This page defines hier_config-specific terminology used throughout the documentation and source code.
The string that precedes a positive (enabling) command in platforms that use explicit declarations, such as JunOS (set) and VyOS (set). The driver's declaration_prefix property returns this string; HConfigDriverBase defaults to an empty string (Cisco-style platforms have no explicit declaration keyword).
Example: In JunOS, set interfaces ge-0/0/0 description uplink — the declaration prefix is "set ".
A Python class that encodes all operating-system-specific behaviour for one network platform. Every driver subclasses HConfigDriverBase and provides an HConfigDriverRules instance via _instantiate_rules(). Drivers are selected by passing a Platform enum value to get_hconfig() or get_hconfig_driver().
Example: HConfigDriverCiscoIOS, HConfigDriverJuniperJUNOS.
A configuration command where only the last value applied takes effect — applying the same command twice with different values results in only the second value being active. Typical examples: hostname, ip address, description.
hier_config uses IdempotentCommandsRule to identify these commands. During config_to_get_to(), when both the running and intended configs contain a command that matches an idempotency rule, the running value is not negated before the new value is applied (the new value simply overwrites it).
Example rule:
IdempotentCommandsRule(
match_rules=(
MatchRule(startswith="interface "),
MatchRule(startswith="description "),
)
)A set of IdempotentCommandsAvoidRule entries that prevent specific commands from being treated as idempotent even if they would otherwise match an IdempotentCommandsRule. Useful for commands like secondary IP addresses, where applying the same startswith prefix would incorrectly deduplicate distinct entries.
Example: Avoiding idempotency for ip address ... secondary on Cisco NX-OS.
A pair of IndentAdjustRule entries (start_expression / end_expression) that temporarily shift the indentation level between the two markers. Used on Cisco IOS XR for inline templates whose body is indented differently from the surrounding context.
A MatchRule Pydantic model that acts as a predicate on an HConfigChild.text value. All fields (equals, startswith, endswith, contains, re_search) are optional; when multiple are set every criterion must match. Match rules are composed into tuples to describe a full lineage path.
Example: Match any neighbor X.X.X.X description line under a BGP section:
MatchRule(startswith="router bgp"),
MatchRule(re_search=r"neighbor \S+ description"),The string prepended to a command to negate (remove) it. HConfigDriverBase.negation_prefix defaults to "no " for Cisco-style platforms. Platforms that use a different convention override this property.
| Platform | Negation prefix |
|---|---|
| Cisco IOS / EOS / NX-OS | "no " |
| HP Comware5 / H3C | "undo " |
| JunOS / VyOS / Nokia SRL | "delete " |
A NegationDefaultWhenRule that causes hier_config to use the default <command> form of negation instead of no <command>. Some IOS and EOS commands behave differently when defaulted vs negated (e.g. logging event link-status).
A NegationDefaultWithRule that replaces the standard negation with a fixed command string. Used when a command cannot be simply prepended with "no " — for example, logging console debugging is the correct way to reset the console logging level rather than no logging console.
A ParentAllowsDuplicateChildRule that permits multiple HConfigChild objects with the same text value under a single parent. Required for constructs such as address-family blocks inside router bgp on some platforms, or endif tokens in IOS XR route-policies.
Regex substitution rules applied to configuration text at load time before it is parsed into the tree:
PerLineSubRule— applies the substitution to each line individually (useful for removing inline comments,!, timestamp headers).FullTextSubRule— applies the substitution across the entire text block (useful for multi-line patterns).
Example: Strip Building configuration... banners:
PerLineSubRule(search="^Building configuration.*", replace="")A SectionalExitingRule that instructs hier_config to emit a closing token at the end of a configuration section when rendering output. Different platforms require different exit syntax.
| Platform / section | Exit token |
|---|---|
| Cisco IOS BGP peer-policy | exit-peer-policy |
| Cisco IOS XR route-policy | end-policy |
| Cisco IOS XR prefix-set | end-set |
| Most sections (default) | exit |
A SectionalOverwriteRule that tells config_to_get_to() to negate the entire section and then re-create it from the intended config rather than performing a line-by-line diff. Appropriate for configuration blocks where the order of entries matters globally or where partial changes are not supported by the OS.
A SectionalOverwriteNoNegateRule similar to sectional overwrite, but the existing section is deleted without negation before the new version is written. Used for blocks like prefix-set and route-policy on Cisco IOS XR where issuing a no is not the correct removal mechanism.
TagRule entries that apply a named tag (apply_tags) to all HConfigChild nodes whose lineage matches match_rules. Tags are used by WorkflowRemediation.apply_remediation_tag_rules() to annotate the remediation config for selective filtering via remediation_config_filtered_text().
Example use case: Tag all interface changes as "interfaces" and all BGP changes as "bgp" so that changes can be deployed separately.
The primary user-facing class for computing the delta between a running and an intended configuration. Exposes:
remediation_config— the commands to apply to bring the device into compliance.rollback_config— the commands to revert the device back to its original state.apply_remediation_tag_rules()— annotate remediation lines with tags.remediation_config_filtered_text()— render tagged subset of the remediation.