Gerrit » History » Version 57
neels, 02/20/2017 11:56 AM
1 | 1 | zecke | h1. Contributing using Gerrit |
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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. |
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11 | * patches are build-tested (and possibly even further tested) by jenkins before they are applied |
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12 | * developers + maintainers can formally vote on a patch (developer: -1/0/+1, maintainer: -2/0/+2) |
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13 | * once a patch has +2 score, it can be (automatically) merged into master |
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14 | * patch sumissions not via git send-email but direcly from git |
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15 | |||
16 | h2. Osmocom Subprojects using Gerrit |
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17 | |||
18 | 1 | zecke | The following projects use Gerrit to contribute changes: |
19 | |||
20 | * libosmocore.git |
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21 | * libosmo-abis.git |
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22 | * libosmo-netif.git |
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23 | * libosmo-sccp.git |
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24 | * libsmpp34.git |
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25 | * openbsc.git |
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26 | * osmo-bts.git |
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27 | * osmo-iuh.git |
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28 | * osmo-pcu.git |
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29 | 5 | zecke | * cellmgr-ng.git |
30 | 1 | zecke | * osmo-sip-connector.git |
31 | 30 | neels | |
32 | 1 | zecke | h2. Configuring Gerrit/Account |
33 | |||
34 | 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. |
35 | 1 | zecke | |
36 | 55 | neels | * first sign in on https://osmocom.org. |
37 | * go to https://gerrit.osmocom.org and click the "Sign in" link. |
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38 | * enter "https://osmocom.org/openid" as OpenID provider and hit the "Sign in" button. |
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39 | 54 | neels | |
40 | If you have no Osmocom redmine account, you can simply create one online at the "Register" link in the upper right corner. |
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41 | 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). |
42 | |||
43 | After the initial sign-up you will need to: |
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44 | 1 | zecke | |
45 | * Pick a username (can not be changed) |
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46 | * Add your public ssh key(s) |
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47 | * Add email addresses you intend to use as author/comitter |
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48 | 30 | neels | |
49 | If you would like to push private branches to the Gerrit repository, you also need to be added to the "known users" group. |
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50 | Please send a short requesting email to openbsc@lists.osmocom.org. |
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51 | 1 | zecke | |
52 | h2. Setting up Gerrit for commits and pushing |
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53 | |||
54 | 33 | neels | *Note:* it is easiest to work with gerrit when gerrit is the only remote in your git clone. |
55 | When you clone from git.osmocom.org and add the gerrit remote, git will have two remotes, |
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56 | 36 | neels | so when you first checkout a branch you have to supply the remote explicitly (cumbersome). |
57 | 34 | neels | The gerrit repositories and git.osmocom.org are constantly synced, so it is sufficient |
58 | to clone from gerrit only. |
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59 | 33 | neels | |
60 | h3. Simplest: new clone |
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61 | |||
62 | 35 | neels | * Create a new clone from gerrit |
63 | * Fetch the commit hook that adds Change-Id to each commit to uniquely identify a commit |
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64 | 42 | neels | |
65 | 33 | neels | <pre> |
66 | git clone ssh://$USERNAME@gerrit.osmocom.org:29418/$PROJECT.git |
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67 | scp -P 29418 $USERNAME@gerrit.osmocom.org:hooks/commit-msg $PROJECT/.git/hooks/ |
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68 | </pre> |
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69 | |||
70 | h3. SSH config |
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71 | |||
72 | In '~/.ssh/config', add these lines: |
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73 | <pre> |
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74 | 52 | neels | Host go |
75 | 33 | neels | Hostname gerrit.osmocom.org |
76 | Port 29418 |
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77 | User $USERNAME |
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78 | </pre> |
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79 | 52 | neels | ('go' means gerrit.osmocom, replace with your favorite shortcut name, |
80 | 33 | neels | replace '$USERNAME' with your user name as used on the gerrit website) |
81 | |||
82 | Then you can shorten above commands to |
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83 | 1 | zecke | <pre> |
84 | 52 | neels | git clone ssh://go/$PROJECT.git |
85 | 51 | neels | cd $PROJECT |
86 | scp go:hooks/commit-msg .git/hooks/ |
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87 | 33 | neels | </pre> |
88 | |||
89 | 46 | neels | h3. Committer must match |
90 | |||
91 | 47 | neels | Your email address on gerrit and the email address git places in your |
92 | 46 | neels | commits must match, or you will get rejected with an error message like |
93 | "invalid commiter". You can add email addresses on the gerrit web UI. |
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94 | |||
95 | 33 | neels | h3. Add gerrit to an existing clone |
96 | |||
97 | 7 | neels | * Add the remote to be able to fetch and push to gerrit |
98 | * Fetch the commit hook that adds Change-Id to each commit to uniquely identify a commit |
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99 | |||
100 | <pre> |
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101 | USERNAME=gerrit_user_name |
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102 | PROJECT=$(basename $PWD) |
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103 | 1 | zecke | git remote add gerrit ssh://$USERNAME@gerrit.osmocom.org:29418/$PROJECT.git |
104 | scp -P 29418 $USERNAME@gerrit.osmocom.org:hooks/commit-msg .git/hooks/ |
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105 | 44 | neels | </pre> |
106 | |||
107 | 33 | neels | h2. Push for review |
108 | 1 | zecke | |
109 | 38 | neels | Checkout the revision or branch that you want to submit for review, then |
110 | |||
111 | 31 | neels | <pre> |
112 | 48 | ahuemer | git push gerrit HEAD:refs/for/master |
113 | 1 | zecke | </pre> |
114 | 38 | neels | |
115 | 1 | zecke | You can optionally add a topic name with |
116 | 40 | neels | |
117 | <pre> |
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118 | 48 | ahuemer | git push gerrit HEAD:refs/for/master/my_topic |
119 | 38 | neels | </pre> |
120 | |||
121 | 57 | neels | h2. Merge patch to master |
122 | |||
123 | A patch can be merged when it has CR+2 and V+1 votes, and if, in case of a |
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124 | series of patches pushed from a branch, when its ancestor patches can also be |
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125 | merged. |
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126 | |||
127 | Sometimes the reviewer that gives CR+2 also hits the "Submit" button right away |
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128 | to merge the patch to master. Sometimes it is left up to the owner of the patch |
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129 | to decide when to hit "Submit". |
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130 | |||
131 | The V+1 vote means "build is verified" and is usually given by our jenkins |
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132 | builds (job names end in 'gerrit'). |
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133 | |||
134 | The CR+2 vote means "code reviewed and ready for merge to master branch". |
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135 | Accounts with the "Reviewer" role for a given project are allowed to give CR+2 |
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136 | votes. Others are allowed to give CR+1 (and CR-1). CR votes _don't_ add up. |
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137 | |||
138 | Sometimes hitting the "Submit" button results in an error message saying |
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139 | "Change is New", which is a bug related to a private branch with the same |
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140 | patches being present. Can be fixed e.g. by an admin's manual push to master. |
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141 | 1 | zecke | |
142 | 38 | neels | h2. Push a "private" user branch |
143 | 33 | neels | |
144 | 1 | zecke | *Note* that you must be a member of the "known users" group, see above. |
145 | 33 | neels | |
146 | 43 | neels | If your local branch name is of the form 'your_name/topic', you can just |
147 | 1 | zecke | <pre> |
148 | git push |
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149 | 33 | neels | </pre> |
150 | 41 | neels | and git will tell you what to do. |
151 | 1 | zecke | |
152 | 41 | neels | To push from a "nonstandard" local branch name, do |
153 | <pre> |
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154 | 50 | msuraev | git push gerrit HEAD:refs/heads/user/$USERNAME/branch_name |
155 | 33 | neels | </pre> |
156 | |||
157 | 39 | neels | |
158 | h2. List changesets in gerrit |
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159 | |||
160 | 7 | neels | <pre> |
161 | 48 | ahuemer | git ls-remote gerrit changes/* |
162 | 2 | zecke | </pre> |
163 | 12 | msuraev | |
164 | 17 | neels | h1. Tips and Tricks |
165 | 1 | zecke | |
166 | 17 | neels | h2. Throw-away branch |
167 | |||
168 | 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), |
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169 | 45 | neels | make your changes/amendments and then send patch(es) back to gerrit while removing temporary branch automatically with "git review -f". |
170 | 13 | neels | |
171 | 56 | neels | h2. Fetch a patch from gerrit |
172 | |||
173 | This script (I called it @P@) makes fetching a patch set from gerrit a breeze: |
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174 | <pre> |
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175 | #!/bin/sh |
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176 | # fetch gerrit patch into new branch named like the patch number. |
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177 | # |
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178 | # Usage: go to a git clone and pass a patch number: |
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179 | # |
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180 | # cd openbsc |
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181 | # P 973 |
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182 | # or |
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183 | # P 973/2 |
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184 | # |
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185 | # Will create new local branches '973_4' (if 4 is the latest patch set) |
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186 | # or '973_2', respectively. |
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187 | |||
188 | patch="$1" |
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189 | |||
190 | if [ -z "$patch" ]; then |
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191 | echo "Usage: P 1234[/5]" |
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192 | exit 1 |
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193 | fi |
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194 | |||
195 | if [ -z "$(echo "$patch" | grep '/')" ]; then |
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196 | patch="/$patch/" |
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197 | fi |
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198 | |||
199 | if [ -z "$(echo "$patch" | grep '^/')" ]; then |
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200 | patch="/$patch" |
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201 | fi |
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202 | |||
203 | last_set="$(git ls-remote origin "changes/*" | grep "$patch" | sed 's#.*/\([^/]*\)$#\1 &#' | sort -n | tail -n 1)" |
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204 | if [ -z "$last_set" ]; then |
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205 | echo "Not found: $patch" |
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206 | exit 1 |
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207 | fi |
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208 | |||
209 | change_name="$(echo "$last_set" | sed 's/.*\(refs.*\)/\1/')" |
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210 | branch_name="$(echo "$change_name" | sed 's#refs/changes/../\([0-9]*\)/\([0-9]*\)#\1_\2#')" |
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211 | |||
212 | set -x |
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213 | git fetch origin "$change_name" |
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214 | git co -b "$branch_name" FETCH_HEAD |
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215 | </pre> |
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216 | |||
217 | 25 | neels | h2. Re-submit a Branch with Amended Commits |
218 | 13 | neels | |
219 | 1 | zecke | On a feature branch, one typically has numerous commits that depend on their preceding commits. |
220 | 29 | neels | Often, some of the branch commits need to be amended for fixes. But, Gerrit will refuse your branch |
221 | re-submission if the first branch commit is unchanged. |
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222 | 1 | zecke | |
223 | 16 | neels | To re-submit a branch, make sure to cosmetically tweak the branch's first commit log message |
224 | 22 | neels | before each re-submission (keep the Change-Id, really make just a cosmetic change). |
225 | 13 | neels | |
226 | 16 | neels | <pre> |
227 | git rebase -i master |
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228 | # replace the first line's 'pick' with 'r' (or 'reword'), exit editor |
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229 | # git presents you with commit log message, make any tiny modification. |
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230 | 1 | zecke | </pre> |
231 | |||
232 | 29 | neels | The cause: Gerrit refuses to accept a commit with a Change-Id that it already knows and |
233 | where the commit hash is identical. |
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234 | 1 | zecke | |
235 | 29 | neels | If you just cosmetically tweak the first commit's log message, the commit hash |
236 | is changed. Since the following commits contain their predecessor's commit hash, now |
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237 | all of the branch's commit hashes are modified, and gerrit happily accepts them as a |
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238 | new patch set. It will still pick up the Change-Ids (which you shouldn't edit) and |
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239 | notice if commits have remained identical (keeping the votes). But with the minor |
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240 | commit log tweak, it will no longer thwart your re-submission with an error message. |
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241 | |||
242 | Note: you could modify all the Change-Ids, but now your branch submission would |
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243 | open entirely new review entries and you would have to abandon your previous submission. |
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244 | Comments on the first submission are lost and you cannot diff between patch sets. |
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245 | |||
246 | |||
247 | 26 | neels | h2. Re-submit Previously Abandoned Changes |
248 | 16 | neels | |
249 | You have to edit the Change-Ids, on a branch that would be every single commit log message. |
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250 | |||
251 | 13 | neels | <pre> |
252 | 1 | zecke | cd openbsc |
253 | git co my-branch |
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254 | git rebase -i master |
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255 | # replace all 'pick' with 'r' (or 'reword'), exit your editor |
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256 | 13 | neels | # git presents each commit log message for editing |
257 | </pre> |
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258 | |||
259 | 27 | neels | h2. Submit a "private" branch for master |
260 | 21 | neels | |
261 | If you've pushed a branch to refs/heads/* somewhere, gerrit will already know the Change-Ids on it. |
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262 | 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, |
263 | 21 | neels | or gerrit will refuse to accept your submission. |
264 | |||
265 | 16 | neels | h1. Reasons for Particular Configuration |
266 | 13 | neels | |
267 | 16 | neels | h2. Rebase if necessary |
268 | |||
269 | There are different merge strategies that Gerrit performs to accept patches. |
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270 | 13 | neels | Each project can be configured to a specific merge strategy, but unfortunately you can't |
271 | decide on a strategy per patch submission. |
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272 | |||
273 | It seems that the "Merge if Necessary" strategy is best supported, but it creates non-linear |
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274 | history with numerous merge commits that are usually not at all necessary. |
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275 | |||
276 | Instead, the "Cherry Pick" strategy puts each patch onto current master's HEAD to create |
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277 | linear history. However, this will cause merge failures as soon as one patch depends on |
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278 | another submitted patch, as typical for a feature branch submission. |
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279 | |||
280 | 1 | zecke | So we prefer the "Rebase if Necessary" strategy, which always tries to apply your patches to |
281 | 13 | neels | the current master HEAD, in sequence with the previous patches on the same branch. |
282 | However, some problems still remain, including some bugs in "Rebase if Necessary". |
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283 | 1 | zecke | |
284 | 13 | neels | There's a problem with "Rebase if Necessary": If your branch sits at master's HEAD, Gerrit |
285 | refuses to accept the submission, because it thinks that no new changes are submitted. |
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286 | This is a bug in Gerrit, which holger has fixed manually in our Gerrit installation: |
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287 | 1 | zecke | |
288 | https://bugs.chromium.org/p/gerrit/issues/detail?id=4158 |
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289 | |||
290 | |||
291 | 16 | neels | h2. Private Branches: Create a new change for every commit... |
292 | 1 | zecke | |
293 | 13 | neels | Say you have an extensive feature in development, and you want to keep it on the |
294 | upstream git repository to a) keep it safe and b) collaborate with other devs on it. |
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295 | 16 | neels | So, of course, you have regularly pushed to refs/heads/yoyodyne/feature. |
296 | 13 | neels | |
297 | Since you have the gerrit commit hook installed, your feature branch already has |
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298 | Change-Id tags in all commit log messages. |
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299 | |||
300 | Now your feature is complete and you would like to submit it to master. |
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301 | Alas, Gerrit refuses to accept your patch submission for master, because it |
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302 | knows the Change-Ids are also on a different branch. |
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303 | |||
304 | 16 | neels | Gerrit by default enforces that a Change-Id must be unique across all branches, |
305 | so that each submission for review is separate for each branch. Instead, we |
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306 | want to handle Change-Ids per-branch, so that you can have the same change |
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307 | submitted to different branches, as separate patch submissions, without having |
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308 | to cosmetically adjust the Change-Id. |
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309 | 13 | neels | |
310 | 16 | neels | Solution: set the option |
311 | _Create a new change for every commit not in the target branch_ to _TRUE_ |
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312 | 13 | neels | |
313 | 20 | neels | h2. Allow content merges |
314 | 14 | neels | |
315 | By default, gerrit compares patches only by the files' paths. If two paths are the same, |
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316 | it immediately shows them as conflicts (path conflicts). |
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317 | |||
318 | In software development, a conflict usually means an actual content conflict, so if the |
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319 | edits are in two entirely separate places in the file, we don't consider this a conflict. |
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320 | |||
321 | 23 | neels | By setting _Allow content merges_ to _TRUE_ in the git project config, we tell Gerrit to |
322 | 14 | neels | perform text merges of the submitted patches and only complain about actual content |
323 | conflicts, in the usual software engineering sense. |
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324 | 32 | neels | |
325 | h1. Admin |
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326 | |||
327 | h2. Adding users to groups |
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328 | |||
329 | Normally, the gerrit UI auto-completes a user name in the edit field. It has happened |
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330 | though that an existing user is not auto-completed, as if it didn't exist. In that case, |
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331 | find out the user ID (seven digit number like 1000123) and just enter that. |
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332 | |||
333 | The user ID can be found on the user's "Settings" page, or in the database (s.b.). |
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334 | |||
335 | h2. Querying the database directly |
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336 | |||
337 | If your user has permission to access the database, you can place SQL queries using the |
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338 | 'gerrit gsql' commands over ssh: |
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339 | |||
340 | <pre> |
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341 | 53 | neels | ssh go 'gerrit gsql --format PRETTY -c "show tables"' |
342 | ssh go 'gerrit gsql --format PRETTY -c "select full_name,account_id from accounts"' |
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343 | 1 | zecke | </pre> |
344 | 53 | neels | |
345 | (see ~/.ssh/config above for the 'go' shortcut) |
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346 | 32 | neels | |
347 | This seems to be the MySQL dialect. |