spalling mostly

[rrq/overlay-boot.git] / overlay-boot.8.adoc

diff --git a/overlay-boot.8.adoc b/overlay-boot.8.adoc
index 9646ee2ac49e81ed201b3b719788341ba725750f..e97a8e4676cad9d8da15cc23f55f5469923e9ce0 100644 (file)
--- a/overlay-boot.8.adoc
+++ b/overlay-boot.8.adoc
@@ -24,7 +24,7 @@ an overlay of the main host filesystem to keep the specifics of a
 service distinctly separate from the main host while sharing files
 wherever sensible.
 
-A subhost is started by identifyinf its configuration file on the
+A subhost is started by identifying its configuration file on the
 command line for *overlay-boot*. The configuration file is a plain
 text file with a small collection of "variables" that tell how the
 subhost is set up. When all is good, *overlay-boot* spawns a
@@ -34,7 +34,7 @@ odd computer.
 
 The subhost execution environment may be "entered" to perform
 adminstrative tasks with *overlay-go*, and it is later stopped with
-*overlay-stop*.
+*overlay-stop*. 
 
 OPTIONS
 -------
@@ -71,7 +71,7 @@ section on Networking below for more details.
 
 INIT::
 
-This variable is a command line to run, with envirnment variable
+This variable is a command line to run, with environment variable
 CONFIG set, for producing the initial commands to the running subhost,
 similar to the initrd phase of a computer bootup. The default value
 for this variable is +overlay-init+.
@@ -100,17 +100,21 @@ as UPPER.
 
 *POSTMOUNT*::
 
-This variable is a command line to run, with envirnment variable
+This variable is a command line to run, with environment variable
 CONFIG set, just after the setup of the subhost root filesystem and
 before the services are started. The default for this variable is
-+overlay-postmount+
++overlay-postmount+. Note that this command is executed within the
+mount namespace of the subhost, and still with the main host as root
+filesystem.
 
 *PREMOUNT*::
 
-This variable is a command line to run, with envirnment variable
+This variable is a command line to run, with environment variable
 CONFIG set, just before the setup of the subhost root filesystem and
 before the services are started. The default for this variable is
-+overlay-premount+
++overlay-premount+  Note that this command is executed within the
+mount namespace of the subhost, and still with the main host as root
+filesystem.
 
 *UPPER*::
 
@@ -123,8 +127,8 @@ as an overlay mount. In that case WORK (below) must be defined as a
 directory outside of but on the same mount as UPPER.
 +
 If UPPER is the same as LOWER, then the subhost root filesystem is not
-setup as an overla. Rather it is set up as a bind mount, if UPPER is
-different from LIVE, or just as a pre-mounted LIVE filesystem.
+setup as an overlay. It Is rather set up either as a bind mount if UPPER is
+different from LIVE, or just taken as a pre-mounted LIVE filesystem.
 
 *WORK*::
 
@@ -151,16 +155,16 @@ defult gets mounted on an overlay mount as a +tmpfs+ of 50M. Use
 Networking
 ----------
 
-*overlay-boot* sets up a nework namespace named by the subhost NAME,
-and uses the CABLES variable to set up +veth+ virtual cables. The host
-end of such cables are named by NAME followed by a number from 0 and
-up while the subhost end are named by +eth+ followed by the same
-number.
+*overlay-boot* sets up a nework namespace named by the subhost
++$NAME+, and uses the +$CABLES+ variable to set up +veth+ virtual
+cables. The host end of such cables are named by +$NAME+ followed by a
+number from 0 and up while the subhost end are named by +eth+ followed
+by the same number.
 
-As mentioned above, CABLES consists of a space separated list of cable
-specifiers, each consisting of a bridge interface name and a with an
-equal sign ("=") between them. The equal sign is required while either
-or both of the bridge and MAC address may be left empty.
+As mentioned above, +$CABLES+ consists of a space separated list of
+cable specifiers, each consisting of a bridge interface name and a
+with an equal sign ("=") between them. The equal sign is required
+while either or both of the bridge and MAC address may be left empty.
 
 The bridge interface name, if given, will be given control of the host
 end cable interface. A cable specification with empty bridge name part
@@ -180,7 +184,7 @@ EXAMPLES
 ----
 BASE=.
 CABLES= =
-START= rsyslog networking ssh postfix
+START= rsyslog networking ssh saslauthd postfix dovecot
 ----
 ****
 
@@ -194,5 +198,26 @@ and the main host end is named +mta0+, and upon start, an +ifup mta0+
 is attempted at the host end while the subhost end is handled via its
 neworking service.
 
+./opt/subhost/tiny/tiny.conf
+****
+----
+BASE=.
+CABLES= =
+START= none
+LOWER=!mkdir -p base work root live ; echo base
+WORK= work
+UPPER= root
+LIVE= live
+----
+****
 
+The +tiny+ subhost would be for overlaying a separate +debootstrap+
+root filesystem, without any services (since +START+ is empty). This
+gets started with a +dummy_service+ to hold the overlay for access via
++overlay-go+. The +dummy_service+ sets up and listens on a pipe at
++/run/dummy_service+, and exits when anything is written to that.
+
+SEE ALSO
+--------
 
+*overlay-stop*, *overlay-go*