Defined Type: airflow::instance

Defined in:

modules/airflow/manifests/instance.pp

Overview

SPDX-License-Identifier: Apache-2.0

Define airflow::instance

Sets up an instance of Apache Airflow. This uses the custom WMF airflow debian package. This package installs an isolated conda environment in /usr/lib/airflow. Airflow instances run airflow from this conda environment with AIRFLOW_HOME defaulting to /srv/airflow-$title. By default, all files (configs, dags, logs, etc.) belonging to the airflow instance live in /srv/airflow-$title.

airflow.cfg is rendered directly from the $airflow_config Hash. A few smart airflow configs are set automatically:

• core.sql_alchemy_conn (Deprecated on Airflow >= 2.3.0) If this is set in $airflow_config, then it may be an ERB template string. The final sql_alchemy_conn setting will render this template with local variable context, which allows to include $db_user and $db_password in the sql_alchemy_conn string without providing it directly in the $airflow_config param. E.g. mysql://:<%= @db_user %>:<%= @db_password %>@an-test-coord1001.eqiad.wmnet/airflow_analytics?ssl_ca=/etc/ssl/certs/wmf-ca-certificates.crt Deprecated and replaced with database.sql_alchemy_conn defined below

• database.sql_alchemy_conn If this is set in $airflow_config, then it may be an ERB template string. The final sql_alchemy_conn setting will render this template with local variable context, which allows to include $db_user and $db_password in the sql_alchemy_conn string without providing it directly in the $airflow_config param. E.g. postgresql://<%= @db_user %>:<%= @db_password %>@an-db1001.eqiad.wmnet:5432/airflow_data_engineering_dev?sslmode=require&sslrootcert=/etc/ssl/certs/wmf-ca-certificates.crt connection also updated to a postgresql db on Airflow >= 2.3.0

• kerberos settings If core.security == 'kerberos', it will be assumed that you are installing kerberos keytabs using profile::kerberos::keytabs, and that the keytab for $service_user on this host is defined.

  kerberos

  section configs will be set accordingly. You can still override these if you

  need by setting any [kerberos] section configs in $airflow_config.

• smtp settings These are set to defaults that will work in WMF production networks.

• secrets backend If $connections is provided, it will be rendered as $airflow_home/connections.yaml and a secrets LocalFilesystemBackend will be configured to read connections out of this file. See the $connections parameter for more info. See also:

  • airflow.apache.org/docs/apache-airflow/stable/security/secrets/secrets-backend/index.html

  • airflow.apache.org/docs/apache-airflow/stable/security/secrets/secrets-backend/local-filesystem-secrets-backend.html

NOTE: that airflow::instance will not create any databases or airflow users for you. To do this, see: airflow.apache.org/docs/apache-airflow/stable/howto/set-up-database.html#setting-up-a-mysql-database airflow.apache.org/docs/apache-airflow/stable/howto/set-up-database.html#setting-up-a-postgresql-database

NOTE: This define does not yet support webserver_config.py customization. The webserver_config.py that is installed will grant Admin access to anyone that can access the webserver. The default web_server_host is 127.0.0.1, so access is restricted to anyone who can ssh to the node running this airflow instance. This may be improved in the future.

Parameters

service_user

Airflow service user. airflow services and commands must be run as this user.

service_group

Airflow service group.

airflow_configs

Hash of airflow.cfg settings, keyed by section name. E.g. { 'core' => { 'dags_folder' => '…' }, … }

airflow_home

Default: /srv/airflow-$title

db_user

Only used for rendering a provided sql_alchemy_conn erb template string. Default: airflow_$title

db_password

Only used for rendering a provided sql_alchemy_conn erb template string. Default: batman

connections

Optional hash of Airflow Connections as defined in airflow.apache.org/docs/apache-airflow/stable/howto/connection.html. If given, $airflow_home/connections.yaml will be rendered with these connections, and a smart default Airflow [secrets] config for a Local Filesystem Secrets Backend will be set to read connections out of this file. This allows for using Puppet config management to manage Airflow connections, rather than having to define them in the Airflow UI. NOTE: These connections will not show up in the Airflow UI, but can be retrieved using the airflow CLI like: airflow connections get <connection_name>. They can of course be used in DAGs.

environment_extra

Hash of environment variables to set in the airflow instance's scheduler and webserver processes. Default: {}

monitoring_enabled

Enable monitoring of Airflow system services. Default: false

statsd_monitoring_enabled

Send Airflow metrics to statsd_exporter and then Prometheus. Default: false

clean_logs_older_than_days

If set, a systemd timer will be created to clean files from airflow base_log_folder older than this many days. If undef, the timer will not be created. Default: 90

firewall_srange

A firewall set used to configure firewall access using the generic firewall module. Default: ANALYTICS_NETWORKS

scap_targets

scap::target resource definitions to declare. This is useful to have here at the airflow::instance level so that we can automate deployment of repositories needed for this airflow::instance. These must also be declared in scap::sources in deployment_server.yaml hiera. Default: undef

ensure

Default: present

renew_skein_certificate

If true, make sure the skein certificate is regularly regenerated

Parameters:

• service_user (String)
• service_group (String)
• airflow_config (Hash) (defaults to: {})
• airflow_home (Stdlib::Unixpath) (defaults to: "/srv/airflow-${title}")
• db_user (String) (defaults to: "airflow_${title}")
• db_password (String) (defaults to: 'batman')
• connections (Optional[Hash]) (defaults to: undef)
• environment_extra (Hash) (defaults to: {})
• monitoring_enabled (Boolean) (defaults to: false)
• statsd_monitoring_enabled (Boolean) (defaults to: false)
• clean_logs_older_than_days (Integer) (defaults to: 90)
• firewall_srange (String) (defaults to: 'ANALYTICS_NETWORKS')
• scap_targets (Optional[Hash]) (defaults to: undef)
• ensure (Wmflib::Ensure) (defaults to: 'present')
• renew_skein_certificate (Boolean) (defaults to: true)

# File 'modules/airflow/manifests/instance.pp', line 127

define airflow::instance(
    String $service_user,
    String $service_group,
    Hash $airflow_config                = {},
    Stdlib::Unixpath $airflow_home      = "/srv/airflow-${title}",
    String $db_user                     = "airflow_${title}",
    String $db_password                 = 'batman',
    Optional[Hash] $connections         = undef,
    Hash $environment_extra             = {},
    Boolean $monitoring_enabled         = false,
    Boolean $statsd_monitoring_enabled  = false,
    Integer $clean_logs_older_than_days = 90,
    String $firewall_srange             = 'ANALYTICS_NETWORKS',
    Optional[Hash] $scap_targets        = undef,
    Wmflib::Ensure $ensure              = 'present',
    Boolean $renew_skein_certificate    = true
) {
    # Require that something include the airflow base class
    # before using airflow::instance.
    Class['airflow'] -> Airflow::Instance[$title]

    $airflow_prefix = $::airflow::airflow_prefix

    # Declare any scap::targets for this instance.
    if $scap_targets != undef {
        create_resources('scap::target', $scap_targets)
    }

    # First, construct smart default values and merge them together
    # to build $_airflow_config.  The $_airflow_config Hash will be usd
    # to render airflow.cfg.

    # Base airflow defaults.
    $airflow_config_defaults = {
        'core' => {
            'dags_folder' => "${airflow_home}/dags",
            'executor' => 'SequentialExecutor',
            'load_examples' => 'False',
        },
        'logging' => {
            'base_log_folder' => "${airflow_home}/logs",
        },
        'webserver' => {
            'web_server_host' => '0.0.0.0',
            'web_server_port' => 8600,
            'instance_name' => $title,
            # Since the webserver Public as Admin role, and is only accessible on 127.0.0.1 by default,
            # expose config for admins, except sensitives like passwords.
            'expose_config' => 'non-sensitive-only',
            'expose_hostname' => 'True',
            'expose_stacktrace' => 'True',
        },
        'scheduler' => {
            'parsing_processes' => $::processors['count'],
        },
        'smtp' => {
            # mail_smarthost is set globally in manifests/realm.pp
            'smtp_host' => $airflow::mail_smarthost[0],
            'smtp_starttls' => 'False',
            'smtp_ssl' => 'False',
            'smtp_port' => '25',
            'smtp_mail_from' => "Airflow: ${title} <noreply@wikimedia.org>",
        },
        'metrics' => {
            'statsd_on' => 'False',  # Turn this parameter on in hiera to enable statsd metrics.
            # statsd-exporter is running on the same machine
            'statsd_host' => 'localhost',
            'statsd_port' => '9125',
            'statsd_prefix' => 'airflow',
            # StatsD (https://github.com/etsy/statsd) integration settings.
            # If you want to avoid emitting all the available metrics, you can configure an
            # allow list of prefixes (comma separated) to send only the metrics that start
            # with the elements of the list (e.g: "scheduler,executor,dagrun")
            'metrics_allow_list' => 'operator_failures_,operator_successes_,sla_missed,executor.queued_tasks,dag.,dagrun.duration.,scheduler.scheduler_loop_duration,dag_processing.import_errors,dag_processing.total_parse_time,ti.failures,ti.successes,ti.finish,ti_failures,ti_successes',
            # If you want to utilise your own custom StatsD client set the relevant
            # module path below.
            # Note: The module path must exist on your PYTHONPATH for Airflow to pick it up
            'statsd_custom_client_path' => 'wmf_airflow_common.metrics.custom_statsd_client.CustomStatsClient'
        }
    }

    # Value to be used for sql_alchemy_conn if is not set in provided $airflow_config.
    $sql_alchemy_conn_default = "sqlite:///${airflow_home}/airflow.db"

    # This logic to be smart about core.sql_alchemy_conn can be removed
    # Once all airflow instances are upgraded.
    if $::airflow::version != undef and versioncmp($::airflow::version, '2.3.0') >= 0 {
        # If airflow version >= 2.3.0 use these new config defaults.
        $airflow_config_versioned = {
            'database' => {
                'load_default_connections' => 'False',
            },
            'api' => {
                # Since the webserver is only exposed on 127.0.0.1 by default,
                # allow access to the API.
                'auth_backends' => 'airflow.api.auth.backend.default',
            },
        }

        # If $airflow_config specifies sql_alchemy_conn, we want to possibly render
        # it as an ERB template to apply $db_user and $db_password.
        $sql_alchemy_conn = 'sql_alchemy_conn' in $airflow_config['database'] ? {
            true => inline_template($airflow_config['database']['sql_alchemy_conn']),
            false => $sql_alchemy_conn_default,
        }
        $airflow_config_sql_alchemy_conn = {
            # sql_alchemy_conn is in database section in airflow >= 2.3.0
            'database' => {
                'sql_alchemy_conn' => $sql_alchemy_conn
            }
        }
    } else {
        # Else use the airflow < 2.3.0 config defaults.
        $airflow_config_versioned = {
            'core' => {
                'load_default_connections' => 'False',
            },
            'api' => {
                # Since the webserver is only exposed on 127.0.0.1 by default,
                # allow access to the API.
                'auth_backend' => 'airflow.api.auth.backend.default',
            },
        }

        # If $airflow_config specifies sql_alchemy_conn, we want to possibly render
        # it as an ERB template to apply $db_user and $db_password.
        $sql_alchemy_conn = 'sql_alchemy_conn' in $airflow_config['core'] ? {
            true => inline_template($airflow_config['core']['sql_alchemy_conn']),
            false => $sql_alchemy_conn_default,
        }
        $airflow_config_sql_alchemy_conn = {
            # sql_alchemy_conn is in core section in airflow < 2.3.0
            'core' => {
                'sql_alchemy_conn' => $sql_alchemy_conn
            }
        }
    }

    # Default kerberos security settings if airflow security is set to kerberos.
    # Values from $airflow_config will take precedence over these.
    # These configs expect that a keytab for $service_user for this host has been
    # deployed via profile::kerberos::keytabs.
    if $airflow_config['core'] and $airflow_config['core']['security'] == 'kerberos' {
        $airflow_config_kerberos = {
            'kerberos' => {
                'ccache'           => "${airflow_home}/airflow_${service_user}_krb5_ccache",
                # gets augmented with fqdn
                'principal'        => "${service_user}/${::fqdn}@WIKIMEDIA",
                'reinit_frequency' => 3600,
                'kinit_path'       => 'kinit',
                'keytab'           => "/etc/security/keytabs/${service_user}/${service_user}.keytab",
            }
        }
    } else {
        $airflow_config_kerberos = {}
    }


    # If we are given $connections, we should render them into a connections.yaml file
    # that will be used by the Airflow LocalFilesystemBackend.  This allows us to manage
    # Airflow connections using Puppet, rather than in the Web UI and stored in the Airflow
    # database.
    $connections_file = "${airflow_home}/connections.yaml"
    if $connections {
        $airflow_config_secrets = {
            'secrets' => {
                'backend' => 'airflow.secrets.local_filesystem.LocalFilesystemBackend',
                'backend_kwargs' => "{\"connections_file_path\": \"${connections_file}\"}",
            }
        }
    } else {
        $airflow_config_secrets = {}
    }

    # Merge all the airflow configs we've got.  This is:
    # defaults <- kerberos <- secrets config <- provided config <- airflow_config_new_syntax config with password
    $_airflow_config = deep_merge(
        $airflow_config_defaults,
        $airflow_config_kerberos,
        $airflow_config_secrets,
        $airflow_config_versioned,
        $airflow_config,
        # Usually, we'd put $airflow_config last,
        # so it would take precedence over all default configs.
        # sql_alchemy_conn is a special case, because we've already
        # considered the $airflow_config provided setting in the above code.
        # We've rendered the provided sql_alchemy_conn value as a template
        # into $airflow_config_sql_alchemy_conn.
        $airflow_config_sql_alchemy_conn,
    )

    # Copied into local variables here for easy reference.
    $dags_folder = $_airflow_config['core']['dags_folder']
    $logs_folder = $_airflow_config['logging']['base_log_folder']
    $airflow_config_file = "${airflow_home}/airflow.cfg"
    $webserver_config_file = "${airflow_home}/webserver_config.py"
    $webserver_port = $_airflow_config['webserver']['web_server_port']
    $profile_file = "${airflow_home}/bin/airflow-${title}-profile.sh"
    $airflow_cli_file = "${airflow_home}/bin/airflow-${title}"


    # Default file resource params for this airflow instance.
    File {
        owner => $service_user,
        group => $service_group,
    }

    $ensure_directory = $ensure ? {
        absent  => $ensure,
        default => 'directory',
    }
    $ensure_link = $ensure ? {
        absent => $ensure,
        default => 'link',
    }

    file { [$airflow_home, "${airflow_home}/bin"]:
        ensure => $ensure_directory,
        force  => true,
        mode   => '0755',
    }
    file { $airflow_config_file:
        ensure  => $ensure,
        mode    => '0440', # Likely has $db_password in it.
        content => template('airflow/airflow.cfg.erb'),
        require => File[$airflow_home],
    }

    file { $profile_file:
        ensure  => $ensure,
        mode    => '0444',
        content => template('airflow/profile.sh.erb')
    }

    # airflow CLI wrapper for this instance.
    # Aides running airflow commands without having to think about how
    # to properly set things like AIRFLOW_HOME.
    file { $airflow_cli_file:
        ensure  => $ensure,
        mode    => '0555',
        content => template('airflow/airflow.sh.erb'),
        require => File[$profile_file],
    }
    # Link the airflow command wrapper in /usr/local/bin
    # so it is on regular users PATH.
    file { "/usr/local/bin/airflow-${title}":
        ensure  => $ensure_link,
        target  => "${airflow_home}/bin/airflow-${title}",
        require => File[$airflow_cli_file],
    }

    # No per instance webserver configuration yet.
    # For now, any access to webserver UI port grants Admin access.
    file { $webserver_config_file:
        ensure => $ensure,
        mode   => '0444',
        source => 'puppet:///modules/airflow/webserver_config.py'
    }

    if $dags_folder == "${airflow_home}/dags" {
        # Create $dags_folder if in $airflow_home
        file { $dags_folder:
            ensure => $ensure_directory,
            force  => true,
            mode   => '0755',
        }
    } else {
        # Else create $airflow_home/dags as a symlink
        file { "${airflow_home}/dags":
            ensure => $ensure_link,
            target => $dags_folder,
        }
    }

    # If $connections have been defined, render the connections.yaml file.
    if $connections and $ensure == 'present' {
        $connections_file_ensure = 'present'
    } else {
        $connections_file_ensure = 'absent'
    }
    file { $connections_file:
        ensure  => $connections_file_ensure,
        mode    => '0440', # Could have secrets in it.
        content => template('airflow/connections.yaml.erb')
    }

    # DRY variable for dependencies for airflow webserver and scheduler services.
    $service_dependencies = [
        File[$airflow_config_file],
        File[$webserver_config_file],
        File[$connections_file],
        File[$profile_file],
    ]

    # Control service for all services for this airflow instance.
    systemd::service { "airflow@${title}":
        ensure               => $ensure,
        content              => systemd_template('airflow@'),
        restart              => true,
        monitoring_enabled   => $monitoring_enabled,
        monitoring_notes_url => 'https://wikitech.wikimedia.org/wiki/Analytics/Systems/Airflow',
        require              => $service_dependencies,
    }

    # Airflow webserver for this instance.
    systemd::service { "airflow-webserver@${title}":
        ensure               => $ensure,
        content              => systemd_template('airflow-webserver@'),
        restart              => true,
        monitoring_enabled   => $monitoring_enabled,
        monitoring_notes_url => 'https://wikitech.wikimedia.org/wiki/Analytics/Systems/Airflow',
        require              => $service_dependencies,
        service_params       => {
            'subscribe' => $service_dependencies,
        }
    }
    profile::auto_restarts::service { "airflow-webserver@${title}":
        ensure => $ensure,
    }


    # Airflow scheduler for this instance.
    systemd::service { "airflow-scheduler@${title}":
        ensure               => $ensure,
        content              => systemd_template('airflow-scheduler@'),
        restart              => true,
        monitoring_enabled   => $monitoring_enabled,
        monitoring_notes_url => 'https://wikitech.wikimedia.org/wiki/Analytics/Systems/Airflow',
        require              => $service_dependencies,
        service_params       => {
            'subscribe' => $service_dependencies,
        },
    }
    profile::auto_restarts::service { "airflow-scheduler@${title}":
        ensure => $ensure,
    }


    # Only run airflow kerberos ticket renewer service if kerberos security is configured and
    # $ensure == 'present'
    if $_airflow_config['core']['security'] == 'kerberos' and $ensure == 'present' {
        $kerberos_ensure = 'present'
    } else {
        $kerberos_ensure = 'absent'
    }
    # Airflow kerberos for this instance.
    systemd::service { "airflow-kerberos@${title}":
        ensure               => $kerberos_ensure,
        content              => systemd_template('airflow-kerberos@'),
        restart              => true,
        monitoring_enabled   => $monitoring_enabled,
        monitoring_notes_url => 'https://wikitech.wikimedia.org/wiki/Analytics/Systems/Airflow',
        require              => File[$airflow_config_file],
        service_params       => {
            'subscribe' => File[$airflow_config_file],
        },
    }
    profile::auto_restarts::service { "airflow-kerberos@${title}":
        ensure => $kerberos_ensure,
    }


    # Set up monitoring services if $monitoring_enabled and $ensure == present
    if $monitoring_enabled and $ensure == 'present' {
        $monitoring_ensure = 'present'
    } else {
        $monitoring_ensure = 'absent'
    }
    $airflow_cmd = "/usr/bin/env PYTHONPATH=/srv/deployment/airflow-dags/${title} AIRFLOW_HOME=${airflow_home} ${airflow_prefix}/bin/airflow"
    # See: https://airflow.apache.org/docs/apache-airflow/stable/logging-monitoring/check-health.html

    $check_scheduler_command = "/usr/local/bin/check_cmd ${airflow_cmd} jobs check --job-type SchedulerJob --hostname ${::fqdn}"
    $check_db_command = "/usr/local/bin/check_cmd ${airflow_cmd} db check"

    sudo::user { "airflow_checks_${title}":
        ensure => absent,
    }

    nrpe::monitor_service { "airflow@${title}_check_scheduler":
        ensure       => $monitoring_ensure,
        nrpe_command => $check_scheduler_command,
        sudo_user    => $service_user,
        description  => "Checks that the local airflow scheduler for airflow @${title} is working properly",
        # contact_group => 'victorops-analytics', TODO
        notes_url    => 'https://wikitech.wikimedia.org/wiki/Analytics/Systems/Airflow',
        require      => Systemd::Service["airflow-scheduler@${title}"],
    }
    nrpe::monitor_service { "airflow@${title}_check_db":
        ensure       => $monitoring_ensure,
        nrpe_command => $check_db_command,
        sudo_user    => $service_user,
        description  => "Checks that the airflow database for airflow ${title} is working properly",
        # contact_group => 'victorops-analytics', TODO
        notes_url    => 'https://wikitech.wikimedia.org/wiki/Analytics/Systems/Airflow',
        require      => File[$airflow_config_file],
    }

    # Set up clean logs job if $clean_logs_older_than_days is set and $ensure == present
    if $clean_logs_older_than_days and $ensure == 'present' {
        $clean_logs_ensure = 'present'
    } else {
        $clean_logs_ensure = 'absent'
    }
    systemd::timer::job { "airflow_${title}_clean_logs":
        ensure      => $clean_logs_ensure,
        user        => 'root',
        description => "Delete airflow@${title} logs older than 90 days",
        command     => "/usr/local/bin/clean_logs ${logs_folder} ${clean_logs_older_than_days}",
        interval    => {
            'start'    => 'OnCalendar',
            'interval' => '*-*-* 03:00:00',  # Every day at 3:00
        },
    }

    firewall::service { "airflow-webserver@${title}":
        proto    => 'tcp',
        port     => $webserver_port,
        src_sets => [$firewall_srange],
    }

    $skein_cert_path = "${airflow_home}/.skein/skein.crt"
    prometheus::node_textfile { 'prometheus-check-certificate-expiry':
        ensure         => 'present',
        filesource     => 'puppet:///modules/prometheus/check_certificate_expiry.py',
        interval       => 'daily',
        run_cmd        => "/usr/local/bin/prometheus-check-certificate-expiry --cert-path ${skein_cert_path} --outfile /var/lib/prometheus/node.d/x509-skein.prom",
        extra_packages => ['python3-cryptography', 'python3-prometheus-client'],
    }

    if $renew_skein_certificate {
        systemd::timer::job { 'regenerate-skein-certificate':
            ensure      => 'present',
            description => 'refresh the x509 self-signed Skein certificate',
            user        => $service_user,
            environment => {'HOME' => $airflow_home},
            command     => '/lib/airflow/bin/skein config gencerts --force',
            interval    => [
                {
                    'start'    => 'OnCalendar',
                    # at 10AM UTC on each Tuesday. See https://phabricator.wikimedia.org/T350945 for rationale
                    'interval' => 'Tue 10:00',
                }
            ]
        }
    }

}