diff --git a/cgi-bin/set_membership b/cgi-bin/set_membership
index e69de29b..eb62c5ae 100755
--- a/cgi-bin/set_membership
+++ b/cgi-bin/set_membership
@@ -0,0 +1,215 @@
+#!/usr/bin/perl
+#
+# Accepts a HTTP PUT request to set the cluster membership of a host.
+#
+
+use strict;
+use warnings;
+use Anvil::Tools;
+use Data::Dumper;
+use JSON
+
+$| = 1;
+
+my $THIS_FILE = ($0 =~ /^.*\/(.*)$/)[0];
+my $running_directory = ($0 =~ /^(.*?)\/$THIS_FILE$/)[0];
+if (($running_directory =~ /^\./) && ($ENV{PWD}))
+{
+ $running_directory =~ s/^\./$ENV{PWD}/;
+}
+
+my $anvil = Anvil::Tools->new();
+
+sub handle_invalid_uuid
+{
+ my $parameters = shift;
+ my $name = $parameters->{name};
+ my $uuid = $parameters->{uuid};
+
+ $anvil->Log->entry({
+ source => $THIS_FILE,
+ line => __LINE__,
+ level => 0,
+ 'print' => 1,
+ priority => "err",
+ key => "error_0160",
+ variables => { name => $name, uuid => $uuid }
+ });
+ $anvil->nice_exit({ exit_code => 1 });
+}
+
+sub get_active_member
+{
+ my $parameters = shift;
+ my $host_uuid = $parameters->{host_uuid};
+
+ my $query = "
+SELECT
+ scan_cluster_node_in_ccm,
+ scan_cluster_node_crmd_member,
+ scan_cluster_node_cluster_member
+FROM
+ scan_cluster_nodes
+WHERE
+ scan_cluster_node_host_uuid = ".$anvil->Database->quote($host_uuid)."
+";
+ $anvil->Log->variables({ source => $THIS_FILE, line => __LINE__, level => 2, list => { query => $query } });
+ my $results = $anvil->Database->query({ query => $query, source => $THIS_FILE, line => __LINE__ });
+ my $count = @{$results};
+ $anvil->Log->variables({ source => $THIS_FILE, line => __LINE__, level => 2, list => {
+ results => $results,
+ count => $count
+ } });
+
+ if ($count == 1)
+ {
+ my $row = $results->[0];
+ my $is_in_ccm = $row->[0];
+ my $is_crmd_member = $row->[1];
+ my $is_cluster_member = $row->[2];
+ $anvil->Log->variables({ source => $THIS_FILE, line => __LINE__, level => 2, list => {
+ is_in_ccm => $is_in_ccm,
+ is_crmd_member => $is_crmd_member,
+ is_cluster_member => $is_cluster_member
+ } });
+
+ return $is_in_ccm && $is_crmd_member && $is_cluster_member;
+ }
+
+ return 0;
+}
+
+sub alter_host_membership
+{
+ # Expects the first of positional parameters to be a hash.
+ my $parameters = shift;
+ my $host_uuid = $parameters->{host_uuid};
+ my $is_join_cluster = $parameters->{is_join_cluster};
+
+ if ($is_join_cluster)
+ {
+ join_cluster({ host_uuid => $host_uuid });
+ }
+ else
+ {
+ leave_cluster({ host_uuid => $host_uuid });
+ }
+}
+
+# Re-adds a host to its anvil cluster.
+#
+# Note: not to be confused wtih adding a new host the an anvil.
+sub join_cluster
+{
+ my $parameters = shift;
+ my $host_uuid = $parameters->{host_uuid};
+
+ # Determine whether host is already a cluster member.
+ my $is_active_member = get_active_member({ host_uuid => $host_uuid });
+ # Find out whether the host is online before trying to make it join the cluster.
+ my $is_online = $anvil->data->{hosts}{host_uuid}{$host_uuid}{host_status} eq "online" ? 1 : 0;
+
+ $anvil->Log->variables({ source => $THIS_FILE, line => __LINE__, level => 2, list => {
+ is_active_member => $is_active_member,
+ is_online => $is_online
+ } });
+
+ if (not $is_active_member && $is_online)
+ {
+ $anvil->Database->insert_or_update_jobs({
+ job_command => $anvil->data->{path}{exe}{'anvil-safe-start'},
+ job_host_uuid => $host_uuid,
+ job_description => "job_0337",
+ job_name => "cgi-bin::set_membership::join",
+ job_progress => 0,
+ job_title => "job_0336"
+ });
+ }
+}
+
+# Removes a host from its anvil cluster.
+#
+# Note: does not permanently remove the host; can be re-added.
+sub leave_cluster
+{
+ my $parameters = shift;
+ my $host_uuid = $parameters->{host_uuid};
+
+ # Determine whether host is already a cluster member.
+ my $is_active_member = get_active_member({ host_uuid => $host_uuid });
+
+ $anvil->Log->variables({ source => $THIS_FILE, line => __LINE__, level => 2, list => {
+ is_active_member => $is_active_member
+ } });
+
+ if ($is_active_member)
+ {
+ $anvil->Database->insert_or_update_jobs({
+ job_command => $anvil->data->{path}{exe}{'anvil-safe-stop'},
+ job_host_uuid => $host_uuid,
+ job_description => "job_0339",
+ job_name => "cgi-bin::set_membership::leave",
+ job_progress => 0,
+ job_title => "job_0338"
+ });
+ }
+}
+
+$anvil->Get->switches;
+
+$anvil->Database->connect;
+$anvil->Log->entry({source => $THIS_FILE, line => __LINE__, level => 2, secure => 0, key => "log_0132"});
+if (not $anvil->data->{sys}{database}{connections})
+{
+ # No databases, exit.
+ $anvil->Log->entry({source => $THIS_FILE, line => __LINE__, level => 0, 'print' => 1, priority => "err", key => "error_0003"});
+ $anvil->nice_exit({exit_code => 1});
+}
+
+# Read in any CGI variables, if needed.
+$anvil->Get->cgi();
+
+$anvil->Database->get_hosts();
+$anvil->Database->get_anvils();
+
+print $anvil->Template->get({file => "shared.html", name => "json_headers", show_name => 0})."\n";
+
+my $response_body = {};
+
+my $request_body;
+
+my $is_decode_json_success = eval {
+ $request_body = decode_json($anvil->data->{cgi}{PUTDATA}{value});
+};
+
+if (not $is_decode_json_success)
+{
+ $anvil->Log->entry({
+ source => $THIS_FILE,
+ line => __LINE__,
+ level => 0,
+ 'print' => 1,
+ priority => "err",
+ key => "error_0304",
+ variables => { request_body_string => $anvil->data->{cgi}{PUTDATA}{value}, json_decode_error => $_ }
+ });
+}
+
+my $host_uuid = exists $request_body->{host_uuid} ? $request_body->{host_uuid} : $anvil->data->{switches}{'host-uuid'};
+# Defaults to join; will check whether host is already part of its anvil cluster.
+my $is_member = exists $request_body->{is_member} ? $request_body->{is_member} : $anvil->data->{switches}{'is-member'};
+my $host_uuid_variable_name = "host UUID";
+
+if ($host_uuid)
+{
+ if (exists $anvil->data->{hosts}{host_uuid}{$host_uuid})
+ {
+ alter_host_membership({ host_uuid => $host_uuid, is_join_cluster => $is_member });
+ }
+ else
+ {
+ handle_invalid_uuid({ name => $host_uuid_variable_name, uuid => $host_uuid });
+ }
+}
+
+print JSON->new->utf8->encode($response_body)."\n";
diff --git a/share/words.xml b/share/words.xml
index 67bbc9d2..5136abf4 100644
--- a/share/words.xml
+++ b/share/words.xml
@@ -1081,6 +1081,14 @@ It should be provisioned in the next minute or two.
Power Off Host
Power off the target host by executing a stop script on the host itself.
+
+ Host Join Cluster
+
+ Make target host join its anvil cluster.
+
+ Host Leave Cluster
+
+ Make target host leave its anvil cluster.
Starting: [#!variable!program!#].