Gerrit Code Review - Access Controls
====================================

Access controls in Gerrit are group based.  Every user account is a
member of one or more groups, and access and privileges are granted
to those groups.  Access rights cannot be granted to individual
users.


System Groups
-------------

Gerrit comes with 4 system groups, with special access privileges
and membership management.  The identity of these groups is set
in the `system_config` table within the database, so the groups
can be renamed after installation if desired.

[[administrators]]
Administrators
~~~~~~~~~~~~~~

This is the Gerrit "root" identity.

Users in the 'Administrators' group can perform any action under
the Admin menu, to any group or project, without further validation
of any other access controls.  In most installations only those
users who have direct filesystem and database access would be
placed into this group.

Membership in the 'Administrators' group does not imply any other
access rights.  Administrators do not automatically get code review
approval or submit rights in projects.  This is a feature designed
to permit administrative users to otherwise access Gerrit as any
other normal user would, without needing two different accounts.

[[anonymous_users]]
Anonymous Users
~~~~~~~~~~~~~~~

All users are automatically a member of this group.  Users who are
not signed in are a member of only this group, and no others.

Any access rights assigned to this group are inherited by all users.

Administrators and project owners can grant access rights to this
group in order to permit anonymous users to view project changes,
without requiring sign in first.  Currently it is only worthwhile
to grant `Read` access to this group as Gerrit requires an account
identity for all other operations.

[[non-interactive_users]]
Non-Interactive Users
~~~~~~~~~~~~~~~~~~~~~

This is an internal user group, members of this group are not expected
to perform interactive operations on the Gerrit web frontend.

However, sometimes such a user may need a separate thread pool in
order to prevent it from grabbing threads from the interactive users.

These users live in a second thread pool, which separates operations
made by the non-interactive users from the ones made by the interactive
users. This ensures that the interactive users can keep working when
resources are tight.

[[project_owners]]
Project Owners
~~~~~~~~~~~~~~

Access rights assigned to this group are always evaluated within the
context of a project to which the access rights apply. These rights
therefore apply to all the users who are owners of this project.

By assigning access rights to this group on a parent project Gerrit
administrators can define a set of default access rights for
<<category_owner,project owners>>. Child projects inherit these
access rights where they are resolved to the users that own the child
project.  Having default access rights for
<<category_owner,project owners>> assigned on a parent project may
avoid the need to initially configure access rights for
newly created child projects.

[[registered_users]]
Registered Users
~~~~~~~~~~~~~~~~

All signed-in users are automatically a member of this group (and
also <<anonymous_users,'Anonymous Users'>>, see above).

Any access rights assigned to this group are inherited by all
users as soon as they sign-in to Gerrit.  If OpenID authentication
is being employed, moving from only 'Anonymous Users' into this
group is very easy.  Caution should be taken when assigning any
permissions to this group.

It is typical to assign `Code Review -1..+1` to this group,
allowing signed-in users to vote on a change, but not actually
cause it to become approved or rejected.

Registered users are always permitted to make and publish comments
on any change in any project they have `Read` access to.


Account Groups
--------------

Account groups contain a list of zero or more user account members,
added individually by a group owner.  Any user account listed as
a group member is given any access rights granted to the group.

Every group has one other group designated as its owner.  Users who
are members of the owner group can:

* Add users and other groups to this group
* Remove users and other groups from this group
* Change the name of this group
* Change the description of this group
* Change the owner of this group, to another group

It is permissible for a group to own itself, allowing the group
members to directly manage who their peers are.

Newly created groups are automatically created as owning themselves,
with the creating user as the only member.  This permits the group
creator to add additional members, and change the owner to another
group if desired.

It is somewhat common to create two groups at the same time,
for example `Foo` and `Foo-admin`, where the latter group
`Foo-admin` owns both itself and also group `Foo`.  Users who
are members of `Foo-admin` can thus control the membership of
`Foo`, without actually having the access rights granted to `Foo`.
This configuration can help prevent accidental submits when the
members of `Foo` have submit rights on a project, and the members of
`Foo-admin` typically do not need to have such rights.


Project Access Control Lists
----------------------------

A system wide access control list affecting all projects is stored in
project "`All-Projects`".  This inheritance can be configured
through link:cmd-set-project-parent.html[gerrit set-project-parent].

Per-project access control lists are also supported.

Users are permitted to use the maximum range granted to any of their
groups in an approval category.  For example, a user is a member of
`Foo Leads`, and the following ACLs are granted on a project:

[options="header"]
|=================================================
|Group           |Reference Name |Category|Range
|Anonymous Users |refs/heads/*|Code Review|-1..+1
|Registered Users|refs/heads/*|Code Review|-1..+2
|Foo Leads       |refs/heads/*|Code Review|-2..0
|=================================================

Then the effective range permitted to be used by the user is
`-2..+2`, as the user is a member of all three groups (see above
about the system groups) and the maximum range is chosen (so the
lowest value granted to any group, and the highest value granted
to any group).

Reference-level access control is also possible.

Permissions can be set on a single reference name to match one
branch (e.g. `refs/heads/master`), or on a reference namespace
(e.g. `refs/heads/*`) to match any branch starting with that
prefix. So a permission with `refs/heads/*` will match
`refs/heads/master` and `refs/heads/experimental`, etc.

Reference names can also be described with a regular expression
by prefixing the reference name with `^`.  For example
`^refs/heads/[a-z]{1,8}` matches all lower case branch names
between 1 and 8 characters long.  Within a regular expression `.`
is a wildcard matching any character, but may be escaped as `\.`.
The link:http://www.brics.dk/automaton/[dk.brics.automaton library]
is used for evaluation of regular expression access control
rules. See the library documentation for details on this
particular regular expression flavor.

References can have the current user name automatically included,
creating dynamic access controls that change to match the currently
logged in user.  For example to provide a personal sandbox space
to all developers, `refs/heads/sandbox/${username}/*` allowing
the user 'joe' to use 'refs/heads/sandbox/joe/foo'.

When evaluating a reference-level access right, Gerrit will use
the full set of access rights to determine if the user
is allowed to perform a given action. For example, if a user is a
member of `Foo Leads`, they are reviewing a change destined for
the `refs/heads/qa` branch, and the following ACLs are granted
on the project:

[options="header"]
|===============================================================
|Group            |Reference Name|Category   |Range   |Exclusive
|Registered Users |refs/heads/*  |Code Review| -1..+1 |
|Foo Leads        |refs/heads/*  |Code Review| -2..+2 |
|QA Leads         |refs/heads/qa |Code Review| -2..+2 |
|===============================================================

Then the effective range permitted to be used by the user is
`-2..+2`, as the user's membership of `Foo Leads` effectively grant
them access to the entire reference space, thanks to the wildcard.

Gerrit also supports exclusive reference-level access control.

It is possible to configure Gerrit to grant an exclusive ref level
access control so that only users of a specific group can perform
an operation on a project/reference pair. This is done by ticking
the exclusive flag when setting the permission for the
`refs/heads/qa` branch.

For example, if a user who is a member of `Foo Leads` tries to
review a change destined for branch `refs/heads/qa` in a project,
and the following ACLs are granted:

[options="header"]
|==============================================================
|Group           |Reference Name|Category   |Range   |Exclusive
|Registered Users|refs/heads/*  |Code Review| -1..+1 |
|Foo Leads       |refs/heads/*  |Code Review| -2..+2 |
|QA Leads        |refs/heads/qa |Code Review| -2..+2 |X
|==============================================================

Then this user will not have `Code Review` rights on that change,
since there is an exclusive access right in place for the
`refs/heads/qa` branch. This allows locking down access for a
particular branch to a limited set of users, bypassing inherited
rights and wildcards.

In order to grant the ability to `Code Review` to the members of
`Foo Leads`, in `refs/heads/qa` then the following access rights
would be needed:

[options="header"]
|==============================================================
|Group           |Reference Name|Category   |Range   |Exclusive
|Registered Users|refs/heads/*  |Code Review| -1..+1 |
|Foo Leads       |refs/heads/*  |Code Review| -2..+2 |
|QA Leads        |refs/heads/qa |Code Review| -2..+2 |X
|Foo Leads       |refs/heads/qa |Code Review| -2..+2 |
|==============================================================

OpenID Authentication
~~~~~~~~~~~~~~~~~~~~~

If the Gerrit instance is configured to use OpenID authentication,
an account's effective group membership will be restricted to only
the `Anonymous Users` and `Registered Users` groups, unless *all*
of its OpenID identities match one or more of the patterns listed
in the `auth.trustedOpenID` list from `gerrit.config`.

All Projects
~~~~~~~~~~~~

Any access right granted to a group within `All-Projects`
is automatically inherited by every other project in the same
Gerrit instance.  These rights can be seen, but not modified,
in any other project's `Access` administration tab.

Only members of the groups with the `Administrate Server` capability
may edit the access control list for `All-Projects`. By default this
capability is given to the group `Administrators`, but can be given
to more groups.

Ownership of this project cannot be delegated to another group.
This restriction is by design.  Granting ownership to another
group gives nearly the same level of access as membership in
`Administrators` does, as group members would be able to alter
permissions for every managed project including global capabilities.

Per-Project
~~~~~~~~~~~

The per-project ACL is evaluated before the global `All-Projects` ACL,
permitting some limited override capability to project owners. This
behavior is generally only useful on the `Read` category when
granting 'DENY' within a specific project to deny a group access.


[[access_category]]
Access Categories
-----------------

Gerrit comes pre-configured with several default categories that
can be granted to groups within projects, enabling functionality
for that group's members.

With the release of the Gerrit 2.2.x series, the web GUI for ACL
configuration was rewritten from scratch.  Use this
<<conversion_table,table>> to better understand the access rights
conversions from the Gerrit 2.1.x to the Gerrit 2.2.x series.


[[category_label-Verified]]
Label: Verified
~~~~~~~~~~~~~~~

The verified category is one of two default categories that is
configured upon the creation of a Gerrit instance. It may have
any meaning the project desires.  It was originally invented by
the Android Open Source Project to mean
'compiles, passes basic unit tests'.

The range of values is:

* -1 Fails
+
Tried to compile, but got a compile error, or tried to run tests,
but one or more tests did not pass.  This value is valid
across all patch sets in the same change, i.e. the reviewer must
actively change his/her review to something else before the change
is submittable.
+
*Any -1 blocks submit.*

* 0 No score
+
Didn't try to perform the verification tasks.

* +1 Verified
+
Compiled (and ran tests) successfully.
+
*Any +1 enables submit.*

For a change to be submittable, the change must have a `+1 Verified`
in this category from at least one authorized user, and no `-1 Fails`
from an authorized user.  Thus, `-1 Fails` can block a submit,
while `+1 Verified` enables a submit.

If a Gerrit installation does not wish to use this category in any
project, it can be deleted from the database:

====
  DELETE FROM approval_categories      WHERE category_id = 'VRIF';
  DELETE FROM approval_category_values WHERE category_id = 'VRIF';
====

If a Gerrit installation wants to modify the description text
associated with these category values, the text can be updated
in the `name` column of the `category_id = 'VRIF'` rows in the
`approval_category_values` table.

Additional values could also be added to this category, to allow it
to behave more like `Code Review` (below).  Insert -2 and +2 value
rows into the `approval_category_values` with `category_id` set to
`VRIF` to get the same behavior.

[NOTE]
A restart is required after making database changes.
See <<restart_changes,below>>.

[[category_label-Code-Review]]
Label: Code Review
~~~~~~~~~~~~~~~~~~

The code review category is the second of two default categories that
is configured upon the creation of a Gerrit instance. It may have
any meaning the project desires.  It was originally invented by the
Android Open Source Project to mean 'I read the code and it seems
reasonably correct'.

The range of values is:

* -2 Do not submit
+
The code is so horribly incorrect/buggy/broken that it must not be
submitted to this project, or to this branch.  This value is valid
across all patch sets in the same change, i.e. the reviewer must
actively change his/her review to something else before the change
is submittable.
+
*Any -2 blocks submit.*

* -1 I would prefer that you didn't submit this
+
The code doesn't look right, or could be done differently, but
the reviewer is willing to live with it as-is if another reviewer
accepts it, perhaps because it is better than what is currently in
the project.  Often this is also used by contributors who don't like
the change, but also aren't responsible for the project long-term
and thus don't have final say on change submission.
+
Does not block submit.

* 0 No score
+
Didn't try to perform the code review task, or glanced over it but
don't have an informed opinion yet.

* +1 Looks good to me, but someone else must approve
+
The code looks right to this reviewer, but the reviewer doesn't
have access to the `+2` value for this category.  Often this is
used by contributors to a project who were able to review the change
and like what it is doing, but don't have final approval over what
gets submitted.

* +2 Looks good to me, approved
+
Basically the same as `+1`, but for those who have final say over
how the project will develop.
+
*Any +2 enables submit.*

For a change to be submittable, the latest patch set must have a
`+2 Looks good to me, approved` in this category from at least one
authorized user, and no `-2 Do not submit` from an authorized user.
Thus `-2` on any patch set can block a submit, while `+2` on the
latest patch set can enable it.

If a Gerrit installation does not wish to use this category in any
project, it can be deleted from the database:

====
  DELETE FROM approval_categories      WHERE category_id = 'CRVW';
  DELETE FROM approval_category_values WHERE category_id = 'CRVW';
====

If a Gerrit installation wants to modify the description text
associated with these category values, the text can be updated
in the `name` column of the `category_id = 'CRVW'` rows in the
`approval_category_values` table.

Additional values could be inserted into `approval_category_values`
to further extend the negative and positive range, but there is
likely little value in doing so as this only expands the middle
region.  This category is a `MaxWithBlock` type, which means that
the lowest negative value if present blocks a submit, while the
highest positive value is required to enable submit.

[[function_MaxNoBlock]]
There is also a `MaxNoBlock` category which still requires the
highest positive value to submit, but the lowest negative value will
not block the change, and does not carry over between patch sets.
This level is mostly useful for automated code-reviews that may
have false-negatives that shouldn't block the change.

[NOTE]
A restart is required after making database changes.
See <<restart_changes,below>>.

[[category_create]]
Create reference
~~~~~~~~~~~~~~~~

The create reference category controls whether it is possible to
create new references, branches or tags.  This implies that the
reference must not already exist, it's not a destructive permission
in that you can't overwrite or remove any previosuly existing
references (and also discard any commits in the process).

It's probably most common to either permit the creation of a single
branch in many gits (by granting permission on a parent project), or
to grant this permission to a name pattern of branches.

This permission is often given in conjunction with regular push
branch permissions, allowing the holder of both to create new branches
as well as bypass review for new commits on that branch.

To push lightweight (non annotated) tags, grant
`Create Reference` for reference name `refs/tags/*`, as lightweight
tags are implemented just like branches in Git.

For example, to grant the possibility to create new branches under the
namespace `foo`, you have to grant this permission on
`refs/heads/foo/*` for the group that should have it.
Finally, if you plan to grant each user a personal namespace in
where they are free to create as many branches as they wish, you
should grant the create reference permission so it's possible
to create new branches. This is done by using the special
`${username}` keyword in the reference pattern, e.g.
`refs/heads/sandbox/${username}/*`. If you do, it's also recommended
you grant the users the push force permission to be able to clean up
stale branches.


[[category_forge_author]]
Forge Author
~~~~~~~~~~~~

Normally Gerrit requires the author and the committer identity
lines in a Git commit object (or tagger line in an annotated tag) to
match one of the registered email addresses of the uploading user.
This permission allows users to bypass parts of that validation, which
may be necessary when mirroring changes from an upstream project.

Permits the use of an unverified author line in commit objects.
This can be useful when applying patches received by email from
3rd parties, when cherry-picking changes written by others across
branches, or when amending someone else's commit to fix up a minor
problem before submitting.

By default this is granted to `Registered Users` in all projects,
but a site administrator may disable it if verified authorship
is required.


[[category_forge_committer]]
Forge Committer
~~~~~~~~~~~~~~~

Normally Gerrit requires the author and the committer identity
lines in a Git commit object (or tagger line in an annotated tag) to
match one of the registered email addresses of the uploading user.
This permission allows users to bypass parts of that validation, which
may be necessary when mirroring changes from an upstream project.

Allows the use of an unverified committer line in commit objects, or an
unverified tagger line in annotated tag objects.  Typically this is only
required when mirroring commits from an upstream project repository.


[[category_forge_server]]
Forge Server
~~~~~~~~~~~~

Normally Gerrit requires the author and the committer identity
lines in a Git commit object (or tagger line in an annotated tag) to
match one of the registered email addresses of the uploading user.
This permission allows users to bypass parts of that validation, which
may be necessary when mirroring changes from an upstream project.

Allows the use of the server's own name and email on the committer
line of a new commit object.  This should only be necessary when force
pushing a commit history which has been rewritten by 'git filter-branch'
and that contains merge commits previously created by this Gerrit Code
Review server.


[[category_owner]]
Owner
~~~~~

The `Owner` category controls which groups can modify the project's
configuration.  Users who are members of an owner group can:

* Change the project description
* Create/delete a branch through the web UI (not SSH)
* Grant/revoke any access rights, including `Owner`

Note that project owners implicitly have branch creation or deletion
through the web UI, but not through SSH.  To get SSH branch access
project owners must grant an access right to a group they are a
member of, just like for any other user.

Ownership over a particular branch subspace may be delegated by
entering a branch pattern.  To delegate control over all branches
that begin with `qa/` to the QA group, add `Owner` category
for reference `refs/heads/qa/\*`.  Members of the QA group can
further refine access, but only for references that begin with
`refs/heads/qa/`. See <<project_owners,project owners>> to find
out more about this role.


[[category_push]]
Push
~~~~

This category controls how users are allowed to upload new commits
to projects in Gerrit. It can either give permission to push
directly into a branch, bypassing any code review process
that would otherwise be used. Or it may give permission to upload
new changes for code review, this depends on which namespace the
permission is granted to.


[[category_push_direct]]
Direct Push
^^^^^^^^^^^

Any existing branch can be fast-forwarded to a new commit.
Creation of new branches is controlled by the 
link:access-control.html#category_create['Create Reference']
category.  Deletion of existing branches is rejected.  This is the
safest mode as commits cannot be discarded.

* Force option
+
Allows an existing branch to be deleted. Since a force push is
effectively a delete immediately followed by a create, but performed
atomically on the server and logged, this option also permits forced
push updates to branches.  Enabling this option allows existing commits
to be discarded from a project history.

The push category is primarily useful for projects that only want to
take advantage of Gerrit's access control features and do not need
its code review functionality.  Projects that need to require code
reviews should not grant this category.


[[category_push_review]]
Upload To Code Review
^^^^^^^^^^^^^^^^^^^^^

The `Push` access right granted on the namespace
`refs/for/refs/heads/BRANCH` permits the user to upload a non-merge
commit to the project's `refs/for/BRANCH` namespace, creating a new
change for code review.

A user must be able to clone or fetch the project in order to create
a new commit on their local system, so in practice they must also
have the `Read` access granted to upload a change.

For an open source, public Gerrit installation, it is common to
grant `Read` and `Push` for `refs/for/refs/heads/*`
to `Registered Users` in the `All-Projects` ACL.  For more
private installations, its common to simply grant `Read` and
`Push` for `refs/for/refs/heads/*` to all users of a project.

* Force option
+
The force option has no function when granted to a branch in the
`refs/for/refs/heads/*` namespace.


[[category_push_merge]]
Push Merge Commits
~~~~~~~~~~~~~~~~~~~~

The `Push Merge Commit` permits the user to upload merge commits.
It's an addon to the <<category_push,Push>> access right, and so it
won't be sufficient with only `Push Merge Commit` granted for a push
to happen.  Some projects wish to restrict merges to being created by
Gerrit. By granting `Push` without `Push Merge Commit`, the only
merges that enter the system will be those created by Gerrit.


[[category_push_annotated]]
Push Annotated Tag
~~~~~~~~~~~~~~~~~~

This category permits users to push an annotated tag object over
SSH into the project's repository.  Typically this would be done
with a command line such as:

====
  git push ssh://USER@HOST:PORT/PROJECT tag v1.0
====

Tags must be annotated (created with `git tag -a` or `git tag -s`),
should exist in the `refs/tags/` namespace, and should be new.

This category is intended to be used to publish tags when a project
reaches a stable release point worth remembering in history.

It allows for a new annotated (unsigned) tag to be created.  The
tagger email address must be verified for the current user.

To push tags created by users other than the current user (such
as tags mirrored from an upstream project), `Forge Committer Identity`
must be also granted in addition to `Push Annotated Tag`.

To push lightweight (non annotated) tags, grant
<<category_create,`Create Reference`>> for reference name
`refs/tags/*`, as lightweight tags are implemented just like
branches in Git.

To delete or overwrite an existing tag, grant `Push` with the force
option enabled for reference name `refs/tags/*`, as deleting a tag
requires the same permission as deleting a branch.


[[category_read]]
Read
~~~~

The `Read` category controls visibility to the project's
changes, comments, code diffs, and Git access over SSH or HTTP.
A user must have this access granted in order to see a project, its
changes, or any of its data.

This category has a special behavior, where the per-project ACL is
evaluated before the global all projects ACL.  If the per-project
ACL has granted `Read` with 'DENY', and does not otherwise grant
`Read` with 'ALLOW', then a `Read` in the all projects ACL
is ignored.  This behavior is useful to hide a handful of projects
on an otherwise public server.

For an open source, public Gerrit installation it is common to grant
`Read` to `Anonymous Users` in the `All-Projects` ACL, enabling
casual browsing of any project's changes, as well as fetching any
project's repository over SSH or HTTP.  New projects can be
temporarily hidden from public view by granting `Read` with 'DENY'
to `Anonymous Users` and granting `Read` to the project owner's
group within the per-project ACL.

For a private Gerrit installation using a trusted HTTP authentication
source, granting `Read` to `Registered Users` may be more
typical, enabling read access only to those users who have been
able to authenticate through the HTTP access controls.  This may
be suitable in a corporate deployment if the HTTP access control
is already restricted to the correct set of users.


[[category_submit]]
Submit
~~~~~~

This category permits users to push the `Submit Patch Set n` button
on the web UI.

Submitting a change causes it to be merged into the destination
branch as soon as possible, making it a permanent part of the
project's history.

In order to submit, all approval categories (such as `Verified` and
`Code Review`, above) must enable submit, and also must not block it.
See above for details on each category.

[[category_makeoneup]]
Your Category Here
~~~~~~~~~~~~~~~~~~

Gerrit administrators can also make up their own categories.

See above for descriptions of how <<category_verified,`Verified`>>
and <<category_review,`Code Review`>> work, and insert your own
category with `function_name = 'MaxWithBlock'` to get the same
behavior over your own range of values, in any category you desire.

Ensure `category_id` is unique within your `approval_categories`
table.  The default values `VRIF` and `CVRF` used for the categories
described above are simply that, defaults, and have no special
meaning to Gerrit.

The `position` column of `approval_categories` controls which column
of the 'Approvals' table the category appears in, providing some
layout control to the administrator.

All `MaxWithBlock` categories must have at least one positive value
in the `approval_category_values` table, or else submit will never
be enabled.

To permit blocking submits, ensure a negative value is defined for
your new category.  If you do not wish to have a blocking submit
level for your category, do not define values less than 0.

Keep in mind that category definitions are currently global to
the entire Gerrit instance, and affect all projects hosted on it.
Any change to a category definition affects everyone.

For example, to define a new 3-valued category that behaves exactly
like `Verified`, but has different names/labels:

====
  INSERT INTO approval_categories
    (name
    ,position
    ,function_name
    ,category_id)
  VALUES
    ('Copyright Check'
    ,3
    ,'MaxWithBlock'
    ,'copy');

  INSERT INTO approval_category_values
    (category_id,value,name)
  VALUES
    ('copy', -1, 'Do not have copyright');

  INSERT INTO approval_category_values
    (category_id,value,name)
  VALUES
    ('copy', 0, 'No score');

  INSERT INTO approval_category_values
    (category_id,value,name)
  VALUES
    ('copy', 1, 'Copyright clear');
====

The new column will appear at the end of the table (in position 3),
and `-1 Do not have copyright` will block submit, while `+1 Copyright
clear` is required to enable submit.


[[conversion_table]]
Conversion table from 2.1.x series to 2.2.x series
--------------------------------------------------

[options="header"]
|=================================================================================
|Gerrit 2.1.x                 |Gerrit 2.2.x
|Code review                  |<<category_label-Code-Review,Label: Code review>>
|Verify                       |<<category_label-Verified,Label: Verify>>
|Forge Identity +1            |Forge <<category_forge_author,author>> identity
|Forge Identity +2            |Forge <<category_forge_committer,committer>> & <<category_forge_author,author>> identity
|Forge Identity +3            |Forge <<category_forge_server,server>> & <<category_forge_committer,committer>> & <<category_forge_author,author>> identity
|Owner                        |<<category_owner,Owner>>
|Push branch +1               |<<category_push_direct,Push>>
|Push branch +2               |<<category_create,Create reference>> & <<category_push_direct,Push>>
|Push branch +3               |<<category_push_direct,Push>> (with force) & <<category_create,Create reference>>
|Push tag +1 & Push Branch +2 |No support to limit to push signed tag
|Push tag +2 & Push Branch +2 |<<category_push_annotated,Push annotated tag>>
|Push Branch +2 (refs/tags/*) |<<category_create,Create reference>> (refs/tags/...)
|Push Branch +3 (refs/tags/*) |<<category_push_direct,Push>> (with force on refs/tags/...)
|Read +1                      |<<category_read,Read>>
|Read +2                      |<<category_read,Read>> & <<category_push_review,Push>> (refs/for/refs/...)
|Read +3                      |<<category_read,Read>> & <<category_push_review,Push>> (refs/for/refs/...) & <<category_push_merge,Push Merge Commit>>
|Submit                       |<<category_submit,Submit>>
|=================================================================================


[NOTE]
In Gerrit 2.2.x, the way to set permissions for upload has changed entirely.
To upload a change for review is no longer a separate permission type,
instead you grant ordinary push permissions to the actual
recieving reference. In practice this means that you set push permissions
on `refs/for/refs/heads/<branch>` rather than permissions to upload changes
on `refs/heads/<branch>`.

[[restart_changes]]
[NOTE]
Restart the Gerrit web application and reload all browsers after
making any database changes to approval categories.  Browsers are
sent the list of known categories when they first visit the site,
and don't notice changes until the page is closed and opened again,
or is reloaded.

GERRIT
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Part of link:index.html[Gerrit Code Review]