To get the environment variables in snapping

Jin Hsieh jin.hsieh at
Mon Mar 13 08:29:20 UTC 2017

Hello guys,

We are making a workable mail solution snap,
the selected back-end services are Postfix(SMTP) and Dovecot(POP3/IMAP).

For those services as you known they have some dependencies with classic
for example the /etc/postfix/ and /etc/dovecot/dovecot.conf so we
made some changes on the upstream code,
to get the environment variables such as SNAP, SNAP_DATA/SNAP_COMMON by
then replace the classic one into $SNAP_DATA/etc/postfix/* to make it works

Also, for a bigger snap like this,
the component(one of the parts) will execute external command to trigger
another one,
in such the case Postfix forks its child process: pipe to call dovecot-lda
(which is a sub-process of Dovecot),
to complete the mail retrieving function, now I would say *it is lucky to
have a useful configuration parameter* "export_environment" in Postfix,
so that we can make sure the commands could be executed correctly in our
snap world with specific $SNAP exported.

But you could recognize the modification we made *is hard to upstream guys
to accept/merge the changes into their trunk*,
so many getenv("SNAP") in the code or in where the code flow uses
clean_env() we also need to cache the SNAP-related variables,
I am wondering if we have a better way to do this, for example an interface
or environment-sharing could make the life easier?
    1. then have the chances to make the upstream code up without
getenv("SNAP") to make their code snap-adaptive
    2. then have a much regular way to export environment when one
component calls another one externally without "export_environment" support

Any feedback would be welcomed,
many thanks.


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