This specification defines the QUERY method for HTTP. A QUERY requests that the request target process the enclosed content in a safe and idempotent manner and then respond with the result of that processing. This is similar to POST requests but can be automatically repeated or restarted without concern for partial state changes.

Sledování volebních výsledků Poslanecké sněmovny ČR 2025 v reálném čase. Výsledky Pirátů, Demoblok vs Temnoblok.

@zachleat@zachleat.com Because software in this context usually means a highly complex system and as such it needs to fulfill a lot of requirements. Only a single purpose thing can be done exceptionaly good. With each additional requirement rises the probability of inevitable trade-offs that make the overal appearance "not good". Note that we often don't realize or acknowledge all the requirements on software that it needs to fulfill because they seem secondary or non-functional.

~/.ssh/authorized_keys allows you to specify the command run by the incoming ssh connection. I was searching for a previous blog post to give you some background. I failed. I backup my Bacula database and my Bacula configuration via rsync. These backups go to more than one host. The following are lines from ~rsyncer/.ssh/authorized-keys on my dbclone host – which gathers database backups from various hosts. from="x8dtu.example.org,10.1.1.1",command="/usr/local/sbin/rrsync -ro /usr/home/rsyncer/backups/bacula-database/postgresql/" ssh-ed25519 AAAAC3thisisalsonotmyrealpublickeybcxpFeUMAC2LOitdpRb9l0RoW7vt5hnzwt rsyncer@x8dtu.example.org The above appears on two lines to make it easier to read without horizontal scrolling – in the file, it’s all on one line. This says: * when an ssh connection comes in from a client at x8dtu.example.org, or 10.1.1.1 * run /usr/local/sbin/rrsync -ro /usr/home/rsyncer/backups/bacula-database/postgresql/ * and that client must have this key (as shown) * rsyncer@x8dtu.example.org is a comment, and has no effect What does /usr/local/sbin/rrsync -ro /usr/home/rsyncer/backups/bacula-database/postgresql/ do? See man rrsync, a program supplied with rsync. In short it is “script to setup restricted rsync users via ssh logins”. It means the incoming client can only rsync from the specified path /usr/home/rsyncer/backups/bacula-database/postgresql/ and that the session is ro (read-only). This is a great feature. Given that these passphraseless ssh-keys allow access to a rather important system (it has all the database backups), imposing such restrictions seems a good idea. This works well for transferring the Bacula database back from dbclone over to x8dtu. Now, what if I want to copy a different database backup in the other direction, from x8dtu to dbclone? I have previously decided that dbclone is a pull-only host. That is nobody can push data to it. My solution: the command specified in ~/.ssh/authorized keys initiates an rsync on dbclone, pulling data from x8dtu. That script looks something like this. [rsyncer@dbclone ~]$ cat /home/rsyncer/bin/rsync-backup-from-x8dtu.sh #!/bin/sh # # This file does a backup of each database on the server. # It relies upon a file on the server to do the actual backup, # then uses rsync to copy the files from the server to here. # # the ~/.ssh/authorized keys entry on the server must look like this: # # from="10.55.0.140",command="/usr/local/sbin/rrsync /usr/home/backups/" [ssh key goes here] # # invoking rrsync ensures the incoming rsync process is chrooted to /usr/home/dan/backups/ # Thus, BACKUPDIR is relative to that location. BACKUPDIR=${HOME}/backups/x8dtu-pg01/database-backup IDENTITY_FILE_RSYNC=${HOME}/.ssh/id_ed25519 SERVER_TO_RSYNC=x8dtu.example.org cd ${BACKUPDIR} # # use rsync to get local copies # /usr/local/bin/rsync -e "/usr/bin/ssh -i ${IDENTITY_FILE_RSYNC}" --recursive -av --stats --progress --exclude 'archive' ${SERVER_TO_RSYNC}:/ ${BACKUPDIR} Great. Now all I need to do is add another entry into authorized_keys on dbclone, resulting in something like this: from="x8dtu.example.org,10.1.1.1",command="/usr/local/sbin/rrsync -ro /usr/home/rsyncer/backups/bacula-database/postgresql/" ssh-ed25519 AAAAC3thisisalsonotmyrealpublickeybcxpFeUMAC2LOitdpRb9l0RoW7vt5hnzwt rsyncer@x8dtu.example.org from="x8dtu.startpoint.vpn.unixathome.org,10.8.1.100",command="/home/rsyncer/bin/rsync-backup-from-x8dtu.sh" ssh-ed25519 AAAAC3thisisalsonotmyrealpublickeybcxpFeUMAC2LOitdpRb9l0RoW7vt5hnzwt rsyncer@x8dtu.example.org Here’s the problem. Both lines can’t run. Only one will run. The incoming ssh key will match, and that command will be run. Instead. I added a second ssh key: [rsyncer@x8dtu ~/.ssh]$ ssh-keygen -t ed25519 -f id_ed25519.rsync.bacula ... I modified the above script to use that key: IDENTITY_FILE_RSYNC=${HOME}/.ssh/id_ed25519.rsync.bacula Next, I modified authorized_keys on dbclone to refer to the new public key (again, I’ve added newlines in here so you don’t have to scroll): from="x8dtu.example.org,10.1.1.1",command="/usr/local/sbin/rrsync -ro /usr/home/rsyncer/backups/bacula-database/postgresql/" ssh-ed25519 AAAAC3thisisalsonotmyrealpublickeybcxpFeUMAC2LOitdpRb9l0RoW7vt5hnzwt rsyncer@x8dtu.example.org from="x8dtu.startpoint.vpn.unixathome.org,10.8.1.100",command="/home/rsyncer/bin/rsync-backup-from-x8dtu.sh" ssh-ed25519 AAAAC3thisisthesecondsshkeypKBYib6rCHZ+zK5Q3LvJFukdFzT+Q92GUtej6SLW8 rsyncer@x8dtu.example.org This works. It means that for each task to be carried out, I need a different ssh key. However, so far, there are just two tasks. Hope this helps.