Foreman Maintain

The foreman_maintain aims to provide various features that helps keep the Foreman/Satellite up and running. It supports multiple versions and subparts of the Foreman infrastructure, including server or smart proxy and is smart enough to provide the right tools for the specific version.

Usage

Subcommands:
    health                        Health related commands
      list                          List the checks based on criteria
      list-tags                     List the tags to use for filtering checks
      check                         Run the health checks against the system
        --label label               Run only a specific check with a label
        --tags tags                 Run only those with all specific set of tags

    upgrade                       Upgrade related commands
      check --target-version TARGET_VERSION   Run pre-upgrade checks for upgrading to specified version
            --disable-self-upgrade            Disable automatic self upgrade (default: false)
      run --target-version TARGET_VERSION     Run the full upgrade
          --disable-self-upgrade              Disable automatic self upgrade (default: false)

    advanced                      Advanced tools for server maintenance
      procedure                     Run maintain procedures manually
        run                           Run maintain procedures manually
        by-tag                        Run maintain procedures in bulks

    service                       Control applicable services
      start                         Start applicable services
      stop                          Stop applicable services
      restart                       Restart applicable services
      status                        Get statuses of applicable services
      list                          List applicable services
      enable                        Enable applicable services
      disable                       Disable applicable services

    backup                        Backup server
      online                        Keep services online during backup
      offline                       Shut down services to preserve consistent backup

    restore                       Restore a backup

    maintenance-mode              Control maintenance-mode for application
      start                         Start maintenance-mode
      stop                          Stop maintenance-mode
      status                        Get maintenance-mode status
      is-enabled                    Get maintenance-mode status code

Upgrades

Foreman-maintain implements upgrade tooling that helps the administrator to go through the upgrade process.

The foreman-maintain tool is intended to self upgrade itself to the next major version of the project. This is needed before upgrading, run:

foreman-maintain self-upgrade

To perform just the pre-upgrade checks for the system, run:

foreman-maintain upgrade check --target-version TARGET_VERSION

The upgrade tooling is able to handle the full end-to-end upgrade via:

foreman-maintain upgrade run --target-version TARGET_VERSION

The upgrade is split into several phases with different level of impact the run of the system:

• pre-upgrade check - this phase performs the checks to ensure that the system is in ready state before the upgrade. The system should still be operational at the current version, while this phase runs.

• pre-migrations - these steps perform changes on the system before the actual upgrade starts. An example is disabling access to the system from external sources, a.k.a. maintenance mode or disabling Katello sync plans during the run.

  After this phase ends, the system is still running the old version, and it's possible to revert the changes by running the post-migrations steps.

• migrations - this phase performs the actual migrations, starting with configuring new repositories, updating the packages and running the installer.

  At the end of this phase, the system should be fully migrated to the new version. However, the system is not fully operational yet, as the post-migrations steps need to revert the pre-migrations steps.

• post-migrations - these steps revert the changes made in pre-migrations phase, turning the system into fully-operational again.

• post-upgrade checks - these steps should perform sanity check of the system to ensure the system is valid and ready to be used again.

The state of the upgrade is kept between runs, allowing to re-run the upgrade run in case of failure. The tool should start at the appropriate point. For example, in case the upgrade is already in migrations phase, there is no point in running the pre-upgrade check phase. In case the upgrade failed before migrations phase made some modifying changes, the tool tries to rollback to the previous state of the system.

Self-upgrade for rubygem-foreman_maintain package

When a user runs any foreman-maintain upgrade sub commands (e.g. foreman-maintain upgrade check or foreman-maintain upgrade run) then,

• If update available for rubygem-foreman_maintain package, the sub command tries to update this package. After successful package update, it returns the exit code 75 and requests user to re-run with the updated source code.

  Here, exit code (value 75) is to indicate that it can not continue with further execution & needs re-run. e.g.,

  # foreman-maintain upgrade check --target-version TARGET_VERSION
  Checking for new version of foreman-maintain...
  rubygem-foreman_maintain.noarch   repository
  
  Updating foreman-maintain package.
  
  The foreman-maintain package successfully updated.
  
  Re-run foreman-maintain with required options!
  
  # echo $?
  75
  

• If update is not available for rubygem-foreman_maintain package, then sub command simply executes the further steps without halt.

• If user wants to skip self-update mechanism then --disable-self-upgrade flag can be used with upgrade sub commands. e.g.,

# foreman-maintain upgrade check --target-version TARGET_VERSION --disable-self-upgrade
# foreman-maintain upgrade run --target-version TARGET_VERSION --disable-self-upgrade

Satellite notes

To use custom organization/activation key for configuring repositories during upgrade, set the following environment variables

export EXTERNAL_SAT_ORG='Sat6-CI'
export EXTERNAL_SAT_ACTIVATION_KEY='Satellite QA RHEL7'

Implementation

The foreman_maintain maps the CLI commands into definitions. This allows to keep the set of the commands the user needs to know immutable from version-specific changes. The mapping between the CLI commands and definitions is made by defining various metadata.

Definitions

There are various kinds of definitions possible:

• Features - aspects that can be present on the system. It can be service (foreman, foreman-proxy), a feature (some Foreman plugin), a link to external systems (e.g. registered foreman proxy, compute resource) or another aspect that can be subject of health checks and maintenance procedures.
• Checks - definitions of health checks to indicate health of the system against the present features
• Procedures - steps for performing specific operations on the system
• Scenarios - combinations of checks and procedures to achieve some goal

The definitions for this components are present in definitions folder.

Features

Before foreman_maintain starts, it takes the set of features definition and determines their presence by running their confine blocks against the system.

The confine block can run an external command to check if the feature is there, or it can check present of other features.

A feature can define additional methods that can be used across other definitions.

class Features::Foreman < ForemanMaintain::Feature
  metadata do
    label :foreman

    confine do
      check_min_version('foreman', '1.7')
    end
  end

  # helper method that can be used in other definitions like this:
  #
  #   feature(:foreman).running?
  def running?
    execute?('systemctl foreman status')
  end
end

The features can inherit from each other, which allows overriding methods for older versions, when newer version of the feature is present in the system. This way, we shield the other definitions (checks, procedures, scenarios) from version-specific nuances.

Checks

Checks define assertions to determine status of the system.

class Checks::ForemanIsRunning < ForemanMaintain::Check
  metadata do
    for_feature :foreman
    description 'check foreman service is running'
    tags :default
  end

  def run
    # we are using methods of a feature.
    # we can define additional steps to be executed as a follow-up
    # of assertion failure
    assert(feature(:foreman).running?
           'There are currently paused tasks in the system'),
           :next_steps => Procedures::ForemanStart.new)
  end
end

Similarly as features, also checks (and in fact all definitions) can used label, description confine and tags keyword to describe themselves.

Every definition has a label (if not stated explicitly, it's determined from the class name).

In case some operation take more time, it's possible to enable a spinner and update the spinner continuously with with_spinner method.

def run
  with_spinner do |spinner|
    spinner.update 'checking foreman is running'
    if feature(:foreman).running?
      spinner.update 'foreman is not started, starting'
      feature(:foreman).start
    else
      spinner.update 'foreman is started, restarting'
    end
  end
end

Procedures

Procedure defines some operation that can be performed against the system. It can be part of a scenario or be linked from a check as a remediation step.

class Procedures::ForemanStart < ForemanMaintain::Procedure
  metadata do
    for_feature :foreman
    description 'start foreman service'
  end

  def run
    feature(:foreman).start
  end
end

Preparation steps

Some steps can require some additional steps to be performed before we can proceed. A typical example is installing additional dependencies. A preparation step is usually a procedure.

class Procedures::InstallPackage < ForemanMaintain::Procedure
  metadata do
    # definitions of parameters of the procedure
    param :packages, 'List of packages to install', :array => true
  end

  def run
    packages_action(:install, @packages)
  end

  # if false, the step will be considered as done: it will not be executed
  def necessary?
    @packages.any? { |package| package_version(package).nil? }
  end

  def description
    "Install package(s) #{@packages.join(', ')}"
  end
end

class Checks::DiskIO < ForemanMaintain::Check
  metadata do
    description 'check foreman service is running'
    preparation_steps { Procedures::InstallPackage.new(:packages => %w[fio]) }
  end

  def run
    execute!('fio ...')
  end
end

When running a scenario, all the preparation steps in that scenario will be collected, and run if necessary (the necessary? method returning true). The preparation steps will be run as separate scenario.

Scenarios

Scenarios represent a composition of various steps (checks and procedures) to achieve some complex maintenance operation in the system (such as upgrade).

class Scenarios::PreUpgradeCheckForeman_1_14 < ForemanMaintain::Scenario
  metadata do
    description 'checks before upgrading to Foreman 1.14'
    confine do
      feature(:upstream)
    end
    tags :pre_upgrade_check
  end

  # Method to be called when composing the steps of the scenario
  def compose
    # we can search for the checks by metadata
    steps.concat(find_checks(:default))
  end
end

Hammer

In some cases, it's useful to be able to use the hammer as part of check/fix procedures. It is as simple as:

def run
  feature(:hammer).run('task resume')
end

Before executing the command the feature checks if it has valid hammer configuration to run the command. Foreman maintain always use the 'admin' account to run the commands. The password is taken from the hammer config or installer answer files or asked from the user interactively (in this order). The valid credentials are stored and reused next time if still valid.

Usually we want to do the user interaction at the beginning of our scenario. The easiest way to achieve this is to include ForemanMaintain::Concerns::Hammer module:

include ForemanMaintain::Concerns::Hammer

which adds Procedures::HammerSetup as a preparation step to your metadata. We are adding this to all procedures and checks automatically.

Metadata

A set of data that describes and gives information about any definition.

You can describe a definition using following methods available in metadata:

• label - specify an unique name per definition
• tags - comma separated labels attached for the purpose of creating groups of definitions
• description - specify short description about definition
• param - declare parameters for a definition using this method
• for_feature - specify feature name for a definition. It implicitly confines the presence of that feature.
• preparation_steps - takes block using which you can perform additional steps before executing actual definition
• confine - takes block as argument to restrict execution of it
• advanced_run - takes a boolean value for procedure definition & will restrict execution of procedure from advanced procedure run sub-command
• before, after - methods used to define order for particular check. Specify label of other check.

Implementation components

In order to process the definitions, there are other components present in the lib directory.

• Detector - searches the checks/procedures/scenarios based on metadata & available features
• Runner - executes the scenario
• Reporter - reports the results of the run. It's possible to define multiple reporters, based on the current use case (CLI, reporting to monitoring tool)
• Cli - Clamp-based command line infrastructure, mapping the definitions to user commands.

Testing

Since a single version of foreman_maintain is meant to be used against multiple versions and components combinations, the testing is a crucial part of the process.

There are multiple kind of tests foreman_maintain:

• unit tests for implementation components - can be found in test/lib
  • this tests are independent of the real-world definitions and are focused on the internal implementation (metadata definitions, features detection)
• unit tests for definitions - can be found in test/definitions
  • this tests are focusing on testing of the code in definitions directory. There is an infrastructure to simulate various combinations of features without needing for actually having them present for development
• bats test - TBD
  • to achieve stability, we also want to include bats tests as part of the infrastructure, perhaps in combination with ansible playbooks to make the testing against real-world instances as easy as possible.

Execute rake to run the tests.

Bash completion

The completion offers suggestion of possible command-line subcommands and their options as usual. It can also suggest values for options and params where file or directory path is expected.

Bash completion is automatically installed by RPM. To use it for development setup cp ./config/foreman-maintain.completion /etc/bash_completion.d/foreman-maintain and load it to the current shell source /etc/bash_completion.d/foreman-maintain. Make sure the $PWD/bin is in PATH or there is full path to foreman-maintain-complete executable specified in /etc/bash_completion.d/foreman-maintain.

Bash completion for foreman-maintain needs pre-built cache that holds description of all subcommands and its parameters. The cache is located by default in ~/.cache/foreman_maintain_completion.yml. The location can be changed in foreman-maintain's config file. The cache can be built manually with foreman-maintain advanced prebuild-bash-completion or is built automatically when completion is used and the cache is missing (this may cause slight delay). The cache expires after installer scenario answer file changed (it indicates that the features on the instance may have changed which has impact on foreman-maintain CLI options and subcommands).

Available value types

Completion of values is dependent on CLI option and parameter settings, e.g.:

  parameter 'BACKUP_DIR', 'Path to backup dir', :completion => { :type => :directory }

Possible options for the :completion attribute are:

• { :type => :flag } option has no value, default for flags
• { :type => :value } option has value of unknown type, no suggestions for the value, default
• { :type => :directory } value is directory, suggestions follow directory structure
• { :type => :file, :filter => '\.txt$' } value is file, suggestions follow directory structure, optional :filter is regexp to filter the results.

Difference between maintenance-mode status and is-enabled:

• maintenance-mode status gives a brief output with On/Off message. This includes status of each step.

• maintenance-mode is-enabled returns 0 or 1 output depending upon the maintenance-mode status. Here, 0=ON & 1=OFF.

If users would like to check whether maintenance-mode is ON/OFF on system in their external script then they can use subcommand foreman-maintain maintenance-mode is-enabled.

Exit codes with special meanings -

Every command returns an exit code. Any other exit status than 0 indicates a failure of some kind. Foreman Maintain uses following exit codes with special meaning.

Exit Code	Description
75	Temporary failure and needs re-run
78	Command executed with warning(s)

How to contribute?

Generally, follow the Foreman guidelines. For code-related contributions, fork this project and send a pull request with all changes. Some things to keep in mind:

• Follow the rules about commit message style and create a Redmine issue. Doing this right will help reviewers to get your contribution merged faster.
• We have a development handbook to help developers understand how Foreman developers code.
• All of our pull requests run the full test suite in our Travis CI system. Please include tests in your pull requests for any additions or changes in functionality

License

This project is licensed under the GPLv3+