Gerrit2 - Configuration
=======================

File `gerrit.config`
--------------------

The optional file `'$site_path'/gerrit.config` is a Git-style config
file that controls many host specific settings for Gerrit.

[NOTE]
The contents of the `gerrit.config` file are cached at startup
by Gerrit.  If you modify any propeties in this file, Gerrit needs
to be restarted before it will use the new values.

Sample `gerrit.config`:
----
[core]
	packedGitLimit = 200 m

[cache]
	directory = /var/cache/gerrit2

[cache "diff"]
	diskbuffer = 10 m
----

Section core
~~~~~~~~~~~~

core.packedGitWindowSize::
+
Number of bytes of a pack file to load into memory in a single
read operation.  This is the "page size" of the JGit buffer cache,
used for all pack access operations.  All disk IO occurs as single
window reads.  Setting this too large may cause the process to load
more data than is required; setting this too small may increase
the frequency of `read()` system calls.
+
Default on JGit is 8 KiB on all platforms.
+
Common unit suffixes of 'k', 'm', or 'g' are supported.

core.packedGitLimit::
+
Maximum number of bytes to load and cache in memory from pack files.
If JGit needs to access more than this many bytes it will unload less
frequently used windows to reclaim memory space within the process.
As this buffer must be shared with the rest of the JVM heap, it
should be a fraction of the total memory available.
+
Default on JGit is 10 MiB on all platforms.
+
Common unit suffixes of 'k', 'm', or 'g' are supported.

core.deltaBaseCacheLimit::
+
Maximum number of bytes to reserve for caching base objects
that multiple deltafied objects reference.  By storing the entire
decompressed base object in a cache Git is able to avoid unpacking
and decompressing frequently used base objects multiple times.
+
Default on JGit is 10 MiB on all platforms.  You probably do not
need to adjust this value.
+
Common unit suffixes of 'k', 'm', or 'g' are supported.

core.packedGitOpenFiles::
+
Maximum number of pack files to have open at once.  A pack file
must be opened in order for any of its data to be available in
a cached window.
+
If you increase this to a larger setting you may need to also adjust
the ulimit on file descriptors for the host JVM, as Gerrit needs
additional file descriptors available for network sockets and other
repository data manipulation.
+
Default on JGit is 128 file descriptors on all platforms.

core.packedGitMmap::
+
When true, JGit will use `mmap()` rather than `malloc()+read()`
to load data from pack files.  The use of mmap can be problematic
on some JVMs as the garbage collector must deduce that a memory
mapped segment is no longer in use before a call to `munmap()`
can be made by the JVM native code.
+
In server applications (such as Gerrit) that need to access many
pack files, setting this to true risks artifically running out
of virtual address space, as the garbage collector cannot reclaim
unused mapped spaces fast enough.
+
Default on JGit is false. Although potentially slower, it yields
much more predictable behavior.

Section cache
~~~~~~~~~~~~~

cache.directory::
+
Path to a local directory where Gerrit can write cached entities for
future lookup.  This local disk cache is used to retain expensively
computed information across restarts.
+
If the location does not exist, Gerrit will try to create it.
+
Default is `'$site_path'/disk_cache`.

cache.maxAge::
	Default setting inherited by named caches; see below.
cache.memoryLimit::
	Default setting inherited by named caches; see below.
cache.diskLimit::
	Default setting inherited by named caches; see below.
cache.diskBuffer::
	Default setting inherited by named caches; see below.

cache.<name>.maxAge::
+
Maximum age, in minutes, to keep an entry in the cache.  If an
entry has not been accessed in this period of time, it is removed
from the cache.
+
Default is 129600 (90 days); 5 for cache "openid".

cache.<name>.memoryLimit::
+
Maximum number of cache items to retain in memory.  Keep in mind
this is total number of items, not bytes of heap used.
+
Default is 1024.

cache.<name>.diskLimit::
+
Maximum number of cache items to retain on disk, if this cache
supports storing its items to disk.  Like memoryLimit, this is
total number of items, not bytes of disk used.
+
Default is 16384.

cache.<name>.diskBuffer::
+
Number of bytes to buffer in memory before writing less frequently
accessed cache items to disk, if this cache supports storing its
items to disk.
+
Default is 5 MiB.
+
Common unit suffixes of 'k', 'm', or 'g' are supported.

Standard Caches
^^^^^^^^^^^^^^^

cache `"diff"`::
+
Caches the edit list describing the differences between two versions
of a file.  Gerrit uses this cache to accelerate display of file
contents by computing the difference only once, typically during
the initial upload.
+
The average entry in this cache is approximately 1100 bytes when
stored on disk.  The in-memory representation is only slightly
larger, closer to 1300 bytes, depending on JVM.
+
Keeping entries for 90 days gives sufficient time for most changes
to be submitted or abandoned before their relevant difference items
expire out.

cache `"openid"`::
+
If OpenID authentication is enabled, caches the OpenID discovery
response by URL, for up to 5 minutes.  This can reduce the time
required for OpenID authentication through very common providers,
such as Google Accounts.

cache `"sshkeys"`::
+
Caches unpacked versions of user SSH keys, so the internal SSH daemon
can match against them during authentication.  The unit of storage
is per-user, so 1024 items translates to 1024 unique user accounts.
As each individual user account may configure multiple SSH keys,
the total number of keys may be larger than the item count.

Section sshd
~~~~~~~~~~~~

sshd.reuseAddress::
+
If true, permits the daemon to bind to the port even if the port
is already in use.  If false, the daemon ensures the port is not
in use before starting.  Busy sites may need to set this to true
to permit fast restarts.
+
By default, true.

sshd.tcpKeepAlive::
+
If true, enables TCP keepalive messages to the other side, so
the daemon can terminate connections if the peer disappears.
+
By default, true.

sshd.cipher::
+
Available ciphers.  To permit multiple ciphers, specify multiple
`sshd.cipher` keys in the configuration file, one cipher name
per key.  Cipher names starting with `+` are enabled in addition
to the default ciphers, cipher names starting with `-` are removed
from the default cipher set.
+
Supported ciphers: aes128-cbc, aes128-cbc, aes256-cbc, blowfish-cbc,
3des-cbc, none.
+
By default, all supported ciphers except `none` are available.

sshd.mac::
+
Available MAC (message authentication code) algorithms.  To permit
multiple algorithms, specify multiple `sshd.mac` keys in the
configuration file, one MAC per key.  MAC names starting with `+`
are enabled in addition to the default MACs, MAC names starting with
`-` are removed from the default MACs.
+
Supported MACs: hmac-md5, hmac-md5-96, hmac-sha1, hmac-sha1-96.
+
By default, all supported MACs are available.


File `replication.config`
-------------------------

The optional file `'$site_path'/replication.config` controls how
Gerrit automatically replicates changes it makes to any of the Git
repositories under its control.

* link:config-replication.html[Git Replication/Mirroring]

Database system_config
----------------------

Several columns in the `system_config` table within the metadata
database may be set to control how Gerrit behaves.

[NOTE]
The contents of the `system_config` table are cached at startup
by Gerrit.  If you modify any columns in this table, Gerrit needs
to be restarted before it will use the new values.

Configurable Parameters
~~~~~~~~~~~~~~~~~~~~~~~

max_session_age::
+
Maximum number of seconds that an XSRF token or a session cookie
is permitted to be valid for.
+
By default this is 43200 seconds (12 hours).  Any browser session
which has not been used in this time span will ask the user to
login again.
+
Administrators may increase (or decrease) this setting to control
how long an idle session is allowed to remain alive.

site_path::
+
Local filesystem directory holding the site customization assets.
Placing this directory under version control and/or backup is a
good idea.
+
SSH key files (`ssh_host_rsa_key` and `ssh_host_dsa_key` or
`ssh_host_key`) in this directory provide the host keys for the
internal SSH daemon.
+
Other files support site customization.
+
* link:config-headerfooter.html[Site Header/Footer]
* link:config-replication.html[Git Replication/Mirroring]

git_base_path::
+
Local filesystem directory holding all Git repositories that
Gerrit knows about and can process changes for.  A project
entity in Gerrit maps to a local Git repository by creating
the path string `"$\{git_pase_path}/$\{project_name}.git"`.

gitweb_url::
+
Optional URL of an affiliated gitweb service.
+
* link:config-gitweb.html[Gitweb Integration]

git_daemon_url::
+
Optional base URL for repositories available over the anonymous git
protocol.  For example, set this to `git://mirror.example.com/base/`
to have Gerrit display patch set download URLs in the UI.  Gerrit
automatically appends the project name onto the end of the URL.
+
By default NULL, as the git daemon must be configured externally
by the system administrator, and might not even be running on the
same host as Gerrit.

use_repo_download::
+
If set to `Y`, Gerrit advertises patch set downloads with the
`repo download` command, assuming that all projects managed by this
instance are generally worked on with the repo multi-repository tool.
+
By default, `N`, as not all instances will deploy repo.

gerrit_git_name::
+
Name that Gerrit calls itself in Git when it creates a new Git
commit, such as a merge during change submission.
+
By default this is "Gerrit Code Review".

gerrit_git_email::
+
Email address that Gerrit refers to itself as when it creates a
new Git commit, such as a merge commit during change submission.
+
If NULL, Gerrit generates this as "gerrit@`hostname`", where
`hostname` is the hostname of the system Gerrit is running on.
+
By default, this is NULL, generating the value at startup.

canonical_url::
+
The default URL for Gerrit to be accessed through.
+
Typically this would be set to "http://review.example.com/" or
"http://example.com/gerrit/" so Gerrit can output links that point
back to itself.
+
Setting this is highly recommended, as its necessary for the upload
code invoked by "git push" or "repo upload" to output hyperlinks
to the newly uploaded changes.

use_contributor_agreements::
+
Controls whether or not the contributor agreement features are
enabled for the Gerrit site.  If enabled a user must complete a
contributor agreement before they can upload changes.
+
If enabled, the admin must also insert one or more rows into
`contributor_agreements` and create agreement files under
`'$site_path'/static`, so users can actually complete one or
more agreements. 
+
By default this is `N` (no agreements are used).

contact_store_url, contact_store_appsec::
+
URL and shared secret of the web based contact store Gerrit will
send any offline contact information to when it collects the data
from users as part of a contributor agreement.
+
* link:config-contact.html[Contact Information]

sshd_port::
+
Port number the internal SSHD listens for connections on.
+
Gerrit receives new change submissions through this port by
"git push ssh://you@example.com:$sshd_port/$project.git ...".
+
By default this is 29418.

login_type::
+
Type of user authentication employed by Gerrit.  This setting has
two supported values:
+
* `OPENID`
+
The default setting.  Gerrit uses any valid OpenID
provider chosen by the end-user.  For more information see
http://openid.net/[openid.net]
+
* `HTTP`
+
Gerrit relies upon data in the HTTP request, such as the HTTP basic
authentication, or some types of commerical single-sign-on solutions.
For more information see link:config-sso.html[SSO configuration].

login_http_header::
+
HTTP header to trust the username from, or NULL to select HTTP
basic or digest authentication.  Only used if `login_type = HTTP`.
+
For more information see link:config-sso.html[SSO configuration].

email_format::
+
Optional format string to construct user email addresses out of
user login names.  Only used if `login_type = HTTP`.
+
This value can be set to a format string, where `\{0\}` is replaced
with the login name.  E.g. "\{0\}+gerrit@example.com" with a user
login name of "foo" will produce "foo+gerrit@example.com" during
the first time user "foo" registers.
+
For more information see link:config-sso.html[SSO configuration].

allow_google_account_upgrade::
+
Allow old Gerrit1 users to seamlessly upgrade from Google Accounts
on Google App Engine to OpenID authentication.  This should only be
set to true on a Gerrit2 database that was imported from a Gerrit1
database run on Google App Engine.  Having it enabled incurs an
extra database query when new Google Account users register with
the Gerrit2 server.
+
Its strongly encouraged to set this to 'N' once the following
query drops to 0, or close to 0:
+
====
  SELECT COUNT(*) FROM account_external_ids e
  WHERE e.external_id LIKE 'Google Account %'
  AND NOT EXISTS (SELECT 1
    FROM account_external_ids o
    WHERE o.account_id = e.account_id
	AND o.external_id LIKE '%.google.com%/id?id=%');
====


Not User Serviceable
~~~~~~~~~~~~~~~~~~~~

These fields generally shouldn't be modified.

xsrf_private_key::
+
A private key used to sign the XSRF (cross site request forgey)
protection tokens.  All RPC calls which can potentially modify
data require that the client obtain, and then later present an XSRF
token to Gerrit.  The tokens are signed with this private key.
+
This column is automatically generated when the database is
initialized.  Changing it to a new value would cause all current
XSRF tokens to be invalidated, forcing clients to either fail or
retry any requests in progress.
+
Changing it is not recommended.

account_private_key::
+
Like xsrf_private_key, but used to sign the cookie that tells Gerrit
what account the end-user has signed into.  The key signs the cookie,
preventing a client from spoofing another account.
+
This column is automatically generated when the database is
initialized.  Changing it to a new value would cause all current
cookies to be invalidated, forcing clients to fail their current
requests and require the user to sign in again.
+
Changing it is not recommended.

admin_group_id::
+
Unique identity of the group with full privileges.  Any user who
is a member of this group may manage any other group, any project,
and other system settings over the web.
+
This is initialized by Gerrit to be the "Administrators" group.
+
Changing it is not recommended.

anonymous_group_id::
+
Unique identity of the group for anonymous (not authenticated) users.
+
All users are a member of this group, whether or not they are
actually signed in to Gerrit.  Any access rights assigned to
this group are inherited by all users.
+
This is initialized by Gerrit to be the "Anonymous Users" group.
+
Changing it is not recommended.

registered_group_id::
+
Unique identity of the group for all authenticated users.
+
All signed-in users are a member of this group.  Any access rights
assigned to this group are inherited by all users once they have
authenticated to Gerrit.
+
Since account registration is open and fairly easy to obtain,
moving from the "Anonymous Users" group to this group is not
very difficult.  Caution should be taken when assigning any
permissions to this group.
+
This is initialized by Gerrit to be the "Registered Users" group.
+
Changing it is not recommended.