Help:Standalone puppetmaster

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This page contains information about standalone Puppetmaster, helps you decide why you would use one, and provides basic trouble shooting information.

About standalone Puppetmaster

A standalone Puppetmaster can be used to deliver either a custom or experimental Puppet configuration to one or more hosts in a Cloud VPS project. All Cloud VPS instances run puppet via cron about every 30 minutes. The default configuration pulls from the shared Cloud VPS puppetmaster which has a pristine checkout of operations/puppet.git and labs/private.git. Sometimes you want to have a puppetmaster that you control as a Cloud VPS user. You can use role::puppetmaster::standalone to accomplish this.

Why would I want a local Puppetmaster?

These are the popular reasons for wanting to use one:

  1. Testing puppet patches before they have been merged in operations/puppet.git
  2. Keep project local secrets in a labs/private.git repo

Help! Hiera values from local commits don't seem to apply!

Hiera in Cloud VPS has different settings than in Wikimedia Production puppet, and it can be tricky to get your values into the right place in labs/private.git or puppet in general. First, check /etc/puppet/hiera.yaml on your standalone puppetmaster for guidance. You may just need to add things to labs/private/hieradata/labs/<VPS project name>/common.yaml.

You can verify that a node can "see" your hiera settings with the command sudo puppet lookup --node <fqdn of puppet client> --compile --explain <your::hiera::key> on the standalone puppetmaster. The compile is needed to set all the right facts for hiera in Cloud VPS, and there will be a lot of warnings you can ignore. The answer will be at the end of the command's output.

How can I use a local Puppetmaster?

Step 1: Setup a standalone puppetmaster

  1. Create a Debian Buster instance (an m1.small instance is enough for most projects)
  2. Apply the role role::puppetmaster::standalone
  3. Force two consecutive puppet runs on the instance using sudo -i run-puppet-agent
  4. Generate the server certs: sudo puppet cert generate $(hostname -f)
  5. Make sure puppetmaster can restart: sudo systemctl restart apache2

You will now find a checkout of operations/puppet.git in /var/lib/git/operations/puppet and a checkout of labs/private.git in /var/lib/git/labs/private.

A standalone puppetmaster is not its own client by default; to configure this, see below.

Autosigning

If you are not planning on keeping any secrets in your puppetmaster, you can turn on autosigning. This will automatically accept new clients as they contact the puppetmaster, and save you a step later on when adding clients. You can do that by adding the following to the hiera configuration for the puppetmaster instance:

role::puppetmaster::standalone::autosign: true

If you are keeping secrets, you must not turn this on! If you do, anyone with network access to the puppetmaster can access all your secrets!

Step 2: Setup a puppet client

This works for any number of instances, including the puppetmaster itself.

  1. Using the Horizon interface:
    1. Set the hiera variable puppetmaster: <your puppetmaster's FQDN>. (Scroll all the way to the bottom of the Puppet Configuration tab, to the Hiera Config button, and add the variable name/value in YAML format.) Use the fully qualified domain name of the puppetmaster (i.e. hostname.projectname.eqiad1.wikimedia.cloud which can be found by running hostname -f on the puppetmaster host).
      • This variable can be set either per-instance or project wide.
  2. On the client instance:
    1. Run puppet to apply the modified hiera configuration: sudo -i run-puppet-agent
    2. Remove existing SSL certificates created with the prior puppetmaster: sudo rm -rf /var/lib/puppet/ssl (NOTE: you will see certificate verify failed: [self signed certificate in certificate chain ...] when you run puppet if you don't do this.
    3. Only if the client is the puppetmaster itself, run also: 
      sudo rm /var/lib/puppet/server/ssl/ca/signed/$(hostname -f).pem
sudo mkdir -p /var/lib/puppet/ssl/private_keys
sudo cp -v /var/lib/puppet/{server/,}ssl/private_keys/$(hostname -f).pem
sudo mkdir /var/lib/puppet/ssl/certs/
sudo cp -v /var/lib/puppet/{server/,}ssl/certs/$(hostname -f).pem
    4. Force a puppet run to generate a new local SSL certificate: sudo -i run-puppet-agent
  3. On the puppetmaster (If you enabled autosigning in the master, you can skip this step):
    1. Check that the fingerprint of the client's key matches the one shown when it was generated running: sudo -i puppet cert list
    2. Sign the key of the client: sudo -i puppet cert sign <client-fqdn>.
  4. On the client:
    1. Run puppet twice to check that is connecting correctly to it's new master and that the second run does not produce any new configuration changes: sudo -i run-puppet-agent

Troubleshooting

Forgetting to run puppet agent with sudo

Failing to run puppet agent as root can result in the surprising error: 

Debug: Creating new connection for https://puppet:8140
Error: Could not request certificate: getaddrinfo: Name or service not known
Exiting; failed to retrieve certificate and waitforcert is disabled

Advanced use cases

Using puppetdb

WARNING: This is kind of experimental at this time. Proceed with caution.

Puppetdb can be enabled on standalone puppetmasters on Cloud VPS by designating a puppetdb server with the role::puppetmaster::puppetdb role and a lot of hiera values on both the DB server and the puppetmaster. This requires significant effort and is not a recommended configuration unless you have significant experience with puppet, need it and are able to maintain the setup, including your own postgresql database. It is not likely to succeed unless puppetmaster runs on Debian Stretch/Buster (you may have problems if your puppetmaster OS and puppetdb OS do not match due to PuppetDB termini packaging), and it is guaranteed to break your puppet setup if you just enable it without following a particular order. Notes on that can be found on the standalone puppetdb notes page.

Git push from workstation to puppetmaster

Typically development is done on non-Cloud VPS machines, this applies to Puppet as well, so a common use case is to develop locally and then push to your Cloud VPS project's puppetmaster for testing.

Push using multiple branches

If you want your Cloud VPS instance to act as yet another remote Git repository, you have to configure Git to use sudo as well. To do that, in your local computer's git clone of the Puppet repository 

$ git remote add my-instance my-instance.my-project.eqiad1.wikimedia.cloud:/var/lib/git/operations/puppet
$ git config remote.my-instance.receivepack "sudo git-receive-pack"
$ git config remote.my-instance.uploadpack "sudo git-upload-pack"

After that, you can push and pull branches from and to your Cloud VPS instance. If you pull commits from your Cloud VPS instance, remember to reset authorship information with git commit --amend --reset-author before pushing to Gerrit.

You cannot push to the branch that is currently checked out. To avoid having to log into your Cloud VPS puppet master and checking out branches, etc., you can create a post-receive hook by copying:

Example post-receive hook
The following content has been placed in a collapsed box for improved usability. 
#!/bin/bash
#
# Copyright 2015, 2016 Tim Landscheidt
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#
# When a commit is pushed to a branch with a name starting with
# "development/", this post-update script will replace all "local
# hacks" that have a matching Gerrit "Change-Id:" footer with the ones
# in this branch and add new "local hacks" on top.  When a branch with
# a name starting with "development/" is deleted, it will remove all
# "local hacks" that are referenced in that branch.

# Hooks are executed in the ".git" subdirectory, so move upwards to
# allow rebases, etc. to work.  As hooks have the environment variable
# "GIT_DIR" set to ".", this means we need to amend it.
cd ..
export GIT_DIR=.git

sedcommands=$(mktemp)

# Iterate over all branches that were changed.
while read oldref newref branch; do
    # Only process pushes to branches with a name starting with
    # "development/".
    if [ "$branch" = "${branch#refs/heads/development/}" ]; then
        continue
    fi

    # Iterate over all changes in the branch that are not part of
    # "production".
    if [ "$newref" = "0000000000000000000000000000000000000000" ]; then
        range=production..$oldref
    else
        range=production..$newref
    fi
    for commit in $(git log --format=format:%H --reverse $range); do
        # Check whether there is already a "local hack" with the same
        # Gerrit "Change-Id:" footer and remove it.
        changeid="$(git log -1 --format=format:%B $commit | sed -ne 's/^Change-Id: //p;')"
        localhack="$(git log origin/production..production --format=format:%H --grep "^Change-Id: $changeid\$")"
        # Was the branch deleted?
        if [ "$newref" = "0000000000000000000000000000000000000000" ]; then
            # Then delete the local hack if it exists.
            if [ -n "$localhack" ]; then
                echo "/^pick ${localhack:0:7} .*\$/d" >> "$sedcommands"
            fi
        else
            # Otherwise update or add the local hack.
            if [ -n "$localhack" ]; then
                echo "s/^pick ${localhack:0:7} .*\$/pick $commit/" >> "$sedcommands"
            else
                echo "\$apick $commit" >> "$sedcommands"
            fi
        fi
    done
done

if ! GIT_SEQUENCE_EDITOR="sed -i -f $sedcommands" git rebase -i origin/production; then
    git rebase --abort
    echo "$0: Could not rebase changes." >&2
fi

rm -f $sedcommands
The above content has been placed in a collapsed box for improved usability.

to /var/lib/git/operations/puppet/.git/hooks/post-receive and making it executable (chmod +x /var/lib/git/operations/puppet/.git/hooks/post-receive).

With this hook in place, when you push commits to a branch with a name that starts with development/:

  • if a "local hack" (a commit that is in the production branch, but not in origin/production) with the same Change-Id already exists, it will replace that commit with the one in your pushed branch, or
  • if no local hack with the same Change-Id exists, it will apply it on top of other local hacks.

If you delete a branch (git push -f my-instance :development/branch), the local hacks in that branch are removed.

You can use the script git-puppet-test to combine pushing your local development branch to the Cloud VPS puppet master with running Puppet on several hosts and executing a test script:

git-puppet-test script
The following content has been placed in a collapsed box for improved usability. 
#!/usr/bin/python3
#
# Copyright 2014, 2015, 2016 Tim Landscheidt
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

import argparse
import re
import subprocess
import sys

parser = argparse.ArgumentParser()
parser.add_argument('--set-pre-command',
                    dest='pre_command',
                    help='set the pre-command')
parser.add_argument('--set-post-command',
                    dest='post_command',
                    help='set the post-command')
parser.add_argument('--set-hosts',
                    dest='hosts',
                    help='set the hosts')
args = parser.parse_args()

# Ensure there are no uncommitted changes.
if subprocess.check_output(['git', 'status', '--porcelain']):
    print('Uncommitted changes.')
    sys.exit(1)

# Determine change-ID.
commit_message = subprocess.check_output(['git', 'cat-file', '-p', 'HEAD'],
                                         universal_newlines=True)
change_id = None
for line in commit_message.split('\n'):
    if line.startswith('Change-Id: '):
        change_id = line[len('Change-Id: '):]
if change_id is None:
    print("Couldn't find Change-Id.")
    sys.exit(1)

# Determine remote repository for puppetmaster.
puppetmaster_remote = None
for line in subprocess.check_output(['git', 'remote', '-v'],
                                    universal_newlines=True).split('\n'):
    m = re.fullmatch(r'([^\t]+)\t'
                     r'.*\.wmflabs:/var/lib/git/operations/puppet \(push\)',
                     line)
    if m:
        puppetmaster_remote = m.group(1)
if puppetmaster_remote is None:
    print("Couldn't determine remote repository for puppetmaster.")
    sys.exit(1)

# Process --set-* options and terminate if they were given.
if args.pre_command is not None:
    subprocess.check_call(['git',
                           'config',
                           'puppet-test.%s.pre-command' % change_id,
                           args.pre_command])
if args.post_command is not None:
    subprocess.check_call(['git',
                           'config',
                           'puppet-test.%s.post-command' % change_id,
                           args.post_command])
if args.hosts is not None:
    subprocess.check_call(['git',
                           'config',
                           'puppet-test.%s.hosts' % change_id,
                           args.hosts])
if any((args.pre_command is not None,
        args.post_command is not None,
        args.hosts is not None)):
    sys.exit(0)

# Run pre-command.
try:
    pre_command = subprocess.check_output(['git',
                                           'config',
                                           '--get',
                                           'puppet-test.%s.pre-command' %
                                           change_id],
                                          universal_newlines=True)
    subprocess.call(pre_command, shell=True)
except subprocess.CalledProcessError:
    pass

# Push change to puppetmaster.
subprocess.check_call(['git',
                       'push',
                       '-f',
                       puppetmaster_remote,
                       'HEAD:development/' + change_id])

# Run Puppet on configured hosts.
try:
    hosts = subprocess.check_output(['git',
                                     'config',
                                     '--get',
                                     'puppet-test.%s.hosts' % change_id],
                                    universal_newlines=True)
    subprocess.call(['clush',
                     '-w',
                     hosts,
                     'tmplog="$(mktemp)" && '
                     'if ! sudo puppet agent -tv > "$tmplog" 2>&1; then '
                     'cat "$tmplog"; '
                     'fi && '
                     'rm -f "$tmplog"'])
except subprocess.CalledProcessError:
    pass

# Run post-command.
try:
    post_command = subprocess.check_output(['git',
                                            'config',
                                            '--get',
                                            'puppet-test.%s.post-command' %
                                            change_id],
                                           universal_newlines=True)
    subprocess.call(post_command, shell=True)
except subprocess.CalledProcessError:
    pass
The above content has been placed in a collapsed box for improved usability.

This is especially useful if you work on a patch over a longer period of time, or the tests that you need to run are complex or boring. The shell command to run before and after pushing a branch and the hosts to run Puppet on are specified by the entries puppet-test.$changeid.pre-command, puppet-test.$changeid.post-command and puppet-test.$changeid.hosts in .git/config with $changeid being the Change-Id of the commit at HEAD. You can set those also by git puppet-test --set-post-command $command, etc.

When a patch is merged that you previously pushed as a local hack, if it is identical, i. e. the changes are the same, it will just "disappear" from the list of local hacks. If it has been amended, the automatic pull with git-sync-upstream will fail, and you will have to log in and remove the local hack with git rebase -i origin/production production and deleting the line of the local hack in question. You need to apply the same steps if you want to abandon a local hack that you no longer want to work on.

NOTE: If the puppet master is shared among more than one person, pushing will overwrite or mess in other ways with each other's changes!

Push using a single branch

In case a puppetmaster is used to test a single branch/patchset at a time, a simple solution is to to push to an intermediate bare repo and then update the non-bare authoritative repo.

The git hook added in 159720 achieves this. So assuming you have a role::puppetmaster::standalone configured, you can setup a local bare repo e.g. in your Cloud VPS home (as your user): 

cd ~
[ -d ~/puppet.git ] || git clone --bare --no-hardlinks --branch production /var/lib/git/operations/puppet/ ~/puppet.git
install -m755 /var/lib/git/operations/puppet/modules/puppetmaster/files/self-master-post-receive ~/puppet.git/hooks/post-receive

and on the development host add the relevant remote: 

git remote add project_puppetmaster ssh://PUPPET_MASTER_HOSTNAME/~/puppet.git

then to test a puppet change in your Cloud VPS puppet master from your local host you can force-push to that remote in the "production" branch, e.g. 

git push -f project_puppetmaster HEAD:production

Communication and support

Support and administration of the WMCS resources is provided by the Wikimedia Foundation Cloud Services team and Wikimedia movement volunteers. Please reach out with questions and join the conversation:

Discuss and receive general support
Stay aware of critical changes and plans
Track work tasks and report bugs

Use a subproject of the #Cloud-Services Phabricator project to track confirmed bug reports and feature requests about the Cloud Services infrastructure itself

Read stories and WMCS blog posts

Read the Cloud Services Blog (for the broader Wikimedia movement, see the Wikimedia Technical Blog)

See also

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