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120 lines
5.1 KiB
Markdown
120 lines
5.1 KiB
Markdown
# Default Service Configuration
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## Pseudo Services
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The default configuration contains a number of "pseudo services" in the boot
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target that don't actually do anything but are merely used as anchors in
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service dependencies, i.e. they indicate that some sort of milestone in the
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boot sequence has been reached. Everything that is part of that milestone
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specifies that it should be run *before* that pseudo service and everything
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that requires that this milestone has been reached, specifies that it wants
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to run afterwards.
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The pseudo targets are (in the order that they are executed):
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* vfs
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All services that do mount point setup go before this, all service that
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depend on the fully mounted rootfs go after this.
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* sysinit
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The system has reached a sane state, i.e. the hostname is set, the system
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clock has a sane value, modules and kernel parameters are loaded, some
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very basic, fundamental services are running.
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Everything that is part of that setup process goes between `vfs` and
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`sysinit`, everything that requires a sane setup goes *after* `sysinit`.
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* network
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Network configuration is done. All services that do network configuration
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should position themselves between `sysinit` and `network`. Everything that
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requires a fully configured networking setup should go *after* `network`.
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## Default Bootup Services
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This section outlines the services for the boot target that are enabled by
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default.
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The following services are enabled by default and run *before* the `vfs` target
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for filesystem setup:
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* procfs - mount `procfs` to `/proc` and try to mount additional pseudo
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filesystems in `/proc` such as `binfmt_misc`
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* tmpfs - mount a `tmpfs` to `/tmp`
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* sysfs - mount `sysfs` to `/sys` and try to mount additional pseudo
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filesystems in `/sys` (e.g. `securityfs`, `configfs`, ...)
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* devfs - mount `devtmpfs` to `/dev`, try to mount additional pseudo
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filesystems in `/dev` (e.g. `devpts`, `mqueue`, ...) and try to create
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some additional device nodes and symlinks.
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* tmpfsvar - mount a `tmpfs` to `/var` and populate it with a default set
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of files and directories. Overlay mount `/var/lib` with lower dir on
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`/cfg/preserve/var_lib/` and upper on `/cfg/overlay/var_lib/`.
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* tmpfsrun - mount a `tmpfs` to `/run`, symlink `/var/run` to `/run` and
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`/var/lock` to `/run/lock`.
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* mountusr - overlay mount setup for `/usr`. Lower dir is on
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`/cfg/preserve/usr/` and upper on `/cfg/overlay/usr/`.
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The following services are enabled by default and configured to run *after*
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the `vfs` target and *before* the `sysinit` target:
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* hostname - reload hostname `/etc/hostname`
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* loopback - bring the loopback device up
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* modules - iterate over the file `/etc/modules` and try to load each module
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using modprobe.
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* sysctl - restore kernel parameters using `sysctl --system`. See `sysctl(8)`
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for a list of possible locations that the parameters are read from.
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* usyslogd - Starts and supervises the `usyslogd` syslog implementation.
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* klogd - Starts and supervises the `klogd` daemon.
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The following services are enabled by default and configured to run *after*
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the `sysinit` target and *before* the `network` target:
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* ifcfg - static network configuration
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Does the static network configuration outlined in [network.md](network.md)
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The following services are enabled by default and configured to run *after*
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the `network` target:
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* gcrond
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## Default Shutdown and Reboot Services
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For the shutdown and reboot targets, the following services are executed:
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* sigterm - send the SIGTERM signal to all processes and wait for 5 seconds
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* sigkill - send the SIGKILL signal to all remaining processes
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* ifdown - bring all network interfaces down
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* sync - run the sync command
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## Additional Services not Enabled by Default
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* agetty - A parameterizeable, respawn type `agetty` service. The first
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parameter is the terminal device that the getty should run on.
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* consolefont - If enabled, run once before sysinit. Sets the console font
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to the first parameter.
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* dhcpcdmaster - If one or more network interfaces should be configured using
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dhcpcd, this service starts a central `dhcpcd` master instance.
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* dhcpcd - A parameterizeable single shot service that signals the `dhcpcd`
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master that it should configure a specific interface. The first parameter
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is the interface that should be configured by `dhcpcd`.
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* dnsmasq - A respawn type service for the `dnsmasq` DNS and DHCP server.
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* hostapd - If the system should operate a WIFI access point, this respawn
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type service can be enabled to manage an instace of the `hostapd` program.
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* unbound - A respawn type service that manages an instance of the `unbound`
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name resolver.
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* hwclock - If the system has a hardware clock, this service can restore the
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kernels clock from the hardware at bootup, between the `vfs` and `sysinit`
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targets.
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* nft - If enabled, restores net filter table rules during boot.
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* sshd_keygen - A wait type service that generates host keys for the OpenSSH
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server and then disables itself.
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* sshd - Starts an OpenSSH server after the network pseudo service and after
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the sshd_keygen service.
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* nginx - Starts the Nginx server after the network pseudo serivce.
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