**Report**
Using the `mediawiki:1.30` image, I attempted to run `dumpRdf.php` and got the following error when it reached claims containing dates. It's looking for `cal_days_in_month()` which I believe requires PHP to be compiled with ` --enable-calendar`. I think this can be achieved in Docker by adding `RUN docker-php-ext-install calendar` in the dockerfile.
For the record, I was able to run `dumpJson.php` successfully.
```
sudo docker-compose exec wikibase php ./extensions/Wikibase/repo/maintenance/dumpRdf.php --output wikibase-dump-2018-09-04.ttl
Dumping shard 0/1
Processed 100 entities.
Processed 200 entities.
Processed 300 entities.
Processed 400 entities.
Processed 500 entities.
Processed 600 entities.
Processed 700 entities.
Processed 800 entities.
Processed 900 entities.
Processed 1000 entities.
Processed 1100 entities.
[09016aa90a6f713af43f7436] [no req] Error from line 89 of /var/www/html/extensions/Wikibase/repo/includes/Rdf/DateTimeValueCleaner.php: Call to undefined function Wikibase\Rdf\cal_days_in_month()
Backtrace:
#0 /var/www/html/extensions/Wikibase/repo/includes/Rdf/DateTimeValueCleaner.php(46): Wikibase\Rdf\DateTimeValueCleaner->cleanupGregorianValue(string, integer)
#1 /var/www/html/extensions/Wikibase/repo/includes/Rdf/JulianDateTimeValueCleaner.php(43): Wikibase\Rdf\DateTimeValueCleaner->getStandardValue(DataValues\TimeValue)
#2 /var/www/html/extensions/Wikibase/repo/includes/Rdf/Values/TimeRdfBuilder.php(71): Wikibase\Rdf\JulianDateTimeValueCleaner->getStandardValue(DataValues\TimeValue)
#3 /var/www/html/extensions/Wikibase/repo/includes/Rdf/Values/TimeRdfBuilder.php(63): Wikibase\Rdf\Values\TimeRdfBuilder->sayDateLiteral(Wikimedia\Purtle\TurtleRdfWriter, DataValues\TimeValue)
#4 /var/www/html/extensions/Wikibase/repo/includes/Rdf/DispatchingValueSnakRdfBuilder.php(53): Wikibase\Rdf\Values\TimeRdfBuilder->addValue(Wikimedia\Purtle\TurtleRdfWriter, string, string, string, Wikibase\DataModel\Snak\PropertyValueSnak)
#5 /var/www/html/extensions/Wikibase/repo/includes/Rdf/SnakRdfBuilder.php(128): Wikibase\Rdf\DispatchingValueSnakRdfBuilder->addValue(Wikimedia\Purtle\TurtleRdfWriter, string, string, string, Wikibase\DataModel\Snak\PropertyValueSnak)
#6 /var/www/html/extensions/Wikibase/repo/includes/Rdf/SnakRdfBuilder.php(83): Wikibase\Rdf\SnakRdfBuilder->addSnakValue(Wikimedia\Purtle\TurtleRdfWriter, Wikibase\DataModel\Snak\PropertyValueSnak, string)
#7 /var/www/html/extensions/Wikibase/repo/includes/Rdf/TruthyStatementRdfBuilder.php(85): Wikibase\Rdf\SnakRdfBuilder->addSnak(Wikimedia\Purtle\TurtleRdfWriter, Wikibase\DataModel\Snak\PropertyValueSnak, string)
#8 /var/www/html/extensions/Wikibase/repo/includes/Rdf/TruthyStatementRdfBuilder.php(63): Wikibase\Rdf\TruthyStatementRdfBuilder->addMainSnak(Wikibase\DataModel\Entity\ItemId, Wikibase\DataModel\Statement\Statement)
#9 /var/www/html/extensions/Wikibase/repo/includes/Rdf/TruthyStatementRdfBuilder.php(97): Wikibase\Rdf\TruthyStatementRdfBuilder->addStatements(Wikibase\DataModel\Entity\ItemId, Wikibase\DataModel\Statement\StatementList)
#10 /var/www/html/extensions/Wikibase/repo/includes/Rdf/RdfBuilder.php(381): Wikibase\Rdf\TruthyStatementRdfBuilder->addEntity(Wikibase\DataModel\Entity\Item)
#11 /var/www/html/extensions/Wikibase/repo/includes/Dumpers/RdfDumpGenerator.php(151): Wikibase\Rdf\RdfBuilder->addEntity(Wikibase\DataModel\Entity\Item)
#12 /var/www/html/extensions/Wikibase/repo/includes/Dumpers/DumpGenerator.php(281): Wikibase\Dumpers\RdfDumpGenerator->generateDumpForEntityId(Wikibase\DataModel\Entity\ItemId)
#13 /var/www/html/extensions/Wikibase/repo/includes/Dumpers/DumpGenerator.php(251): Wikibase\Dumpers\DumpGenerator->dumpEntities(array, integer)
#14 /var/www/html/extensions/Wikibase/repo/maintenance/dumpEntities.php(175): Wikibase\Dumpers\DumpGenerator->generateDump(Wikibase\Repo\Store\Sql\SqlEntityIdPager)
#15 /var/www/html/extensions/Wikibase/repo/maintenance/dumpRdf.php(128): Wikibase\DumpScript->execute()
#16 /var/www/html/maintenance/doMaintenance.php(92): Wikibase\DumpRdf->execute()
#17 /var/www/html/extensions/Wikibase/repo/maintenance/dumpRdf.php(177): require_once(string)
#18 {main}
```
**Solution & Acceptance Criteria**
[x] The Calendar PHP extension should be installed on all Wikibase docker images.
- Link to the method used: https://secure.php.net/manual/en/function.cal-days-in-month.php
[] Wikibase composer.json could suggest that the PHP extension be installed?
**Tech Pointers**
The Docker files can be found in https://github.com/wmde/wikibase-docker/tree/master/wikibase on github
The mediawiki base image that we use already installs some extensions, you can find an example at https://github.com/wikimedia/mediawiki-docker/blob/master/stable/Dockerfile#L12-L13
The extension needs to be installed for both the 1.29 and 1.30 base images (and 1.31 if it is merged before this ticket is worked on)