ermnvldmr.com/services/docs/content/en/apex/concepts/node-identity.md

title, description, weight

title	description	weight
Node identity resolution	How a node learns who it is: node.env identity keys and the FQDN fallback.	12

Every apex operation runs in the context of exactly one node. The engine derives that node identity — node name, subnet, FQDN, and public host — from the node.env file at the repository root, with the OS hostname as a fallback for the FQDN only. The framework assumes no domain and no clustering: a node declares who it is explicitly. This resolution step succeeds the root_require_node mechanism of the bash "root" commons framework that apex replaces.

Identity sources

node.env

node.env is a plain KEY=value file (shell-sourceable) located at the repository root. When parsed, comments and blank lines are ignored, and surrounding single or double quotes around values are stripped.

It declares identity explicitly through these keys:

• APEX_NODE_FQDN — the node's real FQDN, used for traefik Host() routing. If unset, the engine falls back to the OS hostname (and warns).
• APEX_NODE_HOST — the node's public host name, used for the backup --host and the observability/notify instance. Defaults to APEX_NODE_FQDN.
• APEX_SUBNET — the node's /24 for the direct network. Required; there is no other source for it (see Concept: Fleet addressing scheme).

APEX_NODE_FQDN=node1.example.com
APEX_NODE_HOST=node1.example.com
APEX_SUBNET=198.18.0.0/24

The OS hostname

The OS hostname is consulted only as a fallback for APEX_NODE_FQDN. When node.env does not set APEX_NODE_FQDN, the engine uses the hostname and emits a warning. It is never parsed for a node name or any other coordinate.

Resolution order

{{% steps %}}

Resolve the FQDN

fqdn is APEX_NODE_FQDN from node.env, or the OS hostname when that key is unset. If neither yields a value, resolution fails (see Failure modes).

Resolve the public host

host is APEX_NODE_HOST from node.env, or fqdn when that key is unset.

Derive the short name

name is the first label of host (host.split(".")[0]) — for example, node1 for node1.example.com. It is used for logs, the sync/<node> branch, and messages.

Read the subnet

subnet is always read from APEX_SUBNET in node.env. It is required.

{{% /steps %}}

The result is a Node record with four fields: name, subnet, fqdn, and host.

Warnings

Identity resolution emits exactly one warning; it signals a recoverable inconsistency that should be fixed.

Condition	Warning message
APEX_NODE_FQDN is unset in node.env (the hostname is used instead)	APEX_NODE_FQDN not set in node.env; using hostname '<fqdn>'.

Failure modes

Resolution refuses to guess. Two conditions are fatal, and both exit with code 66 — the engine's exit-code convention for missing input:

• No FQDN at all. APEX_NODE_FQDN is unset in node.env and the OS hostname is empty. The engine writes identity: APEX_NODE_FQDN missing from node.env and no hostname to stderr and exits.
• No subnet. APEX_SUBNET is absent from node.env (including when the file itself is missing). The engine writes identity: APEX_SUBNET missing from node.env to stderr and exits.

Warning

A valid node.env carrying APEX_SUBNET is required on every node. APEX_NODE_FQDN may be omitted only when the OS hostname supplies a usable FQDN.

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See also:

• GitHub: apex.ermnvldmr.com