte.

Fixed

  • Fixed inconsistency in YAML file InstanceInfo definition

[0.23.0]

Added

  • Added metric for throttled block device events.
  • Added metrics for counting rate limiter throttling events.
  • Added metric for counting MAC address updates.
  • Added metrics for counting TAP read and write errors.
  • Added metrics for counting RX and TX partial writes.
  • Added metrics that measure the duration of pausing and resuming the microVM, from the VMM perspective.
  • Added metric for measuring the duration of the last full/diff snapshot created, from the VMM perspective.
  • Added metric for measuring the duration of loading a snapshot, from the VMM perspective.
  • Added metrics that measure the duration of pausing and resuming the microVM, from the API (user) perspective.
  • Added metric for measuring the duration of the last full/diff snapshot created, from the API (user) perspective.
  • Added metric for measuring the duration of loading a snapshot, from the API (user) perspective.
  • Added track_dirty_pages field to machine-config. If enabled, Firecracker can create incremental guest memory snapshots by saving the dirty guest pages in a sparse file.
  • Added a new API call, PATCH /vm, for changing the microVM state (to Paused or Resumed).
  • Added a new API call, PUT /snapshot/create, for creating a full or diff snapshot.
  • Added a new API call, PUT /snapshot/load, for loading a snapshot.
  • Added new jailer command line argument --cgroup which allow the user to specify the cgroups that are going to be set by the Jailer.
  • Added full support for AMD CPUs (General Availability). More details here.

Fixed

  • Boot time on AMD achieves the desired performance (i.e under 150ms).

Changed

  • The logger level field is now case-insensitive.
  • Disabled boot timer device after restoring a snapshot.
  • Enabled boot timer device only when specifically requested, by using the --boot-timer dedicated cmdline parameter.
  • firecracker and jailer --version now gets updated on each devtool build to the output of git describe --dirty, if the git repo is available.
  • MicroVM process is only attached to the cgroups defined by using --cgroups or the ones defined indirectly by using --node.
  • Changed devtool build to build jailer binary for musl only targets. Building jailer binary for non-musl targets have been removed.

[0.22.0]

Added

  • Added a new API call, PUT /metrics, for configuring the metrics system.
  • Added app_name field in InstanceInfo struct for storing the application name.
  • New command-line parameters for firecracker, named --log-path, --level, --show-level and --show-log-origin that can be used for configuring the Logger when starting the process. When using this method for configuration, only --log-path is mandatory.
  • Added a guide for updating the dev container image.
  • Added a new API call, PUT /mmds/config, for configuring the MMDS with a custom valid link-local IPv4 address.
  • Added experimental JSON response format support for MMDS guest applications requests.
  • Added metrics for the vsock device.
  • Added devtool strip command which removes debug symbols from the release binaries.
  • Added the tx_malformed_frames metric for the virtio net device, emitted when a TX frame missing the VNET header is encountered.

Fixed

  • Added --version flag to both Firecracker and Jailer.
  • Return 405 Method Not Allowed MMDS response for non HTTP GET MMDS requests originating from guest.
  • Fixed folder permissions in the jail (#1802).
  • Any number of whitespace characters are accepted after ":" when parsing HTTP headers.
  • Potential panic condition caused by the net device expecting to find a VNET header in every frame.
  • Potential crash scenario caused by "Content-Length" HTTP header field accepting negative values.
  • Fixed #1754 - net: traffic blocks when running ingress UDP performance tests with very large buffers.

Changed

  • Updated CVE-2019-3016 mitigation information in Production Host Setup
  • In case of using an invalid JSON as a 'config-file' for Firecracker, the process will exit with return code 152.
  • Removed the testrun.sh wrapper.
  • Removed metrics_fifo field from the logger configuration.
  • Renamed log_fifo field from LoggerConfig to log_path and metrics_fifo field from MetricsConfig to metrics_path.
  • PATCH /drives/{id} only allowed post-boot. Use PUT for pre-boot updates to existing configurations.
  • PATCH /network-interfaces/{id} only allowed post-boot. Use PUT for pre-boot updates to existing configurations.
  • Changed returned status code from 500 Internal Server Error to 501 Not Implemented, for queries on the MMDS endpoint in IMDS format, when the requested resource value type is unsupported.
  • Allowed the MMDS data store to be initialized with all supported JSON types. Retrieval of these values within the guest, besides String, Array, and Dictionary, is only possible in JSON mode.
  • PATCH request on /mmds before the data store is initialized returns 403 BadRequest.
  • Segregated MMDS documentation in MMDS design documentation and MMDS user guide documentation.

[0.21.0]

Added

  • Support for booting with an initial RAM disk image. This image can be specified through the new initrd_path field of the /boot-source API request.

Fixed

  • Fixed #1469 - Broken GitHub location for Firecracker release binary.
  • The jailer allows changing the default api socket path by using the extra arguments passed to firecracker.
  • Fixed #1456 - Occasional KVM_EXIT_SHUTDOWN and bad syscall (14) during VM shutdown.
  • Updated the production host setup guide with steps for addressing CVE-2019-18960.
  • The HTTP header parsing is now case insensitive.
  • The put_api_requests and patch_api_requests metrics for net devices were un-swapped.

Changed

  • Removed redundant --seccomp-level jailer parameter since it can be simply forwarded to the Firecracker executable using "end of command options" convention.
  • Removed memory.dirty_pages metric.
  • Removed options field from the logger configuration.
  • Decreased release binary size by ~15%.
  • Changed default API socket path to /run/firecracker.socket. This path also applies when running with the jailer.
  • Disabled KVM dirty page tracking by default.
  • Removed redundant RescanBlockDevice action from the /actions API. The functionality is available through the PATCH /drives API. See docs/api_requests/patch-block.md.

[0.20.0]

Added

  • Added support for GICv2.

Fixed

  • Fixed CVE-2019-18960 - Fixed a logical error in bounds checking performed on vsock virtio descriptors.
  • Fixed #1283 - Can't start a VM in AARCH64 with vcpus number more than 16.
  • Fixed #1088 - The backtrace are printed on panic, no longer causing a seccomp fault.
  • Fixed #1375 - Change logger options type from Value to Vec<LogOption> to prevent potential unwrap on None panics.
  • Fixed #1436 - Raise interrupt for TX queue used descriptors
  • Fixed #1439 - Prevent achieving 100% cpu load when the net device rx is throttled by the ratelimiter
  • Fixed #1437 - Invalid fields in rate limiter related API requests are now failing with a proper error message.
  • Fixed #1316 - correctly determine the size of a virtio device backed by a block device.
  • Fixed #1383 - Log failed api requests.

Changed

  • Decreased release binary size by 10%.

[0.19.0]

Added

  • New command-line parameter for firecracker, named --no-api, which will disable the API server thread. If set, the user won't be able to send any API requests, neither before, nor after the vm has booted. It must be paired with --config-file parameter. Also, when API server is disabled, MMDS is no longer available now.
  • New command-line parameter for firecracker, named --config-file, which represents the path to a file that contains a JSON which can be used for configuring and starting a microVM without sending any API requests.
  • The jailer adheres to the "end of command options" convention, meaning all parameters specified after -- are forwarded verbatim to Firecracker.
  • Added KVM_PTP support to the recommended guest kernel config.
  • Added entry in FAQ.md for Firecracker Guest timekeeping.

Changed

  • Vsock API call: PUT /vsocks/{id} changed to PUT /vsock and no longer appear to support multiple vsock devices. Any subsequent calls to this API endpoint will override the previous vsock device configuration.
  • Removed unused 'Halting' and 'Halted' instance states.
  • Vsock host-initiated connections now implement a trivial handshake protocol. See the vsock doc for details. Related to: #1253, #1432, #1443

Fixed

  • Fixed serial console on aarch64 (GitHub issue #1147).
  • Upon panic, the terminal is now reset to canonical mode.
  • Explicit error upon failure of vsock device creation.
  • The failure message returned by an API call is flushed in the log FIFOs.
  • Insert virtio devices in the FDT in order of their addresses sorted from low to high.
  • Enforce the maximum length of the network interface name to be 16 chars as specified in the Linux Kernel.
  • Changed the vsock property id to vsock_id so that the API client can be successfully generated from the swagger definition.

[0.18.0]

Added

  • New device: virtio-vsock, backed by Unix domain sockets (GitHub issue #650). See docs/vsock.md.

Changed

  • No error is thrown upon a flush metrics intent if logger has not been configured.

Fixed

  • Updated the documentation for integration tests.
  • Fixed high CPU usage before guest network interface is brought up (GitHub issue #1049).
  • Fixed an issue that caused the wrong date (month) to appear in the log.
  • Fixed a bug that caused the seccomp filter to reject legit syscalls in some rare cases (GitHub issue #1206).
  • Docs: updated the production host setup guide.
  • Docs: updated the rootfs and kernel creation guide.

Removed

  • Removed experimental support for vhost-based vsock devices.

[0.17.0]

Added

  • New API call: PATCH /machine-config/, used to update VM configuration, before the microVM boots.
  • Added an experimental swagger definition that includes the specification for the vsock API call.
  • Added a signal handler for SIGBUS and SIGSEGV that immediately terminates the process upon intercepting the signal.
  • Added documentation for signal handling utilities.
  • Added [alpha] aarch64 support.
  • Added metrics for successful read and write operations of MMDS, Net and Block devices.

Changed

  • vcpu_count, mem_size_mib and ht_enabled have been changed to be mandatory for PUT requests on /machine-config/.
  • Disallow invalid seccomp levels by exiting with error.

Fixed

  • Incorrect handling of bind mounts within the jailed rootfs.
  • Corrected the guide for Alpine guest setup.

[0.16.0]

Added

  • Added [alpha] AMD support.
  • New devtool command: prepare_release. This updates the Firecracker version, crate dependencies and credits in preparation for a new release.
  • New devtool command: tag. This creates a new git tag for the specified release number, based on the changelog contents.
  • New doc section about building with glibc.

Changed

  • Dropped the JSON-formatted context command-line parameter from Firecracker in favor of individual classic command-line parameters.
  • When running with jailer the location of the API socket has changed to <jail-root-path>/api.socket (API socket was moved inside the jail).
  • PUT and PATCH requests on /mmds with data containing any value type other than String, Array, Object will returns status code 400.
  • Improved multiple error messages.
  • Removed all kernel modules from the recommended kernel config.

Fixed

  • Corrected the seccomp filter when building with glibc.

Removed

  • Removed the seccomp.bad_syscalls metric.

[0.15.2]

Fixed

  • Corrected the conditional compilation of the seccomp rule for madvise.

[0.15.1]

Fixed

  • A madvise call issued by the musl allocator was added to the seccomp allow list to prevent Firecracker from terminating abruptly when allocating memory in certain conditions.

[0.15.0]

Added

  • New API action: SendCtrlAltDel, used to initiate a graceful shutdown, if the guest has driver support for i8042 and AT Keyboard. See the docs for details.
  • New metric counting the number of egress packets with a spoofed MAC: net.tx_spoofed_mac_count.
  • New API call: PATCH /network-interfaces/, used to update the rate limiters on a network interface, after the start of a microVM.

Changed

  • Added missing vmm_version field to the InstanceInfo API swagger definition, and marked several other mandatory fields as such.
  • New default command line for guest kernel: reboot=k panic=1 pci=off nomodules 8250.nr_uarts=0 i8042.noaux i8042.nomux i8042.nopnp i8042.dumbkbd.

Fixed

  • virtio-blk: VIRTIO_BLK_T_FLUSH now working as expected.
  • Vsock devices can be attached when starting Firecracker using the jailer.
  • Vsock devices work properly when seccomp filtering is enabled.

[0.14.0]

Added

  • Documentation for development environment setup on AWS in dev-machine-setup.md.
  • Documentation for microVM networking setup in docs/network-setup.md.
  • Limit the maximum supported vCPUs to 32.

Changed

  • Log the app version when the Logger is initialized.
  • Pretty print panic information.
  • Firecracker terminates with exit code 148 when a syscall which is not present in the allow list is intercepted.

Fixed

  • Fixed build with the vsock feature.

[0.13.0]

Added

  • Documentation for Logger API Requests in docs/api_requests/logger.md.
  • Documentation for Actions API Requests in docs/api_requests/actions.md.
  • Documentation for MMDS in docs/mmds.md.
  • Flush metrics on request via a PUT /actions with the action_type field set to FlushMetrics.

Changed

  • Updated the swagger definition of the Logger to specify the required fields and provide default values for optional fields.
  • Default seccomp-level is 2 (was previously 0).
  • API Resource IDs can only contain alphanumeric characters and underscores.

Fixed

  • Seccomp filters are now applied to all Firecracker threads.
  • Enforce minimum length of 1 character for the jailer ID.
  • Exit with error code when starting the jailer process fails.

Removed

  • Removed InstanceHalt from the list of possible actions.

[0.12.0]

Added

  • The /logger API has a new field called options. This is an array of strings that specify additional logging configurations. The only supported value is LogDirtyPages.
  • When the LogDirtyPages option is configured via PUT /logger, a new metric called memory.dirty_pages is computed as the number of pages dirtied by the guest since the last time the metric was flushed.
  • Log messages on both graceful and forceful termination.
  • Availability of the list of dependencies for each commit inside the code base.
  • Documentation on vsock experimental feature and host setup recommendations.

Changed

  • PUT requests on /mmds always return 204 on success.
  • PUT operations on /network-interfaces API resources no longer accept the previously required state parameter.
  • The jailer starts with --seccomp-level=2 (was previously 0) by default.
  • Log messages use anonymous-instance as instance id if none is specified.

Fixed

  • Fixed crash upon instance start on hosts without 1GB huge page support.
  • Fixed "fault_message" inconsistency between Open API specification and code base.
  • Ensure MMDS compatibility with C5's IMDS implementation.
  • Corrected the swagger specification to ensure OpenAPI 2.0 compatibility.

[0.11.0]

Added

Changed

  • Improved MMDS network stack performance.
  • If the logging system is not yet initialized (via PUT /logger), log events are now sent to stdout/stderr.
  • Moved the instance_info_fails metric under get_api_requests
  • Improved readme and added links to more detailed information, now featured in subject-specific docs.

Fixed

  • Fixed bug in the MMDS network stack, that caused some RST packets to be sent without a destination.
  • Fixed bug in PATCH /drives, whereby the ID in the path was not checked against the ID in the body.

[0.10.1]

Fixed

  • The Swagger definition was corrected.

[0.10.0]

Added

  • Each Firecracker process has an associated microVM Metadata Store (MMDS). Its contents can be configured using the /mmds API resource.

Changed

  • The boot source is specified only with the kernel_image_path and the optional parameter boot_args. All other fields are removed.
  • The path_on_host property in the drive specification is now marked as mandatory.
  • PATCH drive only allows patching/changing the path_on_host property.
  • All PUT and PATCH requests return the status code 204.
  • CPUID brand string (aka model name) now includes the host CPU frequency.
  • API requests which add guest network interfaces have an additional parameter, allow_mmds_requests which defaults to false.
  • Stopping the guest (e.g. using the reboot command) also terminates the Firecracker process. When the Firecracker process ends for any reason, (other than kill -9), metrics are flushed at the very end.
  • On startup jailer closes all inherited file descriptors based on sysconf(_SC_OPEN_MAX) except input, output and error.
  • The microVM ID prefixes each Firecracker log line. This ID also appears in the process cmdline so it's now possible to ps | grep <ID> for it.

[0.9.0]

Added

  • Seccomp filtering is configured via the --seccomp-level jailer parameter.
  • Firecracker logs the starting addresses of host memory areas provided as guest memory slots to KVM.
  • The metric panic_count gets incremented to signal that a panic has occurred.
  • Firecracker logs a backtrace when it crashes following a panic.
  • Added basic instrumentation support for measuring boot time.

Changed

  • StartInstance is a synchronous API request (it used to be an asynchronous request).

Fixed

  • Ensure that fault messages sent by the API have valid JSON bodies.
  • Use HTTP response code 500 for internal Firecracker errors, and 400 for user errors on InstanceStart.
  • Serialize the machine configuration fields to the correct data types (as specified in the Swagger definition).
  • NUMA node assignment is properly enforced by the jailer.
  • The is_root_device and is_read_only properties are now marked as required in the Swagger definition of Drive object properties.

Removed

  • GET requests on the /actions API resource are no longer supported.
  • The metrics associated with asynchronous actions have been removed.
  • Remove the action_id parameter for InstanceStart, both from the URI and the JSON request body.

[0.8.0]

Added

  • The jailer can now be configured to enter a preexisting network namespace, and to run as a daemon.
  • Enabled PATCH operations on /drives resources.

Changed

  • The microVM id supplied to the jailer may now contain alphanumeric characters and hyphens, up to a maximum length of 64 characters.
  • Replaced the permissions property of /drives resources with a boolean.
  • Removed the state property of /drives resources.

[0.7.0]

Added

  • Rate limiting functionality allows specifying an initial one time burst size.
  • Firecracker can now boot from an arbitrary boot partition by specifying its unique id in the driver's API call.
  • Block device rescan is triggered via a PUT /actions with the drive ID in the action body's payload field and the action_type field set to BlockDeviceRescan.

Changed

  • Removed noapic from the default guest kernel command line.
  • The action_id parameter is no longer required for synchronous PUT requests to /actions.
  • PUT requests are no longer allowed on /drives resources after the guest has booted.

Fixed

  • Fixed guest instance kernel loader to accelerate vCPUs launch and consequently guest kernel boot.
  • Fixed network emulation to improve IO performance.

[0.6.0]

Added

  • Firecracker uses two different named pipes to record human readable logs and metrics, respectively.

Changed

  • Seccomp filtering can be enabled via setting the USE_SECCOMP environment variable.
  • It is possible to supply only a partial specification when attaching a rate limiter (i.e. just the bandwidth or ops parameter).
  • Errors related to guest network interfaces are now more detailed.

Fixed

  • Fixed a bug that was causing Firecracker to panic whenever a PUT request was sent on an existing network interface.
  • The id parameter of the jailer is required to be an RFC 4122-compliant UUID.
  • Fixed an issue which caused the network RX rate limiter to be more restrictive than intended.
  • API requests which contain unknown fields will generate an error.
  • Fixed an issue related to high CPU utilization caused by improper KVM PIT configuration.
  • It is now possible to create more than one network tun/tap interface inside a jailed Firecracker.

[0.5.0]

Added

  • Added metrics for API requests, VCPU and device actions for the serial console (UART), keyboard (i8042), block and network devices. Metrics are logged every 60 seconds.
  • A CPU features template for C3 is available, in addition to the one for T2.
  • Seccomp filters restrict Firecracker from calling any other system calls than the minimum set it needs to function properly. The filters are enabled by setting the USE_SECCOMP environment variable to 1 before running Firecracker.
  • Firecracker can be started by a new binary called jailer. The jailer takes as command line arguments a unique ID, the path to the Firecracker binary, the NUMA node that Firecracker will be assigned to and a uid and gid for Firecracker to run under. It sets up a chroot environment and a cgroup, and calls exec to morph into Firecracker.

Changed

  • In case of failure, the metrics and the panic location are logged before aborting.
  • Metric values are reset with every flush.
  • CPUTemplate is now called CpuTemplate in order to work seamlessly with the swagger code generator for Go.
  • firecracker-beta.yaml is now called firecracker.yaml.

Fixed

  • Handling was added for several untreated KVM exit scenarios, which could have led to panic.
  • Fixed a bug that caused Firecracker to crash when attempting to disable the IA32_DEBUG_INTERFACE MSR flag in the T2 CPU features.

Removed

  • Removed a leftover file generated by the logger unit tests.
  • Removed firecracker-v1.0.yaml.

[0.4.0]

Added

  • The CPU Template can be set with an API call on PUT /machine-config. The only available template is T2.
  • Hyperthreading can be enabled/disabled with an API call on PUT /machine-config. By default, hyperthreading is disabled.
  • Added boot time performance test (tests/performance/test_boottime.py).
  • Added Rate Limiter for VirtIO/net and VirtIO/net devices. The Rate Limiter uses two token buckets to limit rate on bytes/s and ops/s. The rate limiter can be (optionally) configured per drive with a PUT on /drives/{drive_id} and per network interface with a PUT on /network-interface/{iface_id}.
  • Implemented pre-boot PUT updates for /boot-source, /drives, /network-interfaces and /vsock.
  • Added integration tests for PUT updates.

Changed

  • Moved the API definition (swagger/firecracker-beta.yaml) to the api_server crate.
  • Removed "console=ttyS0" and added "8250.nr_uarts=0" to the default kernel command line to decrease the boot time.
  • Changed the CPU topology to have all logical CPUs on a single socket.
  • Removed the upper bound on CPU count as with musl there is no good way to get the total number of logical processors on a host.
  • Build time tests now print the full output of commands.
  • Disabled the Performance Monitor Unit and the Turbo Boost.
  • Check the expected KVM capabilities before starting the VM.
  • Logs now have timestamps.

Fixed

  • testrun.sh can run on platforms with more than one package manager by setting the package manager via a command line parameter (-p).
  • Allow correct set up of multiple network-interfaces with auto-generated MAC.
  • Fixed sporadic bug in VirtIO which was causing lost packages.
  • Don't allow PUT requests with empty body on /machine-config.
  • Deny PUT operations after the microvm boots (exception: the temporarily fix for live resize of block devices).

Removed

  • Removed examples crate. This used to have a Python example of starting Firecracker. This is replaced by test_api.py integration tests.
  • Removed helper scripts for getting coverage and coding style errors. These were replaced by test_coverage.py and test_style.py test integration tests.
  • Removed --vmm-no-api command line option. Firecracker can only be started via the API.

[0.3.0]

Added

  • Users can interrogate the Machine Configuration (i.e. vcpu count and memory size) using a GET request on /machine-config.
  • The logging system can be configured through the API using a PUT on /logger.
  • Block devices support live resize by calling PUT with the same parameters as when the block was created.
  • Release builds have Link Time Optimization (LTO) enabled.
  • Firecracker is built with musl, resulting in a statically linked binary.
  • More in-tree integration tests were added as part of the continuous integration system.

Changed

  • The vcpu count is enforced to 1 or an even number.
  • The Swagger definition of rate limiters was updated.
  • Syslog-enabled logs were replaced with a host-file backed mechanism.

Fixed

  • The host topology of the CPU and the caches is not leaked into the microvm anymore.
  • Boot time was improved by advertising the availability of the TSC deadline timer.
  • Fixed an issue which prevented Firecracker from working on 4.14 (or newer) host kernels.
  • Specifying the MAC address for an interface through the API is optional.

Removed

  • Removed support for attaching vsock devices.
  • Removed support for building Firecracker with glibc.

[0.2.0]

Added

  • Users can now interrogate Instance Information (currently just instance state) through the API.

Changed

  • Renamed api/swagger/all.yaml to api/swagger/firecracker-v1.0.yaml which specifies targeted API support for Firecracker v1.0.
  • Renamed api/swagger/firecracker-v0.1.yaml to api/swagger/firecracker-beta.yaml which specifies the currently supported API.
  • Users can now enforce that an emulated block device is read-only via the API. To specify whether a block device is read-only or read-write, an extra "permissions" field was added to the Drive definition in the API. The root filesystem is automatically mounted in the guest OS as ro/rw according to the specified "permissions". It's the responsibility of the user to mount any other read-only block device as such within the guest OS.
  • Users can now stop the guest VM using the API. Actions of type InstanceHalt are now supported via the API.

Fixed

  • Added support for getDeviceID() in virtIO-block. Without this, the guest Linux kernel would complain at boot time that the operation is unsupported.
  • stdin control is returned to the Firecracker process when guest VM is inactive. Raw mode stdin is forwarded to the guest OS when guest VM is running.

Removed

  • Removed api/swagger/actions.yaml.
  • Removed api/swagger/devices.yaml.
  • Removed api/swagger/firecracker-mvp.yaml.
  • Removed api/swagger/limiters.yaml.

[0.1.1]

Changed

  • Users can now specify the MAC address of a guest network interface via the PUT network interface API request. Previously, the guest MAC address parameter was ignored.

Fixed

  • Fixed a guest memory allocation issue, which previously led to a potentially significant memory chunk being wasted.
  • Fixed an issue which caused compilation problems, due to a compatibility breaking transitive dependency in the tokio suite of crates.

[0.1.0]

Added

  • One-process virtual machine manager (one Firecracker per microVM).
  • RESTful API running on a unix socket. The API supported by v0.1 can be found at api/swagger/firecracker-v0.1.yaml.
  • Emulated keyboard (i8042) and serial console (UART). The microVM serial console input and output are connected to those of the Firecracker process (this allows direct console access to the guest OS).
  • The capability of mapping an existing host tun-tap device as a VirtIO/net device into the microVM.
  • The capability of mapping an existing host file as a GirtIO/block device into the microVM.
  • The capability of creating a VirtIO/vsock between the host and the microVM.
  • Default demand fault paging & CPU oversubscription.