1. Introduction to Hammer

Hammer is a powerful command-line tool provided with Foreman. You can use Hammer to configure and manage a Foreman server either through CLI commands or automation in shell scripts. Hammer also provides an interactive shell.

1.1. Hammer compared to Foreman web UI

Compared to navigating the Foreman web UI, using Hammer can result in much faster interaction with the Foreman server, as common shell features such as environment variables and aliases are at your disposal. You can also incorporate Hammer commands into reusable scripts for automating tasks of various complexity. Output from Hammer commands can be redirected to other tools, which allows for integration with your existing environment. You can issue Hammer commands directly on the base operating system running Foreman.

Access to base operating system on Foreman server is required to issue Hammer commands, which can limit the number of potential users compared to the Foreman web UI. Although the parity between Hammer and the Foreman web UI is almost complete, the Foreman web UI has development priority and can be ahead especially for newly introduced features.

1.2. Hammer compared to Foreman API

For many tasks, both Hammer and Foreman API are equally applicable. Hammer can be used as a human friendly interface to Foreman API, for example to test responses to API calls before applying them in a script (use the -d option to inspect API calls issued by Hammer, for example hammer -d organization list). Changes in the API are automatically reflected in Hammer, while scripts using the API directly have to be updated manually.

In the background, each Hammer command first establishes a binding to the API, then sends a request. This can have performance implications when executing a large number of Hammer commands in sequence. In contrast, a script communicating directly with the API establishes the binding only once.

1.3. Getting help

View the full list of hammer options and subcommands by executing:

$ hammer --help

Use --help to inspect any subcommand, for example:

$ hammer organization --help

You can search the help output using grep, or redirect it to a text viewer, for example:

$ hammer | less

2. Installing standalone Hammer

You can install Hammer on a host running Enterprise Linux that has no Foreman server installed, and use it to connect from the host to a remote Foreman.

Prerequisites

  • Ensure that the CA certificate of Foreman server is deployed to the truststore on the host.

Procedure

  1. Enable the required repositories on the host.

    # dnf install https://yum.theforeman.org/releases/3.13/el9/x86_64/foreman-release.rpm

  2. Install Hammer CLI:

    # dnf install foreman-cli

  3. Set the :host: entry in the /etc/hammer/cli.modules.d/foreman.yml file to the Foreman URL:

    :host: 'https://foreman.example.com'

3. Hammer authentication

A Foreman user must prove their identity to Foreman when entering hammer commands. Hammer commands can be run manually or automatically. In either case, hammer requires Foreman credentials for authentication. There are three methods of hammer authentication:

  • Hammer authentication session

  • Storing credentials in the hammer configuration file

  • Providing credentials with each hammer command

The hammer configuration file method is recommended when running commands automatically. For example, running Foreman maintenance commands from a cron job. When running commands manually, Foreman community recommends using the hammer authentication session and providing credentials with each command.

3.1. Authenticating Hammer using a configuration file

If you ran the Foreman installation with --foreman-initial-admin-username and --foreman-initial-admin-password options, credentials you entered are stored in the ~/.hammer/cli.modules.d/foreman.yml configuration file, and hammer does not prompt for your credentials.

You can also add your credentials to the ~/.hammer/cli.modules.d/foreman.yml configuration file manually:

:foreman:
 :username: 'username'
 :password: 'password'

Use only spaces for indentation in hammer configuration files, do not use tabs.

Important

If you change your credentials on Foreman server, you must update the configuration file manually. The installer does not overwrite the configuration file.

3.2. Authenticating Hammer using CLI options

If you do not have your Foreman credentials saved in the ~/.hammer/cli.modules.d/foreman.yml configuration file, hammer prompts you for them each time you enter a command. You can specify your credentials when executing a command as follows:

$ hammer -u username -p password subcommands
Note

Examples in this guide assume that you have saved credentials in the configuration file, or are using a hammer authentication session.

3.3. Authenticating Hammer using sessions

The hammer authentication session is a cache that stores your credentials, and you have to provide them only once, at the beginning of the session. This method is suited to running several hammer commands in succession, for example a script containing hammer commands. In this scenario, you enter your Foreman credentials once, and the script runs as expected. By using the hammer authentication session, you avoid storing your credentials in the script itself and in the ~/.hammer/cli.modules.d/foreman.yml hammer configuration file.

See the instructions on how to use the sessions:

  • To enable sessions, add :use_sessions: true to the ~/.hammer/cli.modules.d/foreman.yml file:

    :foreman:
 :use_sessions: true

    Note that if you enable sessions, credentials stored in the configuration file will be ignored.

  • To start a session, enter the following command:

    # hammer auth login

    You are prompted for your Foreman credentials, and logged in. You will not be prompted for the credentials again until your session expires.

  • The default length of a session is 60 minutes. You can change the time to suit your preference. For example, to change it to 30 minutes, enter the following command:

    # hammer settings set --name idle_timeout --value 30
Setting [idle_timeout] updated to [30]

  • To see the current status of the session, enter the following command:

    # hammer auth status

  • To end the session, enter the following command:

    # hammer auth logout

4. Configuring Hammer

The default location for global hammer configuration is:

  • /etc/hammer/cli_config.yml for general hammer settings

  • /etc/hammer/cli.modules.d/ for CLI module configuration files

You can set user specific directives for hammer (in ~/.hammer/cli_config.yml) as well as for CLI modules (in respective .yml files under ~/.hammer/cli.modules.d/).

To see the order in which configuration files are loaded, as well as versions of loaded modules, use:

$ hammer -d --version
Note

Loading configuration for many CLI modules can slow down the execution of hammer commands. In such a case, consider disabling CLI modules that are not regularly used.

Apart from saving credentials as described in Hammer authentication, you can set several other options in the ~/.hammer/ configuration directory. For example, you can change the default log level and set log rotation with the following directives in ~/.hammer/cli_config.yml. These directives affect only the current user and are not applied globally.

:log_level: 'warning'
:log_size: 5 #in MB

Similarly, you can configure user interface settings. For example, set the number of entries displayed per request in the Hammer output by changing the following line:

:per_page: 30

This setting is an equivalent of the --per-page Hammer option.

4.1. Setting a default organization and location context

Many hammer commands are organization specific. You can set a default organization and location for hammer commands so that you do not have to specify them every time with the --organization and --location options.

Specifying a default organization is useful when you mostly manage a single organization, as it makes your commands shorter. However, when you switch to a different organization, you must use hammer with the --organization option to specify it.

Procedure

  1. Set a default organization:

    # hammer defaults add --param-name organization \
--param-value "Your_Organization"

    You can find the name of your organization with the hammer organization list command.

  2. Optional: Set a default location:

    # hammer defaults add --param-name location \
--param-value "Your_Location"

    You can find the name of your location with the hammer location list command.

Verification

  1. Review the currently specified default settings:

    # hammer defaults list

4.2. Increasing the logging level for Hammer

You can find the log in ~/.hammer/log/hammer.log.

Procedure

  • In /etc/hammer/cli_config.yml, set the :log_level: option to debug:

:log_level: 'debug'

5. Using interactive Hammer shell

You can issue hammer commands through an interactive shell. To start the shell, run the following command:

$ hammer shell

In the shell, you can enter sub-commands directly without typing "hammer", which can be useful for testing commands before using them in a script. To exit the shell, type exit or press Ctrl + D.

6. Formatting Hammer output

You can modify the default formatting of the output of hammer commands to simplify the processing of this output by other command line tools and applications. For example, to list organizations in a CSV format with a custom separator (in this case a semicolon), use the following command:

$ hammer --csv --csv-separator ";" organization list

Output in CSV format is useful for example when you need to parse IDs and use them in a for loop.

Several other formatting options are available with the --output option:

$ hammer --output output_format organization list

Replace output_format with one of:

  • table – generates output in the form of a human readable table (default).

  • base – generates output in the form of key-value pairs.

  • yaml – generates output in the YAML format.

  • csv – generates output in the Comma Separated Values format. To define a custom separator, use the --csv and --csv-separator options instead.

  • json – generates output in the JavaScript Object Notation format.

  • silent – suppresses the output.

7. Hiding header output from Hammer commands

When you use any hammer command, you have the option of hiding headers from the output. If you want to pipe or use the output in custom scripts, hiding the output is useful.

  • To hide the header output, add the --no-headers option to any hammer command.

8. Using JSON for complex parameters

JSON is the preferred way to describe complex parameters.

An example of JSON formatted content appears below:

# hammer compute-profile values create --compute-profile-id 22 --compute-resource-id 1 --compute-attributes=
'{
"cpus": 2,
"corespersocket": 2,
"memory_mb": 4096,
"firmware": "efi",
"resource_pool": "Resources",
"cluster": "Example_Cluster",
"guest_id": "rhel8",
"path": "/Datacenters/EXAMPLE/vm/",
"hardware_version": "Default",
"memoryHotAddEnabled": 0,
"cpuHotAddEnabled": 0,
"add_cdrom": 0,
"boot_order": [
               "disk",
               "network"
              ],
"scsi_controllers":[
      {
       "type":  "ParaVirtualSCSIController",
       "key":1000
       },
      {
        "type":  "ParaVirtualSCSIController",
        "key":1001
       }
                   ]
}'

9. Troubleshooting Foreman by using Hammer

You can use the hammer ping command to check the status of core Foreman services. Together with the foreman-maintain service status command, this can help you to diagnose and troubleshoot Foreman issues. If all services are running as expected, the output looks as follows:

$ hammer ping
database:
    Status:          ok
    Server Response: Duration: 0ms
cache:
    servers:
     1) Status:          ok
        Server Response: Duration: 1ms
candlepin:
    Status:          ok
    Server Response: Duration: 17ms
candlepin_auth:
    Status:          ok
    Server Response: Duration: 14ms
candlepin_events:
    Status:          ok
    message:         4 Processed, 0 Failed
    Server Response: Duration: 0ms
katello_events:
    Status:          ok
    message:         5 Processed, 0 Failed
    Server Response: Duration: 0ms
pulp3:
    Status:          ok
    Server Response: Duration: 5083ms
pulp3_content:
    Status:          ok
    Server Response: Duration: 5051ms
foreman_tasks:
    Status:          ok
    Server Response: Duration: 2ms

10. Hammer cheat sheet

Hammer is a command-line tool provided with Foreman. You can use Hammer to configure and manage a Foreman server by using either CLI commands or shell script automation. The following cheat sheet provides a condensed overview of essential Hammer commands.

10.1. General information

Subcommand Description and tasks

--help

Display hammer commands and options, append after a subcommand to get more information

org

The setting is organization-specific, append --organization org_name, or set default organization with:

hammer defaults add \
--param-name organization_id \
--param-value org_ID

loc

The setting is location-specific, append --location loc_name, or set default location with:

hammer defaults add \
--param-name location_id \
--param-value loc_ID

Note: This cheat sheet assumes saved credentials in ~/.hammer/cli_config.yml. For more information, see Hammer authentication.

10.2. Organizations, locations, and repositories

Subcommand Description and tasks

organization

Create an organization:

hammer organization create \
--name org_name

List organizations:

hammer organization list

location

See the options for organization

subscription
org

Upload a subscription manifest:

hammer subscription upload \
--file path

repository-set
org

Enable a repository:

hammer repository-set enable \
--product prod_name \
--basearch base_arch \
--releasever rel_v \
--name repo_name

repository
org

Synchronize a repository:

hammer repository synchronize \
--product prod_name \
--name repo_name

Create a repository:

hammer repository create \
--product prod_name \
--content-type cont_type \
--publish-via-http true \
--url repo_url \
--name repo_name

Upload content to a repository:

hammer repository upload-content \
--product prod_name \
--id repo_id \
--path path_to_dir

10.3. Content life cycles

Subcommand Description and tasks

lifecycle-environment
org

Create a life cycle environment:

hammer lifecycle-environment create \
--name env_name
--description env_desc
--prior prior_env_name

List life cycle environments:

hammer lifecycle-environment list

content-view
org

Create a content view:

hammer content-view create \
--name cv_n \
--repository-ids repo_ID1,... \
--description cv_description

Add repositories to a content view:

hammer content-view add-repository \
--name cv_n \
--repository-id repo_ID

Add Puppet modules to a content view:

hammer content-view puppet-module add \
--content-view cv_n \
--name module_name

Publishing a content view:

hammer content-view publish \
--id cv_ID

Promoting a content view:

hammer content-view version promote \
--content-view cv_n \
--to-lifecycle-environment env_name

Incremental update of a content view:

hammer content-view version incremental-update \
--content-view-version-id cv_ID \
--packages pkg_n1,... \
--lifecycle-environment-ids env_ID1,...

10.4. Provisioning environments

Subcommand Description and tasks

domain

Create a domain:

hammer domain create \
--name domain_name

subnet
org
loc

Add a subnet:

hammer subnet create \
--name subnet_name \
--organization-ids org_ID1,... \
--location-ids loc_ID1,... \
--domain-ids dom_ID1,... \
--boot-mode boot_mode \
--network network_address \
--mask netmask --ipam ipam

compute-resource
org
loc

Create a compute resource:

hammer compute-resource create \
--name cr_name \
--organization-ids org_ID1,... \
--location-ids loc_ID1,... \
--provider provider_name

medium

Add an installation medium:

hammer medium create \
--name med_name \
--path path_to_medium

partition-table

Add a partition table:

hammer partition-table create \
--name tab_name \
--path path_to_file \
--os-family os_family

template

Add a provisioning template:

hammer template create \
--name tmp_name \
--file path_to_template

os

Add an operating system:

hammer os create \
--name os_name \
--version version_num

10.5. Activation keys

Subcommand Description and tasks

activation-key
org

Create an activation key:

hammer activation-key create \
--name ak_name \
--content-view cv_n \
--lifecycle-environment lc_name

Add a subscription to the activation key:

hammer activation-key add-subscription \
--id ak_ID \
--subscription-id sub_ID

10.6. Users and permissions

Subcommand Description and tasks

user
org

Create a user:

hammer user create \
--login user_name \
--mail user_mail \
--auth-source-id 1 \
--organization-ids org_ID1,org_ID2,...

Add a role to a user:

hammer user add-role \
--id user_id \
--role role_name

user-group

Create a user group:

hammer user-group create \
--name ug_name

Add a role to a user group:

hammer user-group add-role \
--id ug_id \
--role role_name

role

Create a role:

hammer role create \
--name role_name

filter

Create a filter and add it to a role:

hammer filter create \
--role role_name \
--permission-ids perm_ID1,perm_ID2,...

10.7. Errata

Subcommand Description and tasks

erratum

List errata:

hammer erratum list

Find erratum by CVE:

hammer erratum list --cve CVE

Inspect erratum:

hammer erratum info --id err_ID

host

List errata applicable to a host:

hammer host errata list \
--host host_name

Apply errata to a host:

hammer host errata apply \
--host host_name \
--errata-ids err_ID1,err_ID2,...

10.8. Hosts

Subcommand Description and tasks

hostgroup
org
loc

Create a host group:

hammer hostgroup create \
--name hg_name \
--puppet-environment env_name \
--architecture arch_name \
--domain domain_name \
--subnet subnet_name \
--puppet-proxy proxy_name \
--puppet-ca-proxy ca-proxy_name \
--operatingsystem os_name \
--partition-table table_name \
--medium medium_name \
--organization-ids org_ID1,... \
--location-ids loc_ID1,...

Add an activation key to a host group:

hammer hostgroup set-parameter \
--hostgroup "hg_name" \
--name "kt_activation_keys" \
--value key_name

host
org
loc

Create a host (inheriting parameters from a host group):

hammer host create \
--name host_name \
--hostgroup hg_name \
--interface="primary=true, \
mac=mac_addr, ip=ip_addr, \
provision=true" \
--organization-id org_ID \
--location-id loc_ID \
--ask-root-password yes

Remove the host from host group:

hammer host update --name host_name --hostgroup NIL

job-template

Add a job template for remote execution:

hammer job-template create \
--file path \
--name template_name \
--provider-type SSH \
--job-category category_name

job-invocation

Start a remote job:

hammer job-invocation create \
--job-template template_name \
--inputs key1=value,... \
--search-query query

Monitor the remote job:

hammer job-invocation output \
--id job_id --host host_name

10.9. Tasks

Subcommand Description and tasks

task

List all tasks:

hammer task list
Monitor progress of a running task:
hammer task progress \
--id task_ID

11. Hammer reference

You can review the usage of Hammer statements.

This reference is up to date with the versions of Hammer components released for Foreman 3.13.