unable to reach ssh remote host using ansible using aws key

Question

I am trying to ping a server using ansible, but I am getting some error messages

[ec2-user@ip-172-30-0-64 kafka-scripts]$ ansible zook1 -m ping -vvv

Using /home/ec2-user/kafka-scripts/ansible.cfg as config file
<172.30.0.113> ESTABLISH SSH CONNECTION FOR USER: None
<172.30.0.113> SSH: EXEC ssh -C -q -o ControlMaster=auto -o ControlPersist=60s -o 'IdentityFile="/home/ec2-user/kafka-scripts/keys/kafka_broker.pem"' -o KbdInteractiveAuthentication=no -o PreferredAuthentications=gssapi-with-mic,gssapi-keyex,hostbased,publickey -o PasswordAuthentication=no -o ConnectTimeout=10 -o ControlPath=/home/ec2-user/.ansible/cp/ansible-ssh-%h-%p-%r -tt 172.30.0.113 '/bin/sh -c '"'"'( umask 22 && mkdir -p "` echo $HOME/.ansible/tmp/ansible-tmp-1461268838.85-234429685988133 `" && echo "` echo $HOME/.ansible/tmp/ansible-tmp-1461268838.85-234429685988133 `" )'"'"''
zook1 | UNREACHABLE! => {
     "changed": false,
     "msg": "SSH encountered an unknown error during the connection. We recommend you re-run the command using -vvvv, which will enable SSH debugging output to help diagnose the issue",
     "unreachable": true
}

with -vvvv

[ec2-user@ip-172-30-0-64 kafka-scripts]$ ansible zookservers -m ping -vvvv
Using /home/ec2-user/kafka-scripts/ansible.cfg as config file
Loaded callback minimal of type stdout, v2.0
<172.30.0.113> ESTABLISH SSH CONNECTION FOR USER: None
<172.30.0.113> SSH: EXEC ssh -C -vvv -o ControlMaster=auto -o ControlPersist=60s -o 'IdentityFile="/home/ec2-user/kafka-scripts/keys/kafka_broker.pem"' -o KbdInteractiveAuthentication=no -o PreferredAuthentications=gssapi-with-mic,gssapi-keyex,hostbased,publickey -o PasswordAuthentication=no -o ConnectTimeout=10 -o ControlPath=/home/ec2-user/.ansible/cp/ansible-ssh-%h-%p-%r -tt 172.30.0.113 '/bin/sh -c '"'"'( umask 22 && mkdir -p "` echo $HOME/.ansible/tmp/ansible-tmp-1461270664.7-212192719472156 `" && echo "` echo $HOME/.ansible/tmp/ansible-tmp-1461270664.7-212192719472156 `" )'"'"''
 zook1 | UNREACHABLE! => {
"changed": false,
"msg": "SSH encountered an unknown error. The output was:\nOpenSSH_6.6.1, OpenSSL 1.0.1e-fips 11 Feb 2013\r\ndebug1: Reading configuration data /etc/ssh/ssh_config\r\ndebug1: /etc/ssh/ssh_config line 56: Applying options for *\r\ndebug1: auto-mux: Trying existing master\r\ndebug1: Control socket \"/home/ec2-user/.ansible/cp/ansible-ssh-172.30.0.113-22-ec2-user\" does not exist\r\ndebug2: ssh_connect: needpriv 0\r\ndebug1: Connecting to 172.30.0.113 [172.30.0.113] port 22.\r\ndebug2: fd 3 setting O_NONBLOCK\r\ndebug1: fd 3 clearing O_NONBLOCK\r\ndebug1: Connection established.\r\ndebug3: timeout: 10000 ms remain after connect\r\ndebug3: Incorrect RSA1 identifier\r\ndebug3: Could not load \"/home/ec2-user/kafka-scripts/keys/kafka_broker.pem\" as a RSA1 public key\r\ndebug1: identity file /home/ec2-user/kafka-scripts/keys/kafka_broker.pem type -1\r\ndebug1: identity file /home/ec2-user/kafka-scripts/keys/kafka_broker.pem-cert type -1\r\ndebug1: Enabling compatibility mode for protocol 2.0\r\ndebug1: Local version string SSH-2.0-OpenSSH_6.6.1\r\ndebug1: Remote protocol version 2.0, remote software version OpenSSH_6.6.1\r\ndebug1: match: OpenSSH_6.6.1 pat OpenSSH_6.6.1* compat 0x04000000\r\ndebug2: fd 3 setting O_NONBLOCK\r\ndebug3: load_hostkeys: loading entries for host \"172.30.0.113\" from file \"/home/ec2-user/.ssh/known_hosts\"\r\ndebug3: load_hostkeys: found key type ECDSA in file /home/ec2-user/.ssh/known_hosts:1\r\ndebug3: load_hostkeys: loaded 1 keys\r\ndebug3: order_hostkeyalgs: prefer hostkeyalgs: ecdsa-sha2-nistp256-cert-v01@openssh.com,ecdsa-sha2-nistp384-cert-v01@openssh.com,ecdsa-sha2-nistp521-cert-v01@openssh.com,ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521\r\ndebug1: SSH2_MSG_KEXINIT sent\r\ndebug1: SSH2_MSG_KEXINIT received\r\ndebug2: kex_parse_kexinit: curve25519-sha256@libssh.org,ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256,diffie-hellman-group-exchange-sha1,diffie-hellman-group14-sha1,diffie-hellman-group1-sha1\r\ndebug2: kex_parse_kexinit: ecdsa-sha2-nistp256-cert-v01@openssh.com,ecdsa-sha2-nistp384-cert-v01@openssh.com,ecdsa-sha2-nistp521-cert-v01@openssh.com,ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,ssh-ed25519-cert-v01@openssh.com,ssh-rsa-cert-v01@openssh.com,ssh-dss-cert-v01@openssh.com,ssh-rsa-cert-v00@openssh.com,ssh-dss-cert-v00@openssh.com,ssh-ed25519,ssh-rsa,ssh-dss\r\ndebug2: kex_parse_kexinit: aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,aes128-gcm@openssh.com,aes256-gcm@openssh.com,chacha20-poly1305@openssh.com,aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,aes256-cbc,arcfour,rijndael-cbc@lysator.liu.se\r\ndebug2: kex_parse_kexinit: aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,aes128-gcm@openssh.com,aes256-gcm@openssh.com,chacha20-poly1305@openssh.com,aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,aes256-cbc,arcfour,rijndael-cbc@lysator.liu.se\r\ndebug2: kex_parse_kexinit: hmac-md5-etm@openssh.com,hmac-sha1-etm@openssh.com,umac-64-etm@openssh.com,umac-128-etm@openssh.com,hmac-sha2-256-etm@openssh.com,hmac-sha2-512-etm@openssh.com,hmac-ripemd160-etm@openssh.com,hmac-sha1-96-etm@openssh.com,hmac-md5-96-etm@openssh.com,hmac-md5,hmac-sha1,umac-64@openssh.com,umac-128@openssh.com,hmac-sha2-256,hmac-sha2-512,hmac-ripemd160,hmac-ripemd160@openssh.com,hmac-sha1-96,hmac-md5-96\r\ndebug2: kex_parse_kexinit: hmac-md5-etm@openssh.com,hmac-sha1-etm@openssh.com,umac-64-etm@openssh.com,umac-128-etm@openssh.com,hmac-sha2-256-etm@openssh.com,hmac-sha2-512-etm@openssh.com,hmac-ripemd160-etm@openssh.com,hmac-sha1-96-etm@openssh.com,hmac-md5-96-etm@openssh.com,hmac-md5,hmac-sha1,umac-64@openssh.com,umac-128@openssh.com,hmac-sha2-256,hmac-sha2-512,hmac-ripemd160,hmac-ripemd160@openssh.com,hmac-sha1-96,hmac-md5-96\r\ndebug2: kex_parse_kexinit: zlib@openssh.com,zlib,none\r\ndebug2: kex_parse_kexinit: zlib@openssh.com,zlib,none\r\ndebug2: kex_parse_kexinit: \r\ndebug2: kex_parse_kexinit: \r\ndebug2: kex_parse_kexinit: first_kex_follows 0 \r\ndebug2: kex_parse_kexinit: reserved 0 \r\ndebug2: kex_parse_kexinit: curve25519-sha256@libssh.org,ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256,diffie-hellman-group-exchange-sha1,diffie-hellman-group14-sha1,diffie-hellman-group1-sha1\r\ndebug2: kex_parse_kexinit: ssh-rsa,ecdsa-sha2-nistp256,ssh-ed25519\r\ndebug2: kex_parse_kexinit: aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,aes128-gcm@openssh.com,aes256-gcm@openssh.com,chacha20-poly1305@openssh.com,aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,aes256-cbc,arcfour,rijndael-cbc@lysator.liu.se\r\ndebug2: kex_parse_kexinit: aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,aes128-gcm@openssh.com,aes256-gcm@openssh.com,chacha20-poly1305@openssh.com,aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,aes256-cbc,arcfour,rijndael-cbc@lysator.liu.se\r\ndebug2: kex_parse_kexinit: hmac-md5-etm@openssh.com,hmac-sha1-etm@openssh.com,umac-64-etm@openssh.com,umac-128-etm@openssh.com,hmac-sha2-256-etm@openssh.com,hmac-sha2-512-etm@openssh.com,hmac-ripemd160-etm@openssh.com,hmac-sha1-96-etm@openssh.com,hmac-md5-96-etm@openssh.com,hmac-md5,hmac-sha1,umac-64@openssh.com,umac-128@openssh.com,hmac-sha2-256,hmac-sha2-512,hmac-ripemd160,hmac-ripemd160@openssh.com,hmac-sha1-96,hmac-md5-96\r\ndebug2: kex_parse_kexinit: hmac-md5-etm@openssh.com,hmac-sha1-etm@openssh.com,umac-64-etm@openssh.com,umac-128-etm@openssh.com,hmac-sha2-256-etm@openssh.com,hmac-sha2-512-etm@openssh.com,hmac-ripemd160-etm@openssh.com,hmac-sha1-96-etm@openssh.com,hmac-md5-96-etm@openssh.com,hmac-md5,hmac-sha1,umac-64@openssh.com,umac-128@openssh.com,hmac-sha2-256,hmac-sha2-512,hmac-ripemd160,hmac-ripemd160@openssh.com,hmac-sha1-96,hmac-md5-96\r\ndebug2: kex_parse_kexinit: none,zlib@openssh.com\r\ndebug2: kex_parse_kexinit: none,zlib@openssh.com\r\ndebug2: kex_parse_kexinit: \r\ndebug2: kex_parse_kexinit: \r\ndebug2: kex_parse_kexinit: first_kex_follows 0 \r\ndebug2: kex_parse_kexinit: reserved 0 \r\ndebug2: mac_setup: setup hmac-md5-etm@openssh.com\r\ndebug1: kex: server->client aes128-ctr hmac-md5-etm@openssh.com zlib@openssh.com\r\ndebug2: mac_setup: setup hmac-md5-etm@openssh.com\r\ndebug1: kex: client->server aes128-ctr hmac-md5-etm@openssh.com zlib@openssh.com\r\ndebug1: kex: curve25519-sha256@libssh.org need=16 dh_need=16\r\ndebug1: kex: curve25519-sha256@libssh.org need=16 dh_need=16\r\ndebug1: sending SSH2_MSG_KEX_ECDH_INIT\r\ndebug1: expecting SSH2_MSG_KEX_ECDH_REPLY\r\ndebug1: Server host key: ECDSA 55:88:b1:5a:cd:bb:87:ff:dd:54:b0:36:39:c7:e2:ea\r\ndebug3: load_hostkeys: loading entries for host \"172.30.0.113\" from file \"/home/ec2-user/.ssh/known_hosts\"\r\ndebug3: load_hostkeys: found key type ECDSA in file /home/ec2-user/.ssh/known_hosts:1\r\ndebug3: load_hostkeys: loaded 1 keys\r\ndebug1: Host '172.30.0.113' is known and matches the ECDSA host key.\r\ndebug1: Found key in /home/ec2-user/.ssh/known_hosts:1\r\ndebug1: ssh_ecdsa_verify: signature correct\r\ndebug2: kex_derive_keys\r\ndebug2: set_newkeys: mode 1\r\ndebug1: SSH2_MSG_NEWKEYS sent\r\ndebug1: expecting SSH2_MSG_NEWKEYS\r\ndebug2: set_newkeys: mode 0\r\ndebug1: SSH2_MSG_NEWKEYS received\r\ndebug1: SSH2_MSG_SERVICE_REQUEST sent\r\ndebug2: service_accept: ssh-userauth\r\ndebug1: SSH2_MSG_SERVICE_ACCEPT received\r\ndebug2: key: /home/ec2-user/kafka-scripts/keys/kafka_broker.pem ((nil)), explicit\r\ndebug1: Authentications that can continue: publickey,gssapi-keyex,gssapi-with-mic\r\ndebug3: start over, passed a different list publickey,gssapi-keyex,gssapi-with-mic\r\ndebug3: preferred gssapi-with-mic,gssapi-keyex,hostbased,publickey\r\ndebug3: authmethod_lookup gssapi-with-mic\r\ndebug3: remaining preferred: gssapi-keyex,hostbased,publickey\r\ndebug3: authmethod_is_enabled gssapi-with-mic\r\ndebug1: Next authentication method: gssapi-with-mic\r\ndebug1: Unspecified GSS failure.  Minor code may provide more information\nNo Kerberos credentials available\n\r\ndebug1: Unspecified GSS failure.  Minor code may provide more information\nNo Kerberos credentials available\n\r\ndebug1: Unspecified GSS failure.  Minor code may provide more information\n\n\r\ndebug1: Unspecified GSS failure.  Minor code may provide more information\nNo Kerberos credentials available\n\r\ndebug2: we did not send a packet, disable method\r\ndebug3: authmethod_lookup gssapi-keyex\r\ndebug3: remaining preferred: hostbased,publickey\r\ndebug3: authmethod_is_enabled gssapi-keyex\r\ndebug1: Next authentication method: gssapi-keyex\r\ndebug1: No valid Key exchange context\r\ndebug2: we did not send a packet, disable method\r\ndebug3: authmethod_lookup publickey\r\ndebug3: remaining preferred: ,publickey\r\ndebug3: authmethod_is_enabled publickey\r\ndebug1: Next authentication method: publickey\r\ndebug1: Trying private key: /home/ec2-user/kafka-scripts/keys/kafka_broker.pem\r\n@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@\r\n@         WARNING: UNPROTECTED PRIVATE KEY FILE!          @\r\n@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@\r\nPermissions 0777 for '/home/ec2-user/kafka-scripts/keys/kafka_broker.pem' are too open.\r\nIt is required that your private key files are NOT accessible by others.\r\nThis private key will be ignored.\r\nbad permissions: ignore key: /home/ec2-user/kafka-scripts/keys/kafka_broker.pem\r\ndebug2: we did not send a packet, disable method\r\ndebug1: No more authentication methods to try.\r\nPermission denied (publickey,gssapi-keyex,gssapi-with-mic).\r\n",
"unreachable": true
 }

SSH debugging output:

SSH encountered an unknown error. The output was:\nOpenSSH_6.6.1, OpenSSL 1.0.1e-fips 11 Feb 2013
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: /etc/ssh/ssh_config line 56: Applying options for *
debug1: auto-mux: Trying existing master
debug1: Control socket "/home/ec2-user/.ansible/cp/ansible-ssh-172.30.0.113-22-ec2-user" does not exist
debug2: ssh_connect: needpriv 0
debug1: Connecting to 172.30.0.113 [172.30.0.113] port 22.
debug2: fd 3 setting O_NONBLOCK
debug1: fd 3 clearing O_NONBLOCK
debug1: Connection established.
debug3: timeout: 10000 ms remain after connect
debug3: Incorrect RSA1 identifier
debug3: Could not load "/home/ec2-user/kafka-scripts/keys/kafka_broker.pem" as a RSA1 public key
debug1: identity file /home/ec2-user/kafka-scripts/keys/kafka_broker.pem type -1
debug1: identity file /home/ec2-user/kafka-scripts/keys/kafka_broker.pem-cert type -1
debug1: Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-2.0-OpenSSH_6.6.1
debug1: Remote protocol version 2.0, remote software version OpenSSH_6.6.1
debug1: match: OpenSSH_6.6.1 pat OpenSSH_6.6.1* compat 0x04000000
debug2: fd 3 setting O_NONBLOCK
debug3: load_hostkeys: loading entries for host "172.30.0.113" from file "/home/ec2-user/.ssh/known_hosts"
debug3: load_hostkeys: found key type ECDSA in file /home/ec2-user/.ssh/known_hosts:1
debug3: load_hostkeys: loaded 1 keys
debug3: order_hostkeyalgs: prefer hostkeyalgs: ecdsa-sha2-nistp256-cert-v01@openssh.com,ecdsa-sha2-nistp384-cert-v01@openssh.com,ecdsa-sha2-nistp521-cert-v01@openssh.com,ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521
debug1: SSH2_MSG_KEXINIT sent
debug1: SSH2_MSG_KEXINIT received
debug2: kex_parse_kexinit: curve25519-sha256@libssh.org,ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256,diffie-hellman-group-exchange-sha1,diffie-hellman-group14-sha1,diffie-hellman-group1-sha1
debug2: kex_parse_kexinit: ecdsa-sha2-nistp256-cert-v01@openssh.com,ecdsa-sha2-nistp384-cert-v01@openssh.com,ecdsa-sha2-nistp521-cert-v01@openssh.com,ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,ssh-ed25519-cert-v01@openssh.com,ssh-rsa-cert-v01@openssh.com,ssh-dss-cert-v01@openssh.com,ssh-rsa-cert-v00@openssh.com,ssh-dss-cert-v00@openssh.com,ssh-ed25519,ssh-rsa,ssh-dss
debug2: kex_parse_kexinit: aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,aes128-gcm@openssh.com,aes256-gcm@openssh.com,chacha20-poly1305@openssh.com,aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,aes256-cbc,arcfour,rijndael-cbc@lysator.liu.se
debug2: kex_parse_kexinit: aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,aes128-gcm@openssh.com,aes256-gcm@openssh.com,chacha20-poly1305@openssh.com,aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,aes256-cbc,arcfour,rijndael-cbc@lysator.liu.se
debug2: kex_parse_kexinit: hmac-md5-etm@openssh.com,hmac-sha1-etm@openssh.com,umac-64-etm@openssh.com,umac-128-etm@openssh.com,hmac-sha2-256-etm@openssh.com,hmac-sha2-512-etm@openssh.com,hmac-ripemd160-etm@openssh.com,hmac-sha1-96-etm@openssh.com,hmac-md5-96-etm@openssh.com,hmac-md5,hmac-sha1,umac-64@openssh.com,umac-128@openssh.com,hmac-sha2-256,hmac-sha2-512,hmac-ripemd160,hmac-ripemd160@openssh.com,hmac-sha1-96,hmac-md5-96
debug2: kex_parse_kexinit: hmac-md5-etm@openssh.com,hmac-sha1-etm@openssh.com,umac-64-etm@openssh.com,umac-128-etm@openssh.com,hmac-sha2-256-etm@openssh.com,hmac-sha2-512-etm@openssh.com,hmac-ripemd160-etm@openssh.com,hmac-sha1-96-etm@openssh.com,hmac-md5-96-etm@openssh.com,hmac-md5,hmac-sha1,umac-64@openssh.com,umac-128@openssh.com,hmac-sha2-256,hmac-sha2-512,hmac-ripemd160,hmac-ripemd160@openssh.com,hmac-sha1-96,hmac-md5-96
debug2: kex_parse_kexinit: zlib@openssh.com,zlib,none
debug2: kex_parse_kexinit: zlib@openssh.com,zlib,none
debug2: kex_parse_kexinit: 
debug2: kex_parse_kexinit: 
debug2: kex_parse_kexinit: first_kex_follows 0 
debug2: kex_parse_kexinit: reserved 0 
debug2: kex_parse_kexinit: curve25519-sha256@libssh.org,ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256,diffie-hellman-group-exchange-sha1,diffie-hellman-group14-sha1,diffie-hellman-group1-sha1
debug2: kex_parse_kexinit: ssh-rsa,ecdsa-sha2-nistp256,ssh-ed25519
debug2: kex_parse_kexinit: aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,aes128-gcm@openssh.com,aes256-gcm@openssh.com,chacha20-poly1305@openssh.com,aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,aes256-cbc,arcfour,rijndael-cbc@lysator.liu.se
debug2: kex_parse_kexinit: aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,aes128-gcm@openssh.com,aes256-gcm@openssh.com,chacha20-poly1305@openssh.com,aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,aes256-cbc,arcfour,rijndael-cbc@lysator.liu.se
debug2: kex_parse_kexinit: hmac-md5-etm@openssh.com,hmac-sha1-etm@openssh.com,umac-64-etm@openssh.com,umac-128-etm@openssh.com,hmac-sha2-256-etm@openssh.com,hmac-sha2-512-etm@openssh.com,hmac-ripemd160-etm@openssh.com,hmac-sha1-96-etm@openssh.com,hmac-md5-96-etm@openssh.com,hmac-md5,hmac-sha1,umac-64@openssh.com,umac-128@openssh.com,hmac-sha2-256,hmac-sha2-512,hmac-ripemd160,hmac-ripemd160@openssh.com,hmac-sha1-96,hmac-md5-96
debug2: kex_parse_kexinit: hmac-md5-etm@openssh.com,hmac-sha1-etm@openssh.com,umac-64-etm@openssh.com,umac-128-etm@openssh.com,hmac-sha2-256-etm@openssh.com,hmac-sha2-512-etm@openssh.com,hmac-ripemd160-etm@openssh.com,hmac-sha1-96-etm@openssh.com,hmac-md5-96-etm@openssh.com,hmac-md5,hmac-sha1,umac-64@openssh.com,umac-128@openssh.com,hmac-sha2-256,hmac-sha2-512,hmac-ripemd160,hmac-ripemd160@openssh.com,hmac-sha1-96,hmac-md5-96
debug2: kex_parse_kexinit: none,zlib@openssh.com
debug2: kex_parse_kexinit: none,zlib@openssh.com
debug2: kex_parse_kexinit: 
debug2: kex_parse_kexinit: 
debug2: kex_parse_kexinit: first_kex_follows 0 
debug2: kex_parse_kexinit: reserved 0 
debug2: mac_setup: setup hmac-md5-etm@openssh.com
debug1: kex: server->client aes128-ctr hmac-md5-etm@openssh.com zlib@openssh.com
debug2: mac_setup: setup hmac-md5-etm@openssh.com
debug1: kex: client->server aes128-ctr hmac-md5-etm@openssh.com zlib@openssh.com
debug1: kex: curve25519-sha256@libssh.org need=16 dh_need=16
debug1: kex: curve25519-sha256@libssh.org need=16 dh_need=16
debug1: sending SSH2_MSG_KEX_ECDH_INIT
debug1: expecting SSH2_MSG_KEX_ECDH_REPLY
debug1: Server host key: ECDSA 55:88:b1:5a:cd:bb:87:ff:dd:54:b0:36:39:c7:e2:ea
debug3: load_hostkeys: loading entries for host "172.30.0.113" from file "/home/ec2-user/.ssh/known_hosts"
debug3: load_hostkeys: found key type ECDSA in file /home/ec2-user/.ssh/known_hosts:1
debug3: load_hostkeys: loaded 1 keys
debug1: Host '172.30.0.113' is known and matches the ECDSA host key.
debug1: Found key in /home/ec2-user/.ssh/known_hosts:1
debug1: ssh_ecdsa_verify: signature correct
debug2: kex_derive_keys
debug2: set_newkeys: mode 1
debug1: SSH2_MSG_NEWKEYS sent
debug1: expecting SSH2_MSG_NEWKEYS
debug2: set_newkeys: mode 0
debug1: SSH2_MSG_NEWKEYS received
debug1: SSH2_MSG_SERVICE_REQUEST sent
debug2: service_accept: ssh-userauth
debug1: SSH2_MSG_SERVICE_ACCEPT received
debug2: key: /home/ec2-user/kafka-scripts/keys/kafka_broker.pem ((nil)), explicit
debug1: Authentications that can continue: publickey,gssapi-keyex,gssapi-with-mic
debug3: start over, passed a different list publickey,gssapi-keyex,gssapi-with-mic
debug3: preferred gssapi-with-mic,gssapi-keyex,hostbased,publickey
debug3: authmethod_lookup gssapi-with-mic
debug3: remaining preferred: gssapi-keyex,hostbased,publickey
debug3: authmethod_is_enabled gssapi-with-mic
debug1: Next authentication method: gssapi-with-mic
debug1: Unspecified GSS failure.  Minor code may provide more information\nNo Kerberos credentials available\n
debug1: Unspecified GSS failure.  Minor code may provide more information\nNo Kerberos credentials available\n
debug1: Unspecified GSS failure.  Minor code may provide more information\n\n
debug1: Unspecified GSS failure.  Minor code may provide more information\nNo Kerberos credentials available\n
debug2: we did not send a packet, disable method
debug3: authmethod_lookup gssapi-keyex
debug3: remaining preferred: hostbased,publickey
debug3: authmethod_is_enabled gssapi-keyex
debug1: Next authentication method: gssapi-keyex
debug1: No valid Key exchange context
debug2: we did not send a packet, disable method
debug3: authmethod_lookup publickey
debug3: remaining preferred: ,publickey
debug3: authmethod_is_enabled publickey
debug1: Next authentication method: publickey
debug1: Trying private key: /home/ec2-user/kafka-scripts/keys/kafka_broker.pem
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
@         WARNING: UNPROTECTED PRIVATE KEY FILE!          @
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
Permissions 0777 for '/home/ec2-user/kafka-scripts/keys/kafka_broker.pem' are too open.
It is required that your private key files are NOT accessible by others.
This private key will be ignored.
bad permissions: ignore key: /home/ec2-user/kafka-scripts/keys/kafka_broker.pem
debug2: we did not send a packet, disable method
debug1: No more authentication methods to try.
Permission denied (publickey,gssapi-keyex,gssapi-with-mic).

Answer 1

As written in the error message, your key file is not protected as it should.

@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
@         WARNING: UNPROTECTED PRIVATE KEY FILE!          @
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
Permissions 0777 for '/home/ec2-user/kafka-scripts/keys/kafka_broker.pem' are too open.
It is required that your private key files are NOT accessible by others.

Running the following command should fix your problem, by removing authorization to others to read the key file.

chmod 600 /home/ec2-user/kafka-scripts/keys/kafka_broker.pem