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Diffstat (limited to 'doc/external-dependency-solver-protocol.txt')
| -rw-r--r-- | doc/external-dependency-solver-protocol.txt | 59 |
1 files changed, 43 insertions, 16 deletions
diff --git a/doc/external-dependency-solver-protocol.txt b/doc/external-dependency-solver-protocol.txt index 7a124d8f9..14e9528c8 100644 --- a/doc/external-dependency-solver-protocol.txt +++ b/doc/external-dependency-solver-protocol.txt @@ -1,10 +1,18 @@ -# APT External Dependency Solver Protocol (EDSP) - version 0.4 +# APT External Dependency Solver Protocol (EDSP) - version 0.5 This document describes the communication protocol between APT and external dependency solvers. The protocol is called APT EDSP, for "APT External Dependency Solver Protocol". +## Terminology + +In the following we use the term **architecture qualified package name** +(or *arch-qualified package names* for short) to refer to package +identifiers of the form "package:arch" where "package" is a package name +and "arch" a dpkg architecture. + + ## Components - **APT**: we know this one. @@ -62,6 +70,7 @@ configuration documentation for more, and more up to date, information. - **Dir::Bin::Solvers**: absolute path of the directory where to look for external solvers. Defaults to `/usr/lib/apt/solvers`. + ## Protocol When configured to use an external solver, APT will resort to it to @@ -110,23 +119,31 @@ Within a dependency solving scenario, a request represents the action on installed packages requested by the user. A request is a single Deb 822 stanza opened by a mandatory Request field -and followed by a mixture of action and preference fields. +and followed by a mixture of action, preference, and global +configuration fields. The value of the **Request:** field is a string describing the EDSP protocol which will be used to communicate. At present, the string must -be `EDSP 0.4`. +be `EDSP 0.5`. Request fields are mainly used to identify the beginning +of a request stanza; their actual values are otherwise not used by the +EDSP protocol. -a unique request identifier, such as an -UUID. Request fields are mainly used to identify the beginning of a -request stanza; their actual values are otherwise not used by the EDSP -protocol. +The following **configuration fields** are supported in request stanzas: + +- **Architecture:** (mandatory) The name of the *native* architecture on + the user machine (see also: `dpkg --print-architecture`) + +- **Architectures:** (optional, defaults to the native architecture) A + space separated list of *all* architectures known to APT (this is + roughly equivalent to the union of `dpkg --print-architecture` and + `dpkg --print-foreign-architectures`) The following **action fields** are supported in request stanzas: - **Install:** (optional, defaults to the empty string) A space - separated list of package names, with *no version attached*, to - install. This field denotes a list of packages that the user wants to - install, usually via an APT `install` request. + separated list of arch-qualified package names, with *no version + attached*, to install. This field denotes a list of packages that the + user wants to install, usually via an APT `install` request. - **Remove:** (optional, defaults to the empty string) Same syntax of Install. This field denotes a list of packages that the user wants to @@ -193,7 +210,7 @@ field. The following fields are supported in package stanzas: - **APT-Candidate:** (optional, defaults to `no`). Allowed values: `yes`, `no`. When set to `yes`, the corresponding package is the APT candidate for installation among all available packages with the same - name. + name and architecture. - **APT-Automatic:** (optional, defaults to `no`). Allowed values: `yes`, `no`. When set to `yes`, the corresponding package is marked by @@ -201,6 +218,16 @@ field. The following fields are supported in package stanzas: should be removed by the solver only when the Autoremove action is requested (see Request section). +- **APT-Release:** (optional) The releases the package belongs to, according to + APT. The format of this field is multiline with one value per line and the + first line (the one containing the field name) empty. Each subsequent line + corresponds to one of the releases the package belongs to and looks like + this: `o=Debian,a=unstable,n=sid,l=Debian,c=main`. That is, each release line + is a comma-separated list of "key=value" pairs, each of which denotes a + Release file entry (Origin, Label, Codename, etc.) in the format of + APT_PREFERENCES(5). + + ### Answer An answer from the external solver to APT is either a *solution* or an @@ -209,11 +236,11 @@ An answer from the external solver to APT is either a *solution* or an The following invariant on **exit codes** must hold true. When the external solver is *able to find a solution*, it will write the solution to standard output and then exit with an exit code of 0. When the -external solver is *unable to find a solution* (and s aware of that), it -will write an error to standard output and then exit with an exit code -of 0. An exit code other than 0 will be interpreted as a solver crash -with no meaningful error about dependency resolution to convey to the -user. +external solver is *unable to find a solution* (and is aware of that), +it will write an error to standard output and then exit with an exit +code of 0. An exit code other than 0 will be interpreted as a solver +crash with no meaningful error about dependency resolution to convey to +the user. #### Solution |