Kopia is a new open source backup utility with basically all modern features.
Cross-platform, deduplication, encryption, compression, multithreaded speed, native cloud storage support, repository replication, snapshots mounting, GUI version, server version,...

Written in golang.
Embedded webGUI for server mode is done in React. KopiaUI comes packaged with electron.

Ways to use Kopia

cli - Command line.
You call the kopia binary passing some commands, it executes stuff, done.
Deployment requires extra work - scripts with configs, scheduling.
Kopia Server - kopia binary runs in server mode.
Runs in the background, with its web server answering at url: localhost:51515
Web GUI makes the management easier than using cli. Additionally in server mode kopia can serve as a centralized repository for other machines that run kopia instances.
Deployment requires extra work similar to cli, but actual use is through web GUI.
KopiaUI - GUI version.
Kopia that comes packaged with electron to provide the feel of a standalone desktop app.
Good for simple deployment where average user just wants to backup stuff.
Benefits over cli or server is easier setup and management.
Drawback is that it runs under one user and only when that user is logged in.
Kopia in Docker - Kopia Server running in docker
Can fulfill two needs:
- Backup docker-host stuff to a cloud or a mounted network storage. Managed through webgui instead of cli.
- A centralized kopia repository where other machines on the network, that also use kopia, backup their data.

Some aspects of Kopia

Official Getting Started Guide
Kopia Build Architecture
Official Features

Kopia is a single ~35MB binary file.
Backups are stored in a repository that needs to be created first, and is always encrypted.
Before any action, Kopia needs to connect to a repo.
Snapshots, apart from the typical meaning, kopia also uses the term for targets(paths) that are being backed up.
Policy is a term used to define behavior of the backup/repo, like backups retention, what to ignore, logging, scheduling(server/UI), actions before and after backup,...
Policies are stored inside a repo and can apply at various levels and can inherit from each other
- Global policy, the default that comes predefined during repo creation, can be edited like any other.
- Per user policy, per machine policy.
- Snapshot level policy, only applying for that one path.
Maintenance is automatic
During snapshots Kopia uses local cache, location varies depending on the OS. Default max size is 5GB, but it gets swept periodically every few minutes.
Useful commands are kopia cache info and kopia cache clear
Retention of backups - here's how it works under the hood.
Restore from backups is most easily done by mounting a snapshot.
Web GUI versions have button for it, cli version can do sudo kopia mount all /mnt/temp &
Tasks section in gui gets wiped when Kopia closes, info on snapshots run history and duration then has to be find in logs
Logs rotate with max age 30 days or max 1000 log files, 5000 content log files
..

Kopia in Linux

cli version of kopia will be used to periodically backup to a mounted network storage.
The backup script will be executed using systemd-timers for scheduling.

Install Kopia

For arch linux, kopia is on AUR yay kopia-bin

The initial steps and general use commands

repo creation

sudo kopia repo create filesystem --path /mnt/mirror/KOPIA/docker_host_kopia
sudo kopia repo connect filesystem --path /mnt/mirror/KOPIA/docker_host_kopia
sudo kopia repo status

If the path used during creation does not exists, kopia will create it in full.
After creation the repo is connected, so connnect command is just demonstration.

the policy info and change

sudo kopia policy get --global
sudo kopia policy list
sudo kopia policy set --global --keep-annual 2 --keep-monthly 6 --keep-weekly 4 --keep-daily 14 --keep-hourly 0 --keep-latest 3

manual backup run

sudo kopia snapshot create /home/spravca/docker /etc
sudo kopia snapshot list

Since the connection exists with a repo, all that is needed is target that should be backed up.

mounting backups

sudo kopia mount all /mnt/tmp & - mounts all snapshots
sudo kopia snapshot list
sudo kopia mount k7e2b0a503edd7604ff61c68655cd5ad7 /mnt/tmp &
sudo umount /mnt/tmp

The backup script

In linux, passing multiple paths separated by space seems to work fine.
So both /home and /etc are set to be backed up.

/opt/kopia-backup-home-etc.sh

#!/bin/bash

# initialize repository
#   sudo kopia repo create filesystem --path /mnt/mirror/KOPIA/docker_host_kopia
# adjust global policy
#   sudo kopia policy set --global --keep-annual 2 --keep-monthly 6 --keep-weekly 4 --keep-daily 14 --keep-hourly 0 --keep-latest 3

REPOSITORY_PATH='/mnt/mirror/KOPIA/docker_host_kopia'
BACKUP_THIS='/home /etc'
KOPIA_PASSWORD='aaa'

kopia repository connect filesystem --path $REPOSITORY_PATH --password $KOPIA_PASSWORD
kopia snapshot create $BACKUP_THIS
kopia repository disconnect

make the script executable
sudo chmod +x /opt/kopia-backup-home-etc.sh

Scheduled backups using systemd

Usually cron is used, but systemd provides better logging and control, so better get used to using it.
Heres some discussion on unit files.
ntfy can be used for notifications, more info here

sudo micro /etc/systemd/system/kopia-home-etc.service

kopia-home-etc.service

[Unit]
Description=kopia backup
Wants=network-online.target
After=network-online.target
ConditionACPower=true
# OnFailure=ntfy@failure-%p.service
# OnSuccess=ntfy@success-%p.service

[Service]
Type=oneshot

# Lower CPU and I/O priority.
Nice=19
CPUSchedulingPolicy=batch
IOSchedulingPriority=7

IPAccounting=true
PrivateTmp=true
Environment="HOME=/root"

ExecStart=/opt/kopia-backup-home-etc.sh

sudo micro /etc/systemd/system/kopia-home-etc.timer

kopia-home-etc.timer

[Unit]
Description=Run kopia backup

[Timer]
OnCalendar=*-*-* 02:00:00
RandomizedDelaySec=10min
Persistent=true

[Install]
WantedBy=timers.target

sudo systemctl enable --now kopia-home-etc.timer
systemctl status kopia-home-etc.timer
journalctl -u kopia-home-etc.timer - see history

Mounting network storage using systemd

files are placed in /etc/systemd/system
the name of mount and automount files MUST correspond with the path
replacing / with a -, but otherwise it must be the mounting path in the name
for mounting that does not fail on boot if there are network issues, and mounts the target only on request - enable automount file, not mount file, so:
sudo systemctl enable mnt-mirror.automount

mnt-mirror.mount

[Unit]
Description=3TB truenas mirror mount

[Mount]
What=//10.0.19.11/Mirror
Where=/mnt/mirror
Type=cifs
Options=rw,username=kopia,password=aaa,file_mode=0644,dir_mode=0755,uid=1000,gid=1000

[Install]
WantedBy=multi-user.target

mnt-mirror.automount

[Unit]
Description=3TB truenas mirror mount

[Automount]
Where=/mnt/mirror

[Install]
WantedBy=multi-user.target

Kopia in Windows

KopiaUI in Windows

While KopiaUI seems like the way to go because of the simple deployment and use, it has a drawback. The way the schedule works - that the user must be logged in for backups to take place.

Othewise KopiaUI does not need guide. It just works for normal use.

Kopia Server in Windows

Kopia always running in the background, but also webgui to manage it in.

Download this repo, delete everything except kopia_backup/kopia_server_deploy_win_service folder.
Run DEPLOY.cmd as admin, it will:
- Removes powershell scripts restriction.
- Creates folder C:\Kopia and copies files there.
- Uses shawl to crate Kopia service.
- Places kopia.url on the current user's desktop.
One should check content of C:\Kopia\kopia_server_start.cmd
note credentials set there: admin // aaa
Visit in browser localhost:51515
Setup new repo through webgui.
Setup what to backup and schedule.

Kopia should now run on boot and be easy to manage through web GUI.
Be it creating backup jobs, mounting old snapshots to restore files, or just looking around if all works as it should.

All relevant files are in C:\Kopia, from binaries, repository.config, to logs.

Kopia server runs in insecure mode, so no https and no actual server for other machines on network to use, just local deployment.

Before shawl, task scheduler was used.
This matushorvath/Kopia as Windows Service guide helped move beyond that. It contains more info if one would want to actually run as server repository for other machines.
Also use of nssm is popular.

Kopia cli in Windows

Kopia binary is copied in to C:\Windows\System32\ and a scheduled task is imported that executes a powershell script C:\Kopia\kopia_backup_scipt.ps1 at 21:19. The script executes few kopia commands - connects to a repo, backs up stuff, and disconnects.

Bit more hands on than having a gui, but once setup one can easily get by with two commands: kopia snap list -all and kopia mount all K:
Note that mount command should be executed in non admin terminal. Weird windows thing.

Also at the moment cli is the only way I know how to make kopia actions work, so that VSS snapshots can be used.

Download this repo, delete everything except kopia_cli_deploy_win folder.
Run DEPLOY.cmd, it will:
- Removes powershell scripts restriction.
- kopies kopia.exe in to C:\Windows\System32
- Creates folder C:\Kopia and kopies there
  kopia_backup_scipt.ps1 and the VSS ps1 before and after files.
- imports a task schedule
Read kopia_backup_scipt.ps1 and follow the instructions there.
Which should be to just to create repo before running the script.
kopia repo create filesystem --path C:\kopia_repo --password aaa
edit the scheduled task to the prefered time, default is daily at 21:19
run scheduled task manually
check if it worked
- kopia snap list --all

VSS snapshots

Volume Shadow Copy Service freezes the state of the disk in time and makes this snapshot available to use. This is what allows backup of open files that are in use.
Here's some youtube video on VSS.

To make use of this feature edit kopia_backup_scipt.ps1 changing $USE_SHADOW_COPY = $false to $USE_SHADOW_COPY = $true

Note the use of --enable-actions in the backup script kopia_backup_scipt.ps1, which is required for before/after actions to work.

To test if its working, one can execute command vssadmin list shadows to see current VSS snapshots and then execute it again during the backup.

Kopia install using scoop, machine-wide

Just something to have note of, if decided to switch to heavy scoop use.

open terminal as admin
Set-ExecutionPolicy Bypass
iex "& {$(irm get.scoop.sh)} -RunAsAdmin"
scoop install sudo --global
sudo scoop install kopia --global

Kopia in Docker

Files and directory structure

/mnt/
└── mirror/
    
/home/
└── ~/
    └── docker/
        └── kopia/
            ├── kopia_config/
            ├── kopia_cache/
            ├── kopia_logs/
            ├── some_data/
            ├── kopia_repository/
            ├── kopia_tmp/
            ├── .env
            └── docker-compose.yml

/mnt/mirror/... - a mounted network storage share
kopia_config/ - repository.config and ui-preferences.json
kopia_cache/ - cache
kopia_logs/ - logs
some_data/ - some data to be backed up
kopia_repository/ - repository location
kopia_tmp/ - temp used for snapshots
.env - a file containing environment variables for docker compose
docker-compose.yml - a docker compose file, telling docker how to run the containers

docker-compose

The data to be backed up are mounted in read only mode.
To be able to mount snapshots, extra privileges are required and fuse access.

services:

  kopia:
    image: kopia/kopia:latest
    container_name: kopia
    hostname: kopia
    restart: unless-stopped
    env_file: .env
    privileged: true
    cap_add:
      - SYS_ADMIN
    security_opt:
      - apparmor:unconfined
    devices:
      - /dev/fuse:/dev/fuse:rwm
    ports:
      - "51515:51515"
    command:
      - server
      - start
      - --tls-generate-cert
      - --disable-csrf-token-checks
      - --address=0.0.0.0:51515
      - --server-username=$USERNAME
      - --server-password=$KOPIA_PASSWORD
    volumes:
        # Mount local folders needed by kopia
        - ./kopia_config:/app/config
        - ./kopia_cache:/app/cache
        - ./kopia_logs:/app/logs
        # Mount local folders to snapshot
        - ./some_data:/data:ro
        # Mount repository location
        - /mnt/mirror/kopia_repository:/repository
        # Mount path for browsing mounted snaphots
        - ./kopia_tmp:/tmp:shared

networks:
  default:
    name: $DOCKER_MY_NETWORK
    external: true

.env

DOCKER_MY_NETWORK=caddy_net
TZ=Europe/Bratislava

# KOPIA
USERNAME=admin
KOPIA_PASSWORD=aaa

All containers must be on the same network.
Which is named in the .env file.
If one does not exist yet: docker network create caddy_net

Reverse proxy

Caddy is used, details here.

To function as a repository server, Kopia must be setup with https, which is achieved by using --tls-generate-cert flag and removal of --insecure flag.

So now Kopia sits behind Caddy, but caddy needs to be told the traffic is https and to ignore that the certificate is not valid.

Caddyfile

kopia.{$MY_DOMAIN} {
  reverse_proxy kopia:51515 {
    transport http {
      tls
      tls_insecure_skip_verify
    }
  }
}

First run

visit kopia.example.com
create new repository as Local Directory or NAS, set path to /repository, set password

Now this container can do backups of mounted stuff in to other mounted places or cloud, while managed through webgui.

To also make it function as a repository server a user account needs to be added. The users are stored in the repo.

exec in to the container
docker container exec -it kopia /bin/bash
add user@machine and set the password
kopia server user add user1@machine1
on another machine test with koppiaUI, on the first run:
- Pick Kopia Repository Server
- Server address: https://kopia.example.com:443
- Trusted server certificate fingerprint (SHA256)
  can be left empty, or if you put something there, it gives you error where it tells you fingerprints of the server to pick from.
- In advanced option one can override user@machine with the one set when exec-ed in to the docker container. Or exec again there and add another one.

Troubleshooting

check kopia docker container logs, I like using ctop
nslookup kopia.example.com check if you are getting to you server from client
Make sure you use port 443 in server address.