config: merge environment variable overrides on top of YAML (issue #119) - #172
Merged
Merged
Conversation
wind-c
force-pushed
the
fix/issue-119-config-env-merge
branch
3 times, most recently
from
September 3, 2026 08:31
e1d1136 to
aeef815
Compare
YAML is loaded as the baseline, then COMQTT_* environment variables are applied on top so operators can override scalar values at deploy time without rewriting the config file (e.g. a dynamic Kubernetes pod IP for cluster.bind-addr with Hashicorp Raft). - Env var name: COMQTT_ + dotted yaml path, uppercased, '-' -> '_', segments joined by '_' (e.g. cluster.bind-addr -> COMQTT_CLUSTER_BIND_ADDR). - Structure-aware reflection walk over nested blocks (mqtt, cluster, log, dashboard, redis, ...); supports string, int/uint and bool fields. - Slices/maps are not overridable via env and stay at their YAML value. - YAML baseline is unchanged when no env overrides are set; an empty string explicitly clears a value. Also: - Document the naming rule in README and in code comments. - Tests: baseline load unchanged, env overriding a file value, env supplying a missing value, empty-string clearing, unset-leaves-untouched, and the issue #119 bind-addr scenario. go test ./config/... passes. Refs: #119
wind-c
force-pushed
the
fix/issue-119-config-env-merge
branch
from
September 3, 2026 08:34
aeef815 to
0363430
Compare
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
1 participant
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
Implements the configuration merging described in #119.
Problem
comqtt v2 loads configuration only from a YAML file via config.Load. In Kubernetes the pod IP is dynamic and the Raft/bind-addr must be a real address, so operators today rewrite the whole YAML (or a config template) just to override a value at deploy time.
Change
config.Load still loads and unmarshals the YAML file as the baseline, then applies environment-variable overrides on top:
Env var naming: COMQTT_ + the dotted yaml path of the field, uppercased with - replaced by _, segments joined by _. For example:
Structure-aware walk via reflection, so nested blocks (mqtt, cluster, log, dashboard, redis, ...) can be overridden field-by-field without rewriting the file.
Supports string, int/uint, and bool fields. Slices/maps (e.g. cluster.members) are not overridable via env vars and keep their YAML value.
A value is overridden only when the env var is set; an empty string explicitly clears the YAML value. The YAML baseline is unchanged when no overrides are set.
Docs
Added an "Environment variable overrides" section to the README describing the naming rule and supported types.
Tests
Added config/config_test.go cases covering: baseline load unchanged, env var overriding a file value, env var supplying a value the file omits, empty-string clearing, unset-leaves-untouched, and the issue #119 cluster.bind-addr deploy-time override scenario.
go test ./config/... passes.
Refs: #119