Heterogeneous deployment/Train deploys

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Pairing on the Train

As of October 2019, there are two people assigned to each week's train: One as primary, and one as backup. These are rough guidelines for sharing the work, and should be improved as we learn more.

• On Monday, communicate with your partner and establish how you'll collaborate over the course of the week.
  • Updates on IRC while your partner is working and updates on the train blocker ticket if they're offline seems to be a useful pattern.
  • Liberal use of video chat for pairing on hard problems is encouraged.
  • It seems to work well to have the primary do the work of cutting the branch, syncing wikis, etc., while the backup keeps an eye on logs, works on improvements to deploy tooling, and is generally an extra pair of eyes for the whole process.
  • If you are in doubt about any part of the process and it's during your partner's working hours, consult them first and get their help in resolving your questions.
• If one member of the pair is in the European window and one is in the American window, both train deployment windows should be reserved on the Deployments calendar. This gives a backup deployer a defined window for moving the train forward outside the primary's working hours, if it becomes necessary.
• If the train is blocked or there are any other issues, communicate the transfer of responsibility on the train blocker ticket by assigning it to the responsible party and leaving a note.

Breakage

There will be times when this process does not go smoothly. There are guidelines for what do to when that happens.

In general, if there is an unexplained error that occurs within 1 hour of a train deployment — always roll back the train. Rolling back the train to eliminate it as the cause of unexplained breakage can be especially important if there are many ongoing possible causes for issues as this helps to eliminate one of those causes as the source of problems.

Rollback

To rollback a wikiversion change, it should be pretty quick. Go ahead and rollback production before you send patches up to gerrit since waiting on Jenkins may take a while:

USERNAME@deploy1001:/srv/mediawiki-staging$ git revert $(git log -1 --format=%H -- wikiversions.json)
USERNAME@deploy1001:/srv/mediawiki-staging$ scap sync-wikiversions 'Revert "group[0|1] wikis to [VERSION]"'
USERNAME@deploy1001:/srv/mediawiki-staging$ # Now that you've synced the revert, push patches up to gerrit, you have to run git commit --amend to get the changeid
USERNAME@deploy1001:/srv/mediawiki-staging$ git commit --amend
USERNAME@deploy1001:/srv/mediawiki-staging$ git push origin HEAD:refs/for/master/[VERSION]%l=Code-Review+2

Example:

USERNAME@deploy1001:/srv/mediawiki-staging$ git push origin HEAD:refs/for/master/1.34.0-wmf.0%l=Code-Review+2

• Wait for the patch to merge and the fetch back down to the deployment server

• #Update roadmap.

Places to Watch for Breakage

Train deployers should check for breakage as they are rolling out train as they are effectively the first line of defense for train deploys. Some of the places to watch for breakage:

• IRC
  • primary channel is #wikimedia-operations ^connect
  • useful channels are #mediawiki-core ^connect #wikimedia-dev ^connect
  • for more channels see MediaWiki on IRC and IRC/Channels
• mwlog1001
  • logspam-watch
  • Logfiles in /srv/mw-log
• Logstash Fatal Monitor
• Logstash MediaWiki Errors
• Logstash "mediawiki-new-errors" dashboard (linked from logstash front page)
  • Showing only timeout errors (see T204871)
• Group-specific Logstash Dashboards:
  • group0
  • group1
• Grafana Varnish error-rate dashboard (HTTP 5XX % should have 3+ 0s after the decimal point, e.g. 0.0001%)
• Grafana Frontend Responses NGINX vs Varnish
• Grafana Production Logging
• Minerva Client Errors - Browser JS errors count (only wikipedias on mobile)

If the train is blocked

• A task will be assigned to you, for example T191059 (1.32.0-wmf.13 deployment blockers)
• Any open subtasks block the train from moving forward. This means no further deployments until the blockers are resolved.

Checklist

If there are blocking tasks, please do the following:

• Make sure all tasks blocking train are set to UBN! priority in phabricator
• Comment on the task asking for an ETA or if this can be solved by reverting a recent commit.
• Send e-mail to:
  • ops@lists.wikimedia.org
  • wikitech-l@lists.wikimedia.org
  • Subject: [Train] {version} status update
  • Body

    The {version} version of MediaWiki is blocked[0].
    
    The new version is deployed to {group(s){0,1,2}}[1], but can proceed no
    further until these issues are resolved:
    
    * {Phab task name} - {phab task link}
    
    Once these issues are resolved train can resume. If these issues are
    resolved on a Friday the train will resume Monday.
    
    Thank you for your help resolving these issues!
    
    -- Your humble train toiler
    
    [0]. <{link to phab task for train}>
    [1]. <https://tools.wmflabs.org/versions/>
    

• Add relevant people (see Developers/Maintainers) to the blocking task
• Ping relevant people in IRC
• Once train is unblocked be sure to thank the folks who helped unblock it

Monday: Sync up with your deployment partner

See the train pairing section above.

Tuesday: New branch creation and deploy

The new branch can be created in Gerrit from anywhere. It is often faster to do this step on a host in the cluster to minimize the time needed to clone from Gerrit.

Before the deploy window

Depending on how practiced you are and where you choose to run commands (full clones of mediawiki-core from outside the cluster can take a while) the steps will typically take 45 to 90 minutes.

Setup

The script is run as your regular user member of the wikidev group (as of Feb 16th 2016).

Configure Git. You will need to ensure your user.name and user.email is set correctly. You will also need to ensure that you push to gerrit via ssh (as of Mar 18th, 2019).

USERNAME@MACIHNE-NAME:~$ ssh deployment.eqiad.wmnet

USERNAME@deploy1001:~$ git config --global user.name "[FIRST-NAME] [LAST-NAME]"
USERNAME@deploy1001:~$ git config --global user.email "[USERNAME]@[DOMAIN]"
USERNAME@deploy1001:~$ git config --global url.ssh://[GERRIT-USERNAME]@gerrit.wikimedia.org:29418.pushInsteadOf https://gerrit.wikimedia.org/r

Create a new ssh key to use from the deployment server.

USERNAME@deploy1001:~$ ssh-keygen -t ed25519
Enter file in which to save the key (/home/USERNAME/.ssh/id_ed25519): <enter>
Enter passphrase (empty for no passphrase): <passphrase>
Enter same passphrase again: <passphrase>
Your identification has been saved in /home/USERNAME/.ssh/id_ed25519.
Your public key has been saved in /home/USERNAME/.ssh/id_ed25519.pub.

Add your new ~/.ssh/id_ed25519.pub key to Gerrit:

• In the new UI go to SSH keys, copy the contents of your ~/.ssh/id_ed25519.pub file into the ui.
• In the old UI, go to SSH keys, copy the contents of your ~/.ssh/id_ed25519.pub file into the ui.

Create a new ssh-agent so that your key remains unlocked during branch cutting:

USERNAME@deploy1001:~$ eval $(ssh-agent)
USERNAME@deploy1001:~$ ssh-add ~/.ssh/id_ed25519
Enter passphrase for /home/USERNAME/.ssh/id_ed25519: <passphrase>
Identity added: /home/USERNAME/.ssh/id_ed25519 (USERNAME@deploy1001)

You should be able to list the keys in your agent and see your key there:

USERNAME@deploy1001:~$ ssh-add -l
256 SHA256:WSjdx+WFnlo9Dd+FN63c35+Q3pArOD/TQpFEjNh7ODc USERNAME@deploy1001 (ED25519)

Add Gerrit to ~/.ssh/known_hosts. Fingerprint is available only in the old UI at settings/ssh-keys.

USERNAME@deploy1001:~$ ssh -oFingerPrintHash=md5 -p 29418 GERRIT-USERNAME@gerrit.wikimedia.org
The authenticity of host '[gerrit.wikimedia.org]:29418 ([2620:0:861:3:208:80:154:85]:29418)' can't be established.
RSA key fingerprint is MD5:dc:e9:68:7b:99:1b:27:d0:f9:fd:ce:6a:2e:bf:92:e1.
Are you sure you want to continue connecting (yes/no)? yes
Warning: Permanently added '[gerrit.wikimedia.org]:29418,[2620:0:861:3:208:80:154:85]:29418' (RSA) to the list of known hosts.

  ****    Welcome to Gerrit Code Review    ****

  Hi You, you have successfully connected over SSH.

  Unfortunately, interactive shells are disabled.
  To clone a hosted Git repository, use:

  git clone ssh://GERRIT-USERNAME@gerrit.wikimedia.org:29418/REPOSITORY_NAME.git

Connection to gerrit.wikimedia.org closed.

Clone or update mediawiki/tools/release.

USERNAME@deploy1001:~$ git clone https://gerrit.wikimedia.org/r/mediawiki/tools/release

tmux or screen

Some scripts run for 10-60 minutes so consider using tmux or screen.

If you prefer tmux:

USERNAME@deploy1001:~$ tmux new -s train
...
USERNAME@deploy1001:~$ exit

If you need to leave in the middle you can do ctrl-b d to detach and tmux a -t train to attach.

If you prefer screen:

USERNAME@deploy1001:~$ screen -D -RR train
...
USERNAME@deploy1001:~$ exit

If you need to leave in the middle you can do ctrl-a d to detach and screen -r train to attach.

Create the new branch in Gerrit

USERNAME@deploy1001:~/release/make-wmf-branch$ ./make-wmf-branch -n [VERSION] -o master

Example:

USERNAME@deploy1001:~/release/make-wmf-branch$ ./make-wmf-branch -n 1.34.0-wmf.0 -o master

🐌 Note: the script will run for about 30 minutes.

If the process is interrupted (by rebooting Gerrit, for example), continue from where it stopped:

USERNAME@deploy1001:~/release/make-wmf-branch$ ./make-wmf-branch -n [VERSION] -o master -c extensions/[EXTENSION]

Clone new branch

This command will create a new /srv/mediawiki-staging/php-[VERSION] directory:

USERNAME@deploy1001:/srv/mediawiki-staging$ scap prep [VERSION]

Example:

USERNAME@deploy1001:/srv/mediawiki-staging$ scap prep 1.34.0-wmf.0

This should only take a couple of minutes.

Apply security patches

• Patches should be named sequentially in the order that they will cleanly apply (e.g. 01-T[NUMBER].patch, 02-T[NUMBER].patch)
• Check and apply each patch in both /srv/patches/[VERSION]/core and /srv/patches/[VERSION]/extensions/[NAME] to the new core checkout and extensions, respectively.

Check existing patches:

USERNAME@deploy1001:~$ tree /srv/patches/[VERSION]
/srv/patches/[VERSION]
├── core
│   ├── 01-T[NUMBER].patch
│   └── 02-T[NUMBER].patch
└── extensions
    └── [EXTENSION]
        ├── 01-T[NUMBER].patch
        └── 02-T[NUMBER].patch

Core

• You can check a core patch to see if it will apply cleanly with

USERNAME@deploy1001:/srv/mediawiki-staging/php-[VERSION]$ git apply --check --3way /srv/patches/[VERSION]/core/[NUMBER]-T[NUMBER].patch

• If the patch checks out, apply and commit it with

USERNAME@deploy1001:/srv/mediawiki-staging/php-[VERSION]$ git am --3way /srv/patches/[VERSION]/core/[NUMBER]-T[NUMBER].patch

Extension

• For an extension:

USERNAME@deploy1001:/srv/mediawiki-staging/php-[VERSION]/extensions/[EXTENSION]$ git apply --check --3way /srv/patches/[VERSION]/extensions/[EXTENSION]/[NUMBER]-T[NUMBER].patch

USERNAME@deploy1001:/srv/mediawiki-staging/php-[VERSION]/extensions/[EXTENSION]$ git am --3way /srv/patches/[VERSION]/extensions/[EXTENSION]/[NUMBER]-T[NUMBER].patch

• If the patch fails to apply, investigate whether it's due to a conflict (git status) or the patch having been merged since the new branch cut (search git log for the commit, etc.). If it turns out to be the latter, remove the patch file from the /srv/patches/[VERSION] directory.
• If you need extra help, contact Security Team (Wikimedia Foundation, MediaWiki, Office Wiki), currently Brian (bawolff) and Sam (Reedy) in IRC.

Create patches to update wikiversions.json

Create group0 to [VERSION] patch:

USERNAME@deploy1001:/srv/mediawiki-staging/$ scap update-wikiversions group0 [VERSION]
USERNAME@deploy1001:/srv/mediawiki-staging/$ git add wikiversions.json
USERNAME@deploy1001:/srv/mediawiki-staging/$ git commit -m "Group0 to [VERSION]"

Example:

USERNAME@deploy1001:/srv/mediawiki-staging/$ scap update-wikiversions group0 1.34.0-wmf.0
USERNAME@deploy1001:/srv/mediawiki-staging/$ git add wikiversions.json
USERNAME@deploy1001:/srv/mediawiki-staging/$ git commit -m "Group0 to 1.34.0-wmf.0"

Send staged patches to Gerrit for review

USERNAME@deploy1001:/srv/mediawiki-staging/$ git push origin HEAD:refs/for/master/[VERSION]

Example:

USERNAME@deploy1001:/srv/mediawiki-staging/$ git push origin HEAD:refs/for/master/1.34.0-wmf.0

Discard changes to working directory and index

USERNAME@deploy1001:/srv/mediawiki-staging/$ git reset --hard origin/master

Clean up old stuff

mw:MediaWiki 1.34/Roadmap is a good place to find when a branch was created.

List all branches:

USERNAME@deploy1001:/srv/mediawiki-staging/$ find . -maxdepth 1 -type d -name 'php-*' -print

Find old branches, more than 7 days old:

USERNAME@deploy1001:/srv/mediawiki-staging/$ find . -mindepth 2 -maxdepth 2 -type f -path './php-*/README' -ctime +7 -exec dirname {} \;

For all branches more than 7 days old, drop everything with:

USERNAME@deploy1001:/srv/mediawiki-staging/$ scap clean --delete [some old version from find -ctime +7 output above]

Example:

USERNAME@deploy1001:/srv/mediawiki-staging/$ scap clean --delete 1.34.0-wmf.0

Active branches are visible at Wikimedia MediaWiki versions page.

Deleting a branch is a full sync of that directory, and can take 10-15 minutes each.

Sync to cluster and verify on testwiki

• Edit /srv/mediawiki-staging/wikiversions.json and set testwiki to php-[VERSION]
• Do not commit and push to Gerrit, only make this change locally on the deployment server

USERNAME@deploy1001:/srv/mediawiki-staging/$ vim wikiversions.json

USERNAME@deploy1001:/srv/mediawiki-staging$ git diff
...
-    "testwiki": "php-[VERSION-1]",
+    "testwiki": "php-[VERSION]",
...

• Run scap to (re)build localization caches and sync changes across the cluster.
• 🐌 Note: this step will take about 20 minutes.

USERNAME@deploy1001:/srv/mediawiki-staging/$ scap sync "testwiki to php-[VERSION] and rebuild l10n cache"

Example:

USERNAME@deploy1001:/srv/mediawiki-staging/$ scap sync "testwiki to php-1.34.0-wmf.0 and rebuild l10n cache"

• Verify version change on testwiki (Installed software, Product: MediaWiki, Version: [VERSION]) and l10n cache (Special:Version should not look like Special:Version?uselang=qqx)

This can take half an hour. Opening or reloading the version page on testwiki after the scap sync command can take a minute or two.

• Revert local changes

USERNAME@deploy1001:/srv/mediawiki-staging/$ git checkout -- wikiversions.json

Update deploy notes

• Deploy notes are automatically generated by the Train Deploy Notes Jenkins job after you cut the branch
• Be sure to check that the appropriate Changelog was created at https://www.mediawiki.org/wiki/MediaWiki_[VERSION]/Changelog. Example: MediaWiki 1.34/wmf.4/Changelog

Wait for deploy window

All of the changes above can be done at any time prior to the actual deployment window.

During the deploy window

Switch group0 wikis to [VERSION]

• CR+2 group0 to [VERSION] patch in Gerrit that you submitted earlier
• Wait for Gerrit/Zuul/Jenkins to merge the patch(es)
• Pull patch(es) to deployment server

USERNAME@deploy1001:/srv/mediawiki-staging$ git fetch

• Check diff to ensure it is what you expect (this should show a bunch of version changes in wikiversions.json for group0 wikis)

USERNAME@deploy1001:/srv/mediawiki-staging$ git diff HEAD..origin/master

• Apply changes

USERNAME@deploy1001:/srv/mediawiki-staging$ git rebase origin/master

• Sync the change across the cluster

USERNAME@deploy1001:/srv/mediawiki-staging$ scap sync-wikiversions "group0 to [VERSION]"

Example:

USERNAME@deploy1001:/srv/mediawiki-staging$ scap sync-wikiversions "group0 to 1.34.0-wmf.0"

• Verify that mediawikiwiki switched to the new version (Installed software, Product: MediaWiki, Version: VERSION)
• Monitor irc and logstash and/or logspam-watch for problems, see #Places to Watch for Breakage

Update roadmap

• Change the Deployed to group (if you're using VisualEditor) or the 3rd parameter of the WMFReleaseTableRow template (if you're using the wikitext editor) to 0 (deployed to group0) at mw:MediaWiki 1.35/Roadmap.

For wikitext editor, change

{{WMFReleaseTableHead}}
{{WMFReleaseTableRow|[VERSION]|[DATE]|}}
...
{{WMFReleaseTableFooter}}

to

{{WMFReleaseTableHead}}
{{WMFReleaseTableRow|[VERSION]|[DATE]|0}}
...
{{WMFReleaseTableFooter}}

Example:

{{WMFReleaseTableHead}}
{{WMFReleaseTableRow|12|2018-07-10|0}}
...
{{WMFReleaseTableFooter}}

Wednesday: group0 to group1 deploy

Switch group1 wikis to [VERSION]

Use the release/bin/deploy-promote script to update wikiversions.json

USERNAME@deploy1001:~$ ./release/bin/deploy-promote
Promote group1 from [PREVIOUS-VERSION] to [VERSION] [y/N]

The script automatically Code-Review +2 the patch in Gerrit. Once CI has merged the patch, hit enter at the 2nd prompt.

Now wait for jenkins to merge the patch, then press enter to continue with git pull && scap sync-wikiversions

After the script run is complete, group1 wikis should be running [VERSION].

The above should take about five minutes, including the waiting time for Gerrit/CI.

Update roadmap

• Change the Deployed to group (if you're using VisualEditor) or the 3rd parameter of the WMFReleaseTableRow template (if you're using the wikitext editor) to 1 (deployed to group1) at mw:MediaWiki 1.35/Roadmap.

For wikitext editor, change

{{WMFReleaseTableRow|[VERSION]|[DATE]|0}}

to

{{WMFReleaseTableRow|[VERSION]|[DATE]|1}}

Example:

{{WMFReleaseTableRow|12|2018-07-10|1}}

Thursday: group{0,1} to all deploy

Switch all wikis to [VERSION]

Thursday deploy is very similar to the Wednesday deploy, the only difference in terms of procedure is the target group

Use the release/bin/deploy-promote all script to update wikiversions.json

USERNAME@deploy1001:~$ ./release/bin/deploy-promote all
Promote all from [PREVIOUS-VERSION] to [VERSION] [y/N]

The script automatically Code-Review +2 the patch in Gerrit. Once CI has merged the patch, hit enter at the 2nd prompt.

Now wait for jenkins to merge the patch, then press enter to continue with git pull && scap sync-wikiversions

After the script run is complete, all wikis should be running [VERSION].

Update roadmap

• Change the Deployed to group (if you're using VisualEditor) or the 3rd parameter of the WMFReleaseTableRow template (if you're using the wikitext editor) to 2 (deployed to all wikis) at mw:MediaWiki 1.35/Roadmap.

For wikitext editor, change

{{WMFReleaseTableRow|[VERSION]|[DATE]|1}}

to

{{WMFReleaseTableRow|[VERSION]|[DATE]|2}}

Example:

{{WMFReleaseTableRow|12|2018-07-10|2}}

Incident documentation

• If there were problems during the train, follow instructions at Incident documentation on incident reports and post-mortem review.
• Use Create report form to create a new page, train-[VERSION]. Example: Incident documentation/20181212-Train-1.33.0-wmf.8.
• For Timeline section, events from SAL and Phabricator task are a good start.