.Dd $Mdocdate$
.Dt SNAC 8
.Os
.Sh NAME
.Nm snac
.Nd snac administration
.Sh DESCRIPTION
The
.Nm
daemon processes messages from other servers in the Fediverse
using the ActivityPub protocol.
.Pp
This is the admin manual. For user operation, see
.Xr snac 1 .
For file and data formats, see
.Xr snac 5 .
.Ss Building and Installation
A C compiler must be installed in the system, as well as the development
headers and libraries for OpenSSL and curl. To build
.Nm ,
run
.Bd -literal -offset indent
make
.Ed
.Pp
And, after that, run as root
.Bd -literal -offset indent
make install
.Ed
.Ss Database Initialization
Once
.Nm
is properly installed on the system, designate a directory where
the server and user data are to be stored. This directory
must not exist yet.
.Nm
must always be run as a regular user; you can create one for
it or use your own. To initialize the database, execute
.Bd -literal -offset indent
snac init $HOME/snac-data
.Ed
.Pp
A small set of questions will be asked regarding the installation,
specially the host name it will run under, the local network address
and port
.Nm
will listen to, the optional path prefix and possibly other things.
.Pp
You can launch the
.Nm
process by running
.Bd -literal -offset indent
snac httpd $HOME/snac-data
.Ed
.Pp
Use a web browser to connect to the specified address and port. You
should see a greeting page.
.Pp
Log messages are sent to the standard error stream. By default, only
relevant information is written there. You can increase the debugging
level by editing the 'dbglevel' field in the
.Pa server.json
file or by setting a numeric value between 0 and 3 to the DEBUG
environment variable, see below.
.Pp
If you run
.Nm
in an OS controlled by
.Xr systemd 1 ,
you can prepare a user service to start/stop the daemon. Following the
previous example, create the file
.Pa ~/.config/systemd/user/snac.service
with the following content:
.Bd -literal -offset indent
[Unit]
Description=snac daemon

[Service]
Type=simple
Restart=always
RestartSec=5
ExecStart=/usr/local/bin/snac httpd /path/to/snac-data

[Install]
WantedBy=default.target
.Ed
.Pp
And activate it by running
.Bd -literal -offset indent
systemctl --user enable snac.service
systemctl --user start snac.service
.Ed
.Pp
For other operating systems, please read the appropriate documentation
on how to install a daemon as a non-root service.
.Ss Server Setup
.Pp
An http server with TLS and proxying support must already be
installed and configured.
.Nm
runs as a daemon and listens on a TCP/IP socket, preferrably
on a local interface. It can serve the full domain or only
a directory. The http server must be configured to route to the
.Nm
socket all related traffic and also the webfinger standard
address. The Host header must be propagated.
See the examples below.
.Ss Adding Users
.Pp
Users must be created from the command line.
You can do it by running
.Bd -literal -offset indent
snac adduser $HOME/snac-data
.Ed
.Pp
All needed data will be prompted for. There is no artificial limit
on the number of users that can be created.
.Ss Customization
The
.Pa server.json
configuration file allows some behaviour tuning:
.Bl -tag -width tenletters
.It Ic host
The host name.
.It Ic prefix
The URL path prefix.
.It Ic address
The listen network address.
.It Ic port
The list network port.
.It Ic dbglevel
The debug level. An integer value, being 0 the less verbose (the default).
.It Ic layout
The disk storage layout version. Never touch this.
.It Ic queue_retry_max
Messages sent out are stored in a queue. If the posting of a messages fails,
it's re-enqueued for later. This integer configures the maximum count of
times the sending will be retried.
.It Ic queue_retry_minutes
The number of minutes to wait before the failed posting of a message is
retried. This is not linear, but multipled by the number of retries
already done.
.It Ic max_timeline_entries
This is the maximum timeline entries shown in the web interface.
.It Ic timeline_purge_days
Entries in the timeline older that this number of days are purged.
.It Ic css_urls
This is a list of URLs to CSS files that will be inserted, in this order,
in the HTML before the user CSS. Use these files to configure the global
site layout.
.El
.Pp
You must restart the server to make effective these changes.
.Pp
If a file named
.Pa greeting.html
is present in the server base directory, it will be returned whenever
the base URL of the server is requested. Fill it with whatever
information about the instance you want to supply to people
visiting the server, like sign up requirements, site policies
and such. The special %userlist% mark in the file will cause
the list of users in this instance to be inserted.
.Pp
Users can change a bit of information about themselves from the
web interface. See
.Xr snac 1
for details. Further, every user has a private CSS file in their
.Pa static/style.css
that can be modified to suit their needs. This file contains
a copy of the
.Pa style.css
file in the server root and it's inserted into the HTML output.
It's not easily accesible from the web interface to avoid users
shooting themselves in the foot by destroying everything.
.Ss Old Data Purging
The Fediverse generates big loads of data that get old and
stale very quickly. By default, 
.Nm
does not delete anything; you must do it explicitly by issuing a
.Ar purge
command periodically. A cron entry will suffice. You can add the
following to the
.Nm
user's crontab:
.Bd -literal -offset indent
# execute a data purge on Sundays at 4 am
0 4 * * 0 /usr/local/bin/snac purge /path/to/snac-data
.Ed
.Pp
The user-generated data (the local timeline) is never deleted.
.Ss ActivityPub Support
These are the following activities and objects that
.Nm
supports:
.Bl -tag -width tenletters
.It Vt Follow
Complete support, on input and output.
.It Vt Undo
For
.Vt Follow ,
.Vt Like
and
.Vt Announce
objects, on input and output.
.It Vt Create
For
.Vt Note
objects, on input and output.
.It Vt Accept
For
.Vt Follow
objects, on input and output.
.It Vt Like
For
.Vt Note
objects, on input and output.
.It Vt Announce
For
.Vt Note
objects, on input and output.
.It Vt Update
For
.Vt Person
objects, on input and output. Support for updating
.Vt Note
objects will probably be added in the future.
.It Vt Delete
Supported for
.Vt Note
and
.Vt Tomsbtone
objects on input, and for
.Vt Note
objects on output.
.El
.Pp
The rest of activities and objects are dropped on input.
.Pp
There is partial support for
.Vt OrderedCollection
objects in the
.Pa /outbox 
(with the last 20 entries of the local timeline shown). No pagination
is supported. Intentionally, the
.Pa /followers
and
.Pa /following
paths return empty lists.
.Ss Other Considerations
.Nm
stores all the messages it receives as JSON files, which are usually
bloated and filled with redundant information. Using a filesystem with
file compression enabled (like btrfs or zfs) will probably be a good
choice to store the
.Nm
database into.
.Sh ENVIRONMENT
.Bl -tag -width Ds
.It Ev DEBUG
Overrides the debugging level from the server 'dbglevel' configuration
variable. Set it to an integer value. The higher, the deeper in meaningless
verbiage you'll find yourself into.
.El
.Sh EXAMPLES
You want to install the
.Nm
Fediverse daemon in the host example.com, that is correctly configured
with a valid TLS certificate and running the nginx httpd server.
The service will be installed under the
.Pa fedi
location. Two users, walter and jessie, will be hosted in the system.
Their Fediverse presence addresses will be https://example.com/fedi/walter
and https://example.com/fedi/jesse, respectively. They will be known
in the Fediverse as @walter@example.com and @jesse@example.com. The
.Nm
daemon will run as the user snacusr in the system and listen to the
localhost:8001 network socket. All data will be stored in the
.Pa /home/snacusr/fedidata
directory.
.Pp
Log into the system as snacusr and execute:
.Bd -literal -offset indent
snac init /home/snacusr/fedidata
.Ed
.Pp
Answer "example.com" to the host name question, "/fedi" to the path
prefix question, "localhost" to the address and "8001" to the port.
.Pp
Create the users
.Bd -literal -offset indent
snac adduser /home/snacusr/fedidata walter
snac adduser /home/snacusr/fedidata jesse
.Ed
.Pp
Answer the questions with reasonable values.
.Pp
Execute the server:
.Bd -literal -offset indent
snac httpd /home/snacusr/fedidata
.Ed
.Pp
Edit the nginx configuration and add the following snippet to the
example.com server section:
.Bd -literal -offset indent
location /.well-known/webfinger {
    proxy_pass http://localhost:8001;
    proxy_set_header Host $http_host;
}

location /fedi {
    proxy_pass http://localhost:8001;
    proxy_set_header Host $http_host;
}
.Ed
.Pp
Restart the nginx daemon and connect to https://example.com/fedi/walter.
The empty, default screen will be shown. Enter the admin section with the
credentials defined for this user. Search people, start following
them, engage in arid discussions and generally enjoy the frustrating
experience of Social Media.
.Sh SEE ALSO
.Xr snac 1 ,
.Xr snac 5
.Sh AUTHORS
.An grunfink
.Sh LICENSE
See the LICENSE file for details.
.Sh CAVEATS
JSON files are fragile when modified by hand. Take care.