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| -rw-r--r-- | src/mailman/docs/8-miles-high.rst | 189 | ||||
| -rw-r--r-- | src/mailman/docs/NEWS.rst | 3 |
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diff --git a/src/mailman/docs/8-miles-high.rst b/src/mailman/docs/8-miles-high.rst new file mode 100644 index 000000000..812d78d72 --- /dev/null +++ b/src/mailman/docs/8-miles-high.rst @@ -0,0 +1,189 @@ +======================================== +Notes from the PyCon 2012 Mailman Sprint +======================================== + +.. authorship + The notes are based on Barry Warsaw's description of the Mailman 3 + pipeline at the PyCon 2012 Mailman sprint on March 13, with + diagrams from his "Mailman" presentation at PyCon 2012. + Transcribed by Stephen Turnbull. + +*These are notes from the Mailman sprint at PyCon 2012. They are not +terribly well organized, nor fully fleshed out. Please edit and push +branches to Launchpad at lp:mailman or post patches to +<https://bugs.launchpad.net/mailman>.* + +The intent of this document is to provide a view of Mailman 3's workflow and +structures from "eight miles high". + + +Basic Messaging Handling Workflow +================================= + +Mailman accepts a message via the LMTP protocol (RFC 2033). It implements a +simple LMTP server internally based on the LMTP server provided in the Python +standard library. The LMTP server's responsibility is to parse the message +into a tuple (*mlist*, *msg*, *msgdata*). If the parse fails (including +messages which Mailman considers to be invalid due to lack of `Message-Id` as +strongly recommended by RFC 2822 and RFC 5322), the message will be rejected, +otherwise the parsed message and metadata dictionary are pickled, and the +resulting *message pickle* added to one of the `in`, `command`, or `bounce` +processing queues. + +.. graphviz:: + + digraph msgflow { + rankdir = LR; + node [shape=box, color=lightblue, style=filled]; + msg [shape=ellipse, color=black, fillcolor=white]; + lmtpd [label="LMTP\nSERVER"]; + msg -> MTA [label="SMTP"]; + MTA -> lmtpd [label="LMTP"]; + lmtpd -> MTA [label="reject"]; + lmtpd -> IN -> PIPELINE [label=".pck"]; + lmtpd -> BOUNCES [label=".pck"]; + lmtpd -> COMMAND [label=".pck"]; + } + +The `in` queue is processed by *filter chains* (explained below) to determine +whether the post (or administrative request) will be processed. If not +allowed, the message pickle is discarded, rejected (returned to sender), or +held (saved for moderator approval -- not shown). Otherwise the message is +added to the `pipeline` (i.e. posting) queue. + +Each of the `command`, `bounce`, and `pipeline` queues is processed by a +*pipeline of handlers* as in Mailman 2's pipeline. (Some functions such as +spam detection that were handled in the Mailman 2 pipeline are now in the +filter chains.) + +Handlers may copy messages to other queues (*e.g.*, `archive`), and eventually +posted messages for distribution to the list membership end up in the `out` +queue for injection into the MTA. + +The `virgin` queue is a special queue for messages created by Mailman. + +.. graphviz:: + + digraph pipeline { + node [shape=box, style=rounded, group=0] + { "MIME\ndelete" -> "cleanse headers" -> "add headers" -> \ + "calculate\nrecipients" -> "to digest" -> "to archive" -> \ + "to outgoing" } + node [shape=box, color=lightblue, style=filled, group=1] + { rank=same; PIPELINE -> "MIME\ndelete" } + { rank=same; "to digest" -> DIGEST } + { rank=same; "to archive" -> ARCHIVE } + { rank=same; "to outgoing" -> OUT } + } + + +Message Filtering +================= + +Once a message has been classified as a post or administrivia, rules are +applied to determine whether the message should be distributed or acted on. +Rules include things like "if the message's sender is a non-member, hold it +for moderation", or "if the message contains an `Approved` header with a valid +password, allow it to be posted". A rule may also make no decision, in which +case message processing is passed on to the next rule in the filter chain. +The default set of rules looks something like this: + +.. graphviz:: + + digraph chain_rules { + rankdir=LR /* This gives the right orientation of the columns. */ + rank=same + subgraph in { IN [shape=box, color=lightblue, style=filled] } + subgraph rules { + rankdir=TB + rank=same + node [shape=record] + approved [group=0, label="<f0> approved | {<f1> | <f2>}"] + emergency [group=0, label="<f0> emergency | {<f1> | <f2>}"] + loop [group=0, label="<f0> loop | {<f1> | <f2>}"] + modmember [group=0, label="<f0> member\nmoderated | {<f1> | <f2>}"] + administrivia [group=0, label="<f0> administrivia | <f1>"] + maxsize [group=0, label="<f0> max\ size | {<f1> | <f2>}"] + any [group=0, label="<f0> any | {<f1> | <f2>}"] + truth [label="<f0> truth | <f1>"] + approved:f1 -> emergency:f0 [weight=100] + emergency:f1 -> loop:f0 + loop:f1 -> modmember:f0 + modmember:f1 -> administrivia:f0 + administrivia:f1 -> maxsize:f0 + maxsize:f1 -> any:f0 + any:f1 -> truth:f0 + } + subgraph queues { + rankdir=TB + rank=same + node [shape=box, style=filled]; + DISCARD [shape=invhouse, color=black, style=solid]; + MODERATION [color=wheat]; + HOLD [color=wheat]; + } + { PIPELINE [shape=box, style=filled, color=cyan]; } + + IN -> approved:f0 + approved:f2 -> PIPELINE [minlen=2] + loop:f2 -> DISCARD + modmember:f2 -> MODERATION + + emergency:f2:e -> HOLD + maxsize:f2 -> MODERATION + any:f2 -> MODERATION + truth:f1 -> PIPELINE [minlen=2] + } + + +Configuration +============= + +Uses lazr.config. + +Each Runner's configuration object knows whether it should be started +when the Mailman daemon starts, and what queue the Runner manages. + + +Shell Commands +============== + +`bin/mailman`: This is an ubercommand, with subcommands for all the various +things admins might want to do, similar to Mailman 2's mailmanctl, but with +more functionality. + +`bin/master`: The runner manager: starts, watches, stops the runner +daemons. + +`bin/runner`: Individual runner daemons. Each instance is configured with +arguments specified on the command line. + + +User Model +========== + +A *user* represents a person. A user has an *id* and a *display +name*, and optionally a list of linked addresses. + +Each *address* is a separate object, linked to no more than one user. + +A list *member* associates an address with a mailing list. Each list member +has a id, a mailing list name, an address (which may be `None`, representing +the user's *preferred address*), a list of preferences, and a *role* such as +"owner" or "moderator". Roles are used to determine what kinds of mail the +user receives via that membership. *Owners* will receive mail to +*list*-owner, but not posts and moderation traffic, for example. A user with +multiple roles on a single list will therefore have multiple memberships in +that list, one for each role. + +Roles are implemented by "magical, invisible" *rosters* which are objects +representing queries on the membership database. + + +List Styles +=========== + +Each list *style* is a named object. Its attributes are functions used to +apply the relevant style settings to the mailing list *at creation time*. +Since these are functions, they can be composed in various ways, to create +substyles, *etc*. diff --git a/src/mailman/docs/NEWS.rst b/src/mailman/docs/NEWS.rst index 2906be1cd..31e3ce7b9 100644 --- a/src/mailman/docs/NEWS.rst +++ b/src/mailman/docs/NEWS.rst @@ -48,6 +48,9 @@ Architecture longer set the `X-Message-ID-Hash` header. * The Prototype archiver now stores its files in maildir format inside of `$var_dir/archives/prototype`, given by Toshio Kuratomi. + * Improved "8 mile high" document distilled by Stephen Turnbull from the + Pycon 2012 Mailman 3 sprint. Also improvements to the Sphinx build given + by Andrea Crotti. Database -------- |