Project

General

Profile

Gerrit » History » Version 79

neels, 05/17/2018 01:03 AM

1 1 zecke
h1. Contributing using Gerrit
2
3 11 laforge
{{>toc}}
4
5 10 laforge
At [[OpenBSC:OsmoDevCon2016]] we discussed problems with our past contribution / patch submission process using mails on the mailing list as well as patchwork.  The result is that we want to give Gerrit a try for some time and see if it helps us to have a better process
6 1 zecke
7 10 laforge
Gerrit is a review tool that integrates nicely with git and ssh. You can find general information about Gerrit at https://www.gerritcodereview.com/
8 1 zecke
9 10 laforge
The advantages of Gerrit are:
10
* patch submission status is automatically tracked, also with several revisions for a patch set.
11
* patches are build-tested (and possibly even further tested) by jenkins before they are applied
12
* developers + maintainers can formally vote on a patch (developer: -1/0/+1, maintainer: -2/0/+2)
13
* once a patch has +2 score, it can be (automatically) merged into master
14
* patch sumissions not via git send-email but direcly from git
15
16
h2. Osmocom Subprojects using Gerrit
17
18 73 laforge
The majority of Osmocom sub-projects have chosen to use Gerrit for patch review.  In order to check if a given program uses Gerrit, please check the auto-generated list at https://gerrit.osmocom.org/#/admin/projects/
19 1 zecke
20 75 laforge
If the project is listed there, then it uses Gerrit.   If the project is not listed there, please send patches by e-mail to the respective project [[Mailing_Lists]] instead.
21 30 neels
22 1 zecke
h2. Configuring Gerrit/Account
23
24 54 neels
You will need to sign-up at https://gerrit.osmocom.org/login/. If you have an Osmocom Redmine account you can use https://osmocom.org/openid as OpenID provider.
25 1 zecke
26 68 neels
* first sign in on https://osmocom.org. Do this before logging in on gerrit (the redmine login process loses the gerrit login data and you'd have to do the same thing twice if not logged in on osmocom.org already).
27 55 neels
* go to https://gerrit.osmocom.org and click the "Sign in" link.
28 68 neels
* click the "Sign in with Osmocom":https://gerrit.osmocom.org/login/%23%2Fq%2Fstatus%3Aopen?id=https://osmocom.org/openid link (can be bookmarked). -- This is the same as entering https://osmocom.org/openid as OpenID provider and hitting the "Sign in" button.
29 61 neels
30
*careful:* enter 'https' to ensure that your openid credentials are passed on encryptedly.
31 68 neels
*pitfall:* if you're logged in on 'projects.osmocom.org' (including the 'projects.' part), you should also use the openid provider: https://projects.osmocom.org/openid; the 'projects.' part may be omitted, what's important is that redmine login and OpenID URLs match. Also, decide for one of those URLs once, because when picking a different OpenID URL next time, you will create a new user instead of logging in as yourself.
32 61 neels
*note:* gerrit will create a distinct user for each openid URL you pass. If you logged in successfully but your user seems to have lost permissions, you may have created an evil twin user: contact us on the mailing list so we can fix it in the user database.
33 54 neels
34
If you have no Osmocom redmine account, you can simply create one online at the "Register" link in the upper right corner.
35 10 laforge
Even without an existing or new redmine account, you should also be able to use any other OpenID provider to authenticate against gerrit (untested).
36
37
After the initial sign-up you will need to:
38 1 zecke
39
* Pick a username (can not be changed)
40
* Add your public ssh key(s)
41
* Add email addresses you intend to use as author/comitter
42 30 neels
43
If you would like to push private branches to the Gerrit repository, you also need to be added to the "known users" group.
44
Please send a short requesting email to openbsc@lists.osmocom.org.
45 1 zecke
46
h2. Setting up Gerrit for commits and pushing
47
48 33 neels
*Note:* it is easiest to work with gerrit when gerrit is the only remote in your git clone.
49
When you clone from git.osmocom.org and add the gerrit remote, git will have two remotes,
50 36 neels
so when you first checkout a branch you have to supply the remote explicitly (cumbersome).
51 34 neels
The gerrit repositories and git.osmocom.org are constantly synced, so it is sufficient
52
to clone from gerrit only.
53 33 neels
54
h3. Simplest: new clone
55
56 35 neels
* Create a new clone from gerrit
57
* Fetch the commit hook that adds Change-Id to each commit to uniquely identify a commit
58 42 neels
59 33 neels
<pre>
60
git clone ssh://$USERNAME@gerrit.osmocom.org:29418/$PROJECT.git
61
scp -P 29418 $USERNAME@gerrit.osmocom.org:hooks/commit-msg $PROJECT/.git/hooks/
62
</pre>
63
64
h3. SSH config
65
66
In '~/.ssh/config', add these lines:
67
<pre>
68 52 neels
Host go
69 33 neels
Hostname gerrit.osmocom.org
70
Port 29418
71
User $USERNAME
72
</pre>
73 52 neels
('go' means gerrit.osmocom, replace with your favorite shortcut name,
74 33 neels
replace '$USERNAME' with your user name as used on the gerrit website)
75
76
Then you can shorten above commands to
77 1 zecke
<pre>
78 52 neels
git clone ssh://go/$PROJECT.git
79 51 neels
cd $PROJECT
80
scp go:hooks/commit-msg .git/hooks/
81 33 neels
</pre>
82
83 46 neels
h3. Committer must match
84
85 47 neels
Your email address on gerrit and the email address git places in your
86 46 neels
commits must match, or you will get rejected with an error message like
87
"invalid commiter". You can add email addresses on the gerrit web UI.
88
89 33 neels
h3. Add gerrit to an existing clone
90
91 7 neels
* Add the remote to be able to fetch and push to gerrit
92
* Fetch the commit hook that adds Change-Id to each commit to uniquely identify a commit
93
94
<pre>
95
USERNAME=gerrit_user_name
96
PROJECT=$(basename $PWD)
97 1 zecke
git remote add gerrit ssh://$USERNAME@gerrit.osmocom.org:29418/$PROJECT.git
98
scp -P 29418 $USERNAME@gerrit.osmocom.org:hooks/commit-msg .git/hooks/
99 44 neels
</pre>
100
101 33 neels
h2. Push for review
102 1 zecke
103 77 neels
<pre>
104
git push $REMOTE $GITHASH:refs/for/$BRANCH/$TOPIC
105
</pre>
106
107
$REMOTE: from above instructions, that's either 'origin' (cloned from gerrit) or 'gerrit' (if you added a second remote).
108
$GITHASH: the committed patch to push, typically you're on your branch and simply push 'HEAD'.
109
$BRANCH: you will typically intend a patch to go to 'master'.
110
$TOPIC: an optional name you may choose.
111
112
For example, checkout the revision or branch that you want to submit for review,
113
i.e. the one where your patch or several patches are committed on top of the current master, then:
114 1 zecke
115 76 neels
If you cloned directly from gerrit:
116
117 1 zecke
<pre>
118 76 neels
git push origin HEAD:refs/for/master
119
</pre>
120
121
If you added 'gerrit' as a second remote to an existing clone:
122
123
<pre>
124 1 zecke
git push gerrit HEAD:refs/for/master
125 38 neels
</pre>
126 1 zecke
127 40 neels
You can optionally add a topic name with
128 1 zecke
129 40 neels
<pre>
130 76 neels
git push origin HEAD:refs/for/master/my_topic
131 38 neels
</pre>
132
133 57 neels
h2. Merge patch to master
134
135
A patch can be merged when it has CR+2 and V+1 votes, and if, in case of a
136
series of patches pushed from a branch, when its ancestor patches can also be
137
merged.
138
139
Sometimes the reviewer that gives CR+2 also hits the "Submit" button right away 
140
to merge the patch to master. Sometimes it is left up to the owner of the patch
141 59 neels
to decide when to hit "Submit" (who needs to be in the "Known Users" group).
142 57 neels
143
The V+1 vote means "build is verified" and is usually given by our jenkins
144 59 neels
gerrit builds: https://jenkins.osmocom.org/jenkins/view/Jenkins-Gerrit/
145 57 neels
146
The CR+2 vote means "code reviewed and ready for merge to master branch".
147
Accounts with the "Reviewer" role for a given project are allowed to give CR+2
148
votes. Others are allowed to give CR+1 (and CR-1). CR votes _don't_ add up.
149
150 67 neels
_Fixed by gerrit 2.12.6, see https://bugs.chromium.org/p/gerrit/issues/detail?id=4158:_
151
-Sometimes hitting the "Submit" button results in an error message saying
152 57 neels
"Change is New", which is a bug related to a private branch with the same
153 65 neels
patches being present. Can be fixed e.g. by an admin's manual push to master.-
154 1 zecke
155 38 neels
h2. Push a "private" user branch
156 33 neels
157 1 zecke
*Note* that you must be a member of the "known users" group, see above.
158 33 neels
159 43 neels
If your local branch name is of the form 'your_name/topic', you can just
160 1 zecke
<pre>
161
git push
162 33 neels
</pre>
163 41 neels
and git will tell you what to do.
164 1 zecke
165 41 neels
To push from a "nonstandard" local branch name, do
166
<pre>
167 50 msuraev
git push gerrit HEAD:refs/heads/user/$USERNAME/branch_name
168 33 neels
</pre>
169
170 39 neels
171
h2. List changesets in gerrit
172
173 7 neels
<pre>
174 48 ahuemer
git ls-remote gerrit changes/*
175 2 zecke
</pre>
176 12 msuraev
177 17 neels
h1. Tips and Tricks
178 1 zecke
179 74 neels
h2. Fetch fast from git.osmocom.org, push to gerrit
180
181 79 neels
Gerrit has moved to a faster host, so this should no longer be necessary. Anyway...
182
183
Adding a second remote forces you to often pass the remote on the command line ("origin").
184 1 zecke
It is possible to have only one remote for cmdline convenience, with differing push and pull URLs:
185 74 neels
186
<pre>
187 79 neels
git remote set-url origin git://git.osmocom.org/$PROJECT
188
git remote set-url --push origin ssh://$USERNAME@gerrit.osmocom.org:29418/$PROJECT
189 74 neels
</pre>
190 1 zecke
191 74 neels
With above .ssh config you can also use the shorter ssh:// URL:
192
<pre>
193 79 neels
git remote set-url --push origin ssh://go/$PROJECT
194 74 neels
</pre>
195
196 79 neels
The resulting .git/config in libosmocore would look something like:
197 74 neels
<pre>
198
[remote "origin"]
199
        url = git://git.osmocom.org/libosmocore
200
        pushurl = ssh://go/libosmocore
201
        fetch = +refs/heads/*:refs/remotes/origin/*
202
</pre>
203
204
Now you're fetching from git.osmocom.org, which is lightning fast, while pushing patches will still go to gerrit as usual.
205
206 17 neels
h2. Throw-away branch
207
208
If you need to adjust and re-submit patches, it may be handy to create a throw-away branch ("R D" in magit-gerrit in emacs for example),
209 45 neels
make your changes/amendments and then send patch(es) back to gerrit while removing temporary branch automatically with "git review -f".
210 13 neels
211 56 neels
h2. Fetch a patch from gerrit
212
213
This script (I called it @P@) makes fetching a patch set from gerrit a breeze:
214
<pre>
215
#!/bin/sh
216
# fetch gerrit patch into new branch named like the patch number.
217
#
218
# Usage: go to a git clone and pass a patch number:
219
#
220
#   cd openbsc
221
#   P 973
222
# or
223
#   P 973/2
224
#
225
# Will create new local branches '973_4' (if 4 is the latest patch set)
226
# or '973_2', respectively.
227
228
patch="$1"
229
230
if [ -z "$patch" ]; then
231
  echo "Usage: P 1234[/5]"
232
  exit 1
233
fi
234
235
if [ -z "$(echo "$patch" | grep '/')" ]; then
236
  patch="/$patch/"
237
fi
238
239
if [ -z "$(echo "$patch" | grep '^/')" ]; then
240
  patch="/$patch"
241
fi
242
243
last_set="$(git ls-remote origin "changes/*" | grep "$patch" | sed 's#.*/\([^/]*\)$#\1 &#' | sort -n | tail -n 1)"
244
if [ -z "$last_set" ]; then
245
  echo "Not found: $patch"
246
  exit 1
247
fi
248
249
change_name="$(echo "$last_set" | sed 's/.*\(refs.*\)/\1/')"
250
branch_name="$(echo "$change_name" | sed 's#refs/changes/../\([0-9]*\)/\([0-9]*\)#\1_\2#')"
251
252
set -x
253
git fetch origin "$change_name"
254
git co -b "$branch_name" FETCH_HEAD
255
</pre>
256
257 25 neels
h2. Re-submit a Branch with Amended Commits
258 13 neels
259 1 zecke
On a feature branch, one typically has numerous commits that depend on their preceding commits.
260 58 neels
Often, some of the branch commits need to be amended for fixes. You can re-submit changes to
261
patches on your branch by pushing in the same way that you first submitted the branch.
262 22 neels
263 58 neels
Note: if you modify the Change-Ids in the commit logs, your push would open entirely new
264
review entries and you would have to abandon your previous submission. Comments on the first
265
submission are "lost" and you cannot diff between patch sets.
266 29 neels
267 58 neels
(There used to be a bug in gerrit that required editing the first patch to be able to
268
re-submit a branch, but that's fixed.)
269 29 neels
270
271
272 26 neels
h2. Re-submit Previously Abandoned Changes
273 1 zecke
274
You have to edit the Change-Ids, on a branch that would be every single commit log message.
275
276
<pre>
277
cd openbsc
278
git co my-branch
279
git rebase -i master
280
# replace all 'pick' with 'r' (or 'reword'), exit your editor
281
# git presents each commit log message for editing
282
</pre>
283
284
h2. Submit a "private" branch for master
285
286
If you've pushed a branch to refs/heads/* somewhere, gerrit will already know the Change-Ids on it.
287
Make sure the option [[Gerrit#Private-Branches-Create-a-new-change-for-every-commit|Create a new change for every commit not in the target branch]] is _TRUE_ for your project,
288
or gerrit will refuse to accept your submission.
289
290
h2. 502 Bad Gateway
291
292
When getting a "Bad Gateway" error message upon trying to login on gerrit, you probably just need to restart your web browser. The reason is not clear.
293 78 neels
294
295
h2. Commit hook: Always put Change-Id at the bottom of the log message
296
297
The commit-msg hook places a Change-Id tag in the footer, often above other tags like 'Depends:' or 'Related:'. Since the Change-Id is an implementation detail for Gerrit, I personally prefer it always placed right at the bottom. This simple edit changes the commit-msg hook to add Change-Id at the bottom unconditionally:
298
299
<pre>
300
cd $PROJECT
301
sed -i 's/if (unprinted /if (0 \&\& unprinted /' .git/hooks/commit-msg
302
</pre>
303
304
The goal is to disable the condition in line 163 with an 'if (0...':
305
306
<pre>
307
                        if (0 && unprinted && match(tolower(footer[line]), changeIdAfter) != 1) {
308
                                unprinted = 0
309
                                print "Change-Id: I'"$id"'"
310
                        }
311
</pre>
312
313
Then the Change-Id will be placed by line 170 instead.
314 60 neels
315 16 neels
h1. Reasons for Particular Configuration
316 13 neels
317 16 neels
h2. Rebase if necessary
318
319
There are different merge strategies that Gerrit performs to accept patches.
320 13 neels
Each project can be configured to a specific merge strategy, but unfortunately you can't
321
decide on a strategy per patch submission.
322
323
It seems that the "Merge if Necessary" strategy is best supported, but it creates non-linear
324
history with numerous merge commits that are usually not at all necessary.
325
326
Instead, the "Cherry Pick" strategy puts each patch onto current master's HEAD to create
327
linear history. However, this will cause merge failures as soon as one patch depends on
328
another submitted patch, as typical for a feature branch submission.
329
330 1 zecke
So we prefer the "Rebase if Necessary" strategy, which always tries to apply your patches to
331 13 neels
the current master HEAD, in sequence with the previous patches on the same branch.
332
However, some problems still remain, including some bugs in "Rebase if Necessary".
333 1 zecke
334 13 neels
There's a problem with "Rebase if Necessary": If your branch sits at master's HEAD, Gerrit
335
refuses to accept the submission, because it thinks that no new changes are submitted.
336
This is a bug in Gerrit, which holger has fixed manually in our Gerrit installation:
337 1 zecke
338
https://bugs.chromium.org/p/gerrit/issues/detail?id=4158
339
340
341 16 neels
h2. Private Branches: Create a new change for every commit...
342 1 zecke
343 13 neels
Say you have an extensive feature in development, and you want to keep it on the
344
upstream git repository to a) keep it safe and b) collaborate with other devs on it.
345 16 neels
So, of course, you have regularly pushed to refs/heads/yoyodyne/feature.
346 13 neels
347
Since you have the gerrit commit hook installed, your feature branch already has
348
Change-Id tags in all commit log messages.
349
350
Now your feature is complete and you would like to submit it to master.
351
Alas, Gerrit refuses to accept your patch submission for master, because it
352
knows the Change-Ids are also on a different branch.
353
354 16 neels
Gerrit by default enforces that a Change-Id must be unique across all branches,
355
so that each submission for review is separate for each branch. Instead, we
356
want to handle Change-Ids per-branch, so that you can have the same change
357
submitted to different branches, as separate patch submissions, without having
358
to cosmetically adjust the Change-Id.
359 13 neels
360 16 neels
Solution: set the option 
361
_Create a new change for every commit not in the target branch_ to _TRUE_
362 13 neels
363 20 neels
h2. Allow content merges
364 14 neels
365
By default, gerrit compares patches only by the files' paths. If two paths are the same,
366
it immediately shows them as conflicts (path conflicts).
367
368
In software development, a conflict usually means an actual content conflict, so if the
369
edits are in two entirely separate places in the file, we don't consider this a conflict.
370
371 23 neels
By setting _Allow content merges_ to _TRUE_ in the git project config, we tell Gerrit to
372 14 neels
perform text merges of the submitted patches and only complain about actual content
373
conflicts, in the usual software engineering sense.
374 32 neels
375
h1. Admin
376
377 72 laforge
h2. Adding a new repository
378
379
* create the repository in the Gerrit Ui, inherit from "All-Projects"
380
* create an empty git repository using gitosis on git.osmcoom.org
381
* configure a jenkins build testing job for this project, cloning/copying from any osmo-*-gerrit projects
382
383
git replication to gerrit.osmocom.org is enabled automatically, nothing to be done here.  In case of doubt, try
384
@ssh -p 29418 gerrit.osmocom.org replication start --all --wait@
385
386 32 neels
h2. Adding users to groups
387
388
Normally, the gerrit UI auto-completes a user name in the edit field. It has happened
389
though that an existing user is not auto-completed, as if it didn't exist. In that case,
390
find out the user ID (seven digit number like 1000123) and just enter that.
391
392
The user ID can be found on the user's "Settings" page, or in the database (s.b.).
393
394
h2. Querying the database directly
395
396
If your user has permission to access the database, you can place SQL queries using the
397
'gerrit gsql' commands over ssh:
398
399
<pre>
400 71 neels
ssh go "gerrit gsql -c \"show tables\""
401
ssh go "gerrit gsql -c \"select full_name,account_id from accounts\""
402 1 zecke
</pre>
403 53 neels
404
(see ~/.ssh/config above for the 'go' shortcut)
405 1 zecke
406
This seems to be the MySQL dialect.
407 71 neels
408
The "...\"...\"" quoting allows including single-quotes in the SQL statements.
409 62 neels
410
h2. Fix evil twin users
411
412
If differing openid URLs have lead to evil twin users shadowing the same email address just without the permissions, you can fix it like this:
413
414
<pre>
415 64 neels
ssh go "gerrit gsql -c \"select * from account_external_ids where email_address like '%foo%'\""
416 62 neels
# ACCOUNT_ID | EMAIL_ADDRESS   | PASSWORD | EXTERNAL_ID
417
# -----------+-----------------+----------+----------------------------------
418
# 100004     | foo@example.com | NULL     | https://osmocom.org/openid/user/777
419
# 100021     | foo@example.com | NULL     | https://projects.osmocom.org/openid/user/777
420
421 64 neels
ssh go "gerrit gsql -c \"update account_external_ids set account_id = 100004 where email_address like '%foo%'\""
422 62 neels
423 64 neels
ssh go "gerrit gsql -c \"select * from account_external_ids where email_address like '%foo%'\""
424 62 neels
# ACCOUNT_ID | EMAIL_ADDRESS   | PASSWORD | EXTERNAL_ID
425
# -----------+-----------------+----------+----------------------------------
426
# 100004     | foo@example.com | NULL     | https://osmocom.org/openid/user/777
427
# 100004     | foo@example.com | NULL     | https://projects.osmocom.org/openid/user/777
428
</pre>
Add picture from clipboard (Maximum size: 48.8 MB)