mesh-catalog/modules/logrotate/cmd/logrotate-tools/main.go

// logrotate's tools bundle (novox/hq to-be 42 Phase 1, research 026/05): a process the node's
// runtime launches and speaks MCP over stdio to, through the Go SDK (ADR 0188, ADR 0193). It reads
// when each log was last rotated, the rule files and a dry run of them, and the largest logs; forces
// one rule file; and reads and vacuums the journal. Acts go through sudo -n.
package main

import (
	"context"
	"fmt"
	"os"

	stdio "git.novox.be/novox/mesh-sdk/go"
)

// binaryName is what the build names this bundle's executable: the manifest's `binary`.
const binaryName = "logrotate-tools"

func bg() context.Context { return context.Background() }

func main() {
	// An empty name serves as the module the runtime names (MESH_SERVED_MODULE): logrotate.
	if err := stdio.Serve("", tools(ThisMachine())); err != nil {
		fmt.Fprintln(os.Stderr, err)
		os.Exit(1)
	}
}

// writeTemp writes a file only this account can write, and gives back how to remove it.
func writeTemp(content string) (string, func(), error) {
	f, err := os.CreateTemp("", "mesh-logrotate-*.conf")
	if err != nil {
		return "", nil, err
	}
	_, werr := f.WriteString(content)
	cerr := f.Close()
	done := func() { os.Remove(f.Name()) }
	if werr != nil || cerr != nil {
		done()
		return "", nil, fmt.Errorf("writing %s: %v %v", f.Name(), werr, cerr)
	}
	return f.Name(), done, nil
}

func tools(m *Machine) []stdio.Tool {
	return []stdio.Tool{
		{
			Name:        "logrotate_status",
			Description: "When logrotate last rotated each log (its status file, read through sudo -n), narrowed to logs whose path holds a word; with the timer's last and next run and the last run's result. A machine where it never ran says so.",
			Input:       schema(map[string]any{"match": map[string]any{"type": "string", "description": "only logs whose path holds this"}}),
			Run: func(args map[string]any) (any, error) {
				match, err := text(args, "match", false)
				if err != nil {
					return nil, err
				}
				return m.Status(match)
			},
		},
		{
			Name:        "logrotate_configs",
			Description: "The base configuration's global settings and every rule file of /etc/logrotate.d with the logs it rotates.",
			Input:       schema(map[string]any{}),
			Run:         func(map[string]any) (any, error) { return m.Configs() },
		},
		{
			Name:        "logrotate_check",
			Description: "A dry run of the whole configuration (logrotate -d through sudo -n, which changes nothing): its errors and warnings, so a broken rule is found before the night it runs.",
			Input:       schema(map[string]any{}),
			Run:         func(map[string]any) (any, error) { return m.Check() },
		},
		{
			Name:        "logrotate_big_logs",
			Description: "The largest files under /var/log on its own filesystem (read through sudo -n), with size and modification time; with the total and how much of it is the journal. Journal files are listed only when asked (journals: true).",
			Input: schema(map[string]any{
				"limit":    map[string]any{"type": "integer", "description": "how many (default 20, at most 200)"},
				"journals": map[string]any{"type": "boolean", "description": "list the journal's files too"},
			}),
			Run: func(args map[string]any) (any, error) {
				n, err := whole(args, "limit", 20, 1, 200)
				if err != nil {
					return nil, err
				}
				j, err := flag(args, "journals")
				if err != nil {
					return nil, err
				}
				return m.BigLogs(n, j)
			},
		},
		{
			Name: "logrotate_force",
			Description: "Rotate now (logrotate -f -v, through sudo -n) the logs of one rule file of /etc/logrotate.d, with the base configuration's " +
				"global settings before it so it rotates as the nightly run would; or every log, given logrotate.conf. Answers what was rotated, the errors and the log.",
			Input: schema(map[string]any{"config": map[string]any{"type": "string", "description": "a file name in /etc/logrotate.d, or logrotate.conf for every log"}}, "config"),
			Run: func(args map[string]any) (any, error) {
				config, err := text(args, "config", true)
				if err != nil {
					return nil, err
				}
				return m.Force(config, writeTemp)
			},
		},
		{
			Name:        "logrotate_journal_usage",
			Description: "How much the systemd journal holds on disk (journalctl --disk-usage, through sudo -n so every part is counted) and the journald settings that bound it.",
			Input:       schema(map[string]any{}),
			Run:         func(map[string]any) (any, error) { return m.JournalUsage() },
		},
		{
			Name:        "logrotate_journal_vacuum",
			Description: "Remove archived journal files (through sudo -n) beyond a total size, older than an age, or both; answers what each directory freed and the usage after.",
			Input: schema(map[string]any{
				"size": map[string]any{"type": "string", "description": "keep at most this much, e.g. 500M or 2G"},
				"time": map[string]any{"type": "string", "description": "keep at most this old, e.g. 4weeks or 30d"},
			}),
			Run: func(args map[string]any) (any, error) {
				size, err := text(args, "size", false)
				if err != nil {
					return nil, err
				}
				age, err := text(args, "time", false)
				if err != nil {
					return nil, err
				}
				return m.Vacuum(size, age)
			},
		},
	}
}