About this book

Puppet is a configuration management system written for system administrators to manage a large number of systems efficiently and help maintain order. Deploying Puppet becomes more complex as you increase the number of nodes in your environment. The Puppet tool is an intelligent solution that increases the automation footprint for the proactive management of server infrastructures. Puppet's simple programming language is usable on most operating systems and is portable on different deployment environments.

We begin by looking at the puppet.conf server configuration file, and talk about possible problems that can occur. What does puppet really do in the background and what options does it provide for troubleshooting? This is what we will explore.

Moving on, we will be troubleshooting errors made in modules and templates, finding the best solutions. We will be writing code that will helping us in identify errors. Then we will explain how several ENCs do their job and how puppet communicates with them. We will learn how PuppetDB collects data generated by Puppet. It also enables advanced Puppet features like exported resources, and can be the foundation for other applications that use Puppet’s data. By the end of the book we will have learned the best debugging tips for Puppet and PuppetServer.

Publication date:
August 2015
Publisher
Packt
Pages
144
ISBN
9781784398651

 

Chapter 1. Puppet Infrastructure

As a Puppet engineer, you will encounter many different problems while working with Puppet. Puppet infrastructure comprises all the components that you can use to deploy Puppet on your nodes, and may include applications such as Apache, Passenger, Puppet Server, PuppetDB, and ActiveMQ. Knowing how the infrastructure works, and how the various components fit together and function, will help you troubleshoot your issues. An important aspect of how Puppet infrastructure works is the way the various components communicate with each other. Most of the communication between the components of your Puppet infrastructure is done via an HTTP/SSL REST API. Later in this chapter, we will use this API to troubleshoot our installation.

The first step towards understanding how all the components of a Puppet installation communicate is to know the different components. The components of a typical installation are shown in the following diagram:

In subsequent chapters, we will examine the workings of these various components in detail.

With this picture of the components in mind, we will now go through the main actions that take place during a Puppet run.

 

The lifecycle of a Puppet run


Communication between the nodes and the master in a Puppet environment is verified with a system of X.509 SSL certificates. The master operates as a certificate authority (CA) for the system, although you may specify another server to act as the CA. When the agent first runs on a node, there are several steps taken to set up the trust relationship between the node and the master, which are outlined as follows:

  1. The agent contacts the master and downloads the CA certificate.

  2. The agent generates a certificate for itself based on the certname configuration option, which is usually equivalent to the hostname of the node.

  3. The agent issues a certificate signing request (CSR) to the master, asking the master to sign its certificate.

  4. The master may choose to sign the certificate (if automatic signing is configured) or the operator of the master may sign the certificate.

  5. The agent will check back every 2 minutes by default (configurable with the waitforcert option) to check whether its certificate has been signed.

  6. Once it has been signed, the agent will download its signed certificate.

At this point, the trust relationship between the agent and master has been established. The subsequent Puppet runs will not have to perform these steps. These runs will have a different series of steps, which are outlined in the following list:

  1. The agent contacts and informs the master about its operating environment. Environments are used to separate nodes into logical groups.

  2. The master looks through all the available modules in the given environment and begins sending all the /lib subdirectories of the modules to the agent via the pluginsync method.

  3. Once all the plugins have been downloaded to the node, the node runs the facter utility to generate a list of facts about the node. The agent then ships the fact list back to the master.

  4. If you have PuppetDB configured in your environment, the facts are shipped to PuppetDB, which will decide to either create new entries for the node (if this is the first time, facts have arrived for this node), or update the existing fact values.

  5. At this point, the master will use the fact list to generate values that are needed to compile the catalog for the node. A catalog is the living document of how a node is configured. It consists of all the Puppet modules, classes, and resources, that will be applied to a node.

  6. The master will compile the catalog. This is the process of verifying that it is possible to apply resources to a node in a consistent manner. Puppet will generate a graph, with all the resources as vertices. If the graph has any cycles, then the compilation will fail. A cycle is also known as a circular dependency. It means that there are resources within the catalog that require each other, or that are mutually dependent. A failed compilation results in the agent exiting with an error code.

  7. If the catalog compiles successfully, the catalog is then shipped to the agent.

  8. At this point, the Puppet agent's run begins. All the resources in the catalog are applied sequentially to the node. When troubleshooting, it is important to remember that although the master is capable of running several catalog compilations at once, the agent on a node must be single-threaded by definition.

  9. The catalog will either apply without error to the node, which is called a clean run, or fail and output errors. If the agent has a clean run and does not change any files on the node, the exit code of the process will be 0. If the agent has a clean run and does make any changes, the exit code will be 2. If the agent fails to apply all the resources to the node, which is called a failed run, the agent will exit with the exit code as either 4 (with no file changes) or 6 (with file changes).

    Tip

    To have puppet agent return these exit codes, the --detailed-exitcodes option must be given when running the puppet agent. Note the test option, -t, includes this option.

  10. Facter will be run at the end of a successful or clean run. The fact values that have changed or the new facts will be sent to PuppetDB. Note that if PuppetDB cannot be updated, the agent will mark the run as unclean.

  11. Depending on your configuration, the agent will then generate a report, which will be shipped to the report_server. If reports are configured, then they will be sent for both failed and clean runs.

  12. Several files on the node will also be updated at this point. When troubleshooting, it is often useful to examine the contents of the following files:

    • The classes.txt file contains the list of classes in the catalog

    • The resources.txt file contains a list of resources in the catalog

    • The state.yaml file contains timestamps for various files on the system as well as scheduling information

    • The last_run_report.yaml file contains all the log messages that would be output to the console or during the Puppet run (this may be overridden by the --logdest command-line argument)

    • The last_run_summary.yaml file contains a summary of the last run, with a count of the resources that were changed, the time taken to complete the run, and additional metrics

Beyond initial communication issues between the agents and the master, the bulk of Puppet troubleshooting revolves around failed catalog compilation and application.

With an idea of how the agent runs, we can now look closely at how one can configure Puppet as we examine the puppet.conf file in the next section.

 

Puppet configuration


Configuration of both the Puppet master and the agents (nodes) is done with the same configuration file, puppet.conf. This file is located in different directories, which depend on the version of Puppet that you are running—the open source version, or the commercial version, Puppet Enterprise. The different locations are summarized in the following table:

Operating system

Open source version

Puppet Enterprise

Linux/Mac OS X

/etc/puppet/puppet.conf

/etc/puppetlabs/puppet/puppet.conf

Windows*

%PROGRAMDATA%\PuppetLabs\puppet\etc\puppet\puppet.conf

*Windows 2003 has a different location.

You may also override the name and location of this file with the config_file_name and config options respectively. The puppet.conf configuration file uses the INI-style syntax, which consists of multiple sections. The [main] section is used for settings that apply to both the master and the agent modes of Puppet. The [master] section is for the settings that only affect the master, while the [agent] section is used to specify settings that are specific to the agent.

Here is a sample puppet.conf file:

[main]
logdir = /var/log/puppet
rundir = /var/run/puppet
ssldir = $vardir/ssl

[agent]
classfile = $vardir/classes.txt
localconfig = $vardir/localconfig

There are many more configuration options available. Puppet provides a utility for viewing all the available configuration options. To view all the available configuration options, use puppet config print. To view the options for a specific section, add --section [section] to the command, as shown in the following example in the agent section:

[email protected] ~ $ puppet config print --section agent |sort |head -10
agent_catalog_run_lockfile = /home/thomas/.puppet/var/state/agent_catalog_run.lock
agent_disabled_lockfile = /home/thomas/.puppet/var/state/agent_disabled.lock
allow_duplicate_certs = false
allow_variables_with_dashes = false
always_cache_features = false
archive_file_server = puppet
archive_files = false
async_storeconfigs = false
autoflush = true
autosign = /home/thomas/.puppet/autosign.conf

The important configuration options on the agent (when trying to troubleshoot) are those that are associated with communication with the master. By default, a node will look for a master named puppet. This is actually specified by the server option in the agent section. You can verify this setting with the following command:

[email protected] ~ $ puppet config print server --section agent
puppet

Another important option is the port from which one should contact the master. By default, it is port 8140, but you can change this with the masterport option. It is also possible to specify another server for the certificate (SSL) signing. This is specified by using the ca_server option.

As mentioned previously, the node will use the certname option to specify its own name when communicating with the master. When troubleshooting, it can be useful to specify a different certname option for a node in order to force the generation of a new certificate. You may also find it useful to specify the certname option with an appended domain, which is generally known as the fully qualified domain name (FQDN) of the node.

In summary, when you are troubleshooting the communication between the nodes and the master, the following options are important in determining the servers that will be contacted and the names that will be used in the communication:

  • server: This is the name of the master server

  • ca_server: This is the name of the CA server

  • certname: This is the name of the node that has to be used in the certificate

  • masterport: This is port 8140 by default

If you are new to the Puppet environment that you are troubleshooting, it is also useful to know the values of the following options:

  • config_file_name: This is puppet.conf; this is rarely overridden

  • confdir: This is the directory containing the configuration files of Puppet

  • config: This is a combination of confdir/config_file_name

  • vardir: This is a directory that contains variable files, and it has a value of /var/lib/puppet by default

  • ssldir: This is the directory that contains the SSL certificates, and it has a value of $vardir/ssl by default

 

puppet help


Most commands on Unix-like operating systems provide a manual or man page. The man page provides information on the available options and general guidance on using the command. Puppet initially chose not to follow this standard and instead used the help argument when calling the puppet command to specify documentation. Recent versions of Puppet have included manual pages for specific subcommands of the Puppet command-line tool. To access an individual manual page, type man puppet-[subcommand]. For example, to access the manual page on using puppet help, use man puppet-help. You can also access the same manual page using puppet man help.

The available help topics for a recent edition of Puppet are shown in the following screenshot:

For more information about a specific command, issue the command after puppet help. For example, for more information on puppet config, use puppet help config. This is demonstrated in the following code:

[email protected] ~ $ puppet help config

USAGE: puppet config<action> [--section SECTION_NAME]

This subcommand can inspect and modify settings from Puppet's
'puppet.conf' configuration file. For documentation about individual settings,
see http://docs.puppetlabs.com/references/latest/configuration.html.

OPTIONS:
  --render-as FORMAT             - The rendering format to use.
  --verbose                      - Whether to log verbosely.
  --debug                        - Whether to log debug information.
  --section SECTION_NAME         - The section of the configuration file to
interact with.

ACTIONS:
print    Examine Puppet's current settings.
setSet Puppet's settings.

See 'puppet man config' or 'man puppet-config' for full help.

You can also add subcommands to have even more specific information returned by the command, as follows:

[email protected] ~ $ puppet help config print

USAGE: puppet config print [--section SECTION_NAME] (all | <setting> [<setting> ...]

Prints the value of a single setting or a list of settings.

OPTIONS:
  --render-as FORMAT             - The rendering format to use.
  --verbose                      - Whether to log verbosely.
  --debug                        - Whether to log debug information.
  --section SECTION_NAME         - The section of the configuration file to
interact with.

See 'puppet man config' or 'man puppet-config' for full help.

The output of puppet help shows all the available arguments for the Puppet command-line utility. We will now see the usefulness of a selection of these arguments.

puppet resource

Using puppet resource can be a valuable troubleshooting tool. When you are diagnosing a problem, puppet resource can be used to inspect a node and verify how Puppet sees the state of a resource. For example, if we had a Linux node running an SSH daemon (sshd), we could ask Puppet about the state of the sshd service using puppet resource, as follows:

[email protected] ~ $ sudo puppet resource service sshd
service { 'sshd':
ensure => 'running',
enable => 'true',
}

As you can see, Puppet returned the current status of the service in Puppet code. By using puppet resource, we can query the node for any resource type that is known to Puppet. For instance, we can do this to view the status of the bind package of a node, as follows:

[email protected] ~ $ sudo puppet resource package bind
package { 'bind':
ensure => 'absent',
}

We can also inspect the settings for a file, as follows:

[email protected] ~ $ sudo puppet resource file /etc/resolv.conf
file { '/etc/resolv.conf':
ensure   => 'file',
content  => '{md5}463bd26e077bc01a9368378737ef5bf0',
ctime    => '2015-03-02 21:04:21 -0800',
group    => '0',
mode     => '644',
mtime    => '2015-03-02 21:04:21 -0800',
owner    => '0',
selrange => 's0',
selrole  => 'object_r',
seltype  => 'net_conf_t',
seluser  => 'system_u',
type     => 'file',
}

puppet apply

When troubleshooting, it can often be useful to apply a small chunk of code rather than a whole catalog. By using puppet apply, you can specify a manifest file, which can be applied directly to a node. For example, to create a file named /tmp/trouble on the local node with the content Hello, Troubleshooter!, create the following manifest file named trouble.pp:

file {'/tmp/trouble':
  content => "Hello, Troubleshooter!\n"
}

When we run puppet apply on this manifest, Puppet will create the /tmp/trouble file as expected:

[email protected] ~ $ puppet apply trouble.pp
Notice: Compiled catalog for mylaptop in environment production in 0.21 seconds
Notice: /Stage[main]/Main/File[/tmp/trouble]/ensure: defined content as '{md5}7b6223913adac8607e89a7c2f11744d0'
Notice: Finished catalog run in 0.03 seconds
[email protected] ~ $ cat /tmp/trouble
Hello, Troubleshooter!

When troubleshooting, it can be useful to add the --debug option when running puppet apply. Puppet will print information about how facts were compiled for the node, in addition to debugging information related to the application of resources.

puppet parser validate

The command-line utility can also be used to verify the syntax of your manifests. This can be useful when trying to find an issue with the compilation of your catalog. You can verify individual files by adding them as arguments to the command. For instance, the following manifest has a syntax error:

file {'bad':
ensure => 'directory',
path   => '/tmp/bad'
owner  => 'root',
}

We can verify this with puppet parser validate, which shows the following error:

[email protected] ~/trouble/01 $ puppet parser validate bad.pp
Error: Could not parse for environment production: Syntax error at 'owner'; expected '}' at /home/thomas/trouble/01/bad.pp:4

As you can see, there should be a comma after '/tmp/bad' since there is another attribute specified for the file resource.

I find myself using this command often enough to use the ppv alias for puppet parser validate.

 

Log files and the catalog


Logging in Puppet can be enabled on a client node (agent) with the --debug option to Puppet agent. This will output a lot of information. Each plugin file will be displayed as it is being read and executed. Once the catalog compiles, as each resource is applied to the machine, debugging information will be shown on the agent.

However, when you are debugging, your catalog may fail to compile. If this is the case, then you will need to examine the logs on the master. Where the logs are kept on the master depends on the way you have your master configured. The Puppet master process can be run either through a Ruby HTTP library named WEBrick, or via Passenger on a web server such as Apache or Nginx. Also, a third option now exists. You can also use the puppetserver application, which is a combination of JRuby and Clojure.

puppet master

Both the WEBrick and Passenger methods of running a Puppet master are equivalent to running puppet master from the command line. The configuration options for the Puppet master can be viewed with puppet help master.

By default, Puppet will log using syslog to the system logs (usually /var/log/messages). You can change this by making the --logdest option point at a file (logdest is used to specify the destination for log files, logdest may one of syslog, console, or the path to a file). If you are running the WEBrick server, then you can start the server like this:

# puppet master --logdest /var/log/puppet/master.log

Tip

When using Passenger, you will have a config.ru file, which is installed with the puppet-passenger package. You can add the additional logging options to this file.

To enable the debugging of logs, add the --debug option in addition to the --logdest option. You may also enable the --verbose option.

puppetserver

puppetserver is the new server for Puppet that is based on the server for PuppetDB. It uses a Java Virtual Machine (JVM) to run JRuby for the Puppet Server. This mechanism also uses Clojure. Puppet Labs has already made puppetserver the default Puppet master implementation for the new installations of Puppet Enterprise. The configuration of puppetserver is different from the Puppet master configuration. The server is configured by files that are located in /etc/puppetserver by default. Since the server is running through a JVM, it uses the Logback library. The configuration for Logback is in /etc/puppetserver/logback.xml. To enable debug logs, edit this file and change the log level from info to debug, as follows:

<root level="debug">
<!--<appender-ref ref="STDOUT"/>-->
<appender-ref ref="${logappender:-DUMMY}" />
<appender-ref ref="F1"/>
</root>

Changes made to this file are recognized immediately by the server. There is no need to restart the service. For entirely too much information, try setting the level to trace. More information on puppetserver can be found at https://github.com/puppetlabs/puppet-server.

jq

When the catalog is compiled for a node, the master will send the catalog to the node. The node will store the catalog in the client_data subdirectory of /var/lib/puppet. The catalog will be in the JSON format (previous versions of Puppet used the YAML format for catalogs). Reading the JSON files is not as simple as reading the YAML files. A tool that can help make things easier is jq, a command-line JSON processor. You can use it to search through the JSON files. For instance, to view the classes within a catalog, use the following:

$ jq '.data.classes[]' <hostname.json
"settings"
"default"

To view the resources defined in the catalog, use the following command:

$ jq '.data.resources[]'<hostname.json

To filter out the resources tagged with a specific tag, use "class" as follows:

jq '.data.resources[] | select(.tags[] == "class")' <hostname.json

Once you learn the syntax for jq, searching through large catalogs becomes an easy task. This can help you find out where your resources are defined quickly. More information on jq can be found at http://stedolan.github.io/jq/.

 

Communication issues


Before you can begin debugging complex catalog problems, you need your nodes to communicate with each other. Communication problems between nodes and the master can either be network-related or certificate-related (SSL).

Network-related problems

When the Puppet agent is started on a node, one of the first things that the agent does is look up the value for the server option. You can either specify this with --server on the command line, or with server=[hostname] in the puppet.conf configuration file. By default, Puppet will look for a server named puppet. If it cannot find one named puppet, it will then try puppet.[your domain].

Tip

What Puppet believes to be your domain may be obtained by running facter domain.

When you are debugging the initial communication problems, you need to first verify that your nodes can find the Puppet master. For Unix systems, the way in which the system searches for a machine by name is called the gethostbyname system call. This system call uses the Name Service Switch (NSS) library to find a host in a number of databases. NSS is configured by the /etc/nsswitch.conf file. The line in this file that is used to find hosts by their respective names is the hosts line. The default configuration on most of the systems is the following:

hosts:  files dns

This line means that the system will search for hosts by name in the local files first. Then, if the host is not found, it will search in the Internet Domain Name System (DNS). The local file that is first consulted is /etc/hosts. This file contains static host entries. If you inherited your Puppet environment, you should look in this file for statically defined Puppet entries. If the machine puppet or puppet.[domain] is not found in /etc/hosts, the system then queries the DNS to find the host. The DNS is configured with the /etc/resolv.conf file on the Unix systems.

Tip

When troubleshooting, be aware that the domain fact is calculated using a combination of calls to the utility hostname and looking for a domain line in /etc/resolv.conf.

This file is known as the resolver configuration file. It's important to verify that you can reach the servers listed in the nameserver lines in this file. Your file may contain a search line. This line lists the domains that will be appended to your search queries. Consider a situation where the search line is as follows:

search example.com external.example.com internal.example.com

When you search for Puppet, the system will first search for puppet, then puppet.example.com, then puppet.external.example.com, and finally puppet.internal.example.com.

Several utilities exist for the testing of DNS. Among these utilities, host and dig are the most common. An older utility, nslookup, may also be used. To lookup the ipaddress option of the default Puppet Server, use the following:

[email protected] ~ $ host puppet
Host puppet not found: 3(NXDOMAIN)

In this example, the host puppet is not found. Yet, I know that this node works as expected. Remember that the system uses the gethostbyname system call when looking up the Puppet Server. Another utility on the system uses this call—the ping utility. When we try to ping the Puppet Server, this succeeds, and the output is as follows:

[email protected] ~ $ ping -c 1 puppet
PING localhost (127.0.0.1) 56(84) bytes of data.
64 bytes from localhost (127.0.0.1): icmp_seq=1 ttl=64 time=0.093 ms
--- localhost ping statistics ---
1 packets transmitted, 1 received, 0% packet loss, time 0ms
rtt min/avg/max/mdev = 0.093/0.093/0.093/0.000 ms

As you can see, the loopback address (127.0.0.1) is being used for the Puppet Server. We can verify that this information is coming from the /etc/hosts file using grep:

[email protected] ~ $ grep puppet /etc/hosts
127.0.0.1       localhostlocalhost.localdomainmylaptop localhost4 localhost4.localdomain4 mylaptop.example.com puppet.example.com puppet

Remembering the difference between using host or dig and using the gethostbyname system call can quickly help you find problems with your configuration. Adding an entry to /etc/hosts for your Puppet Server also bypasses any DNS problems that you may have in the initial configuration of your nodes.

Netcat

The next step in diagnosing network issues is verifying that you can reach the Puppet Server on the masterport, which is by default TCP port 8140. The masterport number may be changed, though. So, you should first confirm the port number using puppet config print masterport. One of the simplest tests to verify that you can reach the Puppet Server on port 8140 is to use Netcat. Netcat is known as the Swiss Army knife of network tools. You can do many interesting things with Netcat. More information about Netcat is available at http://nmap.org/ncat/.

Tip

There are several versions of Netcat available. The version installed on the most recent distributions is Ncat. The rewrite was done by Nmap (for more information, visit https://nmap.org).

To verify that you can reach port 8140 on your Puppet Server, issue the following command:

# nc -v puppet 8140
Connection to puppet 8140 port [tcp/*] succeeded!

If your Puppet Server was inaccessible, you will see an error message that looks like this:

nc: connect to puppet port 8140 (tcp) failed: Connection refused

If you see a Connection refused error as in the preceding output, this may indicate that there is a host-based firewall on the Puppet Server that is refusing the connection. Connection refusal means that you were able to contact the server, but the server did not permit the communication on the specified port. The first step in troubleshooting this type of problem is to verify that the Puppet Server is listening for connections on the port. The lsof utility can do this for you, as shown in the following code:

[[email protected] ~]# lsof -i :8140
COMMAND  PID   USER   FD   TYPE DEVICE SIZE/OFF NODE NAME
java    1960 puppet   18r  IPv6  22323      0t0  TCP *:8140 (LISTEN)

My Puppet Server is running the java process because puppetserver runs inside a JVM. We see java as the process name in the lsof output. If you do not see any output here, then you will know that your Puppet Server is not listening on the 8140 port.

If you do see a line with the LISTEN text, then your Puppet Server is listening and a firewall is blocking the communication. Host-based firewalls on Linux are configured with the firewalld system or iptables, depending on your distribution. More information on these two systems can be found at http://en.wikipedia.org/wiki/Iptables and https://fedoraproject.org/wiki/FirewallD.

Tip

Ubuntu distributions also include an Uncomplicated Firewall (ufw) utility to configure iptables. BSD-based systems will use the Berkeley Packet Filter (pf) or IPFilter. Knowing how to configure your host-based firewall configuration is a key troubleshooting skill.

If you are familiar with firewall configuration, you can add port 8140 to the allow list and solve the problem. If you are new to firewall configuration, you may choose to temporarily disable the firewall to aid your troubleshooting. Although a perimeter firewall is often a better solution, host-based firewalls should be used wherever possible to avoid accidentally or unintentionally exposing ports on your servers. When you have fixed the problem, turn the host-based firewall back on. On an Enterprise Linux-based distribution, the following will disable the host-based firewall:

[[email protected] state]# service iptables stop
iptables: Setting chains to policy ACCEPT: filter          [  OK  ]
iptables: Flushing firewall rules:                         [  OK  ]
iptables: Unloading modules:                               [  OK  ]

If removing your host-based firewall does not solve your communication issue and you have verified that the service is listening on the correct port, then you will have to resort to advanced network troubleshooting tools.

Tools that may help in this case are mtr and traceroute. It is important to note that, even if a ping test fails, you may still be able to reach your Puppet Server on the masterport. The ping utility uses ICMP packets, which may be blocked or restricted on your network. If the netcat test still fails after addressing the firewall concerns, then you should try the mtr utility to check whether you can find where your communication is not reaching the server. For example, to test connectivity with the puppet server, issue the following command:

# mtr puppet

As an example, from my laptop, the following is the mtr output when attempting to reach https://puppetlabs.com/:

If you were unable to reach the Puppet Server, the last line in the host list would be ???. The line immediately preceding the ??? line would be the point at which the line of communication between the node and master was broken.

After you have verified that the network communication between the node and master is working as expected, the next issue that you should resolve is certificates.

SSL-related problems

Puppet uses X509 certificates to secure the communication between nodes and the master. As a Puppet administrator, you should know how the SSL certificates and a CA works.

Your infrastructure may have a separate server that acts as a CA for your Puppet installation. The CA is the certificate that is used to sign all the certificates that are generated by your master(s). If your CA is a separate server, the ca_server option will be specified in the puppet.conf file.

Although the server may be specified from the command line when running puppet agent, the ca_server option cannot.

By default, the CA certificate is generated on the first run of either the Puppet master or puppetserver. The certificate is stored in /var/lib/puppet/ssl/ca/ca_crt.pem for the Open Source Puppet (OSS) or /etc/puppetlabs/puppet/ssl/ca/ca_crt.pem for Puppet Enterprise (PE). To view the information in the certificate, use OpenSSL's x509 utility, as follows:

# openssl x509 -in ca_crt.pem -text
Certificate:
    Data:
        Version: 3 (0x2)
        Serial Number: 1 (0x1)
    Signature Algorithm: sha256WithRSAEncryption
        Issuer: CN=Puppet CA: puppet.example.com
        Validity
            Not Before: Feb 28 06:29:29 2015 GMT
            Not After : Feb 28 06:29:29 2020 GMT
        Subject: CN=Puppet CA: puppet.example.com
        Subject Public Key Info:
            Public Key Algorithm: rsaEncryption
                Public-Key: (4096 bit)
                Modulus:
                    00:99:2f:50:c4:5a:9c:e9:3a:4a:f0:1b:9b:9e:d1:
...

If you are new to the openssl command-line utility, try running openssl help (help is not actually an option, but it will cause the openssl command to print helpful information). Each of the subcommands to the openssl utility has its own Unix manual page. The manual page for the x509 subcommand can be found using man x509.

The preceding information shows that the CA certificate was automatically generated and has a five-year expiry. 5 years has been the default expiry time for some time now, and many Puppet installations are nearly 5 years old and require the generation of new CA certificates. If everything suddenly stopped working, you may wish to verify the expiry date of your CA. In addition to the expiry time, we can see the subject of the certificate, puppet.example.com. This is the name that Puppet has given to the CA based on the hostname and domain facts when the master/Puppet Server was started.

If you are diagnosing a certificate issue, you can first start by downloading the CA certificate. This can be done with the curl or wget utilities. In this example, we will use curl and pass the --insecure option to curl (since we have not downloaded the CA yet and cannot verify the certificate at this point), as follows:

$ curl --insecure https://puppet:8140/production/certificate/ca
-----BEGIN CERTIFICATE-----
MIIFfjCCA2agAwIBAgIBATANBgkqhkiG9w0BAQsFADAoMSYwJAYDVQQDDB1QdXBw
ZXQgQ0E6IHB1cHBldC5leGFtcGxlLmNvbTAeFw0xNTAyMjgwNjI5MjlaFw0yMDAy
...

We can use a pipe (|) to direct the curl output to openssl and verify the certificate, as follows:

$ curl --insecure https://puppet:8140/production/certificate/ca |openssl x509 -text
  % Total    % Received % Xferd  Average Speed   Time    TimeTime  Current
Dload  Upload   Total   Spent    Left  Speed
100  1964  100  1964    0     0   6684      0 --:--:-- --:--:-- --:--:--  6680
Certificate:
    Data:
        Version: 3 (0x2)
        Serial Number: 1 (0x1)
    Signature Algorithm: sha256WithRSAEncryption
        Issuer: CN=Puppet CA: puppet.example.com
        Validity
            Not Before: Feb 28 06:29:29 2015 GMT
            Not After : Feb 28 06:29:29 2020 GMT
        Subject: CN=Puppet CA: puppet.example.com
        Subject Public Key Info:
            Public Key Algorithm: rsaEncryption
                Public-Key: (4096 bit)
                Modulus:
                    00:99:2f:50:c4:5a:9c:e9:3a:4a:f0:1b:9b:9e:d1:
...

If the CA certificate verifies correctly, the next step is to attempt to retrieve the certificate for your node. You can do this by first downloading the CA certificate to a local file as follows:

$ curl --insecure https://puppet:8140/production/certificate/ca >ca_crt.pem
  % Total    % Received % Xferd  Average Speed   Time    TimeTime  Current
Dload  Upload   Total   Spent    Left  Speed
100  1964  100  1964    0     0   6851      0 --:--:-- --:--:-- --:--:--  6867

In this example, my hostname is mylaptop. I will attempt to download my certificate from the master using curl (verifying the communication with the previously downloaded CA certificate):

$ curl --cacertca_crt.pem https://puppet:8140/production/certificate/mylaptop
-----BEGIN CERTIFICATE-----
MIIFcTCCA1mgAwIBAgIBBDANBgkqhkiG9w0BAQsFADAoMSYwJAYDVQQDDB1QdXBw
ZXQgQ0E6IHB1cHBldC5leGFtcGxlLmNvbTAeFw0xNTAzMDEwNjMzMDdaFw0yMDAy
...

As you can see, this succeeded. If we pipe the output to OpenSSL, we see that the subject of the certificate is mylaptop and the certificate has not expired:

$ curl --cacertca_crt.pem https://puppet:8140/production/certificate/mylaptop |openssl x509 -text
  % Total    % Received % Xferd  Average Speed   Time    TimeTime  Current
Dload  Upload   Total   Spent    Left  Speed
100  1948  100  1948    0     0   6155      0 --:--:-- --:--:-- --:--:--  6145
Certificate:
    Data:
        Version: 3 (0x2)
        Serial Number: 4 (0x4)
    Signature Algorithm: sha256WithRSAEncryption
        Issuer: CN=Puppet CA: puppet.example.com
        Validity
            Not Before: Mar  1 06:33:07 2015 GMT
            Not After : Feb 29 06:33:07 2020 GMT
        Subject: CN=mylaptop
...

Since we previously downloaded the CA certificate, we can also verify this certificate by using the verify subcommand. To use verify, we will give the path to the CA certificate that was previously downloaded, and the client certificate that we just downloaded, as follows:

$ openssl verify -CAfile ca_crt.pem mylaptop.pem
mylaptop.pem: OK

If your master failed to return a certificate in the previous step, use puppet cert on the master to find the certificate. For the mylaptop example, issue the following commands:

[[email protected] ~]# puppet cert --list mylaptop
+ "mylaptop" (SHA256) 76:05:4E:C6:25:5F:04:63:A3:B7:5D:45:C9:60:48:DF:24:0D:B7:3E:4D:9F:75:5E:C8:9F:64:1D:56:34:C2:D2

If the certificate is present but unsigned, the output will have a missing + symbol at the beginning, like this:

[[email protected] ~]# puppet cert --list mylaptop
  "mylaptop" (SHA256) 87:B3:28:31:B6:A4:3D:4A:BE:E0:4B:BD:DE:24:28:74:E1:00:8A:09:91:3C:CD:B5:17:92:73:44:A1:41:C9:9E

If the certificate is not present, the output will look like this:

Error: Could not find a certificate for mylaptop

A common problem with certificates is an old certificate or a mismatch between the ca_server/master and the node. The simplest solution to this sort of problem is to remove the certificate from both machines and start again.

To remove the certificate on the ca_server, use puppet cert clean with the appropriate hostname, as follows:

[[email protected] ~]# puppet cert clean mylaptop
Notice: Revoked certificate with serial 6
Notice: Removing file Puppet::SSL::Certificate mylaptop at '/var/lib/puppet/ssl/ca/signed/mylaptop.pem'
Notice: Removing file Puppet::SSL::Certificate mylaptop at '/var/lib/puppet/ssl/certs/mylaptop.pem'

As mentioned in the output, the certificates are stored in the subdirectories of /var/lib/puppet/ssl. If the puppet cert clean command does not remove the certificate, you can remove the files manually from this location.

On the node, remove private_key and certificate from the /var/lib/puppet/ssl directory manually (there is no automatic way to do this). Alternatively, you can choose to remove the entire /var/lib/puppet/ssl directory and have the node download the CA certificate again.

This location is different for Puppet Enterprise. Puppet Enterprise stores certificates in /etc/puppetlabs/puppet/ssl. This often involves less work as compared to that of finding all the files that need to be removed.

When we ran puppet cert clean on the master, one of the output lines mentioned that the certificate has been revoked. X509 certificates can be revoked. The list of certificates that have been revoked is kept in the Certificate Revocation List (CRL), which is in the ca_crl.pem file in /var/lib/puppet/ssl/ca.

We can use OpenSSL's crl utility to inspect the CRL, as follows:

[[email protected]]# opensslcrl -in ca_crl.pem -text
Certificate Revocation List (CRL):
        Version 2 (0x1)
    Signature Algorithm: sha1WithRSAEncryption
        Issuer: /CN=Puppet CA: puppet.example.com
        Last Update: Mar  5 06:40:51 2015 GMT
        Next Update: Mar  3 06:40:52 2020 GMT
        CRL extensions:
            X509v3 Authority Key Identifier:
keyid:25:18:D4:0B:37:BD:BA:FE:70:D9:BB:17:8F:D9:84:EC:6D:30:76:71

            X509v3 CRL Number:
                2
Revoked Certificates:
    Serial Number: 06
        Revocation Date: Mar  5 06:40:52 2015 GMT
        CRL entry extensions:
            X509v3 CRL Reason Code:
                Key Compromise

As you can see, the certificate with the serial number 6 has been marked as revoked. The serial number is located within the certificate. When the master verifies a client, it will consult the CRL to verify that the serial number is not in the CRL.

More information on X509 certificates can be found at https://www.ietf.org/rfc/rfc2459.txt and http://en.wikipedia.org/wiki/X.509.

 

Summary


In this chapter, we introduced the main components of Puppet infrastructure. We highlighted the key points of a puppet agent run and the communication that takes place. We then moved on to talk about communication and how the X509 certificates are used by Puppet. We used Puppet's REST API to download and inspect certificates. In the next chapter, we will talk about Puppet manifests and how one can troubleshoot problems with code.

About the Author

  • Thomas Uphill

    Thomas Uphill has been working with Unix and Linux since the 90s. He primarily works on Linux and has an RHCA from RedHat. He's written several books on Puppet and routinely presents on Linux and Puppet at conferences such as Puppet Conf and LISA. He enjoys writing code in Ruby and Python. When not working, he blogs at ramblings.narrabilis.com and @uphillian on Twitter and IRC.

    Browse publications by this author

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