Install the root + letsencrypt CA file, without downloading them from remote.

mongodb-org/defaults/main.yml

@@ -49,15 +49,14 @@ mongodb_storage_engine: wiredTiger
 
 mongodb_ssl_enabled: False
 mongodb_ssl_letsencrypt_managed: True
-mongodb_ssl_letsencrypt_ca_url: 'https://letsencrypt.org/certs/lets-encrypt-x3-cross-signed.pem.txt'
 mongodb_ssl_letsencrypt_ca_dir: '{{ mongodb_ssl_cert_dir }}'
+# This one contains both lets-encrypt-x3-cross-signed.pem.txt and DST_Root_CA_X3.crt
 mongodb_ssl_letsencrypt_ca_filename: lets-encrypt-x3-cross-signed.pem
 # Options: disabled, requireSSL, allowSSL, preferSSL
 mongodb_ssl_mode: requireSSL
 mongodb_ssl_cert_dir: /etc/pki/mongodb
 mongodb_ssl_certkey_file: '{{ mongodb_ssl_cert_dir }}/mongodb.pem'
 mongodb_ssl_CA_file: '{{ mongodb_ssl_letsencrypt_ca_dir }}/{{ mongodb_ssl_letsencrypt_ca_filename }}'
-mongodb_ssl_root_CA_file: '/usr/share/ca-certificates/mozilla/DST_Root_CA_X3.crt'
 mongodb_ssl_allowConnectionsWithoutCertificates: 'true'
 mongodb_ssl_disabled_protocols: 'TLS1_0,TLS1_1'
 

mongodb-org/files/lets-encrypt-x3-cross-signed.pem

@@ -0,0 +1,47 @@
+-----BEGIN CERTIFICATE-----
+MIIEkjCCA3qgAwIBAgIQCgFBQgAAAVOFc2oLheynCDANBgkqhkiG9w0BAQsFADA/
+MSQwIgYDVQQKExtEaWdpdGFsIFNpZ25hdHVyZSBUcnVzdCBDby4xFzAVBgNVBAMT
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+KOqkqm57TH2H3eDJAkSnh6/DNFu0Qg==
+-----END CERTIFICATE-----
+-----BEGIN CERTIFICATE-----
+MIIDSjCCAjKgAwIBAgIQRK+wgNajJ7qJMDmGLvhAazANBgkqhkiG9w0BAQUFADA/
+MSQwIgYDVQQKExtEaWdpdGFsIFNpZ25hdHVyZSBUcnVzdCBDby4xFzAVBgNVBAMT
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+Ob8VZRzI9neWagqNdwvYkQsEjgfbKbYK7p2CNTUQ
+-----END CERTIFICATE-----

mongodb-org/tasks/mongodb-letsencrypt-acmetool.yml

@@ -9,13 +9,8 @@
   - name: Create the mongodb certificate directory
     file: dest={{ mongodb_ssl_cert_dir }} state=directory owner=root group=mongodb mode=0750
 
-  - name: Get the Letsencrypt CA file if there is no local copy yet
-    get_url: url={{ mongodb_ssl_letsencrypt_ca_url }} dest={{ mongodb_ssl_cert_dir }}/{{ mongodb_ssl_letsencrypt_ca_filename }}
-    register: build_mongo_ca_file
-
-  - name: Add the Root CA certificate to the mongodb CA file
-    command: cat {{ mongodb_ssl_root_CA_file }} >> {{ mongodb_ssl_cert_dir }}/{{ mongodb_ssl_letsencrypt_ca_filename }}
-    when: build_mongo_ca_file is changed
+  - name: Install the Letsencrypt CA file with both the root and the trusted CAs
+    copy: src={{ mongodb_ssl_letsencrypt_ca_filename }} dest={{ mongodb_ssl_cert_dir }}/{{ mongodb_ssl_letsencrypt_ca_filename }} mode=0444
 
   - name: Verify if the mongodb pem file exists
     stat: path={{ mongodb_ssl_certkey_file }}