tv backup: initial commit

1 files changed, 254 insertions, 0 deletions

diff --git a/tv/2configs/backup.nix b/tv/2configs/backup.nix
new file mode 100644
index 00000000..1cef0a6d
--- /dev/null
+++ b/tv/2configs/backup.nix
@@ -0,0 +1,254 @@
+{ config, lib, pkgs, ... }:
+with lib;
+let
+  # Users that are allowed to connect to the backup user.
+  # Note: the user must own a push plan destination otherwise no rsync.
+  backup-users = [
+    config.krebs.users.tv
+  ];
+
+  ## TODO parse.file-location admit user
+  ## loc has the form <host-name>:<abs-path>
+  #parse.file-location = loc: let
+  #  parts = splitString ":" loc;
+  #  host-name = head parts;
+  #  path = concatStringsSep ":" (tail parts);
+  #in {
+  #  type = "types.krebs.file-location";
+  #  host = config.krebs.hosts.${host-name};
+  #  path = path;
+  #};
+
+  # TODO assert plan.dst.path & co
+  plans = with config.krebs.users; with config.krebs.hosts; addNames {
+    xu-test-cd = {
+      method = "push";
+      #src = parse.file-location xu:/tmp/xu-test;
+      #dst = parse.file-location cd:/krebs/backup/xu-test;
+      src = { user = tv; host = xu; path = "/tmp/xu-test"; };
+      dst = { user = tv; host = cd; path = "/krebs/backup/xu-test"; };
+      startAt = "0,6,12,18:00";
+      retain = {
+        hourly = 4; # sneakily depends on startAt
+        daily = 7;
+        weekly = 4;
+        monthly = 3;
+      };
+    };
+    #xu-test-wu = {
+    #  method = "push";
+    #  dst = { user = tv; host = wu; path = "/krebs/backup/xu-test"; };
+    #};
+    cd-test-xu = {
+      method = "pull";
+      #src = parse.file-location cd:/tmp/cd-test;
+      #dst = parse.file-location xu:/bku/cd-test;
+      src = { user = tv; host = cd; path = "/tmp/cd-test"; };
+      dst = { user = tv; host = xu; path = "/bku/cd-test"; };
+    };
+
+  };
+
+  out = {
+    #options.krebs.backup = api;
+    config = imp;
+  };
+
+  imp = {
+    users.groups.backup.gid = genid "backup";
+    users.users = map makeUser (filter isPushDst (attrValues plans));
+    systemd.services =
+      flip mapAttrs' (filterAttrs (_:isPushSrc) plans) (name: plan: {
+        name = "backup.${name}";
+        value = makePushService plan;
+      });
+  };
+
+
+  # TODO getFQDN: admit hosts in other domains
+  getFQDN = host: "${host.name}.${config.krebs.search-domain}";
+
+  isPushSrc = plan:
+    plan.method == "push" &&
+    plan.src.host.name == config.krebs.build.host.name;
+
+  makePushService = plan: assert isPushSrc plan; {
+    startAt = plan.startAt;
+    serviceConfig.ExecStart = writeSh plan "rsync" ''
+      exec ${pkgs.rsync}/bin/rsync ${concatMapStringsSep " " shell.escape [
+        "-a"
+        "-e"
+        "${pkgs.openssh}/bin/ssh -F /dev/null -i ${plan.src.host.ssh.privkey.path}"
+        "${plan.src.path}"
+        "${plan.name}@${getFQDN plan.dst.host}::push"
+      ]}
+    '';
+  };
+
+  isPushDst = plan:
+    plan.method == "push" &&
+    plan.dst.host.name == config.krebs.build.host.name;
+
+  makeUser = plan: assert isPushDst plan; rec {
+    name = plan.name;
+    uid = genid name;
+    group = config.users.groups.backup.name;
+    home = plan.dst.path;
+    createHome = true;
+    shell = "${writeSh plan "shell" ''
+      case $2 in
+        'rsync --server --daemon .')
+          exec ${backup.rsync plan [ "--server" "--daemon" "." ]}
+          ;;
+        ''')
+          echo "ERROR: no command specified" >&2
+          exit 23
+          ;;
+        *)
+          echo "ERROR: no unknown command: $SSH_ORIGINAL_COMMAND" >&2
+          exit 23
+          ;;
+      esac
+    ''}";
+    openssh.authorizedKeys.keys = [ plan.src.host.ssh.pubkey ];
+  };
+
+  rsync = plan: args: writeSh plan "rsync" ''
+    install -v -m 0700 -d ${plan.dst.path}/push >&2
+    install -v -m 0700 -d ${plan.dst.path}/list >&2
+
+    ${pkgs.rsync}/bin/rsync \
+        --config=${backup.rsyncd-conf plan {
+          post-xfer = writeSh plan "rsyncd.post-xfer" ''
+            case $RSYNC_EXIT_STATUS in 0)
+              exec ${backup.rsnapshot plan {
+                preexec = writeSh plan "rsnapshot.preexec" ''
+                  touch ${plan.dst.path}/rsnapshot.$RSNAPSHOT_INTERVAL
+                '';
+                postexec = writeSh plan "rsnapshot.postexec" ''
+                  rm ${plan.dst.path}/rsnapshot.$RSNAPSHOT_INTERVAL
+                '';
+              }}
+            esac
+          '';
+        }} \
+        ${toString (map shell.escape args)}
+
+    fail=0
+    for i in monthly weekly daily hourly; do
+      if test -e ${plan.dst.path}/rsnapshot.$i; then
+        rm ${plan.dst.path}/rsnapshot.$i
+        echo "ERROR: $i snapshot failed" >&2
+        fail=1
+      fi
+    done
+    if test $fail != 0; then
+      exit -1
+    fi
+  '';
+
+  rsyncd-conf = plan: conf: pkgs.writeText "${plan.name}.rsyncd.conf" ''
+    fake super = yes
+    use chroot = no
+    lock file = ${plan.dst.path}/rsyncd.lock
+
+    [push]
+    max connections = 1
+    path = ${plan.dst.path}/push
+    write only = yes
+    read only = no
+    post-xfer exec = ${conf.post-xfer}
+
+    [list]
+    path = ${plan.dst.path}/list
+    read only = yes
+    write only = no
+  '';
+
+  rsnapshot = plan: conf: writeSh plan "rsnapshot" ''
+    rsnapshot() {
+      ${pkgs.proot}/bin/proot \
+          -b /bin \
+          -b /nix \
+          -b /run/current-system \
+          -b ${plan.dst.path} \
+          -r ${plan.dst.path} \
+          -w / \
+          ${pkgs.rsnapshot}/bin/rsnapshot \
+              -c ${pkgs.writeText "${plan.name}.rsnapshot.conf" ''
+                config_version	1.2
+                snapshot_root	${plan.dst.path}/list
+                cmd_cp	${pkgs.coreutils}/bin/cp
+                cmd_du	${pkgs.coreutils}/bin/du
+                #cmd_rm	${pkgs.coreutils}/bin/rm
+                cmd_rsync	${pkgs.rsync}/bin/rsync
+                cmd_rsnapshot_diff	${pkgs.rsnapshot}/bin/rsnapshot-diff
+                cmd_preexec	${conf.preexec}
+                cmd_postexec	${conf.postexec}
+                retain	hourly	4
+                retain	daily	7
+                retain	weekly	4
+                retain	monthly	3
+                lockfile	${plan.dst.path}/rsnapshot.pid
+                link_dest	1
+                backup	/push	./
+                verbose	4
+              ''} \
+          "$@"
+    }
+
+    cd ${plan.dst.path}/list/
+
+    now=$(date +%s)
+    is_older_than() {
+      test $(expr $now - $(date +%s -r $1 2>/dev/null || echo 0)) \
+       -ge $2
+    }
+
+    # TODO report stale snapshots
+    # i.e. there are $interval.$i > $interval.$max
+
+    hour_s=3600
+    day_s=86400
+    week_s=604800
+    month_s=2419200 # 4 weeks
+
+    set --
+
+    if test -e weekly.3 && is_older_than monthly.0 $month_s; then
+      set -- "$@" monthly
+    fi
+
+    if test -e daily.6 && is_older_than weekly.0 $week_s; then
+      set -- "$@" weekly
+    fi
+
+    if test -e hourly.3 && is_older_than daily.0 $day_s; then
+      set -- "$@" daily
+    fi
+
+    if is_older_than hourly.0 $hour_s; then
+      set -- "$@" hourly
+    fi
+
+
+    if test $# = 0; then
+      echo "taking no snapshots" >&2
+    else
+      echo "taking snapshots: $@" >&2
+    fi
+
+    export RSNAPSHOT_INTERVAL
+    for RSNAPSHOT_INTERVAL; do
+      rsnapshot "$RSNAPSHOT_INTERVAL"
+    done
+  '';
+
+  writeSh = plan: name: text: pkgs.writeScript "${plan.name}.${name}" ''
+    #! ${pkgs.dash}/bin/dash
+    set -efu
+    export PATH=${makeSearchPath "bin" (with pkgs; [ coreutils ])}
+    ${text}
+  '';
+
+in out