NAME

git-annex sim - simulate a network of repositories

SYNOPSIS

git annex sim start [my.sim]

git annex sim command

git annex sim show

git annex sim end

git annex sim run my.sim

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 keeps a log as it runs, which contains the entire simulation input, as well as the actions performed in the simulation, and the results of the simulation. Use "git-annex sim show" to display the log. This allows re-running the same simulation later, as well as analyzing the results of the simulation.

Use "git annex sim end" to finish the simulation, and clean up.

As a convenience, to run a sim from a file, and then stop it, use "git-annex sim run". If there is a problem running the sim, it will be shown before it is stopped.

Note that interrupting this command while it is running may leave the simulation in an inconsistent state. And running multiple sim commands at the same time can as well, although it is safe to run "git annex sim visit" while running other sim commands.

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 "#" or "--" 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"
visit repo [command]

Runs the specified shell command inside the simulated repository, and waits for it to exit.

When no shell command is specified, it runs an interactive shell.

The command is run in a git repository whosegit-annex branch contains the state of that simulated repository. This allows running any git-annex commands, such as git-annex whereis to examine the state of the simulation. You should avoid making any changes to git-annex state.
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.

When run in a subdirectory of the repository, only files in that subdirectory are considered for addition.

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.
`addmulti N suffix minsize maxsize repo [repo ...]

Add multiple simulated annexed files, with random sizes in the range between minsize and maxsize.

The files are named by combining the number, which starts at 1 and goes up to N, with the suffix.

For example:

addmulti 100 testfile.jpg 100kb 10mb foo

That adds files named "1testfile.jpg", 2testfile.jpg", etc.

Note that adding a large number of files to the simulation can slow it down and make it use a lot of memory.
step N

Run the simulation forward by this many steps.

On each step of the simulation, one file is either transferred or dropped, according to the preferred content and other configuration.

If there are no more files that can be either transferred or dropped according to the current configuration, a message will be displayed to indicate that the simulation has stabilized.

This also simulates git pull and git push being run in each repository, as needed in order to find additional things to do.
stepstable N

Run the simulation forward by this many steps, at which point it is expected to have stabilized.

If the simulation does not stabilize, the command will exit with a nonzero exit state.
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 dropunwantedfrom 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, dropunwantedfrom, and gitpush.
action repo sync remote

Simulate the equivilant of git-annex-sync(1) by combining the actions gitpull, getwanted, sendwanted, dropunwanted, and gitpush.
action [...] while action [...]

Simulate running the two actions concurrently. While the simulation only actually simulates one thing happening at a time, when the actions each operate on multiple files, they will be interleaved randomly.

Any number of actions can be combined this way.

For example:

action foo dropunwanted while action bar getwanted foo

In this example, bar may or may not get a file before foo drops it.
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 it can be used to replay the simulation.
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.
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).
randomwanted repo term...

Configure the preferred content of a repository to a random expression generated by combining a random selection of the provided terms with "and", "or", and "not".

For example, "randomwanted foo exclude=.x include=.x largerthan=100kb" might generate an expression of "exclude=.x or not largerthan=100kb and include=.x" or it might generate an expression of "include=.x and exclude=.x"
randomrequired repo term...

Configure the required content of a repository to a random expression.
randomgroupwanted group term...

Configure the groupwanted to a random expression.
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).
metadata filename expression

Change the metadata of the simulated file. The expression is in the same format as the --set option of the git-annex-metadata command. For example: metadata foo year=2025
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
clusternode name repo

Simulate a repository being a node of a cluster, which can be referred to using the specified name.

Rather than a cluster gateway being simulated as a separate entity, any connection to a cluster node with that name is treated as accessing that repository via the same cluster gateway.

Since a cluster gateway knows about all changes that are made to nodes via it, every repository that has a connection to a cluster node will immediately know about changes that are made via that node, without needing a simulated git pull.

To simulate a repository being a node of more than one cluster, or behind multiple gateways in the same cluster, use this command to give it multiple names.

OPTIONS

The git-annex-common-options(1) can be used.

EXAMPLES

git-annex includes a collection of sim files, at https://git-annex.branchable.com/sims/

AUTHOR

Joey Hess id@joeyh.name

Warning: Automatically converted into a man page by mdwn2man. Edit with care.