git-annex/doc/git-annex-sim.mdwn
2024-09-16 16:48:21 -04:00

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# NAME
git-annex sim - simulate a network of repositories
# SYNOPSIS
git annex sim start [my.sim]
git annex sim command
git annex sim visit repo
git annex sim end
# DESCRIPTION
This command simulates the behavior of git-annex in a network of
repositories, determining which files would reach which repositories
according to the configuration of preferred content, numcopies,
trust level, etc.
The input to the simulation is a sim file, and/or sim commands that are
run after starting it. These are in the form "git annex sim command"
with the command in the same format used in the sim file (see sim commands
list below). For example, "git annex sim step 1" runs the simulation one step.
The simulation writes to an output sim file as it runs, which contains the
entire simulation input, as well as the actions performed in the
simulation, and the results of the simulation.
This allows re-running the same simulation later, as well as analyzing
the results of the simulation.
While a simulation is running, the command "git annex visit repo", where
"repo" is the name of one of the repositories in the simulation, will spawn
a subshell in a git repository whose git-annex branch contains the state of
that simulated repository. This allows running any git-annex command, such
as `git-annex whereis` to examine the state of the simulation.
Exit the subshell to end the visit.
Use "git annex sim end" to finish the simulation, and clean up.
# THE SIM FILE
This text file is used to configure the simulation and also to report on
the results of the simulation. Each line takes the form of a command
followed by parameters to the command. Lines starting with "#" are comments.
Here is an example sim file:
# add repositories to the simulation and connect them as remotes
init foo
init bar
connect foo <-> bar
# add a special remote
initremote baz
connect foo -> baz <- bar
# configure repositories
numcopies 2
group foo client
wanted foo standard
group bar archive
wanted bar standard
wanted baz include=*.mp3
# add annexed files in the working tree to the simulation, as if they
# were just added to repository foo
addtree foo include=*.mp3
addtree foo include=*.jpg
addtree foo include=bigfiles/
# add simulated annexed files
add bigfile 100gb bar
add hugefile 10tb foo
# run the simulation forward by ten steps
step 10
# remove foo's remote bar and see if a new file added to foo reaches bar
disconnect foo -> bar
add foo.mp3 2mb foo
step 5
# SIM COMMANDS
This is the full set of commands that can be used in the sim file as well
as passed to "git annex sim" while a simulation is running.
* `init name`
Initialize a simulated repository, giving it a name that will be used
in the simulation.
* `initremote name`
Initialize a simulated special remote.
* `use name here|remote|description|uuid`
Use an existing repository in the simulation, with its existing
configuration (trust level, groups, preferred and required content,
maxsize, and the groupwanted configuration of its groups).
The repository is given a name for the purposes of the simulation.
The repository to use can be specified by remote name, uuid, etc.
Example: "use myrepo here"
* `connect repo [<-|->|<->] repo [...]`
Add a connection between two or more repositories. The arrow indicates
which direction the connection runs, and it can be bidirectional. For
example, "connect foo -> bar" makes bar be a remote of foo, while
"connect foo <-> bar" makes each be the remote of the other. A chain
of connections can extend to many repositories, eg
"connect foo -> bar -> baz -> foo"
* `disconnect repo [<-|->|<->] repo [...]`
Removes connections between repositories.
For example, "disconnect foo -> bar" makes foo no longer have bar as a
remote.
* `addtree repo expression`
Adds annexed files from the git repository to the simulation making them
be present in the specified repository.
The expression is a preferred content expression
(see [[git-annex-preferred-content]](1)) specifying which annexed files
to add. While it is possible to include all or a large number of files
this way, note that often it's more efficient to simulate a small
quantity of files that have the particular properties you are interested
in.
This can be used with the same files more than once, to make multiple
repositories in the simulation contain the same files.
* `add filename size repo [repo ...]`
Create a simulated annexed file with the specified filename and size,
that is present in the specified repository, or repositories.
The size can be specified using any usual units, eg "10mb" or
"3.3terabytes"
The filename cannot contain a space.
This stages a file in the index, so that regular git-annex commands can
be used to query the state of the simulated annexed file. If there is
already an annexed file by that name, it will be overwritten with the new
file.
Note that the simulation does not cover adding conflicting files to
different repositories. The files in the simulation are the same across
all simulated repositories.
* `step N`
Run the simulation forward by this many steps.
On each step of the simulation, a simulated repository is selected
at random, and a random action is performed in it.
* `action repo getwanted remote`
Simulate the repository getting files it wants from the remote.
* `action repo dropunwanted`
Simulate the repository dropping files it does not want,
when it is able to verify enough copies exist on remotes.
* `action repo dropunwanted remote`
Simulate the repository dropping files from the remote that the remote
does not want, when it is able to verify enouh copies exist.
* `action repo sendwanted remote`
Simulate the repository sending files that the remote wants to it.
* `action repo gitpush remote`
Simulate the repository pushing the git-annex branch to the remote.
* `action repo gitpull remote`
Simulate the repository pulling the git-annex branch from the remote.
* `action repo pull remote`
Simulate the equivilant of [[git-annex-pull]](1), by combining
the actions gitpull, getwanted, and dropunwanted.
* `action repo push remote`
Simulate the equivilant of [[git-annex-push]](1) by combining
the actions sendwanted, dropunwanted, and gitpush.
* `action repo sync remote`
Simulate the equivilant of [[git-annex-sync]](1) by combining
the actions gitpull, getwanted, sendwanted, dropunwanted, and gitpush.
* `seed N`
Sets the random seed to a given number. Using this should make the
results of the simulation deterministic. The output sim file
always has the random seed included in it, so usually you don't need to
specify this.
* `present repo file`
This indicates the expected state of the simulation at this point. The
repository should contain the content of the file. If it does not, the
discrepancy will be indicated on standard error, and the `git-annex sim`
command will eventually exit nonzero.
This is added to the output sim file as the simulation runs.
* `notpresent repo file`
This indicates the expected state of the simulation at this point. The
repository should not contain the content of the file. If it does, the
discrepancy will be indicated on standard error, and the `git-annex sim`
command will eventually exit nonzero.
This is added to the output sim file as the simulation runs.
* `numcopies N`
Sets the desired number of copies. This is equivilant to
[[git-annex-numcopies]](1).
Note that other configuration that sets numcopies, such as .gitattributes
files, is not used by the simulation.
* `mincopies N`
Sets the minimum number of copies. This is equivilant to
[[git-annex-mincopies]](1).
* `trustlevel repo trusted|untrusted|semitrusted|dead`
Sets the trust level of the repository. This is equivilant to
[[git-annex-trust]](1), [[git-annex-untrust]](1), etc.
* `group repo group`
Add a repository to a group. This is equivilant to
[[git-annex-group]](1).
* `ungroup repo group`
Remove a repository from a group. This is equivilant to
[[git-annex-ungroup]](1).
* `wanted repo expression`
Configure the preferred content of a repository. This is equivilant
to [[git-annex-wanted]](1).
* `required repo expression`
Configure the required content of a repository. This is equivilant
to [[git-annex-required]](1).
* `groupwanted group expression`
Configure the groupwanted expression. This is equivilant to
[[git-annex-groupwanted]](1).
* `maxsize repo size`
Configure the maximum size of a repository. This is equivilant to
[[git-annex-maxsize]](1).
* `rebalance [on|off]`
Setting "rebalance on" is the equivilant of passing the --rebalance
option to git-annex. Setting "rebalance off" undoes that.
For example:
maxsize foo 1tb
rebalance on
step 100
rebalance off
# OPTIONS
* The [[git-annex-common-options]](1) can be used.
# HASKELL INTERFACE
There is also a Haskell interface to the simulation,
in the git-annex source tree in the Annex.Sim module. This allows
implementing simulations in pure Haskell code, without the overhead of
using a git repository.
# SEE ALSO
[[git-annex]](1)
[[git-annex-test]](1)
# AUTHOR
Joey Hess <id@joeyh.name>
Warning: Automatically converted into a man page by mdwn2man. Edit with care.