php sendmail not included in docker image?

[ross-spencer]

I am seeing the following error:

• Unknown error in PHP's mail() function.

Which is similar to this: https://phabricator.wikimedia.org/T206517

To recreate this I download the current main branch here, I then replace the most basic of settings in template.env for .env:

diff --git a/example/.env b/example/.env
index 55f9e14..6d87976 100644
--- a/example/.env
+++ b/example/.env
@@ -17,25 +17,25 @@ MYSQL_IMAGE_NAME=mariadb:10.3
 ## Your password must be different from your username.
 ## Your password must not appear within your username.
 ## The password must not be in a list of very commonly used passwords. Please choose a unique password.
-MW_ADMIN_PASS=change-this-password
+MW_ADMIN_PASS=passw0rd12345
 MW_ADMIN_NAME=admin
 [email protected]
 MW_SECRET_KEY=some-secret-key
 MW_WG_ENABLE_UPLOADS=false
 
 ## Jobrunner Configuration
-MAX_JOBS=1
+MAX_JOBS=2
 
 ## Database Configuration
 DB_NAME=my_wiki
 DB_USER=sqluser
-DB_PASS=change-this-sqlpassword
+DB_PASS=passw0rd12345
 
 ## Wikibase Configuration
 WIKIBASE_PINGBACK=false
 # wikibase.svc is the internal docker hostname, change this value to the public hostname
 WIKIBASE_HOST=wikibase.svc
-WIKIBASE_PORT=80
+WIKIBASE_PORT=8882
 
 ## WDQS-frontend Configuration
 # wdqs-frontend.svc is the internal docker hostname, change this value to the public hostname

And run docker-compose up without configuring anything else.

If I try adding an email for a user and sending a confirmation email the error above happens.

Entering the container: sudo docker-compose exec --user=root wikibase bash

We see the following running php in interactive mode:

php > mail("[email protected]", "1", "2");
sh: 1: /usr/sbin/sendmail: not found

And in /usr/sbin/:

root@4a11c0f57991:/var/www/html# ls /usr/sbin/
a2disconf  addgroup	   chpasswd		dpkg-reconfigure  groupdel     invoke-rc.d	    policy-rc.d   rtcwake		  update-rc.d
a2dismod   adduser	   chroot		e2freefrag	  groupmems    ldattach		    pwck	  service		  useradd
a2dissite  apache2	   cpgr			e4crypt		  groupmod     mklost+found	    pwconv	  split-logfile		  userdel
a2enconf   apache2ctl	   cppw			e4defrag	  grpck        newusers		    pwunconv	  tarcat		  usermod
a2enmod    apachectl	   delgroup		faillock	  grpconv      nologin		    readprofile   tzconfig		  vigr
a2ensite   check_forensic  deluser		fdformat	  grpunconv    pam-auth-update	    remove-shell  update-ca-certificates  vipw
a2query    chgpasswd	   dpkg-fsys-usrunmess	filefrag	  httxt2dbm    pam_getenv	    rmt		  update-mime		  zic
add-shell  chmem	   dpkg-preconfigure	groupadd	  iconvconfig  pam_timestamp_check  rmt-tar	  update-passwd

If we follow some of the information in Phabricator, we see PEAR installed:

Providing this is diagnosed correctly, then it looks like sendmail isn't bundled with PHP in the given image.

The impact is on:

• Creating new users with a temporary password.
• Validating user passwords, and therefore OAuth.
• Other functions I'm not thinking about yet, e.g. monitoring pages? etc.