Add configuration options and enable dynamic memory management through cc-backend callback

CLAUDE.md

@@ -0,0 +1,77 @@
+# CLAUDE.md
+
+This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.
+
+## Project Overview
+
+cc-metric-store is an in-memory time-series database for HPC cluster metrics, part of the ClusterCockpit monitoring suite. Data is indexed by a hierarchical tree (cluster → host → socket/cpu/gpu) and accessed via selectors. The core storage engine lives in `cc-backend/pkg/metricstore`; this repo provides the HTTP API wrapper.
+
+## Build Commands
+
+```bash
+make                 # Build binary, copy config template, create checkpoint dirs
+make clean           # Clean build cache and binary
+make distclean       # Also remove ./var and config.json
+make swagger         # Regenerate Swagger from source comments
+make test            # Run go build, go vet, go test
+```
+
+## Testing
+
+```bash
+go test -v ./...              # Run tests
+go test -bench=. -race -v ./...  # With benchmarks and race detector
+```
+
+Integration test scripts in `/endpoint-test-scripts/` for manual API testing.
+
+## Running
+
+```bash
+./cc-metric-store                           # Uses ./config.json
+./cc-metric-store -config /path/to/config.json
+./cc-metric-store -dev                      # Enable Swagger UI at /swagger/
+./cc-metric-store -loglevel debug           # debug|info|warn|err|crit
+```
+
+## Architecture
+
+**Entry point:** `cmd/cc-metric-store/main.go`
+- `run()` → parse flags, init logging/config, connect NATS
+- `runServer()` → init metricstore from cc-backend, start HTTP server
+
+**Key packages:**
+- `internal/api/` - REST endpoints (query, write, free, debug, healthcheck) and JWT auth (Ed25519)
+- `internal/config/` - Config loading and JSON schema validation
+- External: `cc-backend/pkg/metricstore` - actual time-series storage engine
+
+**API endpoints** (all support optional JWT auth):
+- `GET /api/query/` - Query metrics with selectors
+- `POST /api/write/` - Write metrics (InfluxDB line protocol)
+- `POST /api/free/` - Free buffers up to timestamp
+- `GET /api/debug/` - Dump internal state
+- `GET /api/healthcheck/` - Node health status
+
+## Selectors
+
+Data is accessed via hierarchical selectors:
+```
+["cluster1", "host1", "cpu0"]           # Specific CPU
+["cluster1", "host1", ["cpu4", "cpu5"]] # Multiple CPUs
+["cluster1", "host1"]                   # Entire node (all CPUs implied)
+```
+
+## Configuration
+
+Config file structure (see `configs/config.json`):
+- `main` - Server address, TLS certs, JWT public key, user/group for privilege drop
+- `metrics` - Per-metric frequency and aggregation strategy (sum/avg/null)
+- `metric-store` - Checkpoints, memory cap, retention, cleanup mode, NATS subscriptions
+- `nats` - Optional NATS connection for receiving metrics
+
+## Test JWT
+
+For testing with JWT auth enabled:
+```
+eyJ0eXAiOiJKV1QiLCJhbGciOiJFZERTQSJ9.eyJ1c2VyIjoiYWRtaW4iLCJyb2xlcyI6WyJST0xFX0FETUlOIiwiUk9MRV9BTkFMWVNUIiwiUk9MRV9VU0VSIl19.d-3_3FZTsadPjDEdsWrrQ7nS0edMAR4zjl-eK7rJU3HziNBfI9PDHDIpJVHTNN5E5SlLGLFXctWyKAkwhXL-Dw
+```

cmd/cc-metric-store/main.go

@@ -19,6 +19,7 @@ import (
 	cclog "github.com/ClusterCockpit/cc-lib/v2/ccLogger"
 	"github.com/ClusterCockpit/cc-lib/v2/nats"
 	"github.com/ClusterCockpit/cc-lib/v2/runtime"
+	"github.com/ClusterCockpit/cc-metric-store/internal/api"
 	"github.com/ClusterCockpit/cc-metric-store/internal/config"
 	"github.com/google/gops/agent"
 )
@@ -43,14 +44,25 @@ func printVersion() {
 func runServer(ctx context.Context) error {
 	var wg sync.WaitGroup
 
-	// Initialize metric store if configuration is provided
+	mscfg := ccconf.GetPackageConfig("metrics")
-	mscfg := ccconf.GetPackageConfig("metric-store")
+	if mscfg == nil {
-	if mscfg != nil {
+		return fmt.Errorf("missing metrics configuration")
-		metricstore.Init(mscfg, &wg)
+	}
-	} else {
+	config.InitMetrics(mscfg)
+
+	mscfg = ccconf.GetPackageConfig("metric-store")
+	if mscfg == nil {
 		return fmt.Errorf("missing metricstore configuration")
 	}
 
+	metricstore.Init(mscfg, config.GetMetrics(), &wg)
+
+	if config.Keys.BackendURL != "" {
+		ms := metricstore.GetMemoryStore()
+		ms.SetNodeProvider(api.NewBackendNodeProvider(config.Keys.BackendURL))
+		cclog.Infof("Node provider configured with backend URL: %s", config.Keys.BackendURL)
+	}
+
 	// Initialize HTTP server
 	srv, err := NewServer(version, commit, date)
 	if err != nil {

go.mod

@@ -3,8 +3,8 @@ module github.com/ClusterCockpit/cc-metric-store
 go 1.24.0
 
 require (
-	github.com/ClusterCockpit/cc-backend v1.4.4-0.20260126082752-084d00cb0d0c
+	github.com/ClusterCockpit/cc-backend v1.4.4-0.20260128102127-0d857b49a256
-	github.com/ClusterCockpit/cc-lib/v2 v2.2.0
+	github.com/ClusterCockpit/cc-lib/v2 v2.2.1
 	github.com/golang-jwt/jwt/v4 v4.5.0
 	github.com/google/gops v0.3.28
 	github.com/influxdata/line-protocol/v2 v2.2.1
@@ -34,7 +34,6 @@ require (
 	github.com/aws/aws-sdk-go-v2/service/ssooidc v1.35.13 // indirect
 	github.com/aws/aws-sdk-go-v2/service/sts v1.41.6 // indirect
 	github.com/aws/smithy-go v1.24.0 // indirect
-	github.com/cpuguy83/go-md2man/v2 v2.0.7 // indirect
 	github.com/fsnotify/fsnotify v1.9.0 // indirect
 	github.com/go-openapi/jsonpointer v0.22.3 // indirect
 	github.com/go-openapi/jsonreference v0.21.3 // indirect
@@ -53,19 +52,13 @@ require (
 	github.com/nats-io/nats.go v1.47.0 // indirect
 	github.com/nats-io/nkeys v0.4.12 // indirect
 	github.com/nats-io/nuid v1.0.1 // indirect
-	github.com/russross/blackfriday/v2 v2.1.0 // indirect
 	github.com/swaggo/files v1.0.1 // indirect
-	github.com/urfave/cli/v2 v2.27.7 // indirect
-	github.com/xrash/smetrics v0.0.0-20250705151800-55b8f293f342 // indirect
-	go.yaml.in/yaml/v2 v2.4.3 // indirect
 	go.yaml.in/yaml/v3 v3.0.4 // indirect
 	golang.org/x/crypto v0.46.0 // indirect
 	golang.org/x/mod v0.31.0 // indirect
 	golang.org/x/net v0.48.0 // indirect
 	golang.org/x/sync v0.19.0 // indirect
 	golang.org/x/sys v0.39.0 // indirect
-	golang.org/x/text v0.32.0 // indirect
 	golang.org/x/tools v0.40.0 // indirect
 	gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c // indirect
-	sigs.k8s.io/yaml v1.6.0 // indirect
 )

go.sum

@@ -1,7 +1,7 @@
-github.com/ClusterCockpit/cc-backend v1.4.4-0.20260126082752-084d00cb0d0c h1:rN1M3afMjlW4GUsa5jiR5OKA23IVpoeMrkbVlpk2sWw=
+github.com/ClusterCockpit/cc-backend v1.4.4-0.20260128102127-0d857b49a256 h1:PL8UhUBe+G6j1JoXybx27eKhgVgQ+Z0fQnvbVD3OmGA=
-github.com/ClusterCockpit/cc-backend v1.4.4-0.20260126082752-084d00cb0d0c/go.mod h1:RDlfymO/WgrcZ1eDxGpur2jTEFoMA8BfJUvV+Heb+E4=
+github.com/ClusterCockpit/cc-backend v1.4.4-0.20260128102127-0d857b49a256/go.mod h1:y5LuqfWrSnVYjMaxseBwq72Tx4NpyQWwTHXwKsYAPUk=
-github.com/ClusterCockpit/cc-lib/v2 v2.2.0 h1:gqMsh7zsJMUhaXviXzaZ3gqXcLVgerjRJHzIcwX4FmQ=
+github.com/ClusterCockpit/cc-lib/v2 v2.2.1 h1:iCVas+Jc61zFH5S2VG3H1sc7tsn+U4lOJwUYjYZEims=
-github.com/ClusterCockpit/cc-lib/v2 v2.2.0/go.mod h1:JuxMAuEOaLLNEnnL9U3ejha8kMvsSatLdKPZEgJw6iw=
+github.com/ClusterCockpit/cc-lib/v2 v2.2.1/go.mod h1:JuxMAuEOaLLNEnnL9U3ejha8kMvsSatLdKPZEgJw6iw=
 github.com/KyleBanks/depth v1.2.1 h1:5h8fQADFrWtarTdtDudMmGsC7GPbOAu6RVB3ffsVFHc=
 github.com/KyleBanks/depth v1.2.1/go.mod h1:jzSb9d0L43HxTQfT+oSA1EEp2q+ne2uh6XgeJcm8brE=
 github.com/NVIDIA/go-nvml v0.13.0-1 h1:OLX8Jq3dONuPOQPC7rndB6+iDmDakw0XTYgzMxObkEw=
@@ -50,8 +50,6 @@ github.com/beorn7/perks v1.0.1 h1:VlbKKnNfV8bJzeqoa4cOKqO6bYr3WgKZxO8Z16+hsOM=
 github.com/beorn7/perks v1.0.1/go.mod h1:G2ZrVWU2WbWT9wwq4/hrbKbnv/1ERSJQ0ibhJ6rlkpw=
 github.com/cespare/xxhash/v2 v2.3.0 h1:UL815xU9SqsFlibzuggzjXhog7bL6oX9BbNZnL2UFvs=
 github.com/cespare/xxhash/v2 v2.3.0/go.mod h1:VGX0DQ3Q6kWi7AoAeZDth3/j3BFtOZR5XLFGgcrjCOs=
-github.com/cpuguy83/go-md2man/v2 v2.0.7 h1:zbFlGlXEAKlwXpmvle3d8Oe3YnkKIK4xSRTd3sHPnBo=
-github.com/cpuguy83/go-md2man/v2 v2.0.7/go.mod h1:oOW0eioCTA6cOiMLiUPZOpcVxMig6NIQQ7OS05n1F4g=
 github.com/creack/pty v1.1.9/go.mod h1:oKZEueFk5CKHvIhNR5MUki03XCEU+Q6VDXinZuGJ33E=
 github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
@@ -155,8 +153,6 @@ github.com/prometheus/procfs v0.16.1 h1:hZ15bTNuirocR6u0JZ6BAHHmwS1p8B4P6MRqxtzM
 github.com/prometheus/procfs v0.16.1/go.mod h1:teAbpZRB1iIAJYREa1LsoWUXykVXA1KlTmWl8x/U+Is=
 github.com/rogpeppe/go-internal v1.14.1 h1:UQB4HGPB6osV0SQTLymcB4TgvyWu6ZyliaW0tI/otEQ=
 github.com/rogpeppe/go-internal v1.14.1/go.mod h1:MaRKkUm5W0goXpeCfT7UZI6fk/L7L7so1lCWt35ZSgc=
-github.com/russross/blackfriday/v2 v2.1.0 h1:JIOH55/0cWyOuilr9/qlrm0BSXldqnqwMsf35Ld67mk=
-github.com/russross/blackfriday/v2 v2.1.0/go.mod h1:+Rmxgy9KzJVeS9/2gXHxylqXiyQDYRxCVz55jmeOWTM=
 github.com/santhosh-tekuri/jsonschema/v5 v5.3.1 h1:lZUw3E0/J3roVtGQ+SCrUrg3ON6NgVqpn3+iol9aGu4=
 github.com/santhosh-tekuri/jsonschema/v5 v5.3.1/go.mod h1:uToXkOrWAZ6/Oc07xWQrPOhJotwFIyu2bBVN41fcDUY=
 github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
@@ -171,10 +167,6 @@ github.com/swaggo/http-swagger v1.3.4 h1:q7t/XLx0n15H1Q9/tk3Y9L4n210XzJF5WtnDX64
 github.com/swaggo/http-swagger v1.3.4/go.mod h1:9dAh0unqMBAlbp1uE2Uc2mQTxNMU/ha4UbucIg1MFkQ=
 github.com/swaggo/swag v1.16.6 h1:qBNcx53ZaX+M5dxVyTrgQ0PJ/ACK+NzhwcbieTt+9yI=
 github.com/swaggo/swag v1.16.6/go.mod h1:ngP2etMK5a0P3QBizic5MEwpRmluJZPHjXcMoj4Xesg=
-github.com/urfave/cli/v2 v2.27.7 h1:bH59vdhbjLv3LAvIu6gd0usJHgoTTPhCFib8qqOwXYU=
-github.com/urfave/cli/v2 v2.27.7/go.mod h1:CyNAG/xg+iAOg0N4MPGZqVmv2rCoP267496AOXUZjA4=
-github.com/xrash/smetrics v0.0.0-20250705151800-55b8f293f342 h1:FnBeRrxr7OU4VvAzt5X7s6266i6cSVkkFPS0TuXWbIg=
-github.com/xrash/smetrics v0.0.0-20250705151800-55b8f293f342/go.mod h1:Ohn+xnUBiLI6FVj/9LpzZWtj1/D6lUovWYBkxHVV3aM=
 github.com/yuin/goldmark v1.4.13/go.mod h1:6yULJ656Px+3vBD8DxQVa3kxgyrAnzto9xy5taEt/CY=
 go.yaml.in/yaml/v2 v2.4.3 h1:6gvOSjQoTB3vt1l+CU+tSyi/HOjfOjRLJ4YwYZGwRO0=
 go.yaml.in/yaml/v2 v2.4.3/go.mod h1:zSxWcmIDjOzPXpjlTTbAsKokqkDNAVtZO0WOMiT90s8=
@@ -214,8 +206,6 @@ golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
 golang.org/x/text v0.3.3/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
 golang.org/x/text v0.3.7/go.mod h1:u+2+/6zg+i71rQMx5EYifcz6MCKuco9NR6JIITiCfzQ=
 golang.org/x/text v0.7.0/go.mod h1:mrYo+phRRbMaCq/xk9113O4dZlRixOauAjOtrjsXDZ8=
-golang.org/x/text v0.32.0 h1:ZD01bjUt1FQ9WJ0ClOL5vxgxOI/sVCNgX1YtKwcY0mU=
-golang.org/x/text v0.32.0/go.mod h1:o/rUWzghvpD5TXrTIBuJU77MTaN0ljMWE47kxGJQ7jY=
 golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
 golang.org/x/tools v0.0.0-20191119224855-298f0cb1881e/go.mod h1:b+2E5dAYhXwXZwtnZ6UAqBI28+e2cm9otk0dWdXHAEo=
 golang.org/x/tools v0.1.12/go.mod h1:hNGJHUnrk76NpqgfD5Aqm5Crs+Hm0VOH/i9J2+nxYbc=
@@ -233,5 +223,3 @@ gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C
 gopkg.in/yaml.v3 v3.0.0-20200615113413-eeeca48fe776/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
 gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
 gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
-sigs.k8s.io/yaml v1.6.0 h1:G8fkbMSAFqgEFgh4b1wmtzDnioxFCUgTZhlbj5P9QYs=
-sigs.k8s.io/yaml v1.6.0/go.mod h1:796bPqUfzR/0jLAl6XjHl3Ck7MiyVv8dbTdyT3/pMf4=

internal/api/nodeprovider.go

@@ -0,0 +1,54 @@
+// Copyright (C) NHR@FAU, University Erlangen-Nuremberg.
+// All rights reserved. This file is part of cc-metric-store.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package api
+
+import (
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"time"
+)
+
+// BackendNodeProvider implements metricstore.NodeProvider by querying
+// the cc-backend /api/jobs/used_nodes endpoint.
+type BackendNodeProvider struct {
+	backendUrl string
+	client     *http.Client
+}
+
+// NewBackendNodeProvider creates a new BackendNodeProvider that queries
+// the given cc-backend URL for used nodes information.
+func NewBackendNodeProvider(backendUrl string) *BackendNodeProvider {
+	return &BackendNodeProvider{
+		backendUrl: backendUrl,
+		client: &http.Client{
+			Timeout: 10 * time.Second,
+		},
+	}
+}
+
+// GetUsedNodes returns a map of cluster names to sorted lists of unique hostnames
+// that are currently in use by jobs that started before the given timestamp.
+func (p *BackendNodeProvider) GetUsedNodes(ts int64) (map[string][]string, error) {
+	url := fmt.Sprintf("%s/api/jobs/used_nodes?ts=%d", p.backendUrl, ts)
+
+	resp, err := p.client.Get(url)
+	if err != nil {
+		return nil, fmt.Errorf("querying used nodes from backend: %w", err)
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK {
+		return nil, fmt.Errorf("backend returned status %d", resp.StatusCode)
+	}
+
+	var result map[string][]string
+	if err := json.NewDecoder(resp.Body).Decode(&result); err != nil {
+		return nil, fmt.Errorf("decoding used nodes response: %w", err)
+	}
+
+	return result, nil
+}

internal/config/config.go

@@ -10,57 +10,20 @@ import (
 	"encoding/json"
 	"fmt"
 
+	"github.com/ClusterCockpit/cc-backend/pkg/metricstore"
 	cclog "github.com/ClusterCockpit/cc-lib/v2/ccLogger"
 )
 
-// For aggregation over multiple values at different cpus/sockets/..., not time!
+var metrics map[string]metricstore.MetricConfig
-type AggregationStrategy int
-
-const (
-	NoAggregation AggregationStrategy = iota
-	SumAggregation
-	AvgAggregation
-)
-
-func (as *AggregationStrategy) UnmarshalJSON(data []byte) error {
-	var str string
-	if err := json.Unmarshal(data, &str); err != nil {
-		return err
-	}
-
-	switch str {
-	case "":
-		*as = NoAggregation
-	case "sum":
-		*as = SumAggregation
-	case "avg":
-		*as = AvgAggregation
-	default:
-		return fmt.Errorf("invalid aggregation strategy: %#v", str)
-	}
-	return nil
-}
-
-type MetricConfig struct {
-	// Interval in seconds at which measurements will arive.
-	Frequency int64 `json:"frequency"`
-
-	// Can be 'sum', 'avg' or null. Describes how to aggregate metrics from the same timestep over the hierarchy.
-	Aggregation AggregationStrategy `json:"aggregation"`
-
-	// Private, used internally...
-	Offset int
-}
-
-var metrics map[string]MetricConfig
 
 type Config struct {
-	Address  string `json:"addr"`
+	Address    string `json:"addr"`
-	CertFile string `json:"https-cert-file"`
+	CertFile   string `json:"https-cert-file"`
-	KeyFile  string `json:"https-key-file"`
+	KeyFile    string `json:"https-key-file"`
-	User     string `json:"user"`
+	User       string `json:"user"`
-	Group    string `json:"group"`
+	Group      string `json:"group"`
-	Debug    struct {
+	BackendURL string `json:"backend-url"`
+	Debug      struct {
 		DumpToFile string `json:"dump-to-file"`
 		EnableGops bool   `json:"gops"`
 	} `json:"debug"`
@@ -69,13 +32,32 @@ type Config struct {
 
 var Keys Config
 
+type metricConfigJSON struct {
+	Frequency   int64  `json:"frequency"`
+	Aggregation string `json:"aggregation"`
+}
+
 func InitMetrics(metricConfig json.RawMessage) {
 	Validate(metricConfigSchema, metricConfig)
+
+	var tempMetrics map[string]metricConfigJSON
 	dec := json.NewDecoder(bytes.NewReader(metricConfig))
 	dec.DisallowUnknownFields()
-	if err := dec.Decode(&metrics); err != nil {
+	if err := dec.Decode(&tempMetrics); err != nil {
 		cclog.Abortf("Config Init: Could not decode config file '%s'.\nError: %s\n", metricConfig, err.Error())
 	}
+
+	metrics = make(map[string]metricstore.MetricConfig)
+	for name, cfg := range tempMetrics {
+		agg, err := metricstore.AssignAggregationStrategy(cfg.Aggregation)
+		if err != nil {
+			cclog.Warnf("Could not parse aggregation strategy for metric '%s': %s", name, err.Error())
+		}
+		metrics[name] = metricstore.MetricConfig{
+			Frequency:   cfg.Frequency,
+			Aggregation: agg,
+		}
+	}
 }
 
 func Init(mainConfig json.RawMessage) {
@@ -93,3 +75,7 @@ func GetMetricFrequency(metricName string) (int64, error) {
 	}
 	return 0, fmt.Errorf("metric %s not found", metricName)
 }
+
+func GetMetrics() map[string]metricstore.MetricConfig {
+	return metrics
+}

internal/config/schema.go

@@ -29,6 +29,10 @@ var configSchema = `
       "description": "Drop root permissions once the port was taken. Only applicable if using privileged port.",
       "type": "string"
     },
+    "backend-url": {
+      "description": "URL of cc-backend for querying job information (e.g., 'https://localhost:8080').",
+      "type": "string"
+    },
     "debug": {
       "description": "Debug options.",
       "type": "object",