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feat: add Loki log query support to lab-monitoring

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Add 3 opt-in Loki tools (query_logs, list_labels, list_label_values)
that are registered when LOKI_URL is configured. Includes Loki HTTP
client, CLI commands (logs, labels), NixOS module option, formatting,
and tests.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
This commit is contained in:
Torjus Håkestad
2026-02-05 20:55:39 +01:00
parent f4f859fefa
commit 859e35ab5c
13 changed files with 1014 additions and 20 deletions
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155
internal/monitoring/handlers_test.go
View File

@@ -14,7 +14,7 @@ import (
)
// setupTestServer creates a test MCP server with monitoring handlers backed by test HTTP servers.
func setupTestServer(t *testing.T, promHandler, amHandler http.HandlerFunc) (*mcp.Server, func()) {
func setupTestServer(t *testing.T, promHandler, amHandler http.HandlerFunc, lokiHandler ...http.HandlerFunc) (*mcp.Server, func()) {
t.Helper()
promSrv := httptest.NewServer(promHandler)
@@ -26,11 +26,22 @@ func setupTestServer(t *testing.T, promHandler, amHandler http.HandlerFunc) (*mc
prom := NewPrometheusClient(promSrv.URL)
am := NewAlertmanagerClient(amSrv.URL)
RegisterHandlers(server, prom, am, HandlerOptions{EnableSilences: true})
var loki *LokiClient
var lokiSrv *httptest.Server
if len(lokiHandler) > 0 && lokiHandler[0] != nil {
lokiSrv = httptest.NewServer(lokiHandler[0])
loki = NewLokiClient(lokiSrv.URL)
}
RegisterHandlers(server, prom, am, loki, HandlerOptions{EnableSilences: true})
cleanup := func() {
promSrv.Close()
amSrv.Close()
if lokiSrv != nil {
lokiSrv.Close()
}
}
return server, cleanup
@@ -305,8 +316,9 @@ func TestHandler_ToolCount(t *testing.T) {
defer cleanup()
tools := listTools(t, server)
// Without Loki: 7 base + 1 silence = 8
if len(tools) != 8 {
t.Errorf("expected 8 tools with silences enabled, got %d", len(tools))
t.Errorf("expected 8 tools with silences enabled (no Loki), got %d", len(tools))
for _, tool := range tools {
t.Logf(" tool: %s", tool.Name)
}
@@ -325,6 +337,37 @@ func TestHandler_ToolCount(t *testing.T) {
}
}
func TestHandler_ToolCountWithLoki(t *testing.T) {
server, cleanup := setupTestServer(t,
func(w http.ResponseWriter, r *http.Request) {},
func(w http.ResponseWriter, r *http.Request) {},
func(w http.ResponseWriter, r *http.Request) {},
)
defer cleanup()
tools := listTools(t, server)
// With Loki: 7 base + 1 silence + 3 loki = 11
if len(tools) != 11 {
t.Errorf("expected 11 tools with silences and Loki enabled, got %d", len(tools))
for _, tool := range tools {
t.Logf(" tool: %s", tool.Name)
}
}
// Verify Loki tools are present
lokiTools := map[string]bool{"query_logs": false, "list_labels": false, "list_label_values": false}
for _, tool := range tools {
if _, ok := lokiTools[tool.Name]; ok {
lokiTools[tool.Name] = true
}
}
for name, found := range lokiTools {
if !found {
t.Errorf("expected %s tool when Loki enabled", name)
}
}
}
func TestHandler_ToolCountWithoutSilences(t *testing.T) {
promSrv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {}))
amSrv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {}))
@@ -337,7 +380,7 @@ func TestHandler_ToolCountWithoutSilences(t *testing.T) {
prom := NewPrometheusClient(promSrv.URL)
am := NewAlertmanagerClient(amSrv.URL)
RegisterHandlers(server, prom, am, HandlerOptions{EnableSilences: false})
RegisterHandlers(server, prom, am, nil, HandlerOptions{EnableSilences: false})
tools := listTools(t, server)
if len(tools) != 7 {
@@ -384,6 +427,110 @@ func listTools(t *testing.T, server *mcp.Server) []mcp.Tool {
return listResult.Tools
}
func TestHandler_QueryLogs(t *testing.T) {
server, cleanup := setupTestServer(t,
nil,
nil,
func(w http.ResponseWriter, r *http.Request) {
if r.URL.Path != "/loki/api/v1/query_range" {
http.NotFound(w, r)
return
}
w.Header().Set("Content-Type", "application/json")
_, _ = w.Write([]byte(`{
"status": "success",
"data": {
"resultType": "streams",
"result": [
{
"stream": {"job": "varlogs", "filename": "/var/log/syslog"},
"values": [
["1704067200000000000", "Jan 1 00:00:00 host kernel: test message"]
]
}
]
}
}`))
},
)
defer cleanup()
result := callTool(t, server, "query_logs", map[string]interface{}{
"logql": `{job="varlogs"}`,
})
if result.IsError {
t.Fatalf("unexpected error: %s", result.Content[0].Text)
}
if !strings.Contains(result.Content[0].Text, "varlogs") {
t.Errorf("expected output to contain 'varlogs', got: %s", result.Content[0].Text)
}
if !strings.Contains(result.Content[0].Text, "test message") {
t.Errorf("expected output to contain 'test message', got: %s", result.Content[0].Text)
}
}
func TestHandler_ListLabels(t *testing.T) {
server, cleanup := setupTestServer(t,
nil,
nil,
func(w http.ResponseWriter, r *http.Request) {
if r.URL.Path != "/loki/api/v1/labels" {
http.NotFound(w, r)
return
}
w.Header().Set("Content-Type", "application/json")
_, _ = w.Write([]byte(`{
"status": "success",
"data": ["job", "instance", "filename"]
}`))
},
)
defer cleanup()
result := callTool(t, server, "list_labels", map[string]interface{}{})
if result.IsError {
t.Fatalf("unexpected error: %s", result.Content[0].Text)
}
if !strings.Contains(result.Content[0].Text, "3 label") {
t.Errorf("expected output to contain '3 label', got: %s", result.Content[0].Text)
}
if !strings.Contains(result.Content[0].Text, "job") {
t.Errorf("expected output to contain 'job', got: %s", result.Content[0].Text)
}
}
func TestHandler_ListLabelValues(t *testing.T) {
server, cleanup := setupTestServer(t,
nil,
nil,
func(w http.ResponseWriter, r *http.Request) {
if r.URL.Path != "/loki/api/v1/label/job/values" {
http.NotFound(w, r)
return
}
w.Header().Set("Content-Type", "application/json")
_, _ = w.Write([]byte(`{
"status": "success",
"data": ["varlogs", "nginx", "systemd"]
}`))
},
)
defer cleanup()
result := callTool(t, server, "list_label_values", map[string]interface{}{
"label": "job",
})
if result.IsError {
t.Fatalf("unexpected error: %s", result.Content[0].Text)
}
if !strings.Contains(result.Content[0].Text, "3 value") {
t.Errorf("expected output to contain '3 value', got: %s", result.Content[0].Text)
}
if !strings.Contains(result.Content[0].Text, "nginx") {
t.Errorf("expected output to contain 'nginx', got: %s", result.Content[0].Text)
}
}
// callTool is a test helper that calls a tool through the MCP server.
func callTool(t *testing.T, server *mcp.Server, name string, args map[string]interface{}) mcp.CallToolResult {
t.Helper()