Commit e516aebc authored by W. Mark Kubacki's avatar W. Mark Kubacki

Merge pull request #817 from mholt/systemd-service-file

Provides some more guidelines to operators on how to avoid running Caddy as root.

Introduces an user www-data, which really is a placeholder. Such an user with the same UID/GID combination is created on the most popular Linux distribution. I trust any operator can spot the difference to his/her distro and adjust the unit file.

User nobody is not used here to avoid two easy pitfalls: Such an user should not be able to access private keys (for TLS), and should not write private keys (we would do that with Letsencrypt).
parents 389a6eb3 da8ae9e5
# systemd unit for caddy # systemd unit for caddy
Please do not hesitate to ask [me](mailto:klingt.net+caddy@gmail.com) if you've any questions. Please do not hesitate to ask if you have any questions.
## Quickstart ## Quickstart
- install the unit configuration file: `cp caddy@.service /etc/systemd/system` The provided unit file assumes that you want to run caddy as `www-data` and group `www-data`,
- reload the systemd daemon: `systemctl deamon-reload` both having UID and GID 33 here.
- make sure to [configure](#configuration) the service unit before starting caddy Adjust this to your liking according to the preferences of you Linux distribution!
- start caddy: `systemctl start caddy@someuser`
- enable the service (automatically start on boot): `systemctl enable caddy@someuser` ```bash
- the `.caddy` folder will be created inside the users home directory that runs caddy, i.e. `/home/someuser/.caddy` for `systemctl start caddy@someuser` groupadd -g 33 www-data
useradd \
-g www-data --no-user-group \
--home-dir /var/www --no-create-home \
--shell /usr/sbin/nologin \
--system --uid 33 www-data
mkdir /etc/caddy
chown -R root:www-data /etc/caddy
mkdir /etc/ssl/caddy
chown -R www-data:root /etc/ssl/caddy
chmod 0770 /etc/ssl/caddy
```
- Install the unit configuration file: `cp caddy.service /etc/systemd/system/`
- Reload the systemd daemon: `systemctl daemon-reload`
- Make sure to [configure](#configuration) the service unit before starting caddy.
- Start caddy: `systemctl start caddy.service`
- Enable the service (automatically start on boot): `systemctl enable caddy.service`
- A folder `.caddy` will be created inside the home directory of the user that runs caddy;
you can change that by providing an environment variable `HOME`,
i.e. `Environment=HOME=/var/lib/caddy` will result in `/var/lib/caddy/.caddy`.
## Configuration ## Configuration
- do not edit the systemd unit directly, use systemd's builtin tools: - Do not edit the systemd unit file directly. Instead, use systemd's builtin tools:
- `systemctl edit caddy@` to make user local modifications to the service unit - `systemctl edit caddy.service` to make user-local modifications
- `systemctl edit --full caddy@` to make system-wide modifications - `systemctl edit --full caddy.service` for system-wide ones
- in most cases it's enough to adapt the `ExecStart` directive: - In most cases it is enough to override the `ExecStart` directive.
- `systemctl edit caddy@` - systemd needs absolute paths, therefore make sure that the path to caddy is correct.
- systemd needs absolute paths, therefore make sure that the path to caddy is correct
- example: - example:
```ini ```ini
[Service] [Service]
; reset the original setting ; an empty value clears the original (and preceding) settings
ExecStart= ExecStart=
ExecStart=/usr/bin/caddy -conf="/etc/caddy/myCaddy.conf" -agree -email="my@mail.address" ExecStart=/usr/bin/caddy -conf="/etc/caddy/myCaddy.conf" -agree -email="my@mail.address"
``` ```
- to view your configuration use `systemctl cat caddy@` - To view the resulting configuration use `systemctl cat caddy`
- double check the permissions of your web root path to make sure that caddy can access it as its run user and group - Double check permissions of your *document root* path.
The user caddy runs as needs to have access to it. For example:
```bash
# caddy would run as www-data:www-data
# serving, in this example: /var/www
sudo -u www-data -g www-data -s \
ls -hlAS /var/www
```
## Tips ## Tips
- use `log stdout` and `errors stderr` in your Caddyfile to make use of `journalctl` - Use `log stdout` and `errors stderr` in your Caddyfile to utilize `journalctl`.
- `journalctl` is systemd's log query tool - `journalctl` is systemd's log query tool.
- lets say you want all the log entries for caddy since the last boot beginning from the last entry: `journalctl --reverse --boot --unit caddy@someuser` - Let's say you want all the log entries since the last boot, beginning from the last entry:
- maybe you want to follow caddys log output: `journalctl -fu caddy@someuser` `journalctl --reverse --boot --unit caddy.service`
- to send a signal to a service units main PID, e.g. let caddy reload its config: `systemctl kill --signal=USR1 caddy@someuser` - To follow caddy's log output: `journalctl -fu caddy.service`
- Send a signal to a service unit's main PID, e.g. have caddy reload its config:
`systemctl kill --signal=USR1 caddy.service`
- If you have more files that start with `caddy` – like a `caddy.timer`, `caddy.path`, or `caddy.socket` – then it is important to append `.service`.
Although if `caddy.service` is all you have, then you can just use `caddy` without any extension, such as in: `systemctl status caddy`
- You can make your other certificates and private key files accessible to a user `www-data` by command `setfacl`, if you must:
```bash
setfacl -m user:www-data:r-- /etc/ssl/private/my.key
```
[Unit]
Description=Caddy HTTP/2 web server
Documentation=https://caddyserver.com/docs
After=network-online.target
Wants=network-online.target systemd-networkd-wait-online.service
[Service]
Restart=on-failure
; User and group the process will run as.
User=www-data
Group=www-data
; Letsencrypt-issued certificates will be written to this directory.
Environment=HOME=/etc/ssl/caddy
; Always set "-root" to something safe in case it gets forgotten in the Caddyfile.
ExecStart=/usr/bin/caddy -log stdout -agree=true -conf=/etc/caddy/Caddyfile -root=/var/tmp
ExecReload=/bin/kill -USR1 $MAINPID
; Limit the number of file descriptors; see `man systemd.exec` for more limit settings.
LimitNOFILE=1048576
; Unmodified caddy is not expected to use more than that.
LimitNPROC=64
; Use private /tmp and /var/tmp, which are discarded after caddy stops.
PrivateTmp=true
; Use a minimal /dev
PrivateDevices=true
; Hide /home, /root, and /run/user. Nobody will steal your SSH-keys.
ProtectHome=true
; Make /usr, /boot, /etc and possibly some more folders read-only.
ProtectSystem=full
; … except /etc/ssl/caddy, because we want Letsencrypt-certificates there.
; This merely retains r/w access rights, it does not add any new. Must still be writable on the host!
ReadWriteDirectories=/etc/ssl/caddy
; Drop all other capabilities. Important if you run caddy as privileged user (which you should not).
CapabilityBoundingSet=CAP_NET_BIND_SERVICE
; … but permit caddy to open ports reserved for system services.
; This could be redundant here, but is needed in case caddy runs as nobody:nogroup.
AmbientCapabilities=CAP_NET_BIND_SERVICE
; … and prevent gaining any new privileges.
NoNewPrivileges=true
; Caveat: Some plugins need additional capabilities. Add them to both above lines.
; - plugin "upload" needs: CAP_LEASE
[Install]
WantedBy=multi-user.target
; see `man systemd.unit` for configuration details
; the man section also explains *specifiers* `%x`
[Unit]
Description=Caddy HTTP/2 web server %I
Documentation=https://caddyserver.com/docs
After=network-online.target
Wants=network-online.target
Wants=systemd-networkd-wait-online.service
[Service]
; run user and group for caddy
User=%i
Group=http
ExecStart=/usr/bin/caddy -agree=true -conf=/etc/caddy/Caddyfile
Restart=on-failure
; create a private temp folder that is not shared with other processes
PrivateTmp=true
; limit the number of file descriptors, see `man systemd.exec` for more limit settings
LimitNOFILE=8192
[Install]
WantedBy=multi-user.target
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