1 21dc3794 2022-01-28 op # gmid quickstart guide
3 0111ad5d 2021-10-09 op gmid can be run in two different “modes”:
5 0111ad5d 2021-10-09 op * configless: a quick way to serve a directory tree from the shell, useful for testing a capsule before uploading it
6 0111ad5d 2021-10-09 op * daemon mode: gmid reads the configuration file and runs in the background
8 0111ad5d 2021-10-09 op To run gmid in the “configless” mode, just type:
10 0111ad5d 2021-10-09 op ```serve a directory tree from the shell
11 0111ad5d 2021-10-09 op $ gmid path/to/dir
14 540d05de 2021-10-09 op gmid will then generate a certificate inside ~/.local/share/gmid and serve the given directory locally.
16 fc4b58d4 2021-10-11 op ## Setting up a capsule with gmid
18 c57dc42b 2022-01-05 op To host a Gemini capsule you need to run gmid in “daemon” mode, and so a configuration file is needed. The format of the configuration file is described in the manpage and is quite flexible, but something like the following should be enough to start:
20 0111ad5d 2021-10-09 op ```sample configuration file
21 0111ad5d 2021-10-09 op # /etc/gmid.conf
23 0111ad5d 2021-10-09 op server "example.com" {
24 33c4c3a5 2021-10-13 op cert "/etc/ssl/example.com.pem"
25 33c4c3a5 2021-10-13 op key "/etc/ssl/private/example.com.key"
27 33c4c3a5 2021-10-13 op # path to the root directory of your capsule
28 0111ad5d 2021-10-09 op root "/var/gemini/example.com"
32 33c4c3a5 2021-10-13 op A certificate is needed for the capsule. Generate one for e.g. using contrib/gencert:
34 0111ad5d 2021-10-09 op => https://git.omarpolo.com/gmid/tree/contrib/gencert contrib/gencert
36 0111ad5d 2021-10-09 op ```generate a certificate using contrib/gencert
37 0111ad5d 2021-10-09 op $ ./contrib/gencert example.com
38 0111ad5d 2021-10-09 op Generating a 4096 bit RSA private key
39 0111ad5d 2021-10-09 op .................................................++++
40 0111ad5d 2021-10-09 op ..........++++
41 0111ad5d 2021-10-09 op writing new private key to './example.com.key'
44 0111ad5d 2021-10-09 op Generated files:
45 0111ad5d 2021-10-09 op ./example.com.pem : certificate
46 0111ad5d 2021-10-09 op ./example.com.key : private key
49 33c4c3a5 2021-10-13 op Move ‘example.com.pem’ and ‘example.com.key’ to a safe place and double check that the ‘cert’ and ‘key’ options in the configuration points to these files.
51 33c4c3a5 2021-10-13 op For example, save them in ‘/etc/ssl/’ (as root)
53 33c4c3a5 2021-10-13 op ```how to save the certificate and private key in /etc/ssl
54 33c4c3a5 2021-10-13 op # mkdir -p /etc/ssl/private
55 33c4c3a5 2021-10-13 op # chown 700 /etc/ssl/private
56 33c4c3a5 2021-10-13 op # mv example.com.pem /etc/ssl/
57 33c4c3a5 2021-10-13 op # mv example.com.key /etc/ssl/private/
60 0111ad5d 2021-10-09 op Then running gmid is as easy as
62 0111ad5d 2021-10-09 op ```running gmid
63 0111ad5d 2021-10-09 op $ gmid -c /etc/gmid.conf
66 fc4b58d4 2021-10-11 op Congratulations, your capsule is online!
69 0111ad5d 2021-10-09 op ## Securing your gmid installation
71 0111ad5d 2021-10-09 op gmid employs various techniques to prevent the damage caused by bugs, but some steps needs to be done manually.
73 33c4c3a5 2021-10-13 op If gmid was installed from your distribution package manager, chance are that it already does all of this and is also providing a service to run gmid automatically (e.g. a rc script, a systemd unit file, …) Otherwise, it’s heavily suggested to create at least a dedicated user.
76 0111ad5d 2021-10-09 op ### A dedicated user
78 fc4b58d4 2021-10-11 op Ideally, gmid should be started as root and drop privileges to a local user. This way, the certificates can be readable only by root. For example, on GNU/linux systems a ‘gmid’ user can be created with:
80 0111ad5d 2021-10-09 op ```how to create the gmid user
81 35340c9f 2021-10-09 op # useradd --system --no-create-home -s /bin/nologin -c "gmid Gemini server" gmid
84 0111ad5d 2021-10-09 op Please consult your OS documentation for more information on the matter.
86 0111ad5d 2021-10-09 op The configuration then needs to be adjusted to include the ‘user’ directive at the top:
88 0111ad5d 2021-10-09 op ```how to use the ‘user’ option
89 0111ad5d 2021-10-09 op # /etc/gmid.conf
92 0111ad5d 2021-10-09 op server "example.com" { … }
95 fc4b58d4 2021-10-11 op gmid then needs to be started with root privileges, but will then switch to the provided user automatically. If by accident the ‘user’ option is omitted and gmid is running as root, it will complain loudly in the logs.
100 0111ad5d 2021-10-09 op It’s a common practice for system daemons to chroot themselves into a directory. From here on I’ll assume /var/gemini, but it can be any directory.
102 fc4b58d4 2021-10-11 op A chroot on UNIX-like OS is an operation that changes the “apparent” root directory (i.e. the “/”) from the current process and its child. Think of it like imprisoning a process into a directory and never letting it escape until it terminates.
104 fc4b58d4 2021-10-11 op Using a chroot may complicate the use of CGI scripts, because then all the dependencies of the scripts (sh, perl, libraries…) need to be installed inside the chroot too. For this very reason gmid supports FastCGI.
106 0111ad5d 2021-10-09 op The chroot feature requires a dedicate user, see the previous section.
108 0111ad5d 2021-10-09 op To chroot gmid inside a directory, use the ‘chroot’ directive in the configuration file:
110 0111ad5d 2021-10-09 op ```how to use the ‘chroot’ option
111 0111ad5d 2021-10-09 op # /etc/gmid.conf
115 0111ad5d 2021-10-09 op # the given directory, /var/gemini in this case, must exists.
116 0111ad5d 2021-10-09 op chroot "/var/gemini"
119 0111ad5d 2021-10-09 op Note that once ‘chroot’ is in place, every ‘root’ directive is implicitly relative to the chroot, but ‘cert’ and ‘key’ aren’t!
121 0111ad5d 2021-10-09 op For example, given the following configuration:
123 0111ad5d 2021-10-09 op ```example configuration using chroot
124 0111ad5d 2021-10-09 op # /etc/gmid.conf
127 0111ad5d 2021-10-09 op chroot "/var/gemini"
129 0111ad5d 2021-10-09 op server "example.com" {
130 0111ad5d 2021-10-09 op cert "/etc/ssl/example.com.pem"
131 0111ad5d 2021-10-09 op key "/etc/ssl/example.com.key"
132 0111ad5d 2021-10-09 op root "/example.com"
136 0111ad5d 2021-10-09 op The certificate and the key path are the specified ones, but the root directory of the virtual host is actually “/var/gemini/example.com/”.
