1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
|
<?xml version="1.0"?>
<!--*-nxml-*-->
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
<!--
This file is part of systemd.
Copyright 2013 David Strauss
systemd is free software; you can redistribute it and/or modify it
under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1 of the License, or
(at your option) any later version.
systemd is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with systemd; If not, see <http://www.gnu.org/licenses/>.
-->
<refentry id="systemd-sabridge">
<refentryinfo>
<title>systemd-sabridge</title>
<productname>systemd</productname>
<authorgroup>
<author>
<contrib>Developer</contrib>
<firstname>David</firstname>
<surname>Strauss</surname>
<email>david@davidstrauss.net</email>
</author>
</authorgroup>
</refentryinfo>
<refmeta>
<refentrytitle>systemd-sabridge</refentrytitle>
<manvolnum>1</manvolnum>
</refmeta>
<refnamediv>
<refname>systemd-sabridge</refname>
<refpurpose>Inherit a socket. Bidirectionally
proxy.</refpurpose>
</refnamediv>
<refsynopsisdiv>
<cmdsynopsis>
<command>systemd-sabridge</command>
<arg choice="opt" rep="repeat">OPTIONS</arg>
<arg choice="plain"><replaceable>HOSTNAME-OR-IP</replaceable></arg>
<arg choice="plain"><replaceable>PORT-OR-SERVICE</replaceable></arg>
</cmdsynopsis>
<cmdsynopsis>
<command>systemd-sabridge</command>
<arg choice="opt" rep="repeat">OPTIONS</arg>
<arg choice="plain"><replaceable>UNIX-DOMAIN-SOCKET-PATH</replaceable>
</arg>
</cmdsynopsis>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
<para>
<command>systemd-sabridge</command>provides a proxy
to socket-activate services that do not yet support
native socket activation. On behalf of the daemon,
the proxy inherits the socket from systemd, accepts
each client connection, opens a connection to the server
for each client, and then bidirectionally forwards
data between the two.</para>
<para>This utility's behavior is similar to
<citerefentry><refentrytitle>socat</refentrytitle><manvolnum>1</manvolnum> </citerefentry>.
The main differences for <command>systemd-sabridge</command>
are support for socket activation with
<literal>Accept=false</literal> and an event-driven
design that scales better with the number of
connections.</para>
</refsect1>
<refsect1>
<title>Options</title>
<para>The following options are understood:</para>
<variablelist>
<varlistentry>
<term><option>-h</option></term>
<term><option>--help</option></term>
<listitem>
<para>Prints a short help
text and exits.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>--version</option></term>
<listitem>
<para>Prints a version
string and exits.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>--ignore-env</option></term>
<listitem>
<para>Skips verification of
the expected PID and file
descriptor numbers. Use if
invoked indirectly, for
example with a shell script
rather than with
<option>ExecStart=/usr/bin/systemd-sabridge</option>
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1>
<title>Exit status</title>
<para>On success 0 is returned, a non-zero failure
code otherwise.</para>
</refsect1>
<refsect1>
<title>Examples</title>
<refsect2>
<title>Direct-Use Example</title>
<para>Use two services with a dependency
and no namespace isolation.</para>
<example label="bridge socket unit">
<title>/etc/systemd/system/bridge-to-nginx.socket</title>
<programlisting>
<![CDATA[[Socket]
ListenStream=80
[Install]
WantedBy=socket.target]]>
</programlisting>
</example>
<example label="bridge service unit">
<title>/etc/systemd/system/bridge-to-nginx.service</title>
<programlisting>
<![CDATA[[Unit]
After=nginx.service
Requires=nginx.service
[Service]
ExecStart=/usr/bin/systemd-sabridge /tmp/nginx.sock
PrivateTmp=true
PrivateNetwork=true]]>
</programlisting>
</example>
<example label="nginx configuration">
<title>/etc/nginx/nginx.conf</title>
<programlisting>
<![CDATA[[...]
server {
listen unix:/tmp/nginx.sock;
[...]]]>
</programlisting>
</example>
<example label="commands">
<programlisting>
<![CDATA[$ sudo systemctl --system daemon-reload
$ sudo systemctl start bridge-to-nginx.socket
$ sudo systemctl enable bridge-to-nginx.socket
$ curl http://localhost:80/]]>
</programlisting>
</example>
</refsect2>
<refsect2>
<title>Indirect-Use Example</title>
<para>Use a shell script to isolate the
service and bridge into the same namespace.
This is particularly useful for running
TCP-only daemons without the daemon
affecting ports on regular
interfaces.</para>
<example label="combined bridge and nginx socket unit">
<title>
/etc/systemd/system/bridge-with-nginx.socket</title>
<programlisting>
<![CDATA[[Socket]
ListenStream=80
[Install]
WantedBy=socket.target]]>
</programlisting>
</example>
<example label="combined bridge and nginx service unit">
<title>
/etc/systemd/system/bridge-with-nginx.service</title>
<programlisting>
<![CDATA[[Unit]
After=syslog.target remote-fs.target nss-lookup.target
[Service]
ExecStartPre=/usr/sbin/nginx -t
ExecStart=/usr/bin/sabridge-nginx.sh
PrivateTmp=true
PrivateNetwork=true]]>
</programlisting>
</example>
<example label="shell script">
<title>
/usr/bin/sabridge-nginx.sh</title>
<programlisting>
<![CDATA[#!/bin/sh
/usr/sbin/nginx
while [ ! -f /tmp/nginx.pid ]
do
/usr/bin/inotifywait /tmp/nginx.pid
done
/usr/bin/systemd-sabridge --ignore-env localhost 8080]]>
</programlisting>
</example>
<example label="nginx configuration">
<title>
/etc/nginx/nginx.conf</title>
<programlisting>
<![CDATA[[...]
server {
listen 8080;
listen unix:/tmp/nginx.sock;
[...]]]>
</programlisting>
</example>
<example label="commands">
<programlisting>
<![CDATA[$ sudo systemctl --system daemon-reload
$ sudo systemctl start bridge-with-nginx.socket
$ sudo systemctl enable bridge-with-nginx.socket
$ curl http://localhost:80/]]>
</programlisting>
</example>
</refsect2>
</refsect1>
<refsect1>
<title>See Also</title>
<para>
<citerefentry>
<refentrytitle>
systemd.service</refentrytitle>
<manvolnum>5</manvolnum>
</citerefentry>,
<citerefentry>
<refentrytitle>
systemd.socket</refentrytitle>
<manvolnum>5</manvolnum>
</citerefentry>,
<citerefentry>
<refentrytitle>systemctl</refentrytitle>
<manvolnum>1</manvolnum>
</citerefentry>,
<citerefentry>
<refentrytitle>socat</refentrytitle>
<manvolnum>1</manvolnum>
</citerefentry></para>
</refsect1>
</refentry>
|
