PHP 5.6 Client errors out on Alpine about aws-elasticache-cluster-client-memcached-for-php HOT 1 OPEN

pecl list -a
Installed packages, channel __uri:
==================================
Package                        Version State
AmazonElastiCacheClusterClient 1.0.0   beta

Installed packages, channel doc.php.net:
========================================
(no packages installed)

Installed packages, channel pear.php.net:
=========================================
Package          Version State
Archive_Tar      1.4.0   stable
Console_Getopt   1.4.1   stable
PEAR             1.10.1  stable
PEAR_Manpages    1.10.0  stable
Structures_Graph 1.1.1   stable
XML_Util         1.3.0   stable

Installed packages, channel pecl.php.net:
=========================================
(no packages installed)

ll /usr/lib64/php/5.6/modules/
total 7704
-rw-r--r-- 1 root root 1213746 Aug 22 05:31 amazon-elasticache-cluster-client.so
-rwxrwxrwx 1 root root   25304 Mar  8 18:26 bz2.so
-rwxrwxrwx 1 root root   31264 Mar  8 18:26 calendar.so
-rwxrwxrwx 1 root root   13080 Mar  8 18:26 ctype.so
-rwxrwxrwx 1 root root   85752 Mar  8 18:26 curl.so
-rwxrwxrwx 1 root root  174248 Mar  8 18:26 dom.so
-rwxrwxrwx 1 root root   62712 Mar  8 18:26 exif.so
-rwxrwxrwx 1 root root 2897624 Mar  8 18:26 fileinfo.so
-rwxrwxrwx 1 root root   53656 Mar  8 18:26 ftp.so
-rwxrwxrwx 1 root root   12472 Mar  8 18:26 gettext.so
-rwxrwxrwx 1 root root   42264 Mar  8 18:26 iconv.so
-rwxrwxrwx 1 root root   79080 Oct 12  2017 json.so
-rwxrwxrwx 1 root root 1409392 Mar  8 18:26 mbstring.so
-rwxrwxrwx 1 root root   45576 Mar  8 18:26 mcrypt.so
-rwxrwxrwx 1 root root  133864 Mar  8 18:26 mysqli.so
-rwxrwxrwx 1 root root  272768 Mar  8 18:26 mysqlnd.so
-rwxrwxrwx 1 root root   49528 Mar  8 18:26 mysql.so
-rwxrwxrwx 1 root root   28392 Mar  8 18:26 pdo_mysql.so
-rwxrwxrwx 1 root root   41384 Mar  8 18:26 pdo_pgsql.so
-rwxrwxrwx 1 root root  114120 Mar  8 18:26 pdo.so
-rwxrwxrwx 1 root root   26504 Mar  8 18:26 pdo_sqlite.so
-rwxrwxrwx 1 root root  140632 Mar  8 18:26 pgsql.so
-rwxrwxrwx 1 root root  265408 Mar  8 18:26 phar.so
-rwxrwxrwx 1 root root   27672 Mar  8 18:26 posix.so
-rwxrwxrwx 1 root root   11928 Mar  8 18:26 shmop.so
-rwxrwxrwx 1 root root   48616 Mar  8 18:26 simplexml.so
-rwxrwxrwx 1 root root   87672 Mar  8 18:26 sockets.so
-rwxrwxrwx 1 root root   48632 Mar  8 18:26 sqlite3.so
-rwxrwxrwx 1 root root   16504 Mar  8 18:26 sysvmsg.so
-rwxrwxrwx 1 root root    9272 Mar  8 18:26 sysvsem.so
-rwxrwxrwx 1 root root   12376 Mar  8 18:26 sysvshm.so
-rwxrwxrwx 1 root root   15544 Mar  8 18:26 tokenizer.so
-rwxrwxrwx 1 root root   36824 Mar  8 18:26 wddx.so
-rwxrwxrwx 1 root root   30232 Mar  8 18:26 xmlreader.so
-rwxrwxrwx 1 root root   49104 Mar  8 18:26 xml.so
-rwxrwxrwx 1 root root   44984 Mar  8 18:26 xmlwriter.so
-rwxrwxrwx 1 root root   34008 Mar  8 18:26 xsl.so
-rwxrwxrwx 1 root root  116232 Mar  8 18:26 zip.so

[
  "Core",
  "date",
  "ereg",
  "libxml",
  "openssl",
  "pcre",
  "zlib",
  "filter",
  "hash",
  "Reflection",
  "SPL",
  "session",
  "standard",
  "apache2handler",
  "bz2",
  "calendar",
  "ctype",
  "curl",
  "dom",
  "mbstring",
  "fileinfo",
  "ftp",
  "gettext",
  "iconv",
  "exif",
  "mcrypt",
  "mysqlnd",
  "PDO",
  "pgsql",
  "Phar",
  "posix",
  "shmop",
  "SimpleXML",
  "sockets",
  "sqlite3",
  "sysvmsg",
  "sysvsem",
  "sysvshm",
  "tokenizer",
  "xml",
  "xmlwriter",
  "xsl",
  "zip",
  "mysql",
  "mysqli",
  "pdo_mysql",
  "pdo_pgsql",
  "pdo_sqlite",
  "wddx",
  "xmlreader",
  "json",
  "mhash"
]