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Command flags (OPTIONS) in man pages have to date been in haphazard order. Sometimes that order is sensible, e.g., most-important options first, but more often they're just in arbitrary places. This makes life hard for users. Here, I update the man-page-check Makefile script so it checks and enforces alphabetical order in OPTIONS sections. Then -- the hard part -- update all existing man pages to conform to this requirement. Signed-off-by: Ed Santiago <santiago@redhat.com>
169 lines
7.1 KiB
Markdown
169 lines
7.1 KiB
Markdown
% podman-container-checkpoint(1)
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## NAME
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podman\-container\-checkpoint - Checkpoints one or more running containers
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## SYNOPSIS
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**podman container checkpoint** [*options*] *container* [*container* ...]
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## DESCRIPTION
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**podman container checkpoint** checkpoints all the processes in one or more *containers*. A *container* can be restored from a checkpoint with **[podman-container-restore](podman-container-restore.1.md)**. The *container IDs* or *names* are used as input.
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*IMPORTANT: If the container is using __systemd__ as __entrypoint__ checkpointing the container might not be possible.*
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## OPTIONS
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#### **--all**, **-a**
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Checkpoint all running *containers*.\
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The default is **false**.\
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*IMPORTANT: This OPTION does not need a container name or ID as input argument.*
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#### **--compress**, **-c**=**zstd** | *none* | *gzip*
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Specify the compression algorithm used for the checkpoint archive created
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with the **--export, -e** OPTION. Possible algorithms are **zstd**, *none*
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and *gzip*.\
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One possible reason to use *none* is to enable faster creation of checkpoint
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archives. Not compressing the checkpoint archive can result in faster checkpoint
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archive creation.\
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The default is **zstd**.
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#### **--export**, **-e**=*archive*
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Export the checkpoint to a tar.gz file. The exported checkpoint can be used
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to import the *container* on another system and thus enabling container live
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migration. This checkpoint archive also includes all changes to the *container's*
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root file-system, if not explicitly disabled using **--ignore-rootfs**.
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#### **--file-locks**
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Checkpoint a *container* with file locks. If an application running in the container
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is using file locks, this OPTION is required during checkpoint and restore. Otherwise
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checkpointing *containers* with file locks is expected to fail. If file locks are not
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used, this option is ignored.\
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The default is **false**.
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#### **--ignore-rootfs**
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If a checkpoint is exported to a tar.gz file it is possible with the help of **--ignore-rootfs** to explicitly disable including changes to the root file-system into the checkpoint archive file.\
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The default is **false**.\
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*IMPORTANT: This OPTION only works in combination with __--export, -e__.*
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#### **--ignore-volumes**
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This OPTION must be used in combination with the **--export, -e** OPTION.
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When this OPTION is specified, the content of volumes associated with
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the *container* will not be included into the checkpoint tar.gz file.\
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The default is **false**.
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#### **--keep**, **-k**
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Keep all temporary log and statistics files created by CRIU during checkpointing. These files are not deleted if checkpointing fails for further debugging. If checkpointing succeeds these files are theoretically not needed, but if these files are needed Podman can keep the files for further analysis.\
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The default is **false**.
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#### **--latest**, **-l**
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Instead of providing the *container ID* or *name*, use the last created *container*. If other methods than Podman are used to run *containers* such as `CRI-O`, the last started *container* could be from either of those methods.\
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The default is **false**.\
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*IMPORTANT: This OPTION is not available with the remote Podman client, including Mac and Windows (excluding WSL2) machines. This OPTION does not need a container name or ID as input argument.*
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#### **--leave-running**, **-R**
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Leave the *container* running after checkpointing instead of stopping it.\
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The default is **false**.
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#### **--pre-checkpoint**, **-P**
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Dump the *container's* memory information only, leaving the *container* running. Later
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operations will supersede prior dumps. It only works on `runc 1.0-rc3` or `higher`.\
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The default is **false**.
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The functionality to only checkpoint the memory of the container and in a second
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checkpoint only write out the memory pages which have changed since the first
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checkpoint relies on the Linux kernel's soft-dirty bit, which is not available
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on all systems as it depends on the system architecture and the configuration
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of the Linux kernel. Podman will verify if the current system supports this
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functionality and return an error if the current system does not support it.
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#### **--print-stats**
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Print out statistics about checkpointing the container(s). The output is
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rendered in a JSON array and contains information about how much time different
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checkpoint operations required. Many of the checkpoint statistics are created
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by CRIU and just passed through to Podman. The following information is provided
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in the JSON array:
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- **podman_checkpoint_duration**: Overall time (in microseconds) needed to create
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all checkpoints.
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- **runtime_checkpoint_duration**: Time (in microseconds) the container runtime
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needed to create the checkpoint.
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- **freezing_time**: Time (in microseconds) CRIU needed to pause (freeze) all
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processes in the container (measured by CRIU).
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- **frozen_time**: Time (in microseconds) all processes in the container were
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paused (measured by CRIU).
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- **memdump_time**: Time (in microseconds) needed to extract all required memory
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pages from all container processes (measured by CRIU).
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- **memwrite_time**: Time (in microseconds) needed to write all required memory
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pages to the corresponding checkpoint image files (measured by CRIU).
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- **pages_scanned**: Number of memory pages scanned to determine if they need
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to be checkpointed (measured by CRIU).
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- **pages_written**: Number of memory pages actually written to the checkpoint
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image files (measured by CRIU).
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The default is **false**.
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#### **--tcp-established**
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Checkpoint a *container* with established TCP connections. If the checkpoint
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image contains established TCP connections, this OPTION is required during
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restore. Defaults to not checkpointing *containers* with established TCP
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connections.\
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The default is **false**.
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#### **--with-previous**
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Check out the *container* with previous criu image files in pre-dump. It only works on `runc 1.0-rc3` or `higher`.\
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The default is **false**.\
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*IMPORTANT: This OPTION is not available with __--pre-checkpoint__*.
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This option requires that the option __--pre-checkpoint__ has been used before on the
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same container. Without an existing pre-checkpoint, this option will fail.
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Also see __--pre-checkpoint__ for additional information about __--pre-checkpoint__
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availability on different systems.
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## EXAMPLES
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Make a checkpoint for the container "mywebserver".
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```
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# podman container checkpoint mywebserver
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```
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Dumps the container's memory information of the latest container into an archive.
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```
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# podman container checkpoint -P -e pre-checkpoint.tar.gz -l
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```
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Keep the container's memory information from an older dump and add the new container's memory information.
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```
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# podman container checkpoint --with-previous -e checkpoint.tar.gz -l
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```
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Dump the container's memory information of the latest container into an archive with the specified compress method.
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```
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# podman container checkpoint -l --compress=none --export=dump.tar
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# podman container checkpoint -l --compress=gzip --export=dump.tar.gz
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```
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## SEE ALSO
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**[podman(1)](podman.1.md)**, **[podman-container-restore(1)](podman-container-restore.1.md)**, **criu(8)**
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## HISTORY
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September 2018, Originally compiled by Adrian Reber <areber@redhat.com>
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