Consul: Add a nameserver entry poining to localhost for dnsmasq

[vitabaks]

This update sets 127.0.0.1 as the nameserver in /etc/resolv.conf when Consul is utilized as the DCS. This change ensures proper resolution of Consul service DNS names, such as master.postgres-cluster.service.consul and replica.postgres-cluster.service.consul

[vitabaks]

Test

...

TASK [deploy-finish : PostgreSQL list of users] ********************************
ok: [10.172.0.20] => {
    "users_result.stdout_lines": [
        "                              List of roles",
        " Role name  |                         Attributes                         ",
        "------------+------------------------------------------------------------",
        " pgbouncer  | ",
        " postgres   | Superuser, Create role, Create DB, Replication, Bypass RLS",
        " replicator | Replication"
    ]
}

TASK [deploy-finish : Get postgresql database list] ****************************
ok: [10.172.0.20]

TASK [deploy-finish : PostgreSQL list of databases] ****************************
ok: [10.172.0.20] => {
    "dbs_result.stdout_lines": [
        "   name   |  owner   | encoding |   collate   |    ctype    |  size   | tablespace ",
        "----------+----------+----------+-------------+-------------+---------+------------",
        " postgres | postgres | UTF8     | en_US.UTF-8 | en_US.UTF-8 | 7492 kB | pg_default",
        "(1 row)"
    ]
}

TASK [deploy-finish : Check postgresql cluster health] *************************
ok: [10.172.0.20]

TASK [deploy-finish : PostgreSQL Cluster health] *******************************
ok: [10.172.0.20] => {
    "patronictl_result.stdout_lines": [
        "+ Cluster: postgres-cluster (7331448813020401589) --+-----------+",
        "| Member   | Host        | Role    | State     | TL | Lag in MB |",
        "+----------+-------------+---------+-----------+----+-----------+",
        "| pgnode01 | 10.172.0.20 | Leader  | running   |  2 |           |",
        "| pgnode02 | 10.172.0.21 | Replica | streaming |  2 |         0 |",
        "| pgnode03 | 10.172.0.22 | Replica | streaming |  2 |         0 |",
        "+----------+-------------+---------+-----------+----+-----------+"
    ]
}

TASK [deploy-finish : PostgreSQL Cluster connection info] **********************
ok: [10.172.0.20] => {
    "msg": [
        "+------------------------------------------------+",
        "Client access point (DNS):",
        " master.postgres-cluster.service.consul ",
        " replica.postgres-cluster.service.consul ",
        "port 6432 (pgbouncer)",
        "+------------------------------------------------+"
    ]
}

PLAY RECAP *********************************************************************
10.172.0.20                : ok=181  changed=83   unreachable=0    failed=0    skipped=551  rescued=0    ignored=0
10.172.0.21                : ok=149  changed=73   unreachable=0    failed=0    skipped=518  rescued=0    ignored=0
10.172.0.22                : ok=149  changed=73   unreachable=0    failed=0    skipped=518  rescued=0    ignored=0

root@pgnode01:/# cat /etc/dnsmasq.d/10-consul
server=/consul/127.0.0.1#8600
server=8.8.8.8
server=9.9.9.9
root@pgnode01:/# cat /etc/resolv.conf 
nameserver 127.0.0.1
nameserver 8.8.8.8
nameserver 9.9.9.9
options ndots:0

root@pgnode01:/# psql -h master.postgres-cluster.service.consul -p 6432 -U postgres -c "select pg_is_in_recovery()";
 pg_is_in_recovery 
-------------------
 f
(1 row)

root@pgnode01:/# psql -h replica.postgres-cluster.service.consul -p 6432 -U postgres -c "select pg_is_in_recovery()";
 pg_is_in_recovery 
-------------------
 t
(1 row)

passed