Apt-cacher uses a configuration file for setting important options. Additionally there are few command
line options to control behaviour. See COMMAND-LINE OPTIONS above.
The default configuration file is /etc/apt-cacher/apt-cacher.conf. It is read every time the daemon
starts or an inetd/CGI instance is executed. Therefore a stand-alone daemon may need to be restarted or
reloaded using the init script in order to reread its configuration. A running daemon will also reread
the configuration file on receiving SIGHUP (see SIGNALS below).
As an alternative to editing the configuration file, configuration fragments to override the defaults can
also be placed in a directory named conf.d in the same directory as the main configuration file, e.g.
'/etc/apt-cacher/conf.d/'. Files placed here can have an arbitrary name. They are read using glob(7)
semantics: case-insensitive, ascending ASCII order; dot-files (beginning with '.') ignored. Also, backup
files ending with '~' and any files ending with ´.disabled' or '.dpkg-{old,new,dist,tmp}' are also
ignored. Duplicate settings read later will override any previous ones.
Each line in the file consists of
configuration_option = value
Long lines can be split by preceding the newlines with '\'. Whitespace is ignored. Lines beginning with
'#' are comments and are ignored. If multiple assignments of the same option occur, only the last one
will take effect. For binary options, 0 means off or disabled, any other integer means on or enabled.
Options which can accept lists may use either ';' or ',' to separate the individual list members. To
include these separators within a list item escape them with '\'.
The options available in the config file (and their default settings) are:
UniversalOptionsadmin_email[root@localhost]
The email address of the administrator is displayed in the info page and traffic reports.
allowed_locations
Only allow access to specific upstream mirrors. The requested URL must match an item in this list
for access to be granted. The part of the URL referring to the apt-cacher server itself
(http://apt-cacher.server:port[/apt-cacher]/) is ignored. Matching begins immediately after that.
If '%PATH_MAP%' in included in this option, it will be expanded to the keys of the path_map
setting. Note this item contains string(s), not regexps.
allowed_ssl_locations[]
Only allow HTTPS/SSL proxy CONNECT to hosts or IPs which match an item in this list.
allowed_ssl_ports[443]
Only allow HTTPS/SSL proxy CONNECT to ports which match an item in this list. Adding further items
to this can pose a significant security risk. DO NOT do it unless you understand the full
implications.
cache_dir[/var/cache/apt-cacher]
The directory where apt-cacher will store local copies of all packages requested. This can grow to
many hundreds of MB, so make sure it is on a partition with plenty of room. NOTE: the cache
directory needs to contain some subdirectories for correct storage management. If you try to
create a custom directory, please use the script /usr/share/apt-cacher/install.pl or use the
initially created cache directory as example.
concurrent_import_limit[NumberofCPUcoresfrom/proc/cpuinfoor0]
Importing new checksums can cause high CPU usage on slower systems. This option sets a limit to
the number of index files that are imported simultaneously, thereby limiting CPU load average,
but, possibly, taking longer. Leave unset or set to 0 for no limit.
checksum[0]
Switches on checksum validation of cached files. Checksum validation will slow apt-cacher response
as requested files have to be downloaded completely before validation can occur. This slow down
can be prevented by setting this value to 'lazy' in which case files will be passed on as they are
received and checked afterwards. Requires package libberkeleydb-perl to be installed.
checksum_files_regexp[seedefault/etc/apt-cacher/apt-cacher.conf]
Perl regular expression (perlre(1)) which matches the URL filename of all index files from which
checksums are imported into the checksum database if checksum mode is enabled.
clean_cache[1]
Whether to flush obsolete versions of packages from your cache daily. You can check what will be
done by running
/usr/share/apt-cacher/apt-cacher-cleanup.pl-s
which will just show what would be done to the contents of the cache. A package is only obsolete
if none of the (optional) namespaces, distributions (stable, testing, etc) or architectures you
use reference it. It should be safe to leave this on.
curl_idle_timeout[120]
The maximum time in seconds the libcurl backend will wait, unused, before exiting.
curl_ssl_insecure[]
If this is set to 1, HTTPS GET requests (which are inherently insecure as transfer from the proxy
to the client is unverified) is even less secure as the libcurl backend skips peer verification
with the upstream source. You really shouldn't use this. HTTPS CONNECT proxying is more secure.
curl_throttle[10]
Controls how fast the libcurl process runs. Increasing this setting will reduce the CPU load of
the libcurl process, possibly at the expense of slower response times and a lower throughput. On
most systems this option should be left unchanged.
data_timeout[120]
Time in seconds which, if no data is received from upstream, a request will timeout. This option
used to be known as fetch_timeout. The old name is still recognised for backwards compatibility.
debug[0]
Whether debug mode is enabled. Off by default. When turned on (non-nil), lots of extra debug
information will be written to the error log. This can make the error log become quite big, so
only use it when trying to debug problems. Additional information from the libcurl backend can be
obtained by increasing this parameter. The correspondence between this setting and curl_infotype
is:-
1 CURLINFO_TEXT
2 CURLINFO_HEADER_IN
3 CURLINFO_HEADER_OUT
4 CURLINFO_DATA_IN
5 CURLINFO_DATA_OUT
6 CURLINFO_SSL_DATA_IN
7 CURLINFO_SSL_DATA_OUT
See CURLOPT_DEBUGFUNCTION in curl_easy_setopt(3) for further information.
disk_usage_limit[]
Optional upper limit for the disk space usage of cache_dir in bytes. Units (k, KiB, M, MiB etc.)
are recognised with the same semantics as the rate limit option above.
distinct_namespaces[0]
Set this to 1 to enable support for caching multiple Distributions (e.g Debian and Ubuntu) from a
single apt-cacher instance. When enabled, package files are stored in a subdirectory, the name of
which is derived from the matching key of path_map or the part of the URL preceding 'pool' or
'dists'. This is typically ´debian', 'ubuntu' or 'security'. This mechanism prevents clashes
between the Distributions.
If you enable this option, any existing namespace specific package files which are not in the
correct subdirectory of cache_dir would be deleted by apt-cacher-cleanup.pl. If you wish to keep
them and import them into the correct namespace then run (as root)
/usr/share/apt-cacher/apt-cacher-import.pl -u {cache_dir}/packages
If you wish to limit the possible namespaces see path_map.
expire_hours[0]
How many hours Package and Release files are cached before they are assumed to be too old and must
be re-fetched. Setting 0 means that the validity of these files is checked on each access by
comparing time stamps in HTTP headers on the server with those stored locally. Use of this setting
is deprecated as HTTP header validation and sending If-Modified-Requests is much more efficient.
generate_reports[1]
Whether to generate traffic reports daily. Traffic reports can be accessed by pointing a browser
to
http://apt-cacher.server:3142/report/ [daemon mode]
or
http://apt-cacher.server[:port]/apt-cacher/report/ [CGI mode].
group[www-data]
The effective group id to change to.
http_proxy[]
Apt-cacher can pass all its requests to an external http proxy like Squid, which could be very
useful if you are using an ISP that blocks port 80 and requires all web traffic to go through its
proxy. The option takes a URI of the form
[protocol://][user[:password]@]hostname[:port]
The default protocol is http and the default port is 1080.
http_proxy_auth[]
External http proxy sometimes need authentication to get full access. The format is
'username:password', eg: 'proxyuser:proxypass'. This option is deprecated. Proxy authentication
details should be specified in the http_proxy URI.
index_files_regexp[seedefault/etc/apt-cacher/apt-cacher.conf]
Perl regular expression (perlre(1)) which matches the URL filename of all index-type files (files
that are uniquely identified by their full path and need to be checked for freshness).
installer_files_regexp[seedefault/etc/apt-cacher/apt-cacher.conf]
Perl regular expression (perlre(1)) which matches the URL filename of all files used by Aptitude,
Apt, the Debian/Ubuntu installer or Debian Live (files that are uniquely identified by their full
path but don't need to be checked for freshness). Within this item the shorthand
'%VALID_UBUNTU_RELEASE_NAMES%' will be expanded to the list configured in ubuntu_release_names as
regexp alternatives.
interface[]
Specify a particular interface to use for the upstream connection. Can be an interface name, IP
address or host name. If unset, the default route is used.
libcurl[]
This is a list of configuration options for the libcurl backend. Each item consists of the
curl_easy_setopt(3) option (without the CURLOPT_ prefix) and the desired setting. For example:
libcurl = dns_cache_timeout 300, maxredirs 10, noproxy localhost;
Be very careful with this. Apt-cacher depends on the libcurl backend working in a predictable way.
You can very easily break things by configuring this.
limit[0]
Rate limiting sets the maximum rate in bytes per second used for fetching files from the upstream
mirrors. Optionally, use SI unit abbreviations ('k', 'M', 'G' etc.) for decimal multiples (1000)
or 'KiB', 'MiB', or 'GiB' etc. for binary (1024) multiples. Legacy lowercase suffixes based on
wget(1) syntax are interpreted as decimal for backwards compatibility, but should be avoided in
new configurations. Use 0 for no rate limiting. By default this setting is perlibcurlconnection.
For global limiting, see limit_global below.
limit_global[0]
If set, this makes the specified rate limit apply overall. The libcurl backend does not have good
support for this, so it is implemented by a simple division of the rate by the total number of
downloads. There is no way for downloads, dynamically, to use bandwidth released by another
idle/finished download. If you really want good global bandwidth control, don't use this option at
all; use traffic shaping instead.
log_dir[/var/log/apt-cacher]
Directory to use for the access and error log files and traffic report. The access log records all
successful package requests using a timestamp, whether the request was fulfilled from cache, the
IP address of the requesting computer, the size of the package transferred, and the name of the
package. The error log records major faults, and is also used for debug messages if the debug
directive is set to 1. Debugging is toggled by sending SIGUSR1 (see SIGNALS below).
This option was formerly named 'logdir', but was renamed for consistency. logdir is still
recognised but should not be used for new installations.
max_loadavg[]
If set this limits the maximum 1 minute loadavg permitted for apt-cacher to attempt to handle an
client connection.
offline_mode[0]
Avoid making any outgoing connections, return files available in the cache or just return errors
if they are missing.
package_files_regexp[seedefault/etc/apt-cacher/apt-cacher.conf]
Perl regular expression (refer to the perlre(1) manpage) which matches the URL filename of all
package-type files (files that are uniquely identified, within their Distribution, by their
filename).
path_map[]
A mapping scheme to rewrite URLs, which converts the first part of the URL after the apt-cacher
server name (the key) to a remote mirror. For example, if you set
path_map = debian ftp.debian.org/debian
retrieving
http://apt-cacher.server:3142/debian/dists/stable/Release
will actually fetch
http://apt-cacher.server:3142/ftp.debian.org/debian/dists/stable/Release
If distinct_namespaces is set, then you can use multiple mappings to cache different Distributions
separately. For example
path_map = debian ftp.debian.org/debian; ubuntu archive.ubuntu.com/ubuntu
Multiple, space separated, mirrors can be given for each mapping. They will be tried in order in
the event of failure/unavailability of the previous one. For example
path_map = debian ftp.uk.debian.org/debian ftp.debian.org/debian ;
All path_map keys need to be included in allowed_locations, if the latter is used. The shorthand
'%PATH_MAP%' can be used to simplify this.
There are 4 internal path_map settings for the Debian and Ubuntu changelog and AppStream servers
which will be merged with the specified configuration:
debian-changelogs packages.debian.org metadata.ftp-master.debian.org; ubuntu-changelogs
changelogs.ubuntu.com; debian-appstream appstream.debian.org; ubuntu-appstream
appstream.ubuntu.com;
These can be overridden by specifying an alternative mirror for that key, or deleted by just
specifying the key with no mirror.
pdiff_files_regexp[seedefault/etc/apt-cacher/apt-cacher.conf]
Perl regular expression (perlre(1)) which matches APT pdiff files. These are ed(1) scripts which
APT use to patch index files rather than redownloading the whole file afresh.
return_buffer_size[1048576]
The buffer size that is used for reads when returning a file using slower read/write loop. The
default is 1MB. You may wish to adjust this to trade speed against memory consumption. By default
files are returned using sendfile(2) which is much faster and does not make use of this setting.
reverse_path_map[1]
This setting enables a reverse map from the requested URL to the path_map key. It helps prevent
having multiple copies of the same file cached under different file names.
skip_checksum_files_regexp[seedefault/etc/apt-cacher/apt-cacher.conf]
Perl regular expression (perlre(1)) which matches the URL filename for which checksum validation
is not performed. Note that all files matched by installer_files_regexp are automatically skipped
and do not need to be added here as well.
soap_url_regexp[seedefault/etc/apt-cacher/apt-cacher.conf]
Perl regular expression (perlre(1)) which matches URLs that are permitted as upstream source for
apt-listbugs(1) requests.
apt-listbugs(1) makes requests to the Debian Bugs server via SOAP POST requests. These are not
cached, but are simply passed through as a convenience.
supported_archs[seedefault/etc/apt-cacher/apt-cacher.conf]
A list of Architectures that is supported and you wish to allow in fetched filenames. ´all´ and
´any´ are automatically added to this list which is then used to expand %VALID_ARCHS% in
*_files_regexp.
use_proxyuse_proxy_auth[obsolete]
Use of external proxy and proxy authentication used to be turned on or off with these options.
They are now ignored and an upstream proxy will always be used if configured.
use_sendfile[Sys::Syscall::sendfile_defined()]
By default, if sendfile(2) is available on the system, it is used to return files to client and is
much more efficient than read/write. The default, which is determined by the value returned by
Sys::Syscall::sendfile_defined() can be explicitly overridden.
user[www-data]
The effective user id to change to after allocating the ports.
Stand-aloneDaemon-modeOptionsallowed_hosts[]
If your apt-cacher server is directly connected to the Internet and you are worried about
unauthorised fetching of packages through it, you can specify a range of IP addresses that are
allowed to use it. Localhost (127.0.0.1/8, ::1) is always allowed, other addresses must be matched
by allowed_hosts and not by denied_hosts to be permitted to use the cache. This option can be a
single item, list, IP address with netmask or IP range, resolvable hostname, or ´*' to allow all
access. See the default configuration file for further details and examples.
allowed_hosts_6
Deprecated option analogous to allowed_hosts, but for IPv6 clients. allowed_hosts can now take
IPv6 addresses directly.
daemon_addr[]
The daemon can be restricted to listen only on particular local IP address(es). If unset, the
daemon will listen on all available addresses. Single item or list of IPs. Use with care.
daemon_port[3142]
The TCP port to bind to.
denied_hosts
The opposite of allowed_hosts setting, excludes hosts from the list of allowed hosts. Not used in
inetd daemon mode.
denied_hosts_6
Deprecated option analogous to denied_hosts, but for IPv6 clients. denied_hosts can now take IPv6
addresses directly.
request_empty_lines[5]
The number of empty lines tolerated before an incoming connection is closed.
request_timeout[30]
Maximum time in seconds that will be waited for a incoming request before closing the connection.
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