Project

General

Profile

Gerrit » History » Version 75

laforge, 05/11/2018 10:11 AM
fix link to mailing lists

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 69 neels
h3. Commit hook: Always put Change-Id at the bottom of the log message
84
85
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:
86
87
<pre>
88
cd $PROJECT
89
sed -i 's/if (unprinted /if (0 \&\& unprinted /' .git/hooks/commit-msg
90
</pre>
91
92
The goal is to disable the condition in line 163 with an 'if (0...':
93
94
<pre>
95
                        if (0 && unprinted && match(tolower(footer[line]), changeIdAfter) != 1) {
96
                                unprinted = 0
97
                                print "Change-Id: I'"$id"'"
98
                        }
99
</pre>
100
101
Then the Change-Id will be placed by line 170 instead.
102
103 46 neels
h3. Committer must match
104
105 47 neels
Your email address on gerrit and the email address git places in your
106 46 neels
commits must match, or you will get rejected with an error message like
107
"invalid commiter". You can add email addresses on the gerrit web UI.
108
109 33 neels
h3. Add gerrit to an existing clone
110
111 7 neels
* Add the remote to be able to fetch and push to gerrit
112
* Fetch the commit hook that adds Change-Id to each commit to uniquely identify a commit
113
114
<pre>
115
USERNAME=gerrit_user_name
116
PROJECT=$(basename $PWD)
117 1 zecke
git remote add gerrit ssh://$USERNAME@gerrit.osmocom.org:29418/$PROJECT.git
118
scp -P 29418 $USERNAME@gerrit.osmocom.org:hooks/commit-msg .git/hooks/
119 44 neels
</pre>
120
121 33 neels
h2. Push for review
122 1 zecke
123 38 neels
Checkout the revision or branch that you want to submit for review, then
124
125 31 neels
<pre>
126 48 ahuemer
git push gerrit HEAD:refs/for/master
127 1 zecke
</pre>
128 38 neels
129 1 zecke
You can optionally add a topic name with
130 40 neels
131
<pre>
132 48 ahuemer
git push gerrit HEAD:refs/for/master/my_topic
133 38 neels
</pre>
134
135 57 neels
h2. Merge patch to master
136
137
A patch can be merged when it has CR+2 and V+1 votes, and if, in case of a
138
series of patches pushed from a branch, when its ancestor patches can also be
139
merged.
140
141
Sometimes the reviewer that gives CR+2 also hits the "Submit" button right away 
142
to merge the patch to master. Sometimes it is left up to the owner of the patch
143 59 neels
to decide when to hit "Submit" (who needs to be in the "Known Users" group).
144 57 neels
145
The V+1 vote means "build is verified" and is usually given by our jenkins
146 59 neels
gerrit builds: https://jenkins.osmocom.org/jenkins/view/Jenkins-Gerrit/
147 57 neels
148
The CR+2 vote means "code reviewed and ready for merge to master branch".
149
Accounts with the "Reviewer" role for a given project are allowed to give CR+2
150
votes. Others are allowed to give CR+1 (and CR-1). CR votes _don't_ add up.
151
152 67 neels
_Fixed by gerrit 2.12.6, see https://bugs.chromium.org/p/gerrit/issues/detail?id=4158:_
153
-Sometimes hitting the "Submit" button results in an error message saying
154 57 neels
"Change is New", which is a bug related to a private branch with the same
155 65 neels
patches being present. Can be fixed e.g. by an admin's manual push to master.-
156 1 zecke
157 38 neels
h2. Push a "private" user branch
158 33 neels
159 1 zecke
*Note* that you must be a member of the "known users" group, see above.
160 33 neels
161 43 neels
If your local branch name is of the form 'your_name/topic', you can just
162 1 zecke
<pre>
163
git push
164 33 neels
</pre>
165 41 neels
and git will tell you what to do.
166 1 zecke
167 41 neels
To push from a "nonstandard" local branch name, do
168
<pre>
169 50 msuraev
git push gerrit HEAD:refs/heads/user/$USERNAME/branch_name
170 33 neels
</pre>
171
172 39 neels
173
h2. List changesets in gerrit
174
175 7 neels
<pre>
176 48 ahuemer
git ls-remote gerrit changes/*
177 2 zecke
</pre>
178 12 msuraev
179 17 neels
h1. Tips and Tricks
180 1 zecke
181 74 neels
h2. Fetch fast from git.osmocom.org, push to gerrit
182
183
Sometimes these days it can be irritatingly slow to 'git fetch' from gerrit.
184
Also, adding a second remote forces you to often pass the remote on the command line ("origin").
185
It is possible to have only one remote for cmdline convenience, with differing push and pull URLs:
186
187
<pre>
188
git remote set-url origin git://git.osmocom.org/libosmocore
189
git remote set-url --push origin ssh://$USERNAME@gerrit.osmocom.org:29418/libosmocore
190
</pre>
191
192
With above .ssh config you can also use the shorter ssh:// URL:
193
<pre>
194
git remote set-url --push origin ssh://go/libosmocore
195
</pre>
196
197
The resulting .git/config looks something like:
198
<pre>
199
[remote "origin"]
200
        url = git://git.osmocom.org/libosmocore
201
        pushurl = ssh://go/libosmocore
202
        fetch = +refs/heads/*:refs/remotes/origin/*
203
</pre>
204
205
Now you're fetching from git.osmocom.org, which is lightning fast, while pushing patches will still go to gerrit as usual.
206
207 17 neels
h2. Throw-away branch
208
209
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),
210 45 neels
make your changes/amendments and then send patch(es) back to gerrit while removing temporary branch automatically with "git review -f".
211 13 neels
212 56 neels
h2. Fetch a patch from gerrit
213
214
This script (I called it @P@) makes fetching a patch set from gerrit a breeze:
215
<pre>
216
#!/bin/sh
217
# fetch gerrit patch into new branch named like the patch number.
218
#
219
# Usage: go to a git clone and pass a patch number:
220
#
221
#   cd openbsc
222
#   P 973
223
# or
224
#   P 973/2
225
#
226
# Will create new local branches '973_4' (if 4 is the latest patch set)
227
# or '973_2', respectively.
228
229
patch="$1"
230
231
if [ -z "$patch" ]; then
232
  echo "Usage: P 1234[/5]"
233
  exit 1
234
fi
235
236
if [ -z "$(echo "$patch" | grep '/')" ]; then
237
  patch="/$patch/"
238
fi
239
240
if [ -z "$(echo "$patch" | grep '^/')" ]; then
241
  patch="/$patch"
242
fi
243
244
last_set="$(git ls-remote origin "changes/*" | grep "$patch" | sed 's#.*/\([^/]*\)$#\1 &#' | sort -n | tail -n 1)"
245
if [ -z "$last_set" ]; then
246
  echo "Not found: $patch"
247
  exit 1
248
fi
249
250
change_name="$(echo "$last_set" | sed 's/.*\(refs.*\)/\1/')"
251
branch_name="$(echo "$change_name" | sed 's#refs/changes/../\([0-9]*\)/\([0-9]*\)#\1_\2#')"
252
253
set -x
254
git fetch origin "$change_name"
255
git co -b "$branch_name" FETCH_HEAD
256
</pre>
257
258 25 neels
h2. Re-submit a Branch with Amended Commits
259 13 neels
260 1 zecke
On a feature branch, one typically has numerous commits that depend on their preceding commits.
261 58 neels
Often, some of the branch commits need to be amended for fixes. You can re-submit changes to
262
patches on your branch by pushing in the same way that you first submitted the branch.
263 22 neels
264 58 neels
Note: if you modify the Change-Ids in the commit logs, your push would open entirely new
265
review entries and you would have to abandon your previous submission. Comments on the first
266
submission are "lost" and you cannot diff between patch sets.
267 29 neels
268 58 neels
(There used to be a bug in gerrit that required editing the first patch to be able to
269
re-submit a branch, but that's fixed.)
270 29 neels
271
272
273 26 neels
h2. Re-submit Previously Abandoned Changes
274 16 neels
275
You have to edit the Change-Ids, on a branch that would be every single commit log message.
276
277 13 neels
<pre>
278 1 zecke
cd openbsc
279
git co my-branch
280
git rebase -i master
281
# replace all 'pick' with 'r' (or 'reword'), exit your editor
282 13 neels
# git presents each commit log message for editing
283
</pre>
284
285 27 neels
h2. Submit a "private" branch for master
286 21 neels
287
If you've pushed a branch to refs/heads/* somewhere, gerrit will already know the Change-Ids on it.
288 24 neels
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,
289 21 neels
or gerrit will refuse to accept your submission.
290
291 60 neels
h2. 502 Bad Gateway
292
293
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.
294
295 16 neels
h1. Reasons for Particular Configuration
296 13 neels
297 16 neels
h2. Rebase if necessary
298
299
There are different merge strategies that Gerrit performs to accept patches.
300 13 neels
Each project can be configured to a specific merge strategy, but unfortunately you can't
301
decide on a strategy per patch submission.
302
303
It seems that the "Merge if Necessary" strategy is best supported, but it creates non-linear
304
history with numerous merge commits that are usually not at all necessary.
305
306
Instead, the "Cherry Pick" strategy puts each patch onto current master's HEAD to create
307
linear history. However, this will cause merge failures as soon as one patch depends on
308
another submitted patch, as typical for a feature branch submission.
309
310 1 zecke
So we prefer the "Rebase if Necessary" strategy, which always tries to apply your patches to
311 13 neels
the current master HEAD, in sequence with the previous patches on the same branch.
312
However, some problems still remain, including some bugs in "Rebase if Necessary".
313 1 zecke
314 13 neels
There's a problem with "Rebase if Necessary": If your branch sits at master's HEAD, Gerrit
315
refuses to accept the submission, because it thinks that no new changes are submitted.
316
This is a bug in Gerrit, which holger has fixed manually in our Gerrit installation:
317 1 zecke
318
https://bugs.chromium.org/p/gerrit/issues/detail?id=4158
319
320
321 16 neels
h2. Private Branches: Create a new change for every commit...
322 1 zecke
323 13 neels
Say you have an extensive feature in development, and you want to keep it on the
324
upstream git repository to a) keep it safe and b) collaborate with other devs on it.
325 16 neels
So, of course, you have regularly pushed to refs/heads/yoyodyne/feature.
326 13 neels
327
Since you have the gerrit commit hook installed, your feature branch already has
328
Change-Id tags in all commit log messages.
329
330
Now your feature is complete and you would like to submit it to master.
331
Alas, Gerrit refuses to accept your patch submission for master, because it
332
knows the Change-Ids are also on a different branch.
333
334 16 neels
Gerrit by default enforces that a Change-Id must be unique across all branches,
335
so that each submission for review is separate for each branch. Instead, we
336
want to handle Change-Ids per-branch, so that you can have the same change
337
submitted to different branches, as separate patch submissions, without having
338
to cosmetically adjust the Change-Id.
339 13 neels
340 16 neels
Solution: set the option 
341
_Create a new change for every commit not in the target branch_ to _TRUE_
342 13 neels
343 20 neels
h2. Allow content merges
344 14 neels
345
By default, gerrit compares patches only by the files' paths. If two paths are the same,
346
it immediately shows them as conflicts (path conflicts).
347
348
In software development, a conflict usually means an actual content conflict, so if the
349
edits are in two entirely separate places in the file, we don't consider this a conflict.
350
351 23 neels
By setting _Allow content merges_ to _TRUE_ in the git project config, we tell Gerrit to
352 14 neels
perform text merges of the submitted patches and only complain about actual content
353
conflicts, in the usual software engineering sense.
354 32 neels
355
h1. Admin
356
357 72 laforge
h2. Adding a new repository
358
359
* create the repository in the Gerrit Ui, inherit from "All-Projects"
360
* create an empty git repository using gitosis on git.osmcoom.org
361
* configure a jenkins build testing job for this project, cloning/copying from any osmo-*-gerrit projects
362
363
git replication to gerrit.osmocom.org is enabled automatically, nothing to be done here.  In case of doubt, try
364
@ssh -p 29418 gerrit.osmocom.org replication start --all --wait@
365
366 32 neels
h2. Adding users to groups
367
368
Normally, the gerrit UI auto-completes a user name in the edit field. It has happened
369
though that an existing user is not auto-completed, as if it didn't exist. In that case,
370
find out the user ID (seven digit number like 1000123) and just enter that.
371
372
The user ID can be found on the user's "Settings" page, or in the database (s.b.).
373
374
h2. Querying the database directly
375
376
If your user has permission to access the database, you can place SQL queries using the
377
'gerrit gsql' commands over ssh:
378
379
<pre>
380 71 neels
ssh go "gerrit gsql -c \"show tables\""
381
ssh go "gerrit gsql -c \"select full_name,account_id from accounts\""
382 1 zecke
</pre>
383 53 neels
384
(see ~/.ssh/config above for the 'go' shortcut)
385 1 zecke
386
This seems to be the MySQL dialect.
387 71 neels
388
The "...\"...\"" quoting allows including single-quotes in the SQL statements.
389 62 neels
390
h2. Fix evil twin users
391
392
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:
393
394
<pre>
395 64 neels
ssh go "gerrit gsql -c \"select * from account_external_ids where email_address like '%foo%'\""
396 62 neels
# ACCOUNT_ID | EMAIL_ADDRESS   | PASSWORD | EXTERNAL_ID
397
# -----------+-----------------+----------+----------------------------------
398
# 100004     | foo@example.com | NULL     | https://osmocom.org/openid/user/777
399
# 100021     | foo@example.com | NULL     | https://projects.osmocom.org/openid/user/777
400
401 64 neels
ssh go "gerrit gsql -c \"update account_external_ids set account_id = 100004 where email_address like '%foo%'\""
402 62 neels
403 64 neels
ssh go "gerrit gsql -c \"select * from account_external_ids where email_address like '%foo%'\""
404 62 neels
# ACCOUNT_ID | EMAIL_ADDRESS   | PASSWORD | EXTERNAL_ID
405
# -----------+-----------------+----------+----------------------------------
406
# 100004     | foo@example.com | NULL     | https://osmocom.org/openid/user/777
407
# 100004     | foo@example.com | NULL     | https://projects.osmocom.org/openid/user/777
408
</pre>
Add picture from clipboard (Maximum size: 48.8 MB)