X-Git-Url: https://git.saurik.com/apt.git/blobdiff_plain/eed4639e3feea0dd4ebedfac95fb5428753b795f..2a440328ea19e9646a93f847dd9eff21e03ad16d:/doc/external-dependency-solver-protocol.txt?ds=inline diff --git a/doc/external-dependency-solver-protocol.txt b/doc/external-dependency-solver-protocol.txt index 5757991a8..566890665 100644 --- a/doc/external-dependency-solver-protocol.txt +++ b/doc/external-dependency-solver-protocol.txt @@ -58,17 +58,29 @@ configuration documentation for more, and more up to date, information. - **APT::Solver**: the name of the solver to be used for dependency solving. Defaults to `internal` +- **Dir::Bin::Solvers**: absolute path of the directory where to look for + external solvers. Defaults to `/usr/lib/apt/solvers`. + - **APT::Solver::Strict-Pinning**: whether pinning must be strictly respected (as the internal solver does) or can be slightly deviated from. Defaults to `yes`. -- **APT::Solver::NAME::Preferences** (where NAME is a solver name): - solver-specific user preference string used during dependency solving, - when the solver NAME is in use. Check solver-specific documentation - for what is supported here. Defaults to the empty string. +- **APT::Solver::Preferences**: user preference string used during + dependency solving by the requested solver. Check the documentation + of the solver you are using if and what is supported as a value here. + Defaults to the empty string. -- **Dir::Bin::Solvers**: absolute path of the directory where to look for - external solvers. Defaults to `/usr/lib/apt/solvers`. +- **APT::Solver::RunAsUser**: if APT itself is run as root it will + change to this user before executing the solver. Defaults to the value + of APT::Sandbox::User, which itself defaults to `_apt`. Can be + disabled by set this option to `root`. + +The options **Strict-Pinning** and **Preferences** can also be set for +a specific solver only via **APT::Solver::NAME::Strict-Pinning** and +**APT::Solver::NAME::Preferences** respectively where `NAME` is the name +of the external solver this option should apply to. These options if set +override the generic options; for simplicity the documentation will +refer only to the generic options. ## Protocol @@ -149,17 +161,26 @@ The following **action fields** are supported in request stanzas: Install. This field denotes a list of packages that the user wants to remove, usually via APT `remove` or `purge` requests. -- **Upgrade:** (optional, defaults to `no`). Allowed values: `yes`, +- **Upgrade-All:** (optional, defaults to `no`). Allowed values `yes`, `no`. When set to `yes`, an upgrade of all installed packages has been - requested, usually via an APT `upgrade` request. - -- **Dist-Upgrade:** (optional, defaults to `no`). Allowed values: `yes`, - `no`. Same as Upgrade, but for APT `dist-upgrade` requests. + requested, usually via an upgrade command like 'apt full-upgrade'. - **Autoremove:** (optional, defaults to `no`). Allowed values: `yes`, `no`. When set to `yes`, a clean up of unused automatically installed packages has been requested, usually via an APT `autoremove` request. +- **Upgrade:** (deprecated, optional, defaults to `no`). Allowed values: + `yes`, `no`. When set to `yes`, an upgrade of all installed packages + has been requested, usually via an APT `upgrade` request. A value of + `yes` is equivalent to the fields `Upgrade-All`, + `Forbid-New-Install`and `Forbid-Remove` all set to `yes`. + +- **Dist-Upgrade:** (deprecated, optional, defaults to `no`). Allowed + values: `yes`, `no`. Same as Upgrade, but for APT `dist-upgrade` + requests. A value of `yes` is equivalent to the field `Upgrade-All` + set to `yes` and the fields `Forbid-New-Install`and `Forbid-Remove` + set to `no`. + The following **preference fields** are supported in request stanzas: - **Strict-Pinning:** (optional, defaults to `yes`). Allowed values: @@ -171,8 +192,21 @@ The following **preference fields** are supported in request stanzas: field comes from the `APT::Solver::Strict-Pinning` configuration option. -- **Preferences:** a solver-specific optimization string, usually coming - from the `APT::Solver::Preferences` configuration option. +- **Forbid-New-Install:* (optional, defaults to `no`). Allowed values: + `yes`, `no`. When set to `yes` the resolver is forbidden to install + new packages in its returned solution. + +- **Forbid-Remove:* (optional, defaults to `no`). Allowed values: `yes`, + `no`. When set to `yes` the resolver is forbidden to remove currently + installed packages in its returned solution. + +- **Solver:** (optional, defaults to the empty string) a purely + informational string specifying to which solver this request was send + initially. + +- **Preferences:** (optional, defaults to the empty string) + a solver-specific optimization string, usually coming from the + `APT::Solver::Preferences` configuration option. #### Package universe @@ -251,11 +285,11 @@ the user. #### Solution -A solution is a list of Deb 822 stanzas. Each of them could be an -install stanza (telling APT to install a specific package), a remove -stanza (telling APT to remove one), or an autoremove stanza (telling APT -about the *future* possibility of removing a package using the -Autoremove action). +A solution is a list of Deb 822 stanzas. Each of them could be an install +stanza (telling APT to install a specific new package or to upgrade or +downgrade a package to a specific version), a remove stanza (telling APT to +remove one), or an autoremove stanza (telling APT about the *future* +possibility of removing a package using the Autoremove action). An **install stanza** starts with an Install field and supports the following fields: @@ -277,6 +311,16 @@ this protocol makes no assumption on the fact that a subsequent invocation of an Autoremove action will actually remove the very same packages indicated by Autoremove stanzas in the former solution. +A package can't be installed in multiple versions at the same time, so +for each package there can at most one version be selected either for +installation or removal. This especially means that a solver is neither +allowed to represent package upgrades as a remove of the installed +version and the installation of another (the remove is implicit and must +be omitted from the solution) nor is it supported to revert previous +actions in the solution with later actions. APT is allowed to show +warnings and might even misbehave in earlier versions if a solver is +violating this assumption. + In terms of expressivity, install and remove stanzas can carry one single field each, as APT-IDs are enough to pinpoint packages to be installed/removed. Nonetheless, for protocol readability, it is @@ -308,8 +352,9 @@ information to APT using **progress stanzas**. A progress stanza starts with the Progress field and might contain the following fields: - **Progress:** (mandatory). The value of this field is a date and time - timestamp, in RFC 2822 format. The timestamp provides a time - annotation for the progress report. + timestamp from the UTC timezone, in RFC 2822 format (see 'date -uR' as + an example). The timestamp provides a time annotation for the + progress report. - **Percentage:** (optional). An integer from 0 to 100, representing the completion of the dependency solving process, as declared by the