Mirror admin stuff, initial commit.
[mirror-admin] / doc / ftpsync / README
1 Archvsync
2 =========
3
4 This is the central repository for the Debian mirror scripts. The scripts
5 in this repository are written for the purposes of maintaining a Debian
6 archive mirror (and shortly, a Debian bug mirror), but they should be
7 easily generalizable.
8
9
10 Currently the following scripts are available:
11
12 * ftpsync - Used to sync an archive using rsync
13 * runmirrors - Used to notify leaf nodes of available updates
14 * dircombine - Internal script to manage the mirror user's $HOME
15 on debian.org machines
16 * typicalsync - Generates a typical Debian mirror
17 * udh - We are lazy, just a shorthand to avoid typing the
18 commands, ignore... :)
19
20 Usage
21 =====
22 For impatient people, short usage instruction:
23
24 - Create a dedicated user for the whole mirror.
25 - Create a seperate directory for the mirror, writeable by the new user.
26 - Place the ftpsync script in the mirror user's $HOME/bin (or just $HOME)
27 - Place the ftpsync.conf.sample into $HOME/etc as ftpsync.conf and edit
28 it to suit your system. You should at the very least change the TO=
29 and RSYNC_HOST lines.
30 - Create $HOME/log (or wherever you point $LOGDIR to)
31 - Setup the .ssh/authorized_keys for the mirror user and place the public key of
32 your upstream mirror into it. Preface it with
33 no-port-forwarding,no-X11-forwarding,no-agent-forwarding,no-pty,command="~/bin/ftpsync",from="IPADDRESS"
34 and replace $IPADDRESS with that of your upstream mirror.
35 - You are finished
36
37 In order to receive different pushes or syncs from different archives,
38 name the config file ftpsync-$ARCHIVE.conf and call the ftpsync script
39 with the commandline "sync:archive:$ARCHIVE". Replace $ARCHIVE with a
40 sensible value. If your upstream mirror pushes you using runmirrors
41 bundled together with this sync script, you do not need to add the
42 "sync:archive" parameter to the commandline, the scripts deal with it
43 automatically.
44
45
46
47 Debian mirror script minimum requirements
48 =========================================
49 As always, you may use whatever scripts you want for your Debian mirror,
50 but we *STRONGLY* recommend you to not invent your own. However, if you
51 want to be listed as a mirror it *MUST* support the following minimal
52 functionality:
53
54 - Must perform a 2-stage sync
55 The archive mirroring must be done in 2 stages. The first rsync run
56 must ignore the index files. The correct exclude options for the
57 first rsync run are:
58 --exclude Packages* --exclude Sources* --exclude Release* --exclude ls-lR*
59 The first stage must not delete any files.
60
61 The second stage should then transfer the above excluded files and
62 delete files that no longer belong on the mirror.
63
64 Rationale: If archive mirroring is done in a single stage, there will be
65 periods of time during which the index files will reference files not
66 yet mirrored.
67
68 - Must not ignore pushes whil(e|st) running.
69 If a push is received during a run of the mirror sync, it MUST NOT
70 be ignored. The whole synchronization process must be rerun.
71
72 Rationale: Most implementations of Debian mirror scripts will leave the
73 mirror in an inconsistent state in the event of a second push being
74 received while the first sync is still running. It is likely that in
75 the near future, the frequency of pushes will increase.
76
77 - Should understand multi-stage pushes.
78 The script should parse the arguments it gets via ssh, and if they
79 contain a hint to only sync stage1 or stage2, then ONLY those steps
80 SHOULD be performed.
81
82 Rationale: This enables us to coordinate the timing of the first
83 and second stage pushes and minimize the time during which the
84 archive is desynchronized. This is especially important for mirrors
85 that are involved in a round robin or GeoDNS setup.
86
87 The minimum arguments the script has to understand are:
88 sync:stage1 Only sync stage1
89 sync:stage2 Only sync stage2
90 sync:all Do everything. Default if none of stage1/2 are
91 present.
92 There are more possible arguments, for a complete list see the
93 ftpsync script in our git repository.
94
95
96
97 ftpsync
98 =======
99
100 This script is based on the old anonftpsync script. It has been rewritten
101 to add flexibilty and fix a number of outstanding issues.
102
103 Some of the advantages of the new version are:
104 - Nearly every aspect is configurable
105 - Correct support for multiple pushes
106 - Support for multi-stage archive synchronisations
107 - Support for hook scripts at various points
108 - Support for multiple archives, even if they are pushed using one ssh key
109 - Support for multi-hop, multi-stage archive synchronisations
110
111 Correct support for multiple pushes
112 -----------------------------------
113 When the script receives a second push while it is running and syncing
114 the archive it won't ignore it. Instead it will rerun the
115 synchronisation step to ensure the archive is correctly synchronised.
116
117 Scripts that fail to do that risk ending up with an inconsistent archive.
118
119
120 Can do multi-stage archive synchronisations
121 -------------------------------------------
122 The script can be told to only perform the first or second stage of the
123 archive synchronisation.
124
125 This enables us to send all the binary packages and sources to a
126 number of mirrors, and then tell all of them to sync the
127 Packages/Release files at once. This will keep the timeframe in which
128 the mirrors are out of sync very small and will greatly help things like
129 DNS RR entries or even the planned GeoDNS setup.
130
131
132 Multi-hop, multi-stage archive synchronisations
133 -----------------------------------------------
134 The script can be told to perform a multi-hop multi-stage archive
135 synchronisation.
136
137 This is basically the same as the multi-stage synchronisation
138 explained above, but enables the downstream mirror to push his own
139 staged/multi-hop downstreams before returning. This has the same
140 advantage than the multi-stage synchronisation but allows us to do
141 this over multiple level of mirrors. (Imagine one push going from
142 Europe to Australia, where then locally 3 others get updated before
143 stage2 is sent out. Instead of 4times transferring data from Europe to
144 Australia, just to have them all updated near instantly).
145
146
147 Can run hook scripts
148 --------------------
149 ftpsync currently allows 5 hook scripts to run at various points of the
150 mirror sync run.
151
152 Hook1: After lock is acquired, before first rsync
153 Hook2: After first rsync, if successful
154 Hook3: After second rsync, if successful
155 Hook4: Right before leaf mirror triggering
156 Hook5: After leaf mirror trigger (only if we have slave mirrors; HUB=true)
157
158 Note that Hook3 and Hook4 are likely to be called directly after each other.
159 The difference is that Hook3 is called *every* time the second rsync
160 succeeds even if the mirroring needs to re-run due to a second push.
161 Hook4 is only executed if mirroring is completed.
162
163
164 Support for multiple archives, even if they are pushed using one ssh key
165 ------------------------------------------------------------------------
166 If you get multiple archives from your upstream mirror (say Debian,
167 Debian-Backports and Volatile), previously you had to use 3 different ssh
168 keys to be able to automagically synchronize them. This script can do it
169 all with just one key, if your upstream mirror tells you which archive.
170 See "Commandline/SSH options" below for further details.
171
172
173 For details of all available options, please see the extensive documentation
174 in the sample configuration file.
175
176
177 Commandline/SSH options
178 =======================
179 Script options may be set either on the local command line, or passed by
180 specifying an ssh "command". Local commandline options always have
181 precedence over the SSH_ORIGINAL_COMMAND ones.
182
183 Currently this script understands the options listed below. To make them
184 take effect they MUST be prepended by "sync:".
185
186 Option Behaviour
187 stage1 Only do stage1 sync
188 stage2 Only do stage2 sync
189 all Do a complete sync (default)
190 mhop Do a multi-hop sync
191 archive:foo Sync archive foo (if the file $HOME/etc/ftpsync-foo.conf
192 exists and is configured)
193 callback Call back when done (needs proper ssh setup for this to
194 work). It will always use the "command" callback:$HOSTNAME
195 where $HOSTNAME is the one defined in config and
196 will happen before slave mirrors are triggered.
197
198 So, to get the script to sync all of the archive behind bpo and call back when
199 it is complete, use an upstream trigger of
200 ssh $USER@$HOST sync:all sync:archive:bpo sync:callback
201
202
203 Mirror trace files
204 ==================
205 Every mirror needs to have a 'trace' file under project/trace.
206 The file format is as follows:
207
208 The filename has to be the full hostname (eg. hostname -f), or in the
209 case of a mirror participating in RR DNS (where users will never use
210 the hostname) the name of the DNS RR entry, eg. security.debian.org
211 for the security rotation)
212
213 The content has (no leading spaces):
214 Sat Nov 8 13:20:22 UTC 2008
215 Used ftpsync version: 42
216 Running on host: steffani.debian.org
217
218 First line: Output of date -u
219 Second line: Freeform text containing the program name and version
220 Third line: Text "Running on host: " followed by hostname -f
221
222 The third line MUST NOT be the DNS RR name, even if the mirror is part
223 of it. It MUST BE the hosts own name. This is in contrast to the filename,
224 which SHOULD be the DNS RR name.
225
226
227 runmirrors
228 ==========
229 This script is used to tell leaf mirrors that it is time to synchronize
230 their copy of the archive. This is done by parsing a mirror list and
231 using ssh to "push" the leaf nodes. You can read much more about the
232 principle behind the push at [1], essentially it tells the receiving
233 end to run a pre-defined script. As the whole setup is extremely limited
234 and the ssh key is not usable for anything else than the pre-defined
235 script this is the most secure method for such an action.
236
237 This script supports two types of pushes: The normal single stage push,
238 as well as the newer multi-stage push.
239
240 The normal push, as described above, will simply push the leaf node and
241 then go on with the other nodes.
242
243 The multi-staged push first pushes a mirror and tells it to only do a
244 stage1 sync run. Then it waits for the mirror (and all others being pushed
245 in the same run) to finish that run, before it tells all of the staged
246 mirrors to do the stage2 sync.
247
248 This way you can do a nearly-simultaneous update of multiple hosts.
249 This is useful in situations where periods of desynchronization should
250 be kept as small as possible. Examples of scenarios where this might be
251 useful include multiple hosts in a DNS Round Robin entry.
252
253 For details on the mirror list please see the documented
254 runmirrors.mirror.sample file.
255
256
257 [1] http://blog.ganneff.de/blog/2007/12/29/ssh-triggers.html