s6-dns: the s6-dns-hosts-compile program

From 5dc54a39e47148803d950d2facb42500e08f4769 Mon Sep 17 00:00:00 2001 From: Laurent Bercot Date: Mon, 3 Jul 2023 18:57:42 +0000 Subject: Add s6-dns-hosts-compile, prepare for 2.3.6.0 Signed-off-by: Laurent Bercot --- doc/index.html | 5 +-- doc/s6-dns-hosts-compile.html | 75 +++++++++++++++++++++++++++++++++++++++++++ doc/upgrade.html | 2 +- 3 files changed, 79 insertions(+), 3 deletions(-) create mode 100644 doc/s6-dns-hosts-compile.html (limited to 'doc') diff --git a/doc/index.html b/doc/index.html index 49bb4c7..5d27705 100644 --- a/doc/index.html +++ b/doc/index.html @@ -72,7 +72,7 @@ requirement if you link against the shared version of the skalibs library.

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The current released version of s6-dns is 2.3.5.6.
The current released version of s6-dns is 2.3.6.0.
Alternatively, you can checkout a copy of the s6-dns git repository: @@ -147,7 +147,8 @@ relevant page.
Miscellaneous utilities
diff --git a/doc/s6-dns-hosts-compile.html b/doc/s6-dns-hosts-compile.html new file mode 100644 index 0000000..c499ded --- /dev/null +++ b/doc/s6-dns-hosts-compile.html @@ -0,0 +1,75 @@ + + + + + + s6-dns: the s6-dns-hosts-compile program + + + + + + +
+s6-dns
+Software
+skarnet.org +
+ +
The s6-dns-hosts-compile program
+ +
+ s6-dns-hosts-compile compiles the system's /etc/hosts file into a +CDB file for more efficient later use by s6-dns programs that may use the +data contained in the hosts file. +
+ +
Interface
+ +
```
+     s6-dns-hosts-compile [ -i ifile ] [ -o ofile ]
+
```
+ +
- s6-randomip reads the /etc/hosts file, which must follow the +traditional hosts format.
- It outputs a CDB database in the /etc/hosts.cdb file.
- It exits 0.
+ +
Options
+ +
- -i ifile : read from ifile instead of /etc/hosts.
- -o ofile : write to ofile instead of /etc/hosts.cdb.
+ +
Notes
+ +
- The /etc/hosts file is an old way of specifying IP from/to domain +name correspondences. It's convenient in a pinch when a user needs to locally +override DNS data - for instance, to redirect common advertising sites to 127.0.0.1 - +but it does not map exactly to the DNS view of domain names.
- Due to this, and to its line-by-line text syntax, lookups using this file +are terribly inefficient and rely on approximate qualification heuristics.
- To avoid that, s6-dns tools prefer having the /etc/hosts data in +a format that's both more DNS-like and more efficient; the file output by +s6-dns-hosts-compile is the result.
- When asked to take /etc/hosts data into account, s6-dns tools will +first look for a /etc/hosts.cdb file and use the data from it. If +absent, they will read the /etc/hosts file and compile its contents +into a temporary cdb file under /tmp (which they immediately unlink), +and use that cdb to query hosts data.
- As a consequence, lookups are always efficient, but there's an initial +compilation step. Using s6-dns-hosts-compile to produce a /etc/hosts.cdb +file in advance saves the cost of that compilation step in subsequent +invocations of s6-dns tools.
- If s6-dns tools detect that /etc/hosts has been modified more recently +than /etc/hosts.cdb, they will not use /etc/hosts.cdb and will +perform the compilation step into a temporary file. So, remember to run +s6-dns-hosts-compile after modifying your /etc/hosts.
+ + + diff --git a/doc/upgrade.html b/doc/upgrade.html index 29db742..1fe84e6 100644 --- a/doc/upgrade.html +++ b/doc/upgrade.html @@ -18,7 +18,7 @@
What has changed in s6-dns
-
in 2.3.5.6
+
in 2.3.6.0
- skalibs -- cgit v1.2.3

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Miscellaneous utilities

The s6-dns-hosts-compile program

Interface

Options

Notes

What has changed in s6-dns

in 2.3.5.6

in 2.3.6.0