collect metrics for the agent lockfile (if present)

if the agent is currently disabled (`puppet agent --disable`),
additional metrics are being reported. currently only the start
of the lock is repored (the modification time of the agent lockfile)

Signed-off-by: Gordon Bleux <[email protected]>

Author: UiP9AV6Y

README.md

@@ -29,6 +29,9 @@ puppet_last_run_duration_seconds 28.023470087
 # HELP puppet_last_run_success 1 if the last Puppet run was successful.
 # TYPE puppet_last_run_success gauge
 puppet_last_run_success 1
+# HELP puppet_disabled_since_seconds Unix timestamp since when puppet has been disabled.
+# TYPE puppet_disabled_since_seconds gauge
+puppet_disabled_since_seconds 1.6863428664914448e+09
 ```
 
 ### Example Alert Rules

internal/logging/logger.go

@@ -0,0 +1,21 @@
+// Copyright 2023 RetailNext, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package logging
+
+// Logger is a vendor-agnostic interface for event tracking
+type Logger interface {
+	Errorw(msg string, keysAndValues ...interface{})
+	Panicw(msg string, keysAndValues ...interface{})
+}

internal/logging/noop.go

@@ -0,0 +1,24 @@
+// Copyright 2023 RetailNext, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package logging
+
+type noOpLogger struct{}
+
+// NewNoOpLogger returns a Logger implementation with no side effects
+func NewNoOpLogger() Logger { return noOpLogger{} }
+
+func (noOpLogger) Errorw(_msg string, _keysAndValues ...interface{}) {}
+
+func (noOpLogger) Panicw(_msg string, _keysAndValues ...interface{}) {}

internal/logging/noop_test.go

@@ -0,0 +1,30 @@
+// Copyright 2023 RetailNext, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package logging
+
+import (
+	"testing"
+)
+
+func TestNoOpLogger(t *testing.T) {
+	got := NewNoOpLogger()
+
+	got.Errorw("error", "key", "value")
+	got.Panicw("panic", "key", "value")
+	got.Errorw("error", "key")
+	got.Panicw("panic", "key")
+	got.Errorw("error")
+	got.Panicw("panic")
+}

internal/puppet/agent_disabled_lockfile.go

@@ -0,0 +1,61 @@
+// Copyright 2023 RetailNext, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package puppet
+
+import (
+	"encoding/json"
+	"io"
+	"os"
+	"time"
+)
+
+// AgentDisabledLockfile holds metadata when the
+// agent has been administratively disabled.
+type AgentDisabledLockfile struct {
+	DisabledMessage string    `json:"disabled_message"`
+	DisabledSince   time.Time `json:-`
+}
+
+// ParseAgentDisabledLockfile reads the file and its filesystem metadata
+// at the given path. The returned error can be the result of a filesystem
+// operation (including `os.ErrNotExist`) or parsing procedure.
+func ParseAgentDisabledLockfile(path string) (*AgentDisabledLockfile, error) {
+	info, err := os.Stat(path)
+	if err != nil {
+		return nil, err
+	}
+
+	file, err := os.Open(path)
+	if err != nil {
+		return nil, err
+	}
+	defer file.Close()
+
+	data, err := io.ReadAll(file)
+	if err != nil {
+		return nil, err
+	}
+
+	result := &AgentDisabledLockfile{
+		DisabledSince: info.ModTime(),
+	}
+
+	err = json.Unmarshal(data, result)
+	if err != nil {
+		return nil, err
+	}
+
+	return result, nil
+}

internal/puppet/agent_disabled_lockfile_test.go

@@ -0,0 +1,51 @@
+// Copyright 2023 RetailNext, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package puppet
+
+import (
+	"testing"
+)
+
+func TestParseAgentDisabledLockfile(t *testing.T) {
+	testCases := map[string]struct {
+		wantDisabledMessage string
+		wantError           bool
+	}{
+		"404":              {wantError: true},
+		"empty":            {wantError: true},
+		"malformed":        {wantError: true},
+		"empty_hash":       {},
+		"disabled_message": {wantDisabledMessage: "testing unmarshalling"},
+	}
+
+	for name, tc := range testCases {
+		t.Run(name, func(t *testing.T) {
+			got, err := ParseAgentDisabledLockfile("testdata/agent_disabled_lockfile/" + name + ".json")
+
+			if tc.wantError {
+				if err == nil {
+					t.Errorf("expected fixture %q to produce error but got none", name)
+				}
+			} else {
+				if err != nil {
+					t.Errorf("expected fixture %q to parse properly but got error\n%s", name, err)
+				}
+				if got == nil {
+					t.Errorf("expected fixture %q to parse properly but got nil as result", name)
+				}
+			}
+		})
+	}
+}

internal/puppet/defaults.go

@@ -0,0 +1,21 @@
+// Copyright 2023 RetailNext, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package puppet
+
+const (
+	DefaultConfigFile            = "/etc/puppetlabs/puppet/puppet.conf"
+	DefaultAgentDisabledLockfile = "/opt/puppetlabs/puppet/cache/state/agent_disabled.lock"
+	DefaultLastRunReportFile     = "/opt/puppetlabs/puppet/cache/state/last_run_report.yaml"
+)

internal/puppet/testdata/agent_disabled_lockfile/disabled_message.json

@@ -0,0 +1 @@
+{"disabled_message":"testing unmarshalling"}

internal/puppet/testdata/agent_disabled_lockfile/empty.json

@@ -0,0 +1 @@
+{}