Fix OID macro expansion for Zabbix 7.0+ templates in snmp_zabbix plugin

[Copilot]

snmp_zabbix plugin fails with "Invalid object identifier" when loading Zabbix 7.0+ templates. Macros like {#SNMPINDEX} in OIDs remain unexpanded, causing gosnmp to reject non-numeric OID components.

Root Cause

template.ExpandMacros assumed macro keys in context were bare names (SNMPINDEX), but they're stored with braces ({#SNMPINDEX}). The function searched for {#{#SNMPINDEX}} instead of {#SNMPINDEX}.

// Before: double-wraps the macro
result = strings.ReplaceAll(result, fmt.Sprintf("{#%s}", macro), value)
// With macro = "{#SNMPINDEX}", searches for "{#{#SNMPINDEX}}"

// After: normalize first
if strings.HasPrefix(macro, "{#") && strings.HasSuffix(macro, "}") {
    normalizedMacro = strings.TrimPrefix(macro, "{#")
    normalizedMacro = strings.TrimSuffix(normalizedMacro, "}")
}
result = strings.ReplaceAll(result, fmt.Sprintf("{#%s}", normalizedMacro), value)

Changes

• template.go: Normalize macro keys by stripping {# prefix and } suffix before constructing search pattern
• template_test.go: Add unit tests covering braced/unbraced keys, multiple macros, and edge cases

Original prompt

---

This section details on the original issue you should resolve

<issue_title>Categraf v0.4.29 版本的 snmp_zabbix 插件加载 7.0+ 模版报错不可用</issue_title>
<issue_description>
测试：/opt/categraf/categraf --test --debug --inputs snmp_zabbix
模版：https://git.zabbix.com/projects/ZBX/repos/zabbix/browse/templates/net/huawei_snmp/template_net_huawei_snmp.yaml

报错日志：

SEND Error on the first Request Error: marshal: marshalPDU: unable to marshal varbind list: unable to marshal OID: Invalid object identifier
2025/11/27 11:25:19 collector.go:153: D! bulk request failed for agent udp://172.18.48.2:161 (size: 2): marshal: marshalPDU: unable to marshal varbind list: unable to marshal OID: Invalid object identifier. Falling back to individual collection.
SEND INIT
SEND Error on the first Request Error: marshal: marshalPDU: unable to marshal varbind list: unable to marshal OID: Invalid object identifier
SEND INIT
SEND Error on the first Request Error: marshal: marshalPDU: unable to marshal varbind list: unable to marshal OID: Invalid object identifier
2025/11/27 11:25:19 collector.go:78: D! collected agent: udp://172.18.48.2:161, key: sensor.fan.status[hwEntityFanState.1.7], error: marshal: marshalPDU: unable to marshal varbind list: unable to marshal OID: Invalid object identifier
2025/11/27 11:25:19 collector.go:78: D! collected agent: udp://172.18.48.2:161, key: sensor.fan.status[hwEntityFanState.0.7], error: marshal: marshalPDU: unable to marshal varbind list: unable to marshal OID: Invalid object identifier
SEND INIT
SEND Error on the first Request Error: marshal: marshalPDU: unable to marshal varbind list: unable to marshal OID: Invalid object identifier
2025/11/27 11:25:19 collector.go:153: D! bulk request failed for agent udp://172.18.48.2:161 (size: 2): marshal: marshalPDU: unable to marshal varbind list: unable to marshal OID: Invalid object identifier. Falling back to individual collection.
SEND INIT
SEND Error on the first Request Error: marshal: marshalPDU: unable to marshal varbind list: unable to marshal OID: Invalid object identifier
SEND INIT
SEND Error on the first Request Error: marshal: marshalPDU: unable to marshal varbind list: unable to marshal OID: Invalid object identifier
2025/11/27 11:25:19 collector.go:78: D! collected agent: udp://172.18.48.2:161, key: sensor.temp.value[hwEntityTemperature.68157449], error: marshal: marshalPDU: unable to marshal varbind list: unable to marshal OID: Invalid object identifier
2025/11/27 11:25:19 collector.go:78: D! collected agent: udp://172.18.48.2:161, key: sensor.temp.value[hwEntityTemperature.67108873], error: marshal: marshalPDU: unable to marshal varbind list: unable to marshal OID: Invalid object identifier
SEND INIT
SEND Error on the first Request Error: marshal: marshalPDU: unable to marshal varbind list: unable to marshal OID: Invalid object identifier
2025/11/27 11:25:19 collector.go:153: D! bulk request failed for agent udp://172.18.48.2:161 (size: 6): marshal: marshalPDU: unable to marshal varbind list: unable to marshal OID: Invalid object identifier. Falling back to individual collection.
SEND INIT
SEND Error on the first Request Error: marshal: marshalPDU: unable to marshal varbind list: unable to marshal OID: Invalid object identifier
SEND INIT
SEND Error on the first Request Error: marshal: marshalPDU: unable to marshal varbind list: unable to marshal OID: Invalid object identifier
SEND INIT
SEND Error on the first Request Error: marshal: marshalPDU: unable to marshal varbind list: unable to marshal OID: Invalid object identifier
SEND INIT
SEND Error on the first Request Error: marshal: marshalPDU: unable to marshal varbind list: unable to marshal OID: Invalid object identifier
SEND INIT
SEND Error on the first Request Error: marshal: marshalPDU: unable to marshal varbind list: unable to marshal OID: Invalid object identifier
SEND INIT
SEND Error on the first Request Error: marshal: marshalPDU: unable to marshal varbind list: unable to marshal OID: Invalid object identifier
SEND INIT
SEND Error on the first Request Error: marshal: marshalPDU: unable to marshal varbind list: unable to marshal OID: Invalid object identifier
2025/11/27 11:25:19 collector.go:153: D! bulk request failed for agent udp://172.18.48.2:161 (size: 4): marshal: marshalPDU: unable to marshal varbind list: unable to marshal OID: Invalid object identifier. Falling back to individual collection.
SEND INIT
SEND Error on the first Request Error: marshal: marshalPDU: unable to marshal varbind list: unable to marshal OID: Invalid object identifier
SEND INIT
SEND Error on the first Request Error: marshal: marshalPDU: unable to marshal varbind list: unable to marshal OID: Invalid object identifier
SEND INIT
SEND Error on the first Request Error: marshal: marshalPDU: unable to marshal varbind list: unable to marshal OID: Invalid object identifier
SEND INIT
SEND Error on the first Request Error: marshal: marshalPDU: unable to marshal varbind list: unable to marshal OID: Invalid object ident...

• Fixes Categraf v0.4.29 版本的 snmp_zabbix 插件加载 7.0+ 模版报错不可用 #1349

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[Copilot]

Pull request overview

This PR fixes a critical bug in the snmp_zabbix plugin where Zabbix 7.0+ templates fail to load due to unexpanded macros in OIDs. The root cause was that macro keys stored with braces (e.g., {#SNMPINDEX}) were being double-wrapped during replacement, searching for non-existent patterns like {#{#SNMPINDEX}}.

Key Changes:

• Introduced macro key normalization to strip existing {# prefix and } suffix before constructing replacement patterns
• Added comprehensive unit tests covering braced/unbraced keys, multiple macros, OIDs, and malformed edge cases

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
inputs/snmp_zabbix/template.go	Added normalization logic to handle macro keys stored with or without braces, preventing double-wrapping that caused OID expansion failures
inputs/snmp_zabbix/template_test.go	New comprehensive test suite covering the reported bug scenario with Zabbix 7.0+ templates, plus edge cases for macro expansion

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[Copilot]

The normalization can be simplified since both conditions are already checked. Instead of calling TrimPrefix and TrimSuffix separately, you can slice the string directly:

if strings.HasPrefix(normalizedMacro, "{#") && strings.HasSuffix(normalizedMacro, "}") {
    normalizedMacro = normalizedMacro[2 : len(normalizedMacro)-1]
}

This is more efficient as it performs a single allocation instead of two string operations.

Suggested change

	normalizedMacro = strings.TrimPrefix(normalizedMacro, "{#")
	normalizedMacro = strings.TrimSuffix(normalizedMacro, "}")
	normalizedMacro = normalizedMacro[2 : len(normalizedMacro)-1]

[Copilot]

Consider adding a test case for a macro key with only the suffix but missing the prefix (e.g., "SNMPINDEX}": "12345"). This would ensure the normalization logic correctly handles all malformed macro variations, not just the missing closing brace case.