role_config

The role_config role provides the foundational configuration for the pgEdge Ansible Collection. It defines shared variables and computed values that all other roles use for consistent behavior across the collection.

Do not call this role directly in your playbooks. Other roles include role_config as a dependency to ensure variable coordination throughout the deployment process.

This role performs the following tasks:

• Define default values for all configurable parameters.
• Compute derived variables based on user configuration.
• Validate configuration settings for correctness.
• Provide OS-specific path mappings for cross-platform support.
• Filter and organize inventory hosts by zone.

Role Dependencies

This role has no dependencies and serves as the base for all other roles.

When to Use

Other roles automatically include role_config as a dependency. You never need to explicitly call the role in your playbooks.

Configuration

This role reads configuration from the inventory file and provides computed values to other roles. Set the parameters in the inventory file as shown in the following example:

pgedge:
  vars:
    cluster_name: production
    pg_version: 17
    is_ha_cluster: true
    db_names:
      - app_db
      - reporting_db
    db_password: "{{ vault_db_password }}"
    backup_repo_type: s3
    backup_repo_params:
      region: us-west-2
      bucket: my-backups

See the Configuration Reference for a complete list of available parameters.

How It Works

This role processes configuration and provides computed values to other roles.

Variable Validation

This role validates several configuration values to ensure correctness. The exception_behaviour parameter must be one of the following values:

• discard discards the failing transaction and continues.
• transdiscard discards the entire transaction on any error.
• sub_disable disables the subscription on conflict.

The backup_repo_type parameter must be one of the following values:

• ssh uses SSH-based backup repository access.
• s3 uses S3-compatible object storage for backups.

Computed Variables

This role computes several variables for use in other roles. Node filtering variables include the following computed values:

• nodes_in_zone contains hosts in the pgedge group of the current zone.
• proxies_in_zone contains hosts in the haproxy group of the current zone.
• backups_in_zone contains hosts in the backup group of the current zone.
• first_node_in_zone contains the first pgedge node in the current zone.

OS-specific shortcut variables include the following computed values:

• pg_service_name contains the OS-specific Postgres service name.
• pg_config_dir contains the OS-specific configuration directory path.

The default_patroni_dcs_params variable contains the etcd connection settings that setup_patroni applies when the inventory does not supply its own patroni_dcs.parameters value.

Postgres Feature Checks

The pg_version parameter pins a Postgres major version, but some configuration parameters exist only in certain releases, and Postgres refuses to start when its configuration names a parameter it does not recognize. The role provides a pg_feature_checks task file that asks the installed Postgres binary which parameters it recognizes and records the answers as facts:

• pg_supports_output_plugin_libraries reports whether the installed release recognizes output_plugin_libraries.

Asking the binary rather than comparing release numbers keeps the checks correct when a fix reaches an unexpected release, as happens with backports to older branches and with pgEdge's own patched builds.

Unlike the rest of this role, that task file does not run automatically as a dependency, because it requires Postgres to be installed. Roles that need the values include it explicitly:

- name: Determine which configuration parameters Postgres recognizes
  include_role:
    name: role_config
    tasks_from: pg_feature_checks

The setup_postgres and setup_patroni roles both include it. The task file skips each check that already holds a value, so repeated inclusion costs nothing and an inventory may set a check directly when the binary is unreachable.

Platform-Specific Values

The pg_service_name variable contains the appropriate service name for the operating system. The following table shows the values by OS family:

The pg_config_dir variable contains the configuration file directory. The following table shows the values by OS family:

Usage Examples

While you do not invoke this role directly, you can override its defaults in your inventory file.

Basic Configuration

In the following example, the inventory file sets basic cluster parameters:

pgedge:
  vars:
    cluster_name: production
    pg_version: 17
    db_names:
      - myapp

High Availability Configuration

In the following example, the inventory file enables high availability mode:

pgedge:
  vars:
    cluster_name: production
    pg_version: 17
    is_ha_cluster: true
    synchronous_mode: true

Backup Configuration

In the following example, the inventory file configures S3 backups:

pgedge:
  vars:
    backup_repo_type: s3
    backup_repo_params:
      region: us-west-2
      bucket: my-backups
      endpoint: s3.amazonaws.com