`gobottin` is a LDAP server that uses Consul's key-value store as a storage backend,
in order to provide a redundant (high-availability) LDAP server on a Nomad+Consul cluster.
It is a reimplementation of [superboum's Bottin](https://github.com/superboum/bottin)
using the Go programming language.

Building `gobottin` can be done simply by running `go build` in this folder.

`gobottin` takes a single command line argument, `-config <filename>`, which is the
path to its config file (defaults to `./config.json`).
The configuration file is a JSON file whose contents is described in the following section.

# Configuration of `gobottin`

## The LDAP suffix

`gobottin` only handles LDAP entries under a given path, which is typically of the form `dn=sld,dn=tld`, where `sld.tld` is your domain name. Specify this suffix in the `suffix` key of the json config file.

## Connection to the Consul server

By default, `gobottin` connects to the Consul server on localhost.
Change this by specifying the `consul_host` key in the json config file.

## Bind address

By default, `gobottin` listens on all interfaces on port 389.
Change this by setting the `bind_address` key in the json config file.

## TLS

`gobottin` supports SSL connections using the STARTTLS LDAP functionnality.
To use it, specify the following three keys in the json config file:

- `ssl_server_name`: the host name that clients will use to reach your LDAP server
- `ssl_cert_file`: path to your SSL certificate (a `.pem` file)
- `ssl_key_file`: path to your SSL key (a `.pem` file)

## Access control list

`gobottin` supports a flexible syntax to specify access rights to items in the database.
The ACL is specified as a list of rules. A request will be allowed if there exists a rule that allows it. Otherwise an insufficient permission error will be returned.

The list of ACL rules are specified in the `acl` key of the json config file, as a list of strings whose structure is defined in the next paragraph.

### Rule format

A rule is a string composed of five fields separated by `:`. The fields are the following:

1. The name of the user that must be bound (logged in) for the rule to apply. May contain wildcards such as `*` (see the format used by Go's `path.Match`). The special name `ANONYMOUS` applies to clients before they bind to an LDAP entity.
2. The groups that the user must be a part of, separated by spaces. Wildcards may also be used. If several groups (or wildcard group patterns) are specified, for each pattern the user must be part of a group that matches it.
3. The action, a subset of `read`, `add`, `delete`, `modify` separated by spaces.
4. The target entity of the action as a pattern that may contain wildcards. The special word `SELF` is replaced by the entity name of the bound user before trying to match.
5. The allowed attributes for a read, add or modify operation. This is specified as a list of patterns to include and exclude attributes, separated by spaces. A pattern that starts by `!` is an exclude pattern, otherwise it is an include pattern. To read/write an attribute, it has to match at least one include pattern and not match any exclude pattern. Delete operations do not check for any attribute, thus as soon as `delete` is included in the allowed actions, the right to delete entities is granted.


### Rule examples

```
// Anybody (before binding) can bind to an entity under ou=users,dc=gobottin,dc=eu
"ANONYMOUS::bind:*,ou=users,dc=gobottin,dc=eu:",
// Anybody (before binding) can bind to the specific admin entity
"ANONYMOUS::bind:cn=admin,dc=gobottin,dc=eu:",
// Anybody who is logged in can read anything that is not a userpassword attribute
"*,dc=gobottin,dc=eu::read:*:* !userpassword",
// Anybody can read and modify anything from their own entry
"*::read modify:SELF:*",
// The admin can read, add, modify, delete anything
"cn=admin,dc=gobottin,dc=eu::read add modify delete:*:*",
// Members of the admin group can read, add, modify, delete anything
"*:cn=admin,ou=groups,dc=gobottin,dc=eu:read add modify delete:*:*"
```