by the way I found another peculiar behavior...
I deleted the elasticsearch pod, and the replicaset created the new one. (replica cnt is 1)
but newly created pod couldn't become the master.
I 2020-09-04T08:26:59.381794101Z [controller/87] [Main.cc@110] controller (64 bit): Version 7.6.2 (Build e06ef9d86d5332) Copyright (c) 2020 Elasticsearch BV
I 2020-09-04T08:27:01.182674765Z Using REST wrapper from plugin org.elasticsearch.xpack.security.Security
I 2020-09-04T08:27:01.687244232Z using discovery type [zen] and seed hosts providers [settings, file]
I 2020-09-04T08:27:04.864704868Z initialized
I 2020-09-04T08:27:04.871639086Z starting ...
I 2020-09-04T08:27:05.295816650Z publish_address {10.52.0.209:9300}, bound_addresses {0.0.0.0:9300}
I 2020-09-04T08:27:06.080438894Z bound or publishing to a non-loopback address, enforcing bootstrap checks
I 2020-09-04T08:27:06.895612719Z [gc][2] overhead, spent [265ms] collecting in the last [1s]
I 2020-09-04T08:27:16.184743529Z master not discovered yet, this node has not previously joined a bootstrapped (v7+) cluster, and [cluster.initial_master_nodes] is empty on this node: have discovered [{quickstart-es-default-0}{PNUG5jcCT4KQXrZ9U3VzBQ}{4_Q7ayTkSGepKFNNH_25QA}{10.52.0.209}{10.52.0.209:9300}{dilm}{ml.machine_memory=2147483648, xpack.installed=true, ml.max_open_jobs=20}]; discovery will continue using [127.0.0.1:9300, 127.0.0.1:9301, 127.0.0.1:9302, 127.0.0.1:9303, 127.0.0.1:9304, 127.0.0.1:9305] from hosts providers and [{quickstart-es-default-0}{PNUG5jcCT4KQXrZ9U3VzBQ}{4_Q7ayTkSGepKFNNH_25QA}{10.52.0.209}{10.52.0.209:9300}{dilm}{ml.machine_memory=2147483648, xpack.installed=true, ml.max_open_jobs=20}] from last-known cluster state; node term 0, last-accepted version 0 in term 0
I 2020-09-04T08:27:26.184256420Z master not discovered yet, this node has not previously joined a bootstrapped (v7+) cluster, and [cluster.initial_master_nodes] is empty on this node: have discovered [{quickstart-es-default-0}{PNUG5jcCT4KQXrZ9U3VzBQ}{4_Q7ayTkSGepKFNNH_25QA}{10.52.0.209}{10.52.0.209:9300}{dilm}{ml.machine_memory=2147483648, xpack.installed=true, ml.max_open_jobs=20}]; discovery will continue using [127.0.0.1:9300, 127.0.0.1:9301, 127.0.0.1:9302, 127.0.0.1:9303, 127.0.0.1:9304, 127.0.0.1:9305] from hosts providers and [{quickstart-es-default-0}{PNUG5jcCT4KQXrZ9U3VzBQ}{4_Q7ayTkSGepKFNNH_25QA}{10.52.0.209}{10.52.0.209:9300}{dilm}{ml.machine_memory=2147483648, xpack.installed=true, ml.max_open_jobs=20}] from last-known cluster state; node term 0, last-accepted version 0 in term 0
I 2020-09-04T08:27:36.188875120Z master not discovered yet, this node has not previously joined a bootstrapped (v7+) cluster, and [cluster.initial_master_nodes] is empty on this node: have discovered [{quickstart-es-default-0}{PNUG5jcCT4KQXrZ9U3VzBQ}{4_Q7ayTkSGepKFNNH_25QA}{10.52.0.209}{10.52.0.209:9300}{dilm}{ml.machine_memory=2147483648, xpack.installed=true, ml.max_open_jobs=20}]; discovery will continue using [127.0.0.1:9300, 127.0.0.1:9301, 127.0.0.1:9302, 127.0.0.1:9303, 127.0.0.1:9304, 127.0.0.1:9305] from hosts providers and [{quickstart-es-default-0}{PNUG5jcCT4KQXrZ9U3VzBQ}{4_Q7ayTkSGepKFNNH_25QA}{10.52.0.209}{10.52.0.209:9300}{dilm}{ml.machine_memory=2147483648, xpack.installed=true, ml.max_open_jobs=20}] from last-known cluster state; node term 0, last-accepted version 0 in term 0
I 2020-09-04T08:27:36.217100276Z timed out while waiting for initial discovery state - timeout: 30s
I 2020-09-04T08:27:36.328004946Z publish_address {10.52.0.209:9200}, bound_addresses {0.0.0.0:9200}
I 2020-09-04T08:27:36.328034230Z started
I 2020-09-04T08:27:43.062612604Z no known master node, scheduling a retry
I 2020-09-04T08:27:43.673099947Z no known master node, scheduling a retry
I 2020-09-04T08:27:45.632385094Z no known master node, scheduling a retry
I 2020-09-04T08:27:46.213327885Z master not discovered yet, this node has not previously joined a bootstrapped (v7+) cluster, and [cluster.initial_master_nodes] is empty on this node: have discovered [{quickstart-es-default-0}{PNUG5jcCT4KQXrZ9U3VzBQ}{4_Q7ayTkSGepKFNNH_25QA}{10.52.0.209}{10.52.0.209:9300}{dilm}{ml.machine_memory=2147483648, xpack.installed=true, ml.max_open_jobs=20}]; discovery will continue using [127.0.0.1:9300, 127.0.0.1:9301, 127.0.0.1:9302, 127.0.0.1:9303, 127.0.0.1:9304, 127.0.0.1:9305] from hosts providers and [{quickstart-es-default-0}{PNUG5jcCT4KQXrZ9U3VzBQ}{4_Q7ayTkSGepKFNNH_25QA}{10.52.0.209}{10.52.0.209:9300}{dilm}{ml.machine_memory=2147483648, xpack.installed=true, ml.max_open_jobs=20}] from last-known cluster state; node term 0, last-accepted version 0 in term 0
I 2020-09-04T08:27:49.498405950Z no known master node, scheduling a retry
I 2020-09-04T08:27:49.502384335Z no known master node, scheduling a retry
I 2020-09-04T08:27:49.555091949Z no known master node, scheduling a retry
I 2020-09-04T08:27:56.302758227Z master not discovered yet, this node has not previously joined a bootstrapped (v7+) cluster, and [cluster.initial_master_nodes] is empty on this node: have discovered [{quickstart-es-default-0}{PNUG5jcCT4KQXrZ9U3VzBQ}{4_Q7ayTkSGepKFNNH_25QA}{10.52.0.209}{10.52.0.209:9300}{dilm}{ml.machine_memory=2147483648, xpack.installed=true, ml.max_open_jobs=20}]; discovery will continue using [127.0.0.1:9300, 127.0.0.1:9301, 127.0.0.1:9302, 127.0.0.1:9303, 127.0.0.1:9304, 127.0.0.1:9305] from hosts providers and [{quickstart-es-default-0}{PNUG5jcCT4KQXrZ9U3VzBQ}{4_Q7ayTkSGepKFNNH_25QA}{10.52.0.209}{10.52.0.209:9300}{dilm}{ml.machine_memory=2147483648, xpack.installed=true, ml.max_open_jobs=20}] from last-known cluster state; node term 0, last-accepted version 0 in term 0